Getting older brings with it a mixed bag of items. If you are lucky you can get wiser. If you are not so lucky you can get osteoporosis. But while scientists don’t know how to make you wiser, they have gained some new insights into what makes bones weak and so they might be able to help with the osteoporosis.
Around 200 million people worldwide suffer from osteoporosis, a disease that causes bones to become so brittle that in extreme cases even coughing can lead to a fracture.
Scientists have known for some time that the cells that form the building blocks of our skeletons are found in the bone marrow. They are called mesenchymal stem cells (MSCs) and they have the ability to turn into a number of different kinds of cells, including bone or fat. The keys to deciding which direction the MSCs take are things called epigenetic factors, these basically control which genes are switched on or off and in what order. Now researchers from the UCLA School of Dentistry have identified an enzyme that plays a critical role in that process.
The team found that when the enzyme KDM4B is missing in MSCs those cells are more likely to become fat cells rather than bone cells. Over time that leads to weaker bones and more fractures.
In a news release Dr. Cun-Yu Wang, the lead researcher, said: “We know that bone loss comes with age, but the mechanisms behind extreme cases such as osteoporosis have, up until recently, been very vague.”
To see if they were on the right track the team created a mouse model that lacked KDM4B. Just as they predicted the MSCs in the mouse created more fat than bone, leading to weaker skeletons.
They also looked at mice who were placed on a high fat diet – something known to increase bone loss and weaker bones in people – and found that the diet seemed to reduce KDM4B which in turn produced weaker bones.
In the news release Dr. Paul Krebsbach, Dean of the UCLA School of Dentistry, said the implications for the research are enormous. “The work of Dr. Wang, his lab members and collaborators provides new molecular insight into the changes associated with skeletal aging. These findings are an important step towards what may lead to more effective treatment for the millions of people who suffer from bone loss and osteoporosis.”
At CIRM we are modest enough to know that we can’t do everything by ourselves. To succeed we need partners. And in UC Davis we have a terrific partner. The work they do in advancing stem cell research is exciting and really promising. But it’s not just the science that makes them so special. It’s also their compassion and commitment to caring for patients.
What follows is an excerpt from an article by Lisa Howard on the work they do at UC Davis. When you read it you’ll see why we are honored to be a part of this research.
Gene therapy research at UC Davis
UC Davis’ commitment to stem cell and gene therapy research dates back more than a decade.
In 2010, with major support from the California Institute for Regenerative Medicine (CIRM), UC Davis launched the UC Davis Institute for Regenerative Cures, which includes research facilities as well as a Good Manufacturing Practice (GMP) facility.
Led by Jan Nolta, a professor of cell biology and human anatomy and the director of the UC Davis Institute for Regenerative Cures, the new center leverages UC Davis’ network of expert researchers, facilities and equipment to establish a center of excellence aimed at developing lifelong cures for diseases.
Nolta began her career at the University of Southern California working with Donald B. Kohn on a cure for bubble baby disease, a condition in which babies are born without an immune system. The blood stem cell gene therapy has cured more than 50 babies to date.
Work at the UC Davis Gene Therapy Center targets disorders that potentially can be treated through gene replacement, editing or augmentation.
“The sectors that make up the core of our center stretch out across campus,” said Nolta. “We work with the MIND Institute a lot. We work with the bioengineering and genetics departments, and with the Cancer Center and the Center for Precision Medicine and Data Sciences.”
A recent UC Davis stem cell study shows a potential breakthrough for healing diabetic foot ulcers with a bioengineered scaffold made up of human mesenchymal stem cells (MSCs). Another recent study revealed that blocking an enzyme linked with inflammation enables stem cells to repair damaged heart tissue. A cell gene therapy study demonstrated restored enzyme activity in Tay-Sachs disease affected cells in humanized mouse models.
“Some promising and exciting research right now at the Gene Therapy Center comes from work with hematopoietic stem cells and with viral vector delivery,” said Nolta.
Hematopoietic stem cells give rise to other blood cells. A multi-institutional Phase I clinical trial using hematopoietic stem cells to treat HIV-lymphoma patients is currently underway at UC Davis.
“We are genetically engineering a patient’s own blood stem cells with genes that block HIV infection,” said Joseph Anderson, an associate professor in the UC Davis Department of Internal Medicine. The clinical trial is a collaboration with Mehrdad Abedi, the lead principal investigator.
“When the patients receive the modified stem cells, any new immune system cell, like T-cell or macrophage, that is derived from one of these stem cells, will contain the HIV-resistant genes and block further infection,” said Anderson.
He explained that an added benefit with the unique therapy is that it contains an additional gene that “tags” the stem cells. “We are able to purify the HIV-resistant cells prior to transplantation, thus enriching for a more protective cell population.
Kyle David Fink
Kyle David Fink, an assistant professor of neurology at UC Davis, is affiliated with the Stem Cell Program and Institute for Regenerative Cures. His lab is focused on leveraging institutional expertise to bring curative therapies to rare, genetically linked neurological disorders.
“We are developing novel therapeutics targeted to the underlying genetic condition for diseases such as CDKL5 deficiency disorder, Angelman, Jordan and Rett syndromes, and Juvenile Huntington’s disease,” said Fink.
The lab is developing therapies to target the underlying genetic condition using DNA-binding domains to modify gene expression in therapeutically relevant ways. They are also creating novel delivery platforms to allow these therapeutics to reach their intended target: the brain.
“The hope is that these highly innovative methods will speed up the progress of bringing therapies to these rare neurodegenerative disease communities,” said Fink.
Jasmine Carter, a graduate research assistant at the UC Davis Stem Cell Program, October 18, 2019. (AJ Cheline/UC Davis)
Developing potential lifetime cures
Among Nolta’s concerns is how expensive gene therapy treatments can be.
“Some of the therapies cost half a million dollars and that’s simply not available to everyone. If you are someone with no insurance or someone on Medicare, which reimburses about 65 percent, it’s harder for you to get these life-saving therapies,” said Nolta.
To help address that for cancer patients at UC Davis, Nolta has set up a team known as the “CAR T Team.”
Chimeric antigen receptor (CAR) T-cell therapy is a type of immunotherapy in which a patient’s own immune cells are reprogrammed to attack a specific protein found in cancer cells.
“We can develop our own homegrown CAR T-cells,” said Nolta. “We can use our own good manufacturing facility to genetically engineer treatments specifically for our UC Davis patients.”
Although safely developing stem cell treatments can be painfully slow for patients and their families hoping for cures, Nolta sees progress every day. She envisions a time when gene therapy treatments are no longer considered experimental and doctors will simply be able to prescribe them to their patients.
“And the beauty of the therapy is that it can work for the lifetime of a patient,” said Nolta.
Small state agencies like CIRM don’t normally get to partner with a behemoth like the Department of Defense (DOD), but these are not normal times. Far from it. That’s why we are both joining forces with the National Institutes of Health to fund a clinical trial that hopes to help patients on a ventilator battling a sometime fatal condition that attacks their lungs.
The study is being run by Dr. Michael Matthay from U.C. San Francisco. CIRM awarded Dr. Matthay $750,000 to help expand an existing trial and to partner with U.C. Davis to bring in more patients, particularly from underserved communities.
This approach uses mesenchymal stem cells (MSCs) taken from bone marrow to help patients with a condition called acute respiratory distress syndrome (ARDS). This occurs when the virus attacks the lungs.
In an article in UCSF News, Dr. Matthay says the impact can be devastating.
“Tiny air spaces in the lungs fill up with fluid and prevent normal oxygen uptake in the lungs. That’s why the patient has respiratory failure. Usually these patients have to be intubated and treated with a mechanical ventilator.”
Many patients don’t survive. Dr. Matthay estimates that as many as 60 percent of COVID-19 patients who get ARDS die.
This is a Phase 2 double blind clinical trial which means that half the 120 patients who are enrolled will get MSCs (which come from young, health donors) and the other half will get a placebo. Neither the patients getting treated nor the doctors and nurses treating them will know who gets what.
Interestingly this trial did not get started as a response to COVID-19. In fact, it’s the result of years of work by Dr. Matthay and his team hoping to see if MSC’s could help people who have ARDs as a result of trauma, bacterial or other infection. They first started treating patients earlier this year when most people still considered the coronavirus a distant threat.
“We started the study in January 2020, and then COVID-19 hit, so we have been enrolling patients over the last eight months. Most of the patients we’ve enrolled in the trial have ended up having severe viral pneumonia from COVID.”
So far CIRM has funded 17 different projects targeting COVID-19. You can read about those in our Press Release section.
Imagine being told that you have a condition that gradually causes you to lose the ability to control your body movements, from picking up a pencil to walking to even breathing. Such is the reality for the nearly 6,000 people who are diagnosed with amyotrophic lateral sclerosis (ALS) every year, in the United States alone.
ALS, also known as Lou Gehrig’s disease, is a neurodegenerative disease that causes the degradation of motor neurons, or nerves that are responsible for all voluntary muscle movements, like the ones mentioned above. It is a truly devastating disease with a particularly poor prognosis of two to five years from the time of diagnosis to death. There are only two approved drugs for ALS and these do not stop it but only slow progression of the disease; and even then only for some patients, not all.
Two small Phase I clinical trials detailed in Cell Journal demonstrated that injecting mesenchymal stem cells (MSCs), derived from the patient’s own bone marrow, was safe when administered via injection into the bloodstream or the spinal cord. Previous studies had shown that MSCs both revived motor neurons and extended the lifespan in a rodent model of the disease.
In humans, many studies have shown that MSCs taken from bone marrow are safe for use in humans, but these studies have disagreed about whether injection via the bloodstream or spinal cord route is the most effective way to deliver the therapy. This report confirms that both routes of administration are safe as no adverse clinical events were observed for either group throughout the study time frame.
While an important stepping stone, there is still a long way to go. For example, while no adverse clinical events were observed in either group, the overall ALS-FRS score, a clinical scale to determine ALS disease progression, worsened in all patients over the course of the study. Whether this was just due to natural progression of the disease, or because of the stem cell treatment is difficult to determine given the small size of the cohort.
One reason the scientists suggest that could explain the disease decline is because the MSCs were taken from the ALS patients themselves, which means these cells were likely not functioning optimally prior to re-introduction into the patient. To remedy this, they hope to test the effect of MSCs taken from healthy donors in both injection routes in the future. They also need a larger cohort of patients to determine whether or not there is a difference in the therapeutic effect of administering stem cells via the two different routes.
While it may seem that the results from this clinical trial are not particularly groundbreaking or innovative, it is important to remember that these incremental improvements through clinical trials are critical for bringing safe and effective therapies to the market. For more information on the different phases of clinical trials, please refer to this video.
We usually think that starving something of oxygen is going to make it weaker and maybe even kill it. But a new study by J. Kent Leach at UC Davis shows that instead of weakening bone defects, depriving them of oxygen might help boost their ability to create new bone or repair existing bone.
Leach says in the past the use of stem cells to repair damaged or defective bone had limited success because the stem cells often didn’t engraft in the bone or survive long if they did. That was because the cells were being placed in an environment that lacked oxygen (concentration levels in bone range from 3% to 8%) so the cells found it hard to survive.
However, studies in the lab had shown that if you preconditioned mesenchymal stem cells (MSCs), by exposing them to low oxygen levels before you placed them on the injury site, you helped prolong their viability. That was further enhanced by forming the MSCs into three dimensional clumps called spheroids.
Lightbulb goes off
In the current study, published in Stem Cells, Leach says the earlier spheroid results gave him an idea:
“We hypothesized that preconditioning MSCs in hypoxic (low oxygen) culture before spheroid formation would increase cell viability, proangiogenic potential (ability to create new blood vessels), and resultant bone repair compared with that of individual MSCs.”
So, the researchers placed one group of human MSCs, taken from bone marrow, in a dish with just 1% oxygen, and another identical group of MSCs in a dish with normal oxygen levels. After three days both groups were formed into spheroids and placed in an alginate hydrogel, a biopolymer derived from brown seaweed that is often used to build cellular cultures.
The team found that the oxygen-starved cells lasted longer than the ones left in normal oxygen, and the longer those cells were deprived of oxygen the better they did.
Theory is great, how does it work in practice?
Next was to see how those two groups did in actually repairing bones in rats. Leach says the results were encouraging:
“Once again, the oxygen-deprived, spheroid-containing gels induced significantly more bone healing than did gels containing either preconditioned individual MSCs or acellular gels.”
The team say this shows the use of these oxygen-starved cells could be an effective approach to repairing hard-to-heal bone injuries in people.
“Short‐term exposure to low oxygen primes MSCs for survival and initiates angiogenesis (the development of new blood vessels). Furthermore, these pathways are sustained through cell‐cell signaling following spheroid formation. Hypoxic (low oxygen) preconditioning of MSCs, in synergy with transplantation of cells as spheroids, should be considered for cell‐based therapies to promote cell survival, angiogenesis, and bone formation.”
CIRM & Dr. Leach
While CIRM did not fund this study we have invested more than $1.8 million in another study Dr. Leach is doing to develop a new kind of imaging technology that will help us see more clearly what is happening in bone and cartilage-targeted therapies.
In addition, back in March of 2012, Dr. Leach spoke to the CIRM Board about his work developing new approaches to growing bone.
At CIRM we don’t have a disease hierarchy list that we use to guide where our funding goes. We don’t rank a disease by how many people suffer from it, if it affects children or adults, or how painful it is. But if we did have that kind of hierarchy you can be sure that Amyotrophic Lateral Sclerosis (ALS), also known as Lou Gehrig’s disease, would be high on that list.
ALS is a truly nasty disease. It attacks the neurons, the cells in our brain and spinal cord that tell our muscles what to do. As those cells are destroyed we lose our ability to walk, to swallow, to talk, and ultimately to breathe.
As Dr. Maria Millan, CIRM’s interim President and CEO, said in a news release, it’s a fast-moving disease:
“ALS is a devastating disease with an average life expectancy of less than five years, and individuals afflicted with this condition suffer an extreme loss in quality of life. CIRM’s mission is to accelerate stem cell treatments to patients with unmet medical needs and, in keeping with this mission, our objective is to find a treatment for patients ravaged by this neurological condition for which there is currently no cure.”
Having given several talks to ALS support groups around the state, I have had the privilege of meeting many people with ALS and their families. I have seen how quickly the disease works and the devastation it brings. I’m always left in awe by the courage and dignity with which people bear it.
I thought of those people, those families, today, when our governing Board voted to invest $15.9 million in a Phase 3 clinical trial for ALS run by BrainStorm Cell Therapeutics. BrainStorm is using mesenchymal stem cells (MSCs) that are taken from the patient’s own bone marrow. This reduces the risk of the patient’s immune system fighting the therapy.
After being removed, the MSCs are then modified in the laboratory to boost their production of neurotrophic factors, proteins which are known to help support and protect the cells destroyed by ALS. The therapy, called NurOwn, is then re-infused back into the patient.
In an earlier Phase 2 clinical trial, NurOwn showed that it was safe and well tolerated by patients. It also showed evidence that it can help stop, or even reverse the progression of the disease over a six month period, compared to a placebo.
CIRM is already funding one clinical trial program focused on treating ALS – that’s the work of Dr. Clive Svendsen and his team at Cedars Sinai, you can read about that here. Being able to add a second project, one that is in a Phase 3 clinical trial – the last stage before, hopefully, getting approval from the Food and Drug Administration (FDA) for wider use – means we are one step closer to being able to offer people with ALS a treatment that can help them.
Diane Winokur, the CIRM Board Patient Advocate member for ALS, says this is something that has been a long time coming:
CIRM Board member and ALS Patient Advocate Diane Winokur
“I lost two sons to ALS. When my youngest son was diagnosed, he was confident that I would find something to save him. There was very little research being done for ALS and most of that was very limited in scope. There was one drug that had been developed. It was being released for compassionate use and was scheduled to be reviewed by the FDA in the near future. I was able to get the drug for Douglas. It didn’t really help him and it was ultimately not approved by the FDA.
When my older son was diagnosed five years later, he too was convinced I would find a therapy. Again, I talked to everyone in the field, searched every related study, but could find nothing promising.
I am tenacious by nature, and after Hugh’s death, though tempted to give up, I renewed my search. There were more people, labs, companies looking at neurodegenerative diseases.
These two trials that CIRM is now funding represent breakthrough moments for me and for everyone touched by ALS. I feel that they are a promising beginning. I wish it had happened sooner. In a way, though, they have validated Douglas and Hugh’s faith in me.”
These therapies are not a cure for ALS. At least not yet. But what they will do is hopefully help buy people time, and give them a sense of hope. For a disease that leaves people desperately short of both time and hope, that would be a precious gift. And for people like Diane Winokur, who have fought so hard to find something to help their loved ones, it’s a vindication that those efforts have not been in vain.
Mesenchymal stem cells are adult stem cells with the potential to specialize into a somewhat limited number of cell types – those responsible for making fat, bone and cartilage. But MSCs are also known for their anti-inflammatory properties which are carried out via the release of protein factors. This ability to dampen the immune system makes the MSC an extremely attractive source material for cell therapies. In fact, there are over 500 mesenchymal stem cell-based clinical trials testing treatments for diseases that target a wide range of tissues including spinal cord injury, diabetes, multiple sclerosis, respiratory disorders and graft versus host disease, just to name a few.
Human mesenchymal stem cells grown in a single layer on the bottom of a flask; 4x magnification Image source: EuroStemCell
MSCs and the Variability Problem While some MSC-based human trials have had promising results in patients, other studies haven’t been as successful. A key culprit of these mixed results is the lack of standardization on what exactly is a MSC. It’s well documented that preparations of MSC vary significantly from one patient to the next. Even the composition of MSCs from one patient is far from a pure population of cells. And few of the cell surface markers used to define MSCs provide a measure of the cells’ function. This is a real problem for demonstrating the effectiveness and the marketability of MSC-based cell therapies which rely on the delivery of cell product with a consistent, well-defined composition and functional activity.
Help is now on the way based on research reported this week in EBioMedicine by a research team led by Professor Donald Phinney at the Florida campus of The Scripps Research Institute. In the study, the team found that the amount of TWIST1, a protein that regulates gene activity, in a given batch of MSCs could reliably predict the therapeutic effectiveness of those cells.
Meet TWIST1: predictor of a MSC therapy’s potential They set their sights on TWIST1 because previous research described its important role in driving a MSC fate during human development. The team examined the natural variability of TWIST1 levels in human MSCs from several donors. They showed that lower levels of TWIST1 correlated to MSCs with stronger anti-inflammatory properties. Higher levels of TWIST1, on the other hand, were consistent with MSCs that induced angiogenesis, or blood vessel growth, another known ability of this versatile cell type. In another set of experiments, TWIST1 production was silenced using genetic tools. As predicted by the earlier results, these MSCs showed increased anti-inflammatory properties.
Putting this data together, the team devised a scale they call Clinical Indication Prediction, or CLIP for short. The scale gives a clinical researcher an indication of the therapeutic potential of a given batch of donor MSCs based on the TWIST1 protein levels. This information could have a major impact on a clinical trial’s fate. Depending on the goal of a MSC-based cell therapy, a clinical team could set themselves up for failure before the trial even gets underway if they don’t take TWIST1 levels into account. First author Siddaraju V. Boregowda explains this scenario in a press release:
Siddaraju V. Boregowda
“There are a number of clinical trials testing mesenchymal stem cells to treat arthritis. Since angiogenesis is a key part of the disease process, stem cells with high levels of TWIST1 (indicating they are more angiogenic) would not be beneficial. These cells might be helpful instead for indications such as peripheral vascular disease where new vascularization is beneficial. The proposed CLIP scale accurately predicts these indications and contra-indications.”
We’ll be keeping our eye on this exciting discovery to see if CLIP becomes an integral step in developing MSC-based cell therapies. If it pans out, the CLIP scale could help accelerate the development of new therapies by providing scientists with more clarity and confidence around classifying the identity of a MSC cell product. Stay tuned!