Bye Bye bubble baby disease: promising results from stem cell gene therapy trial for SCID

Evangelina Padilla-Vaccaro
(Front cover of CIRM’s 2016 Annual Report)

You don’t need to analyze any data to know for yourself that Evangelina Vaccaro’s experimental stem cell therapy has cured her of a devastating, often fatal disease of the immune system. All you have to do is look at a photo or video of her to see that she’s now a happy, healthy 5-year-old with a full life ahead of her.

But a casual evaluation of one patient won’t get therapies approved in the U.S. by the Food and Drug Administration (FDA). Instead, a very careful collection of quantitative data from a series of clinical trial studies is a must to prove that a treatment is safe and effective. Each study’s results also provide valuable information on how to tweak the procedures to improve each follow on clinical trial.

A CIRM-funded clinical trial study published this week by a UCLA research team in the Journal of Clinical Investigation did just that. Of the ten participants in the trial, nine including Evangelina were cured of adenosine deaminase-deficient severe combined immunodeficiency, or ADA-SCID, a disease that is usually fatal within the first year of life if left untreated.

In the past, children with SCID were isolated in a germ-free sterile clear plastic bubbles, thus the name “bubble baby disease”. [Credit: Baylor College of Medicine Archives]

ADA-SCID, also referred to as bubble baby disease, is so lethal because it destroys the ability to fight off disease. Affected children have a mutation in the adenosine deaminase gene which, in early development, causes the death of cells that normally would give rise to the immune system. Without those cells, ADA-SCID babies are born without an effective immune system. Even the common cold can be fatal so they must be sheltered in clean environments with limited physical contact with family and friends and certainly no outdoor play.

A few treatments exist but they have limitations. The go-to treatment is a blood stem cell transplant (also known as a bone marrow transplant) from a sibling with matched blood. The problem is that a match isn’t always available and a less than perfect match can lead to serious, life-threatening complications. Another treatment called enzyme replacement therapy (ERT) involves a twice-weekly injection of the missing adenosine deaminase enzyme. This approach is not only expensive but its effectiveness in restoring the immune system varies over a lifetime.

Evangelina being treated by Don Kohn and his team in 2012.  Photo: UCLA

The current study led by Don Kohn, avoids donor cells and enzyme therapy altogether by fixing the mutation in the patient’s own cells. Blood stem cells are isolated from a bone marrow sample and taken back to the lab where a functional copy of the adenosine deaminase gene is inserted into the patient’s cells. When those cells are ready, the patient is subjected to drugs – the same type that are used in cancer therapy – that kill off a portion of the patient’s faulty immune system to provide space in the bone marrow. Then the repaired blood stem cells are transplanted back into the body where they settle into the bone marrow and give rise to a healthy new immune system.

The ten patients were treated between 2009 and 2012 and their health was followed up for at least four years. As of June 2016, nine of the patients in the trial – (all infants except for an eight-year old) – no longer need enzyme injections and have working immune systems that allow them to play outside, attend school and survive colds and other infections that inevitably get passed around the classroom. The tenth patient was fifteen years old at the time of the trial and their treatment was not effective suggesting that early intervention is important. No serious side effects were seen in any of the patients.

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Evangelina Vaccaro (far right), who received Dr. Kohn’s treatment for bubble baby disease in 2012, with her family before her first day of school. Photo: UCLA, courtesy of the Vaccaro family

Now, this isn’t the first ever stem cell gene therapy clinical trial to successfully treat ADA-SCID. Kohn’s team and others have carried out clinical trials over the past few decades, and this current study builds upon the insights of those previous results. In a 2014 press release reporting preliminary results of this week’s published journal article, Kohn described the importance of these follow-on clinical trials for ensuring the therapy’s success:

UCLA Jonsson Comprehensive Cancer Center
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Don Kohn

“We were very happy that over the course of several clinical trials and after making refinements and improvements to the treatment protocol, we are now able to provide a cure for babies with this devastating disease using the child’s own cells.”

The team’s next step is getting FDA approval to use this treatment in all children with ADA-SCID. To reach this aim, the team is carrying out another clinical trial which will test a frozen preparation of the repaired blood stem cells. Being able to freeze the therapy product buys researchers more time to do a thorough set of safety tests on the cells before transplanting them into the patient. A frozen product is also much easier to transport for treating children who live far from the laboratories that perform the gene therapy. In November of last year, CIRM’s governing Board awarded Kohn’s team $20 million to support this project.

If everything goes as planned, this treatment will be the first stem cell gene therapy ever approved in the U.S. We look forward to adding many new photos next to Evangelina’s as more and more children are cured of ADA-SCID.

Stem cell stories that caught our eye: spinal cord injury trial update, blood stem cells in lungs, and using parsley for stem cell therapies

More good news on a CIRM-funded trial for spinal cord injury. The results are now in for Asterias Biotherapeutics’ Phase 1/2a clinical trial testing a stem cell-based therapy for patients with spinal cord injury. They reported earlier this week that six out of six patients treated with 10 million AST-OPC1 cells, which are a type of brain cell called oligodendrocyte progenitor cells, showed improvements in their motor function. Previously, they had announced that five of the six patients had shown improvement with the jury still out on the sixth because that patient was treated later in the trial.

 In a news release, Dr. Edward Wirth, the Chief Medical officer at Asterias, highlighted these new and exciting results:

 “We are excited to see the sixth and final patient in the AIS-A 10 million cell cohort show upper extremity motor function improvement at 3 months and further improvement at 6 months, especially because this particular patient’s hand and arm function had actually been deteriorating prior to receiving treatment with AST-OPC1. We are very encouraged by the meaningful improvements in the use of arms and hands seen in the SciStar study to date since such gains can increase a patient’s ability to function independently following complete cervical spinal cord injuries.”

Overall, the trial suggests that AST-OPC1 treatment has the potential to improve motor function in patients with severe spinal cord injury. So far, the therapy has proven to be safe and likely effective in improving some motor function in patients although control studies will be needed to confirm that the cells are responsible for this improvement. Asterias plans to test a higher dose of 20 million cells in AIS-A patients later this year and test the 10 million cell dose in AIS-B patients that a less severe form of spinal cord injury.

 Steve Cartt, CEO of Asterias commented on their future plans:

 “These results are quite encouraging, and suggest that there are meaningful improvements in the recovery of functional ability in patients treated with the 10 million cell dose of AST-OPC1 versus spontaneous recovery rates observed in a closely matched untreated patient population. We look forward to reporting additional efficacy and safety data for this cohort, as well as for the currently-enrolling AIS-A 20 million cell and AIS-B 10 million cell cohorts, later this year.”

Lungs aren’t just for respiration. Biology textbooks may be in need of some serious rewrites based on a UCSF study published this week in Nature. The research suggests that the lungs are a major source of blood stem cells and platelet production. The long prevailing view has been that the bone marrow was primarily responsible for those functions.

The new discovery was made possible by using special microscopy that allowed the scientists to view the activity of individual cells within the blood vessels of a living mouse lung (watch the fascinating UCSF video below). The mice used in the experiments were genetically engineered so that their platelet-producing cells glowed green under the microscope. Platelets – cell fragments that clump up and stop bleeding – were known to be produced to some extent by the lungs but the UCSF team was shocked by their observations: the lungs accounted for half of all platelet production in these mice.

Follow up experiments examined the movement of blood cells between the lung and bone marrow. In one experiment, the researchers transplanted healthy lungs from the green-glowing mice into a mouse strain that lacked adequate blood stem cell production in the bone marrow. After the transplant, microscopy showed that the green fluorescent cells from the donor lung traveled to the host’s bone marrow and gave rise to platelets and several other cells of the immune system. Senior author Mark Looney talked about the novelty of these results in a university press release:

Mark Looney, MD

“To our knowledge this is the first description of blood progenitors resident in the lung, and it raises a lot of questions with clinical relevance for the millions of people who suffer from thrombocytopenia [low platelet count].”

If this newfound role of the lung is shown to exist in humans, it may provide new therapeutic approaches to restoring platelet and blood stem cell production seen in various diseases. And it will give lung transplants surgeons pause to consider what effects immune cells inside the donor lung might have on organ rejection.

Add a little vanilla to this stem cell therapy. Typically, the only connection between plants and stem cell clinical trials are the flowers that are given to the patient by friends and family. But research published this week in the Advanced Healthcare Materials journal aims to use plant husks as part of the cell therapy itself.

Though we tend to focus on the poking and prodding of stem cells when discussing the development of new therapies, an equally important consideration is the use of three-dimensional scaffolds. Stem cells tend to grow better and stay healthier when grown on these structures compared to the flat two-dimensional surface of a petri dish. Various methods of building scaffolds are under development such as 3D printing and designing molds using materials that aren’t harmful to human tissue.

Human fibroblast cells growing on decellularized parsley.
Image: Gianluca Fontana/UW-Madison

But in the current study, scientists at the University of Wisconsin-Madison took a creative approach to building scaffolds: they used the husks of parsley, vanilla and orchid plants. The researchers figured that millions of years of evolution almost always leads to form and function that is much more stable and efficient than anything humans can create. Lead author Gianluca Fontana explained in a university press release how the characteristics of plants lend themselves well to this type of bioengineering:

Gianluca Fontana, PhD

“Nature provides us with a tremendous reservoir of structures in plants. You can pick the structure you want.”

The technique relies on removing all the cells of the plant, leaving behind its outer layer which is mostly made of cellulose, long chains of sugars that make up plant cell walls. The resulting hollow, tubular husks have similar shapes to those found in human intestines, lungs and the bladder.

The researchers showed that human stem cells not only attach and grow onto the plant scaffolds but also organize themselves in alignment with the structures’ patterns. The function of human tissues rely on an organized arrangement of cells so it’s possible these plant scaffolds could be part of a tissue replacement cell product. Senior author William Murphy also points out that the scaffolds are easily altered:

William Murphy, PhD

“They are quite pliable. They can be easily cut, fashioned, rolled or stacked to form a range of different sizes and shapes.”

And the fact these scaffolds are natural products that are cheap to manufacture makes this a project well worth watching.

A stem cell clinical trial for blindness: watch Rosie’s story

Everything we do at CIRM is laser-focused on our mission: to accelerate stem cell treatments for patients with unmet medical needs. So, you might imagine what a thrill it is to meet the people who could be helped by the stem cell research we fund. People like Rosie Barrero who suffers from Retinitis Pigmentosa (RP), an inherited, incurable form of blindness, which she describes as “an impressionist painting in a foggy room”.

The CIRM team first met Rosie Barrero back in 2012 at one of our governing Board meetings. She and her husband, German, attended the meeting to advocate for a research grant application submitted by UC Irvine’s Henry Klassen. The research project aimed to bring a stem cell-based therapy for RP to clinical trials. The Board approved the project giving a glimmer of hope to Rosie and many others stricken with RP.

Now, that hope has become a reality in the form of a Food and Drug Administration (FDA)-approved clinical trial which Rosie participated in last year. Sponsored by jCyte, a company Klassen founded, the CIRM-funded trial is testing the safety and effectiveness of a non-surgical treatment for RP that involves injecting stem cells into the eye to help save or even restore the light-sensing cells in the back of the eye. The small trial has shown no negative side effects and a larger, follow-up trial, also funded by CIRM, is now recruiting patients.

Almost five years after her first visit, Rosie returned to the governing Board in February and sprinkled in some of her witty humor to describe her preliminary yet encouraging results.

“It has made a difference. I’m still afraid of public speaking but early on [before the clinical trial] it was much easier because I couldn’t see any of you. But, hello everybody! I can see you guys. I can see this room. I can see a lot of things.”

After the meeting, she sat down for an interview with the Stem Cellar team to talk about her RP story and her experience as a clinical trial participant. The three-minute video above is based on that interview. Watch it and be inspired!

A horse, stem cells and an inspiring comeback story that may revolutionize tendon repair

Everyone loves a good comeback story. Probably because it leaves us feeling inspired and full of hope. But the comeback story about a horse named Dream Alliance may do more than that: his experience promises to help people with Achilles tendon injuries get fully healed and back on their feet more quickly.

Dream Alliance

Dream Alliance was bred and raised in a very poor Welsh town in the United Kingdom. One of the villagers had the dream of owning a thoroughbred racehorse. She convinced a group of her fellow townsfolk to pitch in $15 dollars a week to cover the costs of training the horse. Despite his lowly origins, Dream Alliance won his fourth race ever and his future looked bright. But during a race in 2008, one of his back hoofs cut a tendon in his front leg. The seemingly career-ending injury was so severe that the horse was nearly euthanized.

It works in horses, how about humans?
Instead, he received a novel stem cell procedure which healed the tendon and, incredibly, the thoroughbred went on to win the Welsh Grand National race 15 months later – one of the biggest races in the UK that is almost 4 miles long and involves jumping 22 fences. Researchers at the Royal Veterinary College in Liverpool developed the method and data gathered from the treatment of 1500 horses with this stem cell therapy show a 50% decrease in re-injury of the tendon.

It’s been so successful in horses that researchers at the University College of London and the Royal National Orthopaedic Hospital are currently running a clinical trial to test the procedure in humans.  Over the weekend, the Daily Mail ran a news story about the clinical trial. In it, team lead Andrew Goldberg explained how they got the human trial off the ground:

“Tendon injuries in horses are identical to those in humans, and using this evidence [from the 1500 treated horses] we were able to persuade the regulators to allow us to launch a small safety study in humans.”

Tendon repair: there’s got to be another way

Achilles tendon connects the calf muscle to the heel bone

The Achilles tendon is the largest tendon in the body and connects the calf muscle to the heel bone. It takes on a lot of strain during running and jumping so it’s a well-known injury to professional and recreational athletes but injuries also occur in those with a sedentary lifestyle. Altogether Achilles tendon injury occurs in about 5-10 people per 100,000. And about 25%-45% of those injuries require surgery which involves many months of crutches and it doesn’t always work. That’s why this stem cell approach is sorely needed.

The procedure is pretty straight forward as far as stem cell therapies go. Bone marrow from the patient’s hip is collected and mesenchymal stem cells – making up a small fraction of the marrow – are isolated. The stem cells are transferred to petri dishes and allowed to divide until there are several million cells. Then they are injected directly into the injured tendon.

A reason to be cautiously optimistic
Early results from the clinical trial are encouraging with a couple of the patients experiencing improvements. The Daily Mail article featured the clinical trial’s first patient who went from a very active lifestyle to one of excruciating ankle pain due to a gradually deteriorating Achilles tendon. Though hesitant when she first learned about the trial, the 46-year-old ultimately figured that the benefits outweighed the risk. That turned out to be a good decision:

“I worried, because no one had ever had it before, except a horse. But I was more worried I’d end up in a wheelchair. The difference now is amazing. I can do five miles on the treadmill without pain, and take my dog Honey on long walks again.”

The researchers aren’t exactly sure how the therapy works but mesenchymal stem cells are known to release factors that promote regeneration and reduce inflammation. The first patient’s positive results are just anecdotal at this point. The clinical trial is still recruiting volunteers so definitive results are still on the horizon. And even if that small trial is successful, larger clinical trials will be required to confirm effectiveness and safety. It will take time but without the careful gathering of this data, doctors and patients will remain in the dark about their chances for success with this stem cell treatment.

Hopefully the treatment proves to be successful and ushers in a golden era of comeback stories. Not just for star athletes eager to get back on the field but also for the average person whose career, good health and quality of life depends on their mobility.

3D printing blood vessels: a key step to solving the organ donor crisis

About 120,000 people in the U.S. are on a waiting list for an organ donation and every day 22 of those people will die because there aren’t enough available organs. To overcome this organ donor crisis, bioengineers are working hard to develop 3D printing technologies that can construct tissues and organs from scratch by using cells as “bio-ink”.

Though each organ type presents its own unique set of 3D bioprinting challenges, one key hurdle they all share is ensuring that the transplanted organ is properly linked to a patient’s  circulatory system, also called the vasculature. Like the intricate system of pipes required to distribute a city’s water supply to individual homes, the blood vessels of our circulatory system must branch out and reach our organs to provide oxygen and nutrients via the blood. An organ won’t last long after transplantation if it doesn’t establish this connection with the vasculature.

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Digital model of blood vessel network. Photo: Erik Jepsen/UC San Diego Publications

In a recent UC San Diego (UCSD) study, funded in part by CIRM, a team of engineers report on an important first step toward overcoming this challenge: they devised a new 3D bioprinting method to recreate the complex architecture of blood vessels found near organs. This type of 3D bioprinting approach has been attempted by other labs but these earlier methods only produced simple blood vessel shapes that were costly and took hours to fabricate.  The UCSD team’s home grown 3D bioprinting process, in comparison, uses inexpensive components and only takes seconds to complete. Wei Zhu, the lead author on the Biomaterials publication, expanded on this comparison in a press release:

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Wei Zhu

“We can directly print detailed microvasculature structures in extremely high resolution. Other 3D printing technologies produce the equivalent of ‘pixelated’ structures in comparison and usually require … additional steps to create the vessels.”

 

As a proof of principle, the bioprinted vessel structures – made with two human cell types found in blood vessels – were transplanted under the skin of mice. After two weeks, analysis of the skin showed that the human grafts were thriving and had integrated with the mice’s blood vessels. In fact, the presence of red blood cells throughout these fused vessels provided strong evidence that blood was able to circulate through them. Despite these promising results a lot of work remains.

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Microscopic 3D printed blood vessel structure. Photo: Erik Jepsen/UC San Diego Publications

As this technique comes closer to a reality, the team envisions using induced pluripotent stem cells to grow patient-specific organs and vasculature which would be less likely to be rejected by the immune system.

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Shaochen Chen

“Almost all tissues and organs need blood vessels to survive and work properly. This is a big bottleneck in making organ transplants, which are in high demand but in short supply,” says team lead Shaochen Chen. “3D bioprinting organs can help bridge this gap, and our lab has taken a big step toward that goal.”

 

We eagerly await the day when those transplant waitlists become a thing of the past.

Stem cell stories that caught our eye: building an embryo and reviving old blood stem cells

Building an embryo in the lab from stem cells
The human body has been studied for centuries yet little is known about the first 14 days of human development when the fertilized embryo implants into the mother’s uterus and begins to divide and grow. Being able to precisely examine this critical time window may help researchers better understand why 75% of conceptions never implant and why 30% of pregnancies end in miscarriage.

This lack of knowledge is due in part to a lack of embryos to study. Researchers rely on embryos donated by couples who’ve gone through in vitro fertilization to get pregnant and have left over embryos that are otherwise discarded. Using mouse stem cells, a research team from Cambridge University reports today in Nature that they’ve generated a cellular structure that has the hallmarks of a fertilized embryo.

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Stem cell-modeled mouse embryo (left) Mouse embryo (right); The red part is embryonic and the blue extra-embryonic.
Credit: Sarah Harrison and Gaelle Recher, Zernicka-Goetz Lab, University of Cambridge

This technique has been tried before without success. The breakthrough here was in the types of cells used. Rather that only relying on embryonic stems cells (ESCs), this study also included extra-embryonic trophoblast stem cells (TSCs), the cell type that goes on to form the placenta.

When grown on a 3D scaffold made from biological materials, the two cell types self-organized themselves into a pattern that closely resembles the early development of a true embryo. In a press release that was picked up by many media outlets, senior author Zernicka-Goetz spoke about the importance of including both TSCs and ESCs:

“We knew that interactions between the different types of stem cell are important for development, but the striking thing that our new work illustrates is that this is a real partnership – these cells truly guide each other. Without this partnership, the correct development of shape and form and the timely activity of key biological mechanisms doesn’t take place properly.”

The researchers think that lab-made embryos from mouse or human stem cells have little chance of developing into a fetus because other cell types critical for continued growth are not included. And there’s much to be learned by focusing on these very early events:

“We are very optimistic that this will allow us to study key events of this critical stage of human development without actually having to work on embryos.  Knowing how development normally occurs will allow us to understand why it so often goes wrong,” says Zernicka-Goetz.

Reviving old blood stem cells, part 1: repair the garbage collectors
One of the reasons that our bodies begin to deteriorate in old age is a weakening, dysfunctional immune system that increases the risk for serious infection, blood cancers and chronic inflammatory diseases like atherosclerosis (hardening of the arteries). Reporting this week in Nature, a UCSF research team presents evidence that a breakdown in our cell’s natural garbage collecting system may be partially to blame.

The team focused on a process called autophagy (literally meaning self “auto”-eating “phagy”) that keeps cells functioning properly by degrading faulty proteins and cellular structures. In particular, they examined autophagy in blood-forming stem cells, which give rise to all the cell types of the immune system. They found that autophagy was not working in 70 percent of blood stem cells from old mice. And these cells had all the hallmarks of an old cell. And the other 30 percent? In those cells, autophagy was fully functional and they looked like blood stem cells found in young mice.

The team went on to show that in blood stem cells, autophagy had an additional role that until now had not been observed: it helped slow the activity of the stem cells back to its default state by gobbling up excess mitochondria, the structures that produces a cell’s energy needs. Without this quieting of the stem cell, the over-active mitochondria led to chemical modification of the cell’s DNA that disrupted the blood stem cells’ ability to give rise to a proper balance of immune cells. In fact, young mice with genetic modifications that block autophagy generated blood stem cells with these old age-related characteristics.

But the researchers were also able to restore autophagy in blood stem cells collected from old mice by adding various drugs. Team lead Emmanuelle Passegué is optimistic this result could be translated into a therapeutic approach:

“This discovery might provide an interesting therapeutic angle to use in re-activating autophagy in all of the old HSCs, to slow the aging of the blood system and to improve engraftment during bone marrow or HSC transplantation,” Passegué said in a university press release.

Reviving old blood stem cells, part 2: fix the aging neighborhood
Another study this week focused on age-related disruptions in the function of blood stem cells but in this case an aging neighborhood is to blame. Blood stem cells form and hang out in areas of the bone marrow called niches. Researchers at the Cincinnati Children’s Hospital Medical Center and the University of Ulm in Germany reported this week in EMBO that the age of the niche affects blood stem cell function.

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Microscopy of bone marrow. Red staining indicates osteopotin, blue staining indicates cell nuclei. Credit: University of Ulm

 

When blood stem cells from two-year old mice were transplanted into the bone marrow of eight-week old mice, the older stem cells took on characteristics of young stem cells including an enhance ability to form all the different cell types of the immune system. In trying to understand what was going on, the researchers focused on a bone marrow cell called an osteoblast which gives rise to bone. Osteoblasts produce osteopontin, a protein that plays an important role in the structure of the bone marrow. The team showed that as the bone marrow ages, osteopontin levels go down. And this reduction had effects on the health of blood stem cells. But, as team lead Hartmut Geiger mentions in a press release, this impact could be reversed which points to a potential new therapeutic strategy for age-related disease:

“We show that the place where HSCs form in the bone marrow loses osteopontin upon aging, but if you give back the missing protein to the blood-forming cells they suddenly rejuvenate and act younger. Our study points to exciting novel ways to have a better immune system and possibly less blood cancer upon aging by therapeutically targeting the place where blood stem cells form.”

Reducing animal testing with stem cells and electronic petri dishes

botoxThough the celebrities at Sunday’s Academy Awards worked hard to sport unique clothing and hair styles, I bet many had something in common: Botox injections. Botox, an FDA-approved, marketed form of Botulism neurotoxin, is well known for its wrinkle reducing effects. The neurotoxin’s other claim to fame is the fact that it’s the most lethal, naturally occurring poison known. Inhaling a minuscule amount – just 0.0000007 grams! – is enough to kill a 150 pound person.

Much smaller, non-lethal doses of Botulism neurotoxin are obviously used for its cosmetic application. It’s also used to treat a wide range of disorders including back pain, migraines and muscle spasms related to stroke and cerebral palsy. Because the toxin is produced naturally by the Clostridium botulinum bacteria, the amount of toxin can vary in each batch during the manufacturing process. So, it’s critical to carefully analyze the Botulism neurotoxin dose.  The standard test which has been around since the 1920’s is the mouse bioassay. During the test, increasing concentrations of the neurotoxin are injected into mice which are then observed for signs of paralysis (Botulism neurotoxin acts by blocking communication between nerves and muscle).

As you might expect, the lab mice suffer during the test, sometimes suffocating during the process. Because of the large market for these Botulism neurotoxin-based products, it’s estimated that about 600,000 laboratory mice in US and Europe are killed via the mouse bioassay each year. Though the media often portrays scientists as callous, cold-hearted people that couldn’t care less about the welfare of their lab animals, in reality, it’s just the opposite. Case in point: a research group at the University of Bern in Switzerland reported this week in Frontiers in Pharmacology that they have devised an alternative system that could help make this mouse bioassay obsolete.

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Multi-electrode assay petri dish. Credit: Multichannel Systems

To set up this new assay system, the researchers relied on mouse embryonic stem cells. The researchers added chemicals to the cells, stimulating them to transform into nerve cells, or neurons. These stem cell-derived neurons were placed in specialized petri dishes that look something like a computer chip. Wired with mini electrodes, the lab dishes allowed the continuous recording of electrical signals generated by the neurons. Adding small doses of Botox to the cells, the scientists could detect a shutdown of the neuron signaling which is the same underlying effect that causes paralysis in the mouse bioassay.

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Stem cell-derived neurons (green) grown on electrodes (outlined in white) allows monitoring of electrical nerve signals. Credit: Stephen Jenkinson, Institute for Infectious Diseases, University of Bern

This sensitive test could have applications beyond the detection of Botulism neurotoxin. The electrode dishes are easy to scale up and do not require highly trained staff. So, without the need for expensive animal testing, this system could be used as a high throughput drug screening platform to find other substances that have beneficial effects on neuron signaling.

Stem cells stories that caught our eye: switching cell ID to treat diabetes, AI predicts cell fate, stem cell ALS therapy for Canada

Treating diabetes by changing a cell’s identity. Stem cells are an ideal therapy strategy for treating type 1 diabetes. That’s because the disease is caused by the loss of a very specific cell type: the insulin-producing beta cell in the pancreas. So, several groups are developing treatments that aim to replace the lost cells by transplanting stem cell-derived beta cells grown in the lab. In fact, Viacyte is applying this approach in an ongoing CIRM-funded clinical trial.

In preliminary animal studies published late last week, a Stanford research team has shown another approach may be possible which generates beta cells inside the body instead of relying on cells grown in a petri dish. The CIRM-funded Cell Metabolism report focused on alpha cells, another cell type in pancreas which produces the hormone glucagon.

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Microscopy of islet cells, round clusters of cells found in the pancreas. The brown stained cells are glucagon-producing alpha cells. Credit: Wikimedia Commons

After eating a meal, insulin is critical for getting blood sugar into your cells for their energy needs. But glucagon is needed to release stored up sugar, or glucose, into your blood when you haven’t eaten for a while. The research team, blocked two genes in mice that are critical for maintaining an alpha cell state. Seven weeks after inhibiting the activity of these genes, the researchers saw that many alpha cells had converted to beta cells, a process called direct reprogramming.

Does the same thing happen in humans? A study of cadaver donors who had been recently diagnosed with diabetes before their death suggests the answer is yes. An analysis of pancreatic tissue samples showed cells that produced both insulin and glucagon, and appeared to be in the process of converting from beta to alpha cells. Further genetic tests showed that diabetes donor cells had lost activity in the two genes that were blocked in the mouse studies.

It turns out that there’s naturally an excess of alpha cells so, as team lead Seung Kim mentioned in a press release, this strategy could pan out:

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Seung Kim. Credit: Steve Fisch, Stanford University

“This indicates that it might be possible to use targeted methods to block these genes or the signals controlling them in the pancreatic islets of people with diabetes to enhance the proportion of alpha cells that convert into beta cells.”

Using computers to predict cell fate. Deep learning is a cutting-edge area of computer science that uses computer algorithms to perform tasks that border on artificial intelligence. From beating humans in a game of Go to self-driving car technology, deep learning has an exciting range of applications. Now, scientists at Helmholtz Zentrum München in Germany have used deep learning to predict the fate of cells.

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Using deep learning, computers can predict the fate of these blood stem cells.
Credit: Helmholtz Zentrum München.

The study, published this week in Nature Methods, focused on blood stem cells also called hematopoietic stem cells. These cells live in the bone marrow and give rise to all the different types of blood cells. This process can go awry and lead to deadly disorders like leukemia, so scientists are very interested in exquisitely understanding each step that a blood stem cell takes as it specializes into different cell types.

Researchers can figure out the fate of a blood stem cells by adding tags, which glow with various color, to the cell surface . Under a microscope these colors reveal the cells identity. But this method is always after the fact. There no way to look at a cell and predict what type of cell it is turning into. In this study, the team filmed the cells under a microscope as they transformed into different cell types. The deep learning algorithm processed the patterns in the cells and developed cell fate predictions. Now, compared to the typical method using the glowing tags, the researchers knew the eventual cell fates much sooner. The team lead, Carsten Marr, explained how this new technology could help their research:

“Since we now know which cells will develop in which way, we can isolate them earlier than before and examine how they differ at a molecular level. We want to use this information to understand how the choices are made for particular developmental traits.”

Stem cell therapy for ALS seeking approval in Canada. (Karen Ring) Amyotrophic lateral sclerosis (ALS) is a progressive neuromuscular disease that kills off the nerve cells responsible for controlling muscle movement. Patients with ALS suffer from muscle weakness, difficulty in speaking, and eventually breathing. There is no cure for ALS and the average life expectancy after diagnosis is just 2 – 5 years. But companies are pursuing stem cell-based therapies in clinical trials as promising treatment options.

One company in particular, BrainStorm Cell Therapeutics based in the US and Israel, is testing a mesenchymal stem cell-based therapy called NurOwn in ALS patients in clinical trials. In their Phase 2 trials, they observed clinical improvements in slowing down the rate of disease progression following the stem cell treatment.

In a recent update from our friends at the Signals Blog, BrainStorm has announced that it is seeking regulatory approval of its NurOwn treatment for ALS patients in Canada. They will be working with the Centre for Commercialization of Regenerative Medicine (CCRM) to apply for a special regulatory approval pathway with Health Canada, the Canadian government department responsible for national public health.

In a press release, BrainStorm CEO Chaim Lebovits, highlighted this new partnership and his company’s mission to gain regulatory approval for their ALS treatment:

“We are pleased to partner with CCRM as we continue our efforts to develop and make NurOwn available commercially to patients with ALS as quickly as possible. We look forward to discussing with Health Canada staff the results of our ALS clinical program to date, which we believe shows compelling evidence of safety and efficacy and may qualify for rapid review under Canada’s regulatory guidelines for drugs to treat serious or life-threatening conditions.”

Stacey Johnson who wrote the Signals Blog piece on this story explained that while BrainStorm is not starting a clinical trial for ALS in Canada, there will be significant benefits if its treatment is approved.

“If BrainStorm qualifies for this pathway and its market authorization request is successful, it is possible that NurOwn could be available for patients in Canada by early 2018.  True access to improved treatments for Canadian ALS patients would be a great outcome and something we are all hoping for.”

CIRM is also funding stem cell-based therapies in clinical trials for ALS. Just yesterday our Board awarded Cedars-Sinai $6.15 million dollars to conduct a Phase 1 trial for ALS patients that will use “cells called astrocytes that have been specially re-engineered to secrete proteins that can help repair and replace the cells damaged by the disease.” You can read more about this new trial in our latest news release.

Stem cell stories that caught our eye: drug safety for heart cells, worms hijack plant stem cells & battling esophageal cancer

Devising a drug safety measuring stick in stem cell-derived heart muscle cells
One of the mantras in the drug development business is “fail early”. That’s because most of the costs of getting a therapy to market occur at the later stages when an experimental treatment is tested in clinical trials in people. So, it’s best for a company’s bottom line and, more importantly, for patient safety to figure out sooner rather than later if a therapy has dangerous toxic side effects.

Researchers at Stanford reported this week in Science Translational Medicine on a method they devised that could help weed out cancer drugs with toxic effects on the heart before the treatment is tested in people.

In the lab, the team grew beating heart muscle cells, or cardiomyocytes, from induced pluripotent stem cells derived from both healthy volunteers and kidney cancer patients. A set of cancer drugs called tyrosine kinase inhibitors which are known to have a range of serious side effects on the heart, were added to the cells. The effect of the drugs on the heart cell function were measured with several different tests which the scientists combined into a single “safety index”.

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A single human induced pluripotent stem cell-derived cardiomyocyte. Cells such as these were used to assess tyrosine kinase inhibitors for cardiotoxicity in a high-throughput fashion. Credit: Dr. Arun Sharma at Dr. Joseph Wu’s laboratory at Stanford University

They found that the drugs previously shown to have toxic effects on patients’ hearts had the worst safety index values in the current study. And because these cells were in a lab dish and not in a person’s heart, the team was able to carefully examine cell activity and discovered that the toxic effects of three drugs could be alleviated by also adding insulin to the cells.

As lead author Joseph Wu, director of the Stanford Cardiovascular Institute, mentions in a press release, the development of this drug safety index could provide a powerful means to streamline the drug development process and make the drugs safer:

“This type of study represents a critical step forward from the usual process running from initial drug discovery and clinical trials in human patients. It will help pharmaceutical companies better focus their efforts on developing safer drugs, and it will provide patients more effective drugs with fewer side effects”

Worm feeds off of plants by taking control of their stem cells
In what sounds like a bizarre mashup of a vampire movie with a gardening show, a study reported this week pinpoints how worms infiltrate plants by commandeering the plants’ own stem cells. Cyst nematodes are microscopic roundworms that invade and kill soybean plants by sucking out their nutrients. This problem isn’t a trivial matter since nematodes wreak billions of dollars of damage to the world’s soybean crops each year. So, it’s not surprising that researchers want to understand how exactly these critters attack the plants.

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A nematode, the oblong object on the left, activates the vascular stem cell pathway in the developing nematode feeding site on a plant root. Credit: Xiaoli Guo, University of Missouri

Previous studies by Melissa Goellner Mitchum, a professor at the University of Missouri, had shown that the nematodes release protein fragments, called peptides, near a plant’s roots that help divert the flow of plant nutrients to the worm.

“These parasites damage root systems by creating a unique feeding cell within the roots of their hosts and leeching nutrients out of the soybean plant. This can lead to stunting, wilting and yield loss for the plant,” Mitchum explained in a press release.

In the current PLOS Pathogens study, Mitchum’s team identified another peptide produced by the nematode that is identical to a plant peptide that instructs stem cells to form the plant equivalent of blood vessels. This devious mimicking of the plant peptides is what allows the nematode to trick the plant stem cells into building vessels that reroute the plants’ nutrients directly to the worm.

Mitchum described the big picture implications of this fascinating discovery:

“Understanding how plant-parasitic nematodes modulate host plants to their own benefit is a crucial step in helping to create pest-resistant plants. If we can block those peptides and the pathways nematodes use to overtake the soybean plant, then we can enhance resistance for this very valuable global food source.”

Finding vulnerabilities in treatment-resistant esophageal cancer stem cells

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Illustration of radiation therapy for esophageal cancer.
Credit: Cancer Research UK

The incidence of esophageal cancer has increased more than any other disease over the past 30 years. And while some patients respond well to chemotherapy and radiation treatment, most do not because the cancer becomes resistant to these treatments.

Focusing on cancer stem cells, researchers at Trinity College Dublin have identified an approach that may overcome treatment resistance.

Within tumors are thought to lie cancer stem cells that, just like stem cells, have the ability to multiply indefinitely. Even though they make up a small portion of a tumor, in some patients the cancer stem cells evade the initial rounds of treatment and are responsible for the return of the cancer which is often more aggressive. Currently, there’s no effective way to figure out how well a patient with esophageal cancer will response to treatment.

In the current study published in Oncotarget, the researchers found that a genetic molecule called miR-17 was much less abundant in the esophageal cancer stem cells. In fact, the cancer stem cells with the lowest levels of miR-17, were the most resistant to radiation therapy. The researchers went on to show that adding back miR-17 to the highly resistant cells made them sensitive again to the radiation. Niamh Lynam-Lennon, the study’s first author, explained in a press release that these results could have direct clinical applications:

“Going forward, we could use synthetic miR-17 as an addition to radiotherapy to enhance its effectiveness in patients. This is a real possibility as a number of other synthetic miR-molecules are currently in clinical trials for treating other diseases.”

Rhythmic brain circuits built from stem cells

The TV commercial is nearly 20 years old but I remember it vividly: a couple is driving down a street when they suddenly realize the music on their tape deck is in sync with the repetitive activity on the street. From the guy casually dribbling a basketball to people walking along the sidewalk to the delivery people passing packages out of their truck, everything and everyone is moving rhythmically to the beat.

The ending tag line was, “Sometimes things just come together,” which is quite true. Many of our basic daily activities like breathing and walking just come together as a result of repetitive movement. It’s easy to take them for granted but those rhythmic patterns ultimately rely on very intricate, interconnected signals between nerve cells, also called neurons, in the brain and spinal cord.

Circuitoids: a neural network in a lab dish

A CIRM-funded study published yesterday in eLife by Salk Institute scientists reports on a method to mimic these repetitive signals in a lab dish using neurons grown from embryonic stem cells. This novel cell circuitry system gives the researchers a tool for gaining new insights into neurodegenerative diseases, like Parkinson’s and ALS, and may even provide a means to fix neurons damaged by injury or disease.

The researchers changed or specialized mouse embryonic stem cells into neurons that either stimulate nerve signals, called excitatory neurons, or neurons that block nerve signals, called inhibitory neurons. Growing these groups of cells together led to spontaneous rhythmic nerve signals. These clumps of cells containing about 50,000 neurons each were dubbed circuitoids by the team.

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Confocal microscope immunofluorescent image of a spinal cord neural circuit made entirely from stem cells and termed a “circuitoid.” Credit: Salk Institute.

Making neural networks dance to a different beat

A video produced by the Salk Institute (see below), shows some fascinating microscopy visualizations of these circuitoids’ repetitive signals. In the video, team leader Samuel Pfaff explains that changing the ratio of excitatory vs inhibitory neurons had noticeable effects on the rhythm of the nerve impulses:

“What we were able to do is combine different ratios of cell types and study properties of the rhythmicity of the circuitoid. And that rhythmicity could be very tightly control depending on the cellular composition of the neural networks that we were forming. So we could regulate the speed [of the rhythmicity] which is kind of equivalent to how fast you’re walking.”

It’s possible that the actual neural networks in our brains have the flexibility to vary the ratio of the active excitatory to inhibitory neurons as a way to allow adjustments in the body’s repetitive movements. But the complexity of those networks in the human brain are staggering which is why these circuitoids could help:

Samuel Pfaff. (Salk Institute)

Samuel Pfaff. (Salk Institute)

“It’s still very difficult to contemplate how large groups of neurons with literally billions if not trillions of connections take information and process it,” says Pfaff in a press release. “But we think that developing this kind of simple circuitry in a dish will allow us to extract some of the principles of how real brain circuits operate. With that basic information maybe we can begin to understand how things go awry in disease.”