A few weeks ago we held a Facebook Live “Ask the Stem Cell Team About Parkinson’s Disease” event. As you can imagine we got lots of questions but, because of time constraints, only had time to answer a few. Thanks to my fabulous CIRM colleagues, Dr. Lila Collins and Dr. Kent Fitzgerald, for putting together answers to some of the other questions. Here they are.
Q:It seems like we have been hearing for years that stem cells can help people with Parkinson’s, why is it taking so long?
A: Early experiments in Sweden using fetal tissue did provide a proof of concept for the strategy of replacing dopamine producing cells damaged or lost in Parkinson’s disease (PD) . At first, this seemed like we were on the cusp of a cell therapy cure for PD, however, we soon learned based on some side effects seen with this approach (in particular dyskinesias or uncontrollable muscle movements) that the solution was not as simple as once thought.
While this didn’t produce the answer it did provide some valuable lessons.
The importance of dopaminergic (DA) producing cell type and the location in the brain of the transplant. Simply placing the replacement cells in the brain is not enough. It was initially thought that the best site to place these DA cells is a region in the brain called the SN, because this area helps to regulate movement. However, this area also plays a role in learning, emotion and the brains reward system. This is effectively a complex wiring system that exists in a balance, “rewiring” it wrong can have unintended and significant side effects.
Another factor impacting progress has been understanding the importance of disease stage. If the disease is too advanced when cells are given then the transplant may no longer be able to provide benefit. This is because DA transplants replace the lost neurons we use to control movement, but other connected brain systems have atrophied in response to losing input from the lost neurons. There is a massive amount of work (involving large groups and including foundations like the Michael J Fox Foundation) seeking to identify PD early in the disease course where therapies have the best chance of showing an effect. Clinical trials will ultimately help to determine the best timing for treatment intervention.
Ideally, in addition to the cell therapies that would replace lost or damaged cells we also want to find a therapy that slows or stops the underlying biology causing progression of the disease.
So, I think we’re going to see more gene therapy trials including those targeting the small minority of PD that is driven by known mutations. In fact, Prevail Therapeutics will soon start a trial in patients with GBA1 mutations. Hopefully, replacing the enzyme in this type of genetic PD will prevent degeneration.
And, we are also seeing gene therapy approaches to address forms of PD that we don’t know the cause, including a trial to rescue sick neurons with GDNF which is a neurotrophic factor (which helps support the growth and survival of these brain cells) led by Dr Bankiewicz and trials by Axovant and Voyager, partnered with Neurocrine aimed at restoring dopamine generation in the brain.
A small news report came out earlier this year about a recently completed clinical trial by Roche Pharma and Prothena. This addressed the build up in the brain of what are called lewy bodies, a problem common to many forms of PD. While the official trial results aren’t published yet, a recent press release suggests reason for optimism. Apparently, the treatment failed to statistically improve the main clinical measurement, but other measured endpoints saw improvement and it’s possible an updated form of this treatment will be tested again in the hopes of seeing an improved effect.
Finally, I’d like to call attention to the G force trials. Gforce is a global collaborative effort to drive the field forward combining lessons learned from previous studies with best practices for cell replacement in PD. These first-in-human safety trials to replace the dopaminergic neurons (DANs) damaged by PD have shared design features including identifying what the best goals are and how to measure those.
And the Summit PD trial, Dr Jeanne Loring of Aspen Neuroscience.
Taken together these should tell us quite a lot about the best way to replace these critical neurons in PD.
As with any completely novel approach in medicine, much validation and safety work must be completed before becoming available to patients
The current approach (for cell replacement) has evolved significantly from those early studies to use cells engineered in the lab to be much more specialized and representing the types believed to have the best therapeutic effects with low probability of the side effects (dyskinesias) seen in earlier trials.
If we don’t really know the cause of Parkinson’s disease, how can we cure it or develop treatments to slow it down?
PD can now be divided into major categories including 1. Sporadic, 2. Familial.
For the sporadic cases, there are some hallmarks in the biology of the neurons affected in the disease that are common among patients. These can be things like oxidative stress (which damages cells), or clumps of proteins (like a-synuclein) that serve to block normal cell function and become toxic, killing the DA neurons.
The second class of “familial” cases all share one or more genetic changes that are believed to cause the disease. Mutations in genes (like GBA, LRRK2, PRKN, SNCA) make up around fifteen percent of the population affected, but the similarity in these gene mutations make them attractive targets for drug development.
CIRM has funded projects to generate “disease in a dish” models using neurons made from adults with Parkinson’s disease. Stem cell-derived models like this have enabled not only a deep probing of the underlying biology in Parkinson’s, which has helped to identify new targets for investigation, but have also allowed for the testing of possible therapies in these cell-based systems.
iPSC-derived neurons are believed to be an excellent model for this type of work as they can possess known familial mutations but also show the rest of the patients genetic background which may also be a contributing factor to the development of PD. They therefore contain both known and unknown factors that can be tested for effective therapy development.
I have heard of scientists creating things called brain organoids, clumps of brain cells that can act a little bit like a brain. Can we use these to figure out what’s happening in the brain of people with Parkinson’s and to develop treatments?
There is considerable excitement about the use of brain organoids as a way of creating a model for the complex cell-to-cell interactions in the brain. Using these 3D organoid models may allow us to gain a better understanding of what happens inside the brain, and develop ways to treat issues like PD.
The organoids can contain multiple cell types including microglia which have been a hot topic of research in PD as they are responsible for cleaning up and maintaining the health of cells in the brain. CIRM has funded the Salk Institute’s Dr. Fred Gage’s to do work in this area.
If you go online you can find lots of stem cells clinics, all over the US, that claim they can use stem cells to help people with Parkinson’s. Should I go to them?
In a word, no! These clinics offer a wide variety of therapies using different kinds of cells or tissues (including the patient’s own blood or fat cells) but they have one thing in common; none of these therapies have been tested in a clinical trial to show they are even safe, let alone effective. These clinics also charge thousands, sometimes tens of thousands of dollars these therapies, and because it’s not covered by insurance this all comes out of the patient’s pocket.
These predatory clinics are peddling hope, but are unable to back it up with any proof it will work. They frequently have slick, well-designed websites, and “testimonials” from satisfied customers. But if they really had a treatment for Parkinson’s they wouldn’t be running clinics out of shopping malls they’d be operating huge medical centers because the worldwide need for an effective therapy is so great.
Here’s a link to the page on our website that can help you decide if a clinical trial or “therapy” is right for you.
Is it better to use your own cells turned into brain cells, or cells from a healthy donor?
This is the BIG question that nobody has evidence to provide an answer to. At least not yet.
Let’s start with the basics. Why would you want to use your own cells? The main answer is the immune system. Transplanted cells can really be viewed as similar to an organ (kidney, liver etc) transplant. As you likely know, when a patient receives an organ transplant the patient’s immune system will often recognize the tissue/organ as foreign and attack it. This can result in the body rejecting what is supposed to be a life-saving organ. This is why people receiving organ transplants are typically placed on immunosuppressive “anti-rejection “drugs to help stop this reaction.
In the case of transplanted dopamine producing neurons from a donor other than the patient, it’s likely that the immune system would eliminate these cells after a short while and this would stop any therapeutic benefit from the cells. A caveat to this is that the brain is a “somewhat” immune privileged organ which means that normal immune surveillance and rejection doesn’t always work the same way with the brain. In fact analysis of the brains collected from the first Swedish patients to receive fetal transplants showed (among other things) that several patients still had viable transplanted cells (persistence) in their brains.
Transplanting DA neurons made from the patient themselves (the iPSC method) would effectively remove this risk of the immune system attack as the cells would not be recognized as foreign.
CIRM previously funded a discovery project with Jeanne Loring from Scripps Research Institute that sought to generate DA neurons from Parkinson’s patients for use as a potential transplant therapy in these same patients. This project has since been taken on by a company formed, by Dr Loring, called Aspen Neuroscience. They hope to bring this potential therapy into clinical trials in the near future.
A commonly cited potential downside to this approach is that patients with genetic (familial) Parkinson’s would be receiving neurons generated with cells that may have the same mutations that caused the problem in the first place. However, as it can typically take decades to develop PD, these cells could likely function for a long time. and prove to be better than any current therapies.
Creating cells from each individual patient (called autologous) is likely to be very expensive and possibly even cost-prohibitive. That is why many researchers are working on developing an “off the shelf” therapy, one that uses cells from a donor (called allogeneic)would be available as and when it’s needed.
When the coronavirus happened, it seemed as if overnight the FDA was approving clinical trials for treatments for the virus. Why can’t it work that fast for Parkinson’s disease?
While we don’t know what will ultimately work for COVID-19, we know what the enemy looks like. We also have lots of experience treating viral infections and creating vaccines. The coronavirus has already been sequenced, so we are building upon our understanding of other viruses to select a course to interrupt it. In contrast, the field is still trying to understand the drivers of PD that would respond to therapeutic targeting and therefore, it’s not precisely clear how best to modify the course of neurodegenerative disease. So, in one sense, while it’s not as fast as we’d like it to be, the work on COVID-19 has a bit of a head start.
Much of the early work on COVID-19 therapies is also centered on re-purposing therapies that were previously in development. As a result, these potential treatments have a much easier time entering clinical trials as there is a lot known about them (such as how safe they are etc.). That said, there are many additional therapeutic strategies (some of which CIRM is funding) which are still far off from being tested in the clinic.
The concern of the Food and Drug Administration (FDA) is often centered on the safety of a proposed therapy. The less known, the more cautious they tend to be.
As you can imagine, transplanting cells into the brain of a PD patient creates a significant potential for problems and so the FDA needs to be cautious when approving clinical trials to ensure patient safety.
On December 12th we hosted our latest ‘Facebook Live: Ask the Stem Cell Team’ event. This time around we really did mean team. We had a host of our Science Officers answering questions from friends and supporters of CIRM. We got a lot of questions and didn’t have enough time to address them all. So here’s answers to all the questions.
What are the obstacles to using partial cellular reprogramming to return people’s entire bodies to a youthful state.Paul Hartman. San Leandro, California
Dr. Kelly Shepard: Certainly, scientists have observed that various manipulations of cells, including reprogramming, partial reprogramming, de-differentiation and trans-differentiation, can restore or change properties of cells, and in some cases, these changes can reflect a more “youthful” state, such as having longer telomeres, better proliferative capacity, etc. However, some of these same rejuvenating properties, outside of their normal context, could be harmful or deadly, for example if a cell began to grow and divide when or where it shouldn’t, similar to cancer. For this reason, I believe the biggest obstacles to making this approach a reality are twofold: 1) our current, limited understanding of the nature of partially reprogrammed cells; and 2) our inability to control the fate of those cells that have been partially reprogrammed, especially if they are inside a living organism. Despite the challenges, I think there will be step wise advances where these types of approaches will be applied, starting with specific tissues. For example, CIRM has recently funded an approach that uses reprogramming to make “rejuvenated” versions of T cells for fighting lung cancer. There is also a lot of interest in using such approaches to restore the reparative capacity of aged muscle. Perhaps some successes in these more limited areas will be the basis for expanding to a broader use.
What’s going on with Stanford’s stem cell trials for stroke? I remember the first trial went really well In 2016 have not heard anything about since? Elvis Arnold
Dr. Lila Collins: Hi Elvis, this is an evolving story. I believe you are referring to SanBio’s phase 1/2a stroke trial, for which Stanford was a site. This trial looked at the safety and feasibility of SanBio’s donor or allogeneic stem cell product in chronic stroke patients who still had motor deficits from their strokes, even after completing physical therapy when natural recovery has stabilized. As you note, some of the treated subjects had promising motor recoveries.
SanBio has since completed a larger, randomized phase 2b trial in stroke, and they have released the high-level results in a press release. While the trial did not meet its primary endpoint of improving motor deficits in chronic stroke, SanBio conducted a very similar randomized trial in patients with stable motor deficits from chronic traumatic brain injury (TBI). In this trial, SanBio saw positive results on motor recovery with their product. In fact, this product is planned to move towards a conditional approval in Japan and has achieved expedited regulatory status in the US, termed RMAT, in TBI which means it could be available more quickly to patients if all goes well. SanBio plans to continue to investigate their product in stroke, so I would stay tuned as the work unfolds.
Also, since you mentioned Stanford, I should note that Dr Gary Steinberg, who was a clinical investigator in the SanBio trial you mentioned, will soon be conducting a trial with a different product that he is developing, neural progenitor cells, in chronic stroke. The therapy looks promising in preclinical models and we are hopeful it will perform well for patients in the clinic.
I am a stroke survivor will stem cell treatment able to restore my motor skills?Ruperto
Dr. Lila Collins:
Hi Ruperto. Restoring motor loss after stroke is a very active area of research. I’ll touch upon a few ongoing stem cell trials. I’d just like to please advise that you watch my colleague’s comments on stem cell clinics (these can be found towards the end of the blog) to be sure that any clinical research in which you participate is as safe as possible and regulated by FDA.
Back to stroke, I mentioned SanBio’s ongoing work to address motor skill loss in chronic stroke earlier. UK based Reneuron is also conducting a phase 2 trial, using a neural progenitor cell as a candidate therapy to help recover persistent motor disability after stroke (chronic). Dr Gary Steinberg at Stanford is also planning to conduct a clinical trial of a human embryonic stem cell-derived neuronal progenitor cell in stroke.
There is also promising work being sponsored by Athersys in acute stroke. Athersys published results from their randomized, double blinded placebo controlled Ph2 trial of their Multistem product in patients who had suffered a stroke within 24-48 hours. After intravenous delivery, the cells improved a composite measure of stroke recovery, including motor recovery. Rather than acting directly on the brain, Multistem seems to work by traveling to the spleen and reducing the inflammatory response to a stroke that can make the injury worse.
Athersys is currently recruiting a phase 3 trial of its Multistem product in acute stroke (within 1.5 days of the stroke). The trial has an accelerated FDA designation, called RMAT and a special protocol assessment. This means that if the trial is conducted as planned and it reaches the results agreed to with the FDA, the therapy could be cleared for marketing. Results from this trial should be available in about two years.
Questions from several hemorrhagic stroke survivors who say most clinical trials are for people with ischemic strokes. Could stem cells help hemorrhagic stroke patients as well?
Dr. Lila Collins:
Regarding hemorrhagic stroke, you are correct the bulk of cell therapies for stroke target ischemic stroke, perhaps because this accounts for the vast bulk of strokes, about 85%.
That said, hemorrhagic strokes are not rare and tend to be more deadly. These strokes are caused by bleeding into or around the brain which damages neurons. They can even increase pressure in the skull causing further damage. Because of this the immediate steps treating these strokes are aimed at addressing the initial bleeding insult and the blood in the brain.
While most therapies in development target ischemic stroke, successful therapies developed to repair neuronal damage or even some day replace lost neurons, could be beneficial after hemorrhagic stroke as well.
I had an Ischemic stroke in 2014, and my vision was also affected. Can stem cells possibly help with my vision issues. James Russell
Dr. Lila Collins:
Hi James. Vision loss from stroke is complex and the type of loss depends upon where the stroke occurred (in the actual eye, the optic nerve or to the other parts of the brain controlling they eye or interpreting vision). The results could be:
Visual loss from damage to the retina
You could have a normal eye with damage to the area of the brain that controls the eye’s movement
You could have damage to the part of the brain that interprets vision.
You can see that to address these various issues, we’d need different cell replacement approaches to repair the retina or the parts of the brain that were damaged.
Replacing lost neurons is an active effort that at the moment is still in the research stages. As you can imagine, this is complex because the neurons have to make just the right connections to be useful.
Is there any stem cell therapy for optical nerve damage? Deanna Rice
Dr. Ingrid Caras: There is currently no proven stem cell therapy to treat optical nerve damage, even though there are shady stem cell clinics offering treatments. However, there are some encouraging early gene therapy studies in mice using a virus called AAV to deliver growth factors that trigger regeneration of the damaged nerve. These studies suggest that it may be possible to restore at least some visual function in people blinded by optic nerve damage from glaucoma
I read an article about ReNeuron’s retinitis pigmentosa clinical trial update. In the article, it states: “The company’s treatment is a subretinal injection of human retinal progenitors — cells which have almost fully developed into photoreceptors, the light-sensing retinal cells that make vision possible.” My question is: If they can inject hRPC, why not fully developed photoreceptors?Leonard
Dr. Kelly Shepard: There is evidence from other studies, including from other tissue types such as blood, pancreas, heart and liver, that fully developed (mature) cell types tend not to engraft as well upon transplantation, that is the cells do not establish themselves and survive long term in their new environment. In contrast, it has been observed that cells in a slightly less “mature” state, such as those in the progenitor stage, are much more likely to establish themselves in a tissue, and then differentiate into more mature cell types over time. This question gets at the crux of a key issue for many new therapies, i.e. what is the best cell type to use, and the best timing to use it.
My question for the “Ask the Stem Cell Team” event is: When will jCyte publish their Phase IIb clinical trial results. Chris Allen
Dr. Ingrid Caras: The results will be available sometime in 2020.
I understand the hRPC cells are primarily neurotropic (rescue/halt cell death); however, the literature also says hRPC can become new photoreceptors. My questions are:Approximately what percentage develop into functioning photoreceptors? And what percentage of the injected hRPC are currently surviving?Leonard Furber, an RP Patient
Dr. Kelly Shepard: While we can address these questions in the lab and in animal models, until there is a clinical trial, it is not possible to truly recreate the environment and stresses that the cells will undergo once they are transplanted into a human, into the site where they are expected to survive and function. Thus, the true answer to this question may not be known until after clinical trials are performed and the results can be evaluated. Even then, it is not always possible to monitor the fate of cells after transplantation without removing tissues to analyze (which may not be feasible), or without being able to transplant labeled cells that can be readily traced.
Dr. Ingrid Caras – Although the cells have been shown to be capable of developing into photoreceptors, we don’t know if this actually happens when the cells are injected into a patient’s eye. The data so far suggest that the cells work predominantly by secreting growth factors that rescue damaged retinal cells or even reverse the damage. So one possible outcome is that the cells slow or prevent further deterioration of vision. But an additional possibility is that damaged retinal cells that are still alive but are not functioning properly may become healthy and functional again which could result in an improvement in vision.
What advances have been made using stem cells for the treatment of Type 2 Diabetes?Mary Rizzo
Dr. Ross Okamura: Type 2 Diabetes (T2D) is a disease where the body is unable to maintain normal glucose levels due to either resistance to insulin-regulated control of blood sugar or insufficient insulin production from pancreatic beta cells. The onset of disease has been associated with lifestyle influenced factors including body mass, stress, sleep apnea and physical activity, but it also appears to have a genetic component based upon its higher prevalence in certain populations.
Type 1 Diabetes (T1D) differs from T2D in that in T1D patients the pancreatic beta cells have been destroyed by the body’s immune system and the requirement for insulin therapy is absolute upon disease onset rather than gradually developing over time as in many T2D cases. Currently the only curative approach to alleviate the heavy burden of disease management in T1D has been donor pancreas or islet transplantation. However, the supply of donor tissue is small relative to the number of diabetic patients. Donor islet and pancreas transplants also require immune suppressive drugs to prevent allogenic immune rejection and the use of these drugs carry additional health concerns. However, for some patients with T1D, especially those who may develop potentially fatal hypoglycemia, immune suppression is worth the risk.
To address the issue of supply, there has been significant activity in stem cell research to produce insulin secreting beta cells from pluripotent stem cells and recent clinical data from Viacyte’s CIRM funded trial indicates that implanted allogeneic human stem cell derived cells in T1D patients can produce circulating c-peptide, a biomarker for insulin. While the trial is not designed specifically to cure insulin-dependent T2D patients, the ability to produce and successfully engraft stem cell-derived beta cells would be able to help all insulin-dependent diabetic patients.
It’s also worth noting that there is a sound scientific reason to clinically test a patient-derived pluripotent stem cell-based insulin-producing cells in insulin-dependent T2D diabetic patients; the cells in this case could be evaluated for their ability to cure diabetes in the absence of needing to prevent both allogeneic and autoimmune responses.
SPINAL CORD INJURY
Is there any news on clinical trials for spinal cord injury? Le Ly
Kevin McCormack: The clinical trial CIRM was funding, with Asterias (now part of a bigger company called Lineage Cell Therapeutics, is now completed and the results were quite encouraging. In a news release from November of 2019 Brian Culley, CEO of Lineage Cell Therapeutics, described the results this way.
“We remain extremely excited about the potential for OPC1 (the name of the therapy used) to provide enhanced motor recovery to patients with spinal cord injuries. We are not aware of any other investigative therapy for SCI (spinal cord injury) which has reported as encouraging clinical outcomes as OPC1, particularly with continued improvement beyond 1 year. Overall gains in motor function for the population assessed to date have continued, with Year 2 assessments measuring the same or higher than at Year 1. For example, 5 out of 6 Cohort 2 patients have recovered two or more motor levels on at least one side as of their Year 2 visit whereas 4 of 6 patients in this group had recovered two motor levels as of their Year 1 visit. To put these improvements into perspective, a one motor level gain means the ability to move one’s arm, which contributes to the ability to feed and clothe oneself or lift and transfer oneself from a wheelchair. These are tremendously meaningful improvements to quality of life and independence. Just as importantly, the overall safety of OPC1 has remained excellent and has been maintained 2 years following administration, as measured by MRI’s in patients who have had their Year 2 follow-up visits to date. We look forward to providing further updates on clinical data from SCiStar as patients continue to come in for their scheduled follow up visits.”
Lineage Cell Therapeutics plans to meet with the FDA in 2020 to discuss possible next steps for this therapy.
In the meantime the only other clinical trial I know that is still recruiting is one run by a company called Neuralstem. Here is a link to information about that trial on the www.clinicaltrials.gov website.
Now that the Brainstorm ALS trial is finished looking for new patients do you have any idea how it’s going and when can we expect to see results? Angela Harrison Johnson
Dr. Ingrid Caras: The treated patients have to be followed for a period of time to assess how the therapy is working and then the data will need to be analyzed. So we will not expect to see the results probably for another year or two.
Are there treatments for autism or fragile x using stem cells? Magda Sedarous
Dr. Kelly Shepard: Autism and disorders on the autism spectrum represent a collection of many different disorders that share some common features, yet have different causes and manifestations, much of which we still do not understand. Knowing the origin of a disorder and how it affects cells and systems is the first step to developing new therapies. CIRM held a workshop on Autism in 2009 to brainstorm potential ways that stem cell research could have an impact. A major recommendation was to exploit stem cells and new technological advances to create cells and tissues, such as neurons, in the lab from autistic individuals that could then be studied in great detail. CIRM followed this recommendation and funded several early-stage awards to investigate the basis of autism, including Rett Syndrome, Fragile X, Timothy Syndrome, and other spectrum disorders. While these newer investigations have not yet led to therapies that can be tested in humans, this remains an active area of investigation. Outside of CIRM funding, we are aware of more mature studies exploring the effects of umbilical cord blood or other specific stem cell types in treating autism, such as an ongoing clinical trial conducted at Duke University.
What is happening with Parkinson’s research? Hanifa Gaphoor
Dr. Kent Fitzgerald: Parkinson’s disease certainly has a significant amount of ongoing work in the regenerative medicine and stem cell research.
The nature of cell loss in the brain, specifically the dopaminergic cells responsible for regulating the movement, has long been considered a good candidate for cell replacement therapy.
This is largely due to the hypothesis that restoring function to these cells would reverse Parkinson’s symptoms. This makes a lot of sense as front line therapy for the disease for many years has been dopamine replacement through L-dopa pills etc. Unfortunately, over time replacing dopamine through a pill loses its benefit, whereas replacing or fixing the cells themselves should be a more permanent fix.
Because a specific population of cells in one part of the brain are lost in the disease, multiple labs and clinicians have sought to replace or augment these cells by transplantation of “new” functional cells able to restore function to the area an theoretically restore voluntary motor control to patients with Parkinson’s disease.
Early clinical research showed some promise, however also yielded mixed results, using fetal tissue transplanted into the brains of Parkinson’s patients. As it turns out, the cell types required to restore movement and avoid side effects are somewhat nuanced. The field has moved away from fetal tissue and is currently pursuing the use of multiple stem cell types that are driven to what is believed to be the correct subtype of cell to repopulate the lost cells in the patient.
One project CIRM sponsored in this area with Jeanne Loring sought to develop a cell replacement therapy using stem cells from the patients themselves that have been reprogrammed into the kinds of cell damaged by Parkinson’s. This type of approach may ultimately avoid issues with the cells avoiding rejection by the immune system as can be seen with other types of transplants (i.e. liver, kidney, heart etc).
Still, others are using cutting edge gene therapy technology, like the clinical phase project CIRM is sponsoring with Krystof Bankiewicz to investigate the delivery of a gene (GDNF) to the brain that may help to restore the activity of neurons in the Parkinson’s brain that are no longer working as they should.
The bulk of the work in the field of PD at the present remains centered on replacing or restoring the dopamine producing population of cells in the brain that are affected in disease.
Any plans for Huntington’s?Nikhat Kuchiki
Dr. Lisa Kadyk: The good news is that there are now several new therapeutic approaches to Huntington’s Disease that are at various stages of preclinical and clinical development, including some that are CIRM funded. One CIRM-funded program led by Dr. Leslie Thompson at UC Irvine is developing a cell-based therapeutic that consists of neural stem cells that have been manufactured from embryonic stem cells. When these cells are injected into the brain of a mouse that has a Huntington’s Disease mutation, the cells engraft and begin to differentiate into new neurons. Improvements are seen in the behavioral and electrophysiological deficits in these mutant mice, suggesting that similar improvements might be seen in people with the disease. Currently, CIRM is funding Dr. Thompson and her team to carry out rigorous safety studies in animals using these cells, in preparation for submitting an application to the FDA to test the therapy in human patients in a clinical trial.
There are other, non-cell-based therapies also being tested in clinical trials now, using anti-sense oligonucleotides (Ionis, Takeda) to lower the expression of the Huntington protein. Another HTT-lowering approach is similar – but uses miRNAs to lower HTT levels (UniQure,Voyager)
TRAUMATIC BRAIN INJURY (TBI)
My 2.5 year old son recently suffered a hypoxic brain injury resulting in motor and speech disabilities. There are several clinical trials underway for TBI in adults. My questions are:
Will the results be scalable to pediatric use and how long do you think it would take before it is available to children?
I’m wondering why the current trials have chosen to go the route of intracranial injections as opposed to something slightly less invasive like an intrathecal injection?
Is there a time window period in which stem cells should be administered by, after which the administration is deemed not effective?
Dr. Kelly Shepard: TBI and other injuries of the nervous system are characterized by a lot of inflammation at the time of injury, which is thought to interfere with the healing process- and thus some approaches are intended to be delivered after that inflammation subsides. However, we are aware of approaches that intend to deliver a therapy to a chronic injury, or one that has occurred previously. Thus, the answer to this question may depend on how the intended therapy is supposed to work. For example, is the idea to grow new neurons, or is it to promote the survival of neurons of other cells that were spared by the injury? Is the therapy intended to address a specific symptom, such as seizures? Is the therapy intended to “fill a gap” left behind after inflammation subsides, which might not restore all function but might ameliorate certain symptoms.? There is still a lot we don’t understand about the brain and the highly sophisticated network of connections that cannot be reversed by only replacing neurons, or only reducing inflammation, etc. However, if trials are well designed, they should yield useful information even if the therapy is not as effective as hoped, and this information will pave the way to newer approaches and our technology and understanding evolves.
We have had a doctor recommending administering just the growth factors derived from MSC stem cells. Does the science work that way? Is it possible to isolate the growth factors and boost the endogenous growth factors by injecting allogenic growth factors?
Dr. Stephen Lin: Several groups have published studies on the therapeutic effects in non-human animal models of using nutrient media from MSC cultures that contain secreted factors, or extracellular vesicles from cells called exosomes that carry protein or nucleic acid factors. Scientifically it is possible to isolate the factors that are responsible for the therapeutic effect, although to date no specific factor or combination of factors have been identified to mimic the effects of the undefined mixtures in the media and exosomes. At present no regulatory approved clinical therapy has been developed using this approach.
PREDATORY STEM CELL CLINICS
What practical measures are being taken to address unethical practitioners whose bad surgeries are giving stem cell advances a bad reputation and are making forward research difficult?Kathy Jean Schultz
Dr. Geoff Lomax: Terrific question! I have been doing quite a bit research into the history of this issue of unethical practitioners and I found an 1842 reference to “quack medicines.” Clearly this is nothing new. In that day, the author appealed to make society “acquainted with the facts.”
In California, we have taken steps to (1) acquaint patients with the facts about stem cell treatments and (2) advance FDA authorized treatments for unmet medical needs.
First, CIRM work with Senator Hernandez in 2017 to write a law the requires provides to disclose to patient that a stem cell therapy has not been approved by the Food and Drug administration.
We continue to work with the State Legislature and Medical Board of California to build on policies that require accurate disclosure of the facts to patients.
Second, our clinical trial network the — Alpha Stem Cell Clinics – have supported over 100 FDA-authorized clinical trials to advance responsible clinical research for unmet medical needs.
I’m curious if adipose stem cell being used at clinics at various places in the country is helpful or beneficial?Cheri Hicks
Adipose tissue has been widely used particularly in plastic and reconstructive surgery. Many practitioners suggest adipose cells are beneficial in this context. With regard to regenerative medicine and / or the ability to treat disease and injury, I am not aware of any large randomized clinical trials that demonstrate the safety and efficacy of adipose-derived stem cells used in accordance with FDA guidelines.
I went to a “Luncheon about Stem Cell Injections”. It sounded promising. I went thru with it and got the injections because I was desperate from my knee pain. The price of stem cell injections was $3500 per knee injection. All went well. I have had no complications, but haven’t noticed any real major improvement, and here I am a year later. My questions are:
1) I wonder on where the typical injection cells are coming from?
2) I wonder what is the actual cost of the cells?
3) What kind of results are people getting from all these “pop up” clinics or established clinics that are adding this to there list of offerings?
Dr. Geoff Lomax: You raise a number of questions and point here; they are all very good and it’s is hard to give a comprehensive response to each one, but here is my reaction:
There are many practitioners in the field of orthopedics who sincerely believe in the potential of cell-based treatments to treat injury / pain
Most of the evidence presented is case reports that individuals have benefited
The challenge we face is not know the exact type of injury and cell treatments used.
Well controlled clinical trials would really help us understand for what cells (or cell products) and for what injury would be helpful
Prices of $3000 to $5000 are not uncommon, and like other forms of private medicine there is often a considerable mark-up in relation to cost of goods.
You are correct that there have not been reports of serious injury for knee injections
However the effectiveness is not clear while simultaneously millions of people have been aided by knee replacements.
Do stem cells have benefits for patients going through chemotherapy and radiation therapy?Ruperto
Dr. Kelly Shepard: The idea that a stem cell therapy could help address effects of chemotherapy or radiation is being and has been pursued by several investigators over the years, including some with CIRM support. Towards the earlier stages, people are looking at the ability of different stem cell-derived neural cell preparations to replace or restore function of certain brain cells that are damaged by the effects of chemotherapy or radiation. In a completely different type of approach, a group at City of Hope is exploring whether a bone marrow transplant with specially modified stem cells can provide a protective effect against the chemotherapy that is used to treat a form of brain cancer, glioblastoma. This study is in the final stage of development that, if all goes well, culminates with application to the FDA to allow initiation of a clinical trial to test in people.
Dr. Ingrid Caras: That’s an interesting and valid question. There is a Phase 1 trial ongoing that is evaluating a novel type of stem/progenitor cell from the umbilical cord of healthy deliveries. In animal studies, these cells have been shown to reduce the toxic effects of chemotherapy and radiation and to speed up recovery. These cells are now being tested in a First-in-human clinical trial in patients who are undergoing high-dose chemotherapy to treat their disease.
There is a researcher at Stanford, Michelle Monje, who is investigating that the role of damage to stem cells in the cognitive problems that sometimes arise after chemo- and radiation therapy (“chemobrain”). It appears that damage to stem cells in the brain, especially those responsible for producing oligodendrocytes, contributes to chemobrain. In CIRM-funded work, Dr. Monje has identified small molecules that may help prevent or ameliorate the symptoms of chemobrain.
Is it possible to use a technique developed to fight one disease to also fight another? For instance, the bubble baby disease, which has cured (I think) more than 50 children, may also help fight sickle cell anemia? Don Reed.
Dr. Lisa Kadyk: Hi Don. Yes, the same general technique can often be applied to more than one disease, although it needs to be “customized” for each disease. In the example you cite, the technique is an “autologous gene-modified bone marrow transplant” – meaning the cells come from the patient themselves. This technique is relevant for single gene mutations that cause diseases of the blood (hematopoietic) system. For example, in the case of “bubble baby” diseases, a single mutation can cause failure of immune cell development, leaving the child unable to fight infections, hence the need to have them live in a sterile “bubble”. To cure that disease, blood stem cells, which normally reside in the bone marrow, are collected from the patient and then a normal version of the defective gene is introduced into the cells, where it is incorporated into the chromosomes. Then, the corrected stem cells are transplanted back into the patient’s body, where they can repopulate the blood system with cells expressing the normal copy of the gene, thus curing the disease.
A similar approach could be used to treat sickle cell disease, since it is also caused by a single gene mutation in a gene (beta hemoglobin) that is expressed in blood cells. The same technique would be used as I described for bubble baby disease but would differ in the gene that is introduced into the patient’s blood stem cells.
Is there any concern that CIRM’s lack of support in basic research will hamper the amount of new approaches that can reach clinical stages? Jason
Dr. Kelly Shepard: CIRM always has and continues to believe that basic research is vital to the field of regenerative medicine. Over the past 10 years CIRM has invested $904 million in “discovery stage/basic research”, and about $215 million in training grants that supported graduate students, post docs, clinical fellows, undergraduate, masters and high school students performing basic stem cell research. In the past couple of years, with only a limited amount of funds remaining, CIRM made a decision to invest most of the remaining funds into later stage projects, to support them through the difficult transition from bench to bedside. However, even now, CIRM continues to sponsor some basic research through its Bridges and SPARK Training Grant programs, where undergraduate, masters and even high school students are conducting stem cell research in world class stem cell laboratories, many of which are the same laboratories that were supported through CIRM basic research grants over the past 10 years. While basic stem cell research continues to receive a substantial level of support from the NIH ($1.8 billion in 2018, comprehensively on stem cell projects) and other funders, CIRM believes continued support for basic research, especially in key areas of stem cell research and vital opportunities, will always be important for discovering and developing new treatments.
What is the future of the use of crispr cas9 in clinical trials in california/globally. Art Venegas
Dr. Kelly Shepard: CRISPR/Cas9 is a powerful gene editing tool. In only a few years, CRISPR/Cas9 technology has taken the field by storm and there are already a few CRISPR/Cas9 based treatments being tested in clinical trials in the US. There are also several new treatments that are at the IND enabling stage of development, which is the final testing stage required by the FDA before a clinical trial can begin. Most of these clinical trials involving CRISPR go through an “ex vivo” approach, taking cells from the patient with a disease causing gene, correcting the gene in the laboratory using CRISPR, and reintroducing the cells carrying the corrected gene back into the patient for treatment. Sickle cell disease is a prime example of a therapy being developed using this strategy and CIRM funds two projects that are preparing for clinical trials with this approach. CRISPR is also being used to develop the next generation of cancer T-cell therapies (e.g. CAR-T), where T-cells – a vital part of our immune system – are modified to target and destroy cancer cell populations. Using CRISPR to edit cells directly in patients “in vivo” (inside the body) is far less common currently but is also being developed. It is important to note that any FDA sanctioned “in vivo” CRISPR clinical trial in people will only modify organ-specific cells where the benefits cannot be passed on to subsequent generations. There is a ban on funding for what are called germ line cells, where any changes could be passed down to future generations.
CIRM is currently supporting multiple CRISPR/Cas9 gene editing projects in California from the discovery or most basic stage of research, through the later stages before applying to test the technique in people in a clinical trial.
While the field is new – if early safety signals from the pioneering trials are good, we might expect a number of new CRISPR-based approaches to enter clinical testing over the next few years. The first of these will will likely be in the areas of bone marrow transplant to correct certain blood/immune or metabolic diseases, and cancer immunotherapies, as these types of approaches are the best studied and furthest along in the pipeline.
Explain the differences between gene therapy and stem cell therapy?Renee Konkol
Dr. Stephen Lin: Gene therapy is the direct modification of cells in a patient to treat a disease. Most gene therapies use modified, harmless viruses to deliver the gene into the patient. Gene therapy has recently seen many success in the clinic, with the first FDA approved therapy for a gene induced form of blindness in 2017 and other approvals for genetic forms of smooth muscle atrophy and amyloidosis.
Stem cell therapy is the introduction of stem cells into patients to treat a disease, usually with the purpose of replacing damaged or defective cells that contribute to the disease. Stem cell therapies can be derived from pluripotent cells that have the potential to turn into any cell in the body and are directed towards a specific organ lineage for the therapy. Stem cell therapies can also be derived from other cells, called progenitors, that have the ability to turn into a limited number of other cells in the body. for example hematopoietic or blood stem cells (HSCs), which are found in bone marrow, can turn into other cells of the blood system including B-cells and T-cells: while mesenchymal stem cells (MSCs), which are usually found in fat tissue, can turn into bone, cartilage, and fat cells. The source of these cells can be from the patient’s own body (autologous) or from another person (allogeneic).
Gene therapy is often used in combination with cell therapies when cells are taken from the patient and, in the lab, modified genetically to correct the mutation or to insert a correct form of the defective gene, before being returned to patients. Often referred to as “ex vivo gene therapy” – because the changes are made outside the patient’s body – these therapies include Chimeric Antigen Receptor T (CAR-T) cells for cancer therapy and gene modified HSCs to treat blood disorders such as severe combined immunodeficiency and sickle cell disease. This is an exciting area that has significantly improved and even cured many people already.
Currently, how can the outcome of CIRM stem cell medicine projects and clinical trials be soundly interpreted when their stem cell-specific doses are not known?James L. Sherley, M.D., Ph.D., Director. Asymmetrex, LLC
Dr. Stephen Lin: Stem cell therapies that receive approval to conduct clinical trials must submit a package of data to the FDA that includes studies that demonstrate their effectiveness, usually in animal models of the disease that the cell therapy is targeting. Those studies have data on the dose of the cell therapy that creates the therapeutic effect, which is used to estimate cell doses for the clinical trial. CIRM funds discovery and translational stage awards to conduct these types of studies to prepare cell therapies for clinical trials. The clinical trial is also often designed to test multiple doses of the cell therapy to determine the one that has the best therapeutic effect. Dosing can be very challenging with cell therapies because of issues including survival, engraftment, and immune rejection, but CIRM supports studies designed to provide data to give the best estimate possible.
Is there any research on using stem cells to increase the length of long bones in people?” For example, injecting stem cells into the growth plates to see if the cells can be used to lengthen limbs.Sajid
Dr. Kelly Shepard: There is quite a lot of ongoing research seeking ways to repair bones with stem cell based approaches, which is not the same but somewhat related. Much of this is geared towards repairing the types of bone injuries that do not heal well naturally on their own (large gaps, dead bone lesions, degenerative bone conditions). Also, a lot of this research involves engineering bone tissues in the lab and introducing the engineered tissue into a bone lesion that need be repaired. What occurs naturally at the growth plate is a complex interaction between many different cell types, much of which we do not fully understand. We do not fully understand how to use the cells that are used to engineer bone tissue in the lab. However, a group at Stanford, with some CIRM support, recently discovered a “skeletal stem cell” that exists naturally at the ends of human bones and at sites of fracture. These are quite different than MSCs and offer a new path to be explored for repairing and generating bone.
A program hoping to supercharge a patient’s own immune system cells to attack and kill a treatment resistant form of prostate cancer was today awarded $3.99 million by the governing Board of the California Institute for Regenerative Medicine (CIRM)
In the U.S., prostate cancer is the second most common cause of cancer deaths in men. An estimated 170,000 new cases are diagnosed each year and over 29,000 deaths are estimated in 2018. Early stage prostate cancer is usually managed by surgery, radiation and/or hormone therapy. However, for men diagnosed with castrate-resistant metastatic prostate cancer (CRPC) these treatments often fail to work and the disease eventually proves fatal.
Poseida Therapeutics will be funded by CIRM to develop genetically engineered chimeric antigen receptor T cells (CAR-T) to treat metastatic CRPC. In cancer, there is a breakdown in the natural ability of immune T-cells to survey the body and recognize, bind to and kill cancerous cells. Poseida is engineering T cells and T memory stem cells to express a chimeric antigen receptor that arms these cells to more efficiently target, bind to and destroy the cancer cell. Millions of these cells are then grown in the laboratory and then re-infused into the patient. The CAR-T memory stem cells have the potential to persist long-term and kill residual cancer calls.
“This is a promising approach to an incurable disease where patients have few options,” says Maria T. Millan, M.D., President and CEO of CIRM. “The use of chimeric antigen receptor engineered T cells has led to impressive results in blood malignancies and a natural extension of this promising approach is to tackle currently untreatable solid malignancies, such as castrate resistant metastatic prostate cancer. CIRM is pleased to partner on this program and to add it to its portfolio that involves CAR T memory stem cells.”
Poseida Therapeutics plans to use the funding to complete the late-stage testing needed to apply to the Food and Drug Administration for the go-ahead to start a clinical trial in people.
The CIRM Board also voted to approve investing $10 million for eight projects under its Discovery Quest Program. The Quest program promotes the discovery of promising new stem cell-based technologies that will be ready to move to the next level, the translational category, within two years, with an ultimate goal of improving patient care.
Among those approved for funding are:
Eric Adler at UC San Diego is using genetically modified blood stem cells to treat Danon Disease, a rare and fatal condition that affects the heart
Li Gan at the Gladstone Institutes will use induced pluripotent stem cells to develop a therapy for a familial form of dementia
Saul Priceman at City of Hope will use CAR-T therapy to develop a treatment for recurrent ovarian cancer
Because the amount of funding for the recommended applications exceeded the money set aside, the Application Subcommittee voted to approve partial funding for two projects, DISC2-11192 and DISC2-11109 and to recommend, at the next full Board meeting in October, that the projects get the remainder of the funds needed to complete their research.
The successful applications are:
CIRM COMMITTED FUNDING
Genetically Modified Hematopoietic Stem Cells for the
Treatment of Danon Disease
U.C San Diego
Preclinical Development of An HSC-Engineered Off-
The-Shelf iNKT Cell Therapy for Cancer
U.C. Los Angeles
Non-viral reprogramming of the endogenous TCRα
locus to direct stem memory T cells against shared
neoantigens in malignant gliomas
U.C. San Francisco
Therapeutic immune tolerant human islet-like
organoids (HILOs) for Type 1 Diabetes
Chimeric Antigen Receptor-Engineered Stem/Memory
T Cells for the Treatment of Recurrent Ovarian Cancer
City of Hope
Develop iPSC-derived microglia to treat progranulin-
Stem Cell Photo of the Week: We’re Live on Facebook Live!
Our stem cell photo of the week is a screenshot from yesterday’s Facebook Live event: “Ask the Expert: Stem Cells and Stroke”. It was our first foray into Facebook Live and, dare I say, it was a success with over 150 comments and 4,500 views during the live broadcast.
Screen shot of yesterday’s Facebook Live event. Panelists included (from top left going clockwise): Sonia Coontz, Kevin McCormack, Gary Steinberg, MD, PhD and Lila Collins, PhD.
Our panel included Dr. Gary Steinberg, MD, PhD, the Chair of Neurosurgery at Stanford University, who talked about promising clinical trial results testing a stem cell-based treatment for stroke. Lila Collins, PhD, a Senior Science Officer here at CIRM, provided a big picture overview of the latest progress in stem cell therapies for stroke. Sonia Coontz, a patient of Dr. Steinberg’s, also joined the live broadcast. She suffered a devastating stroke several years ago and made a remarkable recovery after getting a stem cell therapy. She had an amazing story to tell. And Kevin McCormack, CIRM’s Senior Director of Public Communications, moderated the discussion.
Did you miss the Facebook Live event? Not to worry. You can watch it on-demand on our Facebook Page.
What other disease areas would you like us to discuss? We plan to have these Ask the Expert shows on a regular basis so let us know by commenting here or emailing us at email@example.com!
Brain cells’ energy “factories” may be to blame for age-related disease
Salk Institute researchers published results this week that shed new light on why the brains of older individuals may be more prone to neurodegenerative diseases like Parkinson’s and Alzheimer’s. To make this discovery, the team applied a technique they devised back in 2015 which directly converts skin cells into brain cells, aka neurons. The method skips the typical intermediate step of reprogramming the skin cells into induced pluripotent stem cells (iPSCs).
They collected skin samples from people ranging in age from 0 to 89 and generated neurons from each. With these cells in hand, the researchers then examined how increased age affects the neurons’ mitochondria, the structures responsible for producing a cell’s energy needs. Previous studies have shown a connection between faulty mitochondria and age-related disease.
While the age of the skin cells had no bearing on the health of the mitochondria, it was a different story once they were converted into neurons. The mitochondria in neurons derived from older individuals clearly showed signs of deterioration and produced less energy.
Aged mitochondria (green) in old neurons (gray) appear mostly as small punctate dots rather than a large interconnected network. Credit: Salk Institute.
The researchers think this stark difference in the impact of age on skin cells vs. neurons may occur because neurons have higher energy needs. So, the effects of old age on mitochondria only become apparent in the neurons. In a press release, Salk scientist Jerome Mertens explained the result using a great analogy:
“If you have an old car with a bad engine that sits in your garage every day, it doesn’t matter. But if you’re commuting with that car, the engine becomes a big problem.”
The team is now eager to use this method to examine mitochondrial function in neurons derived from Alzheimer’s and Parkinson’s patient skin samples and compared them with skin-derived neurons from similarly-aged, healthy individuals.
The study, funded in part by CIRM, was published in Cell Reports.
“Synthetically” Programming embryo development
One of the most intriguing, most fundamental questions in biology is how an embryo, basically a non-descript ball of cells, turns into a complex animal with eyes, a brain, a heart, etc. A deep understanding of this process will help researchers who aim to rebuild damaged or diseased organs for patients in need.
Researchers programmed cells to self-assemble into complex structures such as this one with three differently colored layers. Credit: Wendell Lim/UCSF
A fascinating report published this week describes a system that allows researchers to program cells to self-organize into three-dimensional structures that mimic those seen during early development. The study applied a customizable, synthetic signaling molecule called synNotch developed in the Wendell Lim’s UCSF lab by co-author Kole Roybal, PhD, now an assistant professor of microbiology and immunology at UCSF, and Leonardo Morsut, PhD, now an assistant professor of stem cell biology and regenerative medicine at the University of Southern California.
A UCSF press release by Nick Weiler describes how synNotch was used:
“The researchers engineered cells to respond to specific signals from neighboring cells by producing Velcro-like adhesion molecules called cadherins as well as fluorescent marker proteins. Remarkably, just a few simple forms of collective cell communication were sufficient to cause ensembles of cells to change color and self-organize into multi-layered structures akin to simple organisms or developing tissues.”
Senior author Wendell Lim also explained how this system could overcome the challenges facing those aiming to build organs via 3D bioprinting technologies:
“People talk about 3D-printing organs, but that is really quite different from how biology builds tissues. Imagine if you had to build a human by meticulously placing every cell just where it needs to be and gluing it in place. It’s equally hard to imagine how you would print a complete organ, then make sure it was hooked up properly to the bloodstream and the rest of the body. The beauty of self-organizing systems is that they are autonomous and compactly encoded. You put in one or a few cells, and they grow and organize, taking care of the microscopic details themselves.”
A promising new treatment option for hemophiliacs is in the works at the Salk Institute for Biological Sciences. Patients with Hemophilia B experience uncontrolled, and sometimes life threatening, bleeding due to loss or improper function of Factor IX (FIX), a protein involved in blood clotting. There is no cure for the disease and patients rely on routine infusions of FIX to prevent excessive blood loss. As you can imagine, this treatment regimen is both time consuming and expensive, while also becoming less effective over time.
Salk researchers, partially funded by CIRM, aimed to develop a more long-term solution for this devastating disease by using the body’s own cells to fix the problem.
In the study, published in the journal Cell Reports, They harvested blood cells from hemophiliacs and turned them into iPSCs (induced pluripotent stem cells), which are able to turn into any cell type. Using gene editing, they repaired the iPSCs so they could produce FIX and then turned the iPSCs into liver cells, the cell type that naturally produces FIX in healthy individuals.
One step therapy
To test whether these FIX-producing liver cells were able to reduce excess blood loss, the scientists injected the repaired human cells into a hemophiliac mouse. The results were very encouraging; they saw a greater than two-fold increase in clotting efficiency in the mice, reaching about a quarter of normal activity. This is particularly promising because other studies showed that increasing FIX activity to this level in hemophiliac humans significantly reduces bleeding rates. On top of that they also observed that these cells were able to survive and produce FIX for up to a year in the mice.
In a news release Suvasini Ramaswamy, the first author of the paper, said this method could eliminate the need for multiple treatments, as well as avoiding the immunosuppressive therapy that would be required for a whole liver transplant.
“The appeal of a cell-based approach is that you minimize the number of treatments that a patient needs. Rather than constant injections, you can do this in one shot.”
While these results provide an exciting new avenue in hemophilia treatment, there is still much more work that needs to be done before this type of treatment can be used in humans. This approach, however, is particularly exciting because it provides an important proof of principle that combining stem cell reprogramming with genetic engineering can lead to life-changing breakthroughs for treating genetic diseases that are not currently curable.
One of the reasons why it’s so hard to develop treatments for problems in the brain – things like Alzheimer’s, autism and schizophrenia – is that you can’t do an autopsy of a living brain to see what’s going wrong. People tend to object. To get around that, scientists have used stem cells to create models of what’s happening inside the brain. They’re good, but they have their limitations. Now a team at the Salk Institute for Biological Studies has found a way to create a better brain model, and hopefully a faster route to developing new treatments.
For a few years now, scientists have been able to take skin cells from patients with neurodegenerative disorders and turn them into neurons, the kind of brain cell affected by these different diseases. They grow these cells in the lab and turn them into clusters of cells, so-called brain “organoids”, to help us better understand what’s happening inside the brain and even allow us to test medications on them to see if those treatments can help ease some symptoms.
Human organoid tissue (green) grafted into mouse tissue. Neurons are labeled with red. Credit: Salk Institute
But those models don’t really capture the complexity of our brains – how could they – and so only offer a glimpse into what’s happening inside our skulls.
Now the team at Salk have developed a way of transplanting these organoids into mouse brains, giving them access to oxygen and nutrients that can help them not only survive longer but also display more of the characteristics found in the human brain.
In a news release, CIRM Grantee and professor at Salk’s Laboratory of Genetics, Rusty Gage said this new approach gives researchers a powerful new tool:
“This work brings us one step closer to a more faithful, functional representation of the human brain and could help us design better therapies for neurological and psychiatric diseases.”
The transplanted human brain organoids showed plenty of signs that they were becoming engrafted in the mouse brain:
They had blood vessels form in them and blood flowing through them
They formed neurons
They formed other brain support cells called astrocytes
They also used a series of imaging techniques to confirm that the neurons in the organoid were not just connecting but also sending signals, in essence, communicating with each other.
Abed AlFattah Mansour, a Salk research associate and the paper’s first author, says this is a big accomplishment.
“We saw infiltration of blood vessels into the organoid and supplying it with blood, which was exciting because it’s perhaps the ticket for organoids’ long-term survival. This indicates that the increased blood supply not only helped the organoid to stay healthy longer, but also enabled it to achieve a level of neurological complexity that will help us better understand brain disease.”
A better understanding of what’s going wrong is a key step in being able to develop new treatments to fix the problem.
In honor of brain awareness week, our featured stem cell photo is of the brain! Scientists at the Massachusetts General Hospital and Harvard Stem Cell Institute identified a genetic switch that could potentially improve memory during aging and symptoms of PTSD. Shown in this picture are dentate gyrus cells (DGC) (green) and CA3 interneurons (red) located in the memory-forming area of the brain known as the hippocampus. By reducing the levels of a protein called abLIM3 in the DGCs of older mice, the researchers were able to boost the connections between DGCs and CA3 cells, which resulted in an improvement in the memories of the mice. The team believes that targeting this protein in aging adults could be a potential strategy for improving memory and treating patients with post-traumatic stress disorder (PTSD). You can read more about this study in The Harvard Gazette.
New target for obesity. Fat cells typically get a bad rap, but there’s actually a type of fat cell that is considered “healthier” than others. Unlike white fat cells that store calories in the form of energy, brown fat cells are packed with mitochondria that burn energy and produce heat. Babies have brown fat, so they can regulate their body temperature to stay warm. Adults also have some brown fat, but as we get older, our stores are slowly depleted.
In the fight against obesity, scientists are looking for ways to increase the amount of brown fat and decrease the amount of white fat in the body. This week, CIRM-funded researchers from the Salk Institute identified a molecule called ERRg that gives brown fat its ability to burn energy. Their findings, published in Cell Reports, offer a new target for obesity and obesity-related diseases like diabetes and fatty liver disease.
The team discovered that brown fat cells produce the ERRg molecule while white fat cells do not. Additionally, mice that couldn’t make the ERRg weren’t able to regulate their body temperature in cold environments. The team concluded in a news release that ERRg is “involved in protection against the cold and underpins brown fat identity.” In future studies, the researchers plan to activate ERRg in white fat cells to see if this will shift their identity to be more similar to brown fat cells.
Mice that lack ERR aren’t able to regulate their body temperature and are much colder (right) than normal mice (left). (Image credit Salk Institute)
Tale of two nanomedicine stories: making gene therapies more efficient with a bit of caution (Todd Dubnicoff). This week, the worlds of gene therapy, stem cells and nanomedicine converged for not one, but two published reports in the journal American Chemistry Society NANO.
The first paper described the development of so-called nanospears – tiny splinter-like magnetized structures with a diameter 5000 times smaller than a strand of human hair – that could make gene therapy more efficient and less costly. Gene therapy is an exciting treatment strategy because it tackles genetic diseases at their source by repairing or replacing faulty DNA sequences in cells. In fact, several CIRM-funded clinical trials apply this method in stem cells to treat immune disorders, like severe combined immunodeficiency and sickle cell anemia.
This technique requires getting DNA into diseased cells to make the genetic fix. Current methods have low efficiency and can be very damaging to the cells. The UCLA research team behind the study tested the nanospear-delivery of DNA encoding a gene that causes cells to glow green. They showed that 80 percent of treated cells did indeed glow green, a much higher efficiency than standard methods. And probably due to their miniscule size, the nanospears were gentle with 90 percent of the green glowing cells surviving the procedure.
As Steve Jonas, one of the team leads on the project mentions in a press release, this new method could bode well for future recipients of gene therapies:
“The biggest barrier right now to getting either a gene therapy or an immunotherapy to patients is the processing time. New methods to generate these therapies more quickly, effectively and safely are going to accelerate innovation in this research area and bring these therapies to patients sooner, and that’s the goal we all have.”
While the study above describes an innovative nanomedicine technology, the next paper inserts a note of caution about how experiments in this field should be set up and analyzed. A collaborative team from Brigham and Women’s Hospital, Stanford University, UC Berkeley and McGill University wanted to get to the bottom of why the many advances in nanomedicine had not ultimately led to many new clinical trials. They set out looking for elements within experiments that could affect the uptake of nanoparticles into cells, something that would muck up the interpretation of results.
imaging of female human amniotic stem cells incubated with nanoparticles demonstrated a significant increase in uptake compared to male cells. (Green dots: nanoparticles; red: cell staining; blue: nuclei) Credit: Morteza Mahmoudi, Brigham and Women’s Hospital.
In this study, they report that the sex of cells has a surprising, noticeable impact on nanoparticle uptake. Nanoparticles were incubated with human amniotic stem cells derived from either males or females. The team showed that the female cells took up the nanoparticles much more readily than the male cells. Morteza Mahmoudi, PhD, one of the authors on the paper, explained the implications of these results in a press release:
“These differences could have a critical impact on the administration of nanoparticles. If nanoparticles are carrying a drug to deliver [including gene therapies], different uptake could mean different therapeutic efficacy and other important differences, such as safety, in clinical data.”
Here’s a heartwarming story for the holidays. Scientists from the Salk Institute in La Jolla, California have figured out a simple, easy way to make beating heart cells from human stem cells that will aid research and therapy development for heart disease. Their study, which received funding support from CIRM, was published last week in the journal Genes & Development.
The Salk team discovered that making beating heart tissue from human stem cells is as simple as turning off a single gene called YAP. You might be wondering how the team settled on this gene and no, it doesn’t involve pulling a random gene name out of a hat.
In previous studies, the researchers found that two cell signaling pathways, Wnt and Activin, are crucial for the development of embryonic stem cells into specialized cells like cardiomyocytes (beating heart cells). This research led to the discovery of a third pathway, controlled by YAP, which sets up a road block for cell specialization and keeps stem cells in their undifferentiated state.
Only hESCs without YAP (right panel) make heart cells (green) in one step. Blue dye marks cell nuclei. (Salk Institute)
The team deleted YAP from these stem cells using CRISPR gene editing technology, and then treated the stem cells to the Activin signaling molecule. Without YAP, exposure to Activin prompted the stem cells to develop immediately into beating cardiomyocytes that you can see beating away in the Salk video below.
Dr. Kathy Jones, Salk professor and senior author on the study, explained why this discovery is important to the field in a news release:
“This discovery is really exciting because it means we can potentially create a reliable protocol for taking normal cells and moving them very efficiently from stem cells to heart cells. Researchers and commercial companies want to easily generate cardiomyocytes to study their capacity for repair in heart attacks and disease—this brings us one step closer to being able to do that.”
First author, Conchi Estarás, emphasized how their new method for making cardiomyocytes is attractive not only for its simplicity, but also for its cost-effectiveness in enabling large-scale manufacturing of these cells for treatment.
“Instead of requiring two steps to achieve specialization, removing YAP cut it to just one step. That would mean a huge savings for industry in terms of reagent materials and expense.”
Looking ahead, Jones and her team do not plan on deleting the YAP gene from stem cells because of the potential side effects cause by the loss of YAP’s other cellular functions. Instead, they will be using commercially available molecules that can temporarily inhibit the function of YAP in hopes that this less permanent action will still readily produce beating heart cells from stem cells.
Kathy Jones and Conchi Estarás. (Image courtesy of Salk Institute)
Yesterday, we discussed a useful stem cell tool called the CIRM iPSC Repository, which will contain over 3000 human induced pluripotent stem cell (iPSC) lines – from patients and healthy individuals – that contain a wealth of information about human diseases. Now that scientists have access to these lines, they need the proper tools to study them. This is where CIRM’s Genomics Initiative comes into play.
Crunching stem cell data
In 2014, CIRM funded the Genomics Initiative, which created the Center of Excellence in Stem Cell Genomics (CESCG). The goal of the CESCG is to develop novel genomics and bioinformatics tools specifically for stem cell research. These technologies aim to advance our fundamental understanding of human development and disease mechanisms, improve current cell and tissue production methods, and accelerate personalized stem cell-based therapies.
The CESCG is a consortium between Stanford University, the Salk Institute and UC Santa Cruz. Together, the groups oversee or support more than 20 different research projects throughout California focused on generating and analyzing sequencing data from stem or progenitor cells. Sequencing technology today is not only used to decode DNA, but also used to study other genomic data like that provides information about how gene activity is regulated.
Many of the projects within the CESCG are using these sequencing techniques to define the basic genetic properties of specific cell types, and will use this information to create better iPSC-based tissue models. For example, scientists can determine what genes are turned on or off in cells by analyzing raw data from RNA sequencing experiments (RNA is like a photocopy of DNA sequences and is the cell’s way of carrying out the instructions contained in the DNA. This technology sequences and identifies all the RNA that is generated in a tissue or cell at a specific moment). Single cell RNA sequencing, made possible by techniques such as Drop-seq mentioned in yesterday’s blog, are now further revealing the diversity of cell types within tissues and creating more exact reference RNA sequences to identify a specific cell type. By comparing RNA sequencing data from single cells of stem cell-based models to previously referenced cell types, researchers can estimate how accurate, or physiologically relevant, those stem cell models are.
Such comparative analyses can only be done using powerful software that can compare millions of sequence data at the same time. Part of a field termed bioinformatics, these activities are a significant portion of the CESCG and several software tools are being created within the Initiative. Josh Stuart, a faculty member at UC Santa Cruz School of Engineering and a primary investigator in the CESCG, explained their team’s vision:
“A major challenge in the field is recognizing cell types or different states of the same cell type from raw data. Another challenge is integrating multiple data sets from different labs and figuring out how to combine measurements from different technologies. At the CESCG, we’re developing bioinformatics models that trace through all this data. Our goal is to create a database of these traces where each dot is a cell and the curves through these dots explain how the cells are related to one another.”
Stuart’s hope is that scientists will input their stem cell data into the CESCG database and receive a scorecard that explains how accurate their cell model is based on a specific genetic profile. The scorecard will help will not only provide details on the identity of their cells, but will also show how they relate to other cell types found in their database.
The Brain of Cells
An image of a 3D brain organoid grown from stem cells in the Kriegstein Lab at UCSF. (Photo by Elizabeth DiLullo)
A good example of how this database will work is a project called the Brain of Cells (BOC). It’s a collection of single cell RNA sequencing data from thousands of fetal-derived brain cells provided by multiple labs. The idea is that researchers will input RNA sequencing data from the stem cell-derived brain cells they make in their labs and the BOC will give them back a scorecard that describes what types of cells they are and their developmental state by comparing them to the referenced brain cells.
One of the labs that is actively involved in this project and is providing the bulk of the BOC datasets is Arnold Kriegstein’s lab at UC San Francisco. Aparna Bhaduri, a postdoctoral fellow in the Kriegstein lab working on the BOC project, outlined the goal of the BOC and how it will benefit researchers:
“The goal of the Brain of Cells project is to find ways to leverage existing datasets to better understand the cells in the developing human brain. This tool will allow researchers to compare cell-based models (such as stem cell-derived 3D organoids) to the actual developing brain, and will create a query-able resource for researchers in the stem cell community.”
Pablo Cordero, a former postdoc in Josh Stuart’s lab who designed a bioinformatics tool used in BOC called SCIMITAR, explained how the BOC project is a useful exercise in combining single cell data from different external researchers into one map that can predict cell type or cell fate.
“There is no ‘industry standard’ at the moment,” said Cordero. “We have to find various ways to perform these analyses. Approximating the entire human cell lineage is the holy grail of regenerative medicine since in theory, we would have maps of gene circuits that guide cell fate decisions.”
Once the reference data from BOC is ready, the group will use a bioinformatics program called Sample Psychic to create the scorecards for outside researchers. Clay Fischer, project manager of the CESCG at UC Santa Cruz, described how Sample Psychic works:
“Sample Psychic can look at how often genes are being turned off and on in cells. It uses this information to produce a scorecard, which shows how closely the data from your cells maps up to the curated cell types and can be used to infer the probability of the cell type.”
The BOC group believes that the analyses and data produced in this effort will be of great value to the research community and scientists interested in studying developmental neuroscience or neurodegeneration.
The Brain of Cells project is still in its early stages, but soon scientists will be able to use this nifty tool to help them build better and more accurate models of human brain development and brain-related diseases.
CESCG is also pursuing stem cell data driven projects focused on developing similar databases and scorecards for heart cells and pancreatic cells. These genomics and bioinformatics tools are pushing the envelope to a day when scientists can connect the dots between how different cell states and cell fates are determined by computational analysis and leverage this information to generate better iPSC-based systems for disease modeling in the lab or therapeutics in the clinic.
Here’s your weekly roundup of interesting stem cell stories!
Partnership for a healthy brain. To differentiate or not to differentiate. That is the question the stem cells in our tissues and organs face.
In the case of the brain, neural precursor cells can either remain in a stem cell state or they can differentiate into mature brain cells called neurons and astrocytes. Scientists are interested in understanding how the brain maintains the balance between these different cell states in order to understand how disruption to this balance are associated with psychiatric and neurodegenerative diseases.
Scientists from the Salk Institute, led by Genetics Professor Rusty Gage, published a study this week in Cell Stem Cell that sheds light on how this imbalance can cause brain disease. They found that a partnership between two proteins determines whether a neural precursor develops into a neuron or an astrocyte.
One of these proteins is called Nup153. It’s a protein that’s part of the nuclear pore complex, which sits on the surface of the nuclear membrane and controls the entry and exit of various proteins and molecules. In collaboration with another Salk team under the leadership of Martin Hetzer, Gage discovered that Nup153 was expressed at different levels depending on the cell type. Neural precursors had high levels of Nup153 protein, immature neurons had what they defined as an intermediate level while astrocytes had the lowest level.
When they blocked the function of Nup153, neural precursors differentiated, which led them to conclude that the levels of Nup153 can influence the fate of neural precursor cells. The teams also discovered that Nup153 interacts with the transcription factor Sox2 and that the levels of Sox2 in the different cell types was similar to the levels of Nup153.
A fluorescent microscopy image shows Nup153 (red) in pore complexes encircling and associating with Sox2 (green) in a precursor cell nucleus. Credit: Salk Institute/Waitt Center
In a Salk News release, first author on the study, Tomohisa Toda, explained how their findings shed light on basic cellular processes:
“The fact that we were able to connect transcription factors, which are mobile switches, to the pore complex, which is a very stable structure, offers a clue as to how cells maintain their identity through regulated gene expression.”
Gage’s team will next study how this partnership between the nuclear pore complex and transcription factors can influence the function of neurons in hopes of gaining more understanding of how an imbalance in these interactions can lead to neurological diseases.
“Increasingly, we are learning that diseases like schizophrenia, depression and Alzheimer’s all have a cellular basis. So we are eager to understand how specific brain cells develop, what keeps them healthy and why advancing age or other factors can lead to disease.”
Tomohisa Toda and Rusty Gage. Credit: Salk Institute
Targeting KRAS Mutant Cancer.
CIRM-funded scientists at UC San Diego School of Medicine have developed a new strategy to target cancers that are caused by a mutation in the KRAS gene. Their findings were published in the journal Cancer Discovery.
The KRAS protein is essential for normal signaling processes in tissues, but mutant versions of this protein can cause cancer. According to a UC San Diego Health news release about the study, “there are currently no effective treatments for the 95 percent of pancreatic cancers and up to 30 percent of non-small cell lung cancers with KRAS mutations.”
To address this need, the team identified a biomarker called αvb3 that is associated with cancers dependent on the KRAS mutation. They observed that a protein called Galectin-3 binds to αvb3, which is an integrin receptor on the surface of cancer cells, to promote mutant KRAS’s cancer-causing ability.
This realization offered the team a path towards potential treatments. By inhibiting Galectin-3 with a drug called GCS-100, the scientists would make KRAS-addicted cancers go cold turkey. Senior author on the study, David Cheresh, explained,
“This may be among the first approaches to successfully target KRAS mutant cancers. Previously, we didn’t understand why only certain KRAS-initiated cancers would remain addicted to the mutation. Now we understand that expression of integrin αvb3 creates the addiction to KRAS. And it’s those addicted cancers that we feel will be most susceptible to targeting this pathway using Galectin-3 inhibitors.”
Cheresh concluded that this novel approach could pave the way for a personalized medicine approach for KRAS-addicted cancers.
“KRAS mutations impact a large number of patients with cancer. If a patient has a KRAS mutant cancer, and the cancer is also positive for αvb3, then the patient could be a candidate for a therapeutic that targets this pathway. Our work suggests a personalized medicine approach to identify and exploit KRAS addicted tumors, providing a new opportunity to halt the progression of tumors that currently have no viable targeted therapeutic options.”
Commercializing cell therapy.
Our friends at RegMedNet made an infographic that illustrates how cell therapies have developed over time and how these therapies are advancing towards commercialization.
The infographic states, “The cell therapy industry is rapidly evolving, with new techniques, technology and applications being developed all the time. After some high-profile failures, all eyes are on regulating existing therapies to ensure patient safety is paramount. Legislators, regulators and other stakeholders around the world are navigating a difficult line between hope, hype and the scientific evidence.”
Check out their timeline below and visit the RegMedNet website for more news and information about the regenerative medicine field.