A personal reason to develop a better gene therapy

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Credit : Allison Dougherty, Broad Communications

For Sharif Tabebordbar, finding a gene therapy for genetic muscle wasting diseases was personal. When he was a teenager, his father was diagnosed with a rare genetic muscle disease that eventually left him unable to walk.

In an interview with the Broad Institute at MIT he said: “I watched my dad get worse and worse each day. It was a huge challenge to do things together as a family – genetic disease is a burden on not only patients but families. I thought: This is very unfair to patients and there’s got to be a way to fix this. That’s been my motivation during the 10 years that I’ve been working in the field of gene therapy.”

That commitment now seems to be paying off. In a study published in the journal Cell, Tabebordar and his team at MIT and Harvard showed how they have developed a new, safer and easier way to deliver genes to help repair wasting muscles.   

In earlier treatments targeting genetic muscle diseases, researchers used a virus to help deliver the gene that would correct the problem. However, to be effective they had to use high doses of the gene-carrying virus to ensure it reached as many muscles throughout the body as possible. But this meant that more of the payload often ended up in the liver and that led to severe side effects in some patients, even a few deaths.

The usual delivery method of these gene-correcting therapies is something called an adeno-associated virus (AAV), so Dr. Tabebordar set out to develop a new kind of AAV, one that would be safer for patients and more effective at tackling the muscle wasting.

They started by taking an adeno-associated virus called AAV9 and then set out about tweaking its capsid – that’s the outer shell that helps protect the virus and allows it to attach to another cell and penetrate it to deliver the corrected gene. They called this new viral vector MyoAAV and in tests it quickly showed it had an enhanced ability to deliver genes into cells.

The team showed that it not only was around 10 times more efficient at reaching muscle than other AAVs, but that it also reduces the amount that reaches the liver. This meant that MyoAAV could achieve impressive results in doses up to 250 times lower than those previously used.

In animal studies MyoAAV showed encouraging results in diseases like Duchenne Muscular Dystrophy and X-linked myotubular myopathy. Dr. Amy Wagers, a co-senior author of the study, says they are hopeful it will be equally effective in people.

“All of these results demonstrate the broad applicability of the MyoAAV vectors for delivery to muscle. These vectors work in different disease models and across different ages, strains and species, which demonstrates the robustness of this family of AAVs. We have an enormous amount of information about this class of vectors from which the field can launch many exciting new studies.”

Cures, clinical trials and unmet medical needs

When you have a great story to tell there’s no shame in repeating it as often as you can. After all, not everyone gets to hear first time around. Or second or third time. So that’s why we wanted to give you another opportunity to tune into some of the great presentations and discussions at our recent CIRM Alpha Stem Cell Clinic Network Symposium.

It was a day of fascinating science, heart-warming, and heart-breaking, stories. A day to celebrate the progress being made and to discuss the challenges that still lie ahead.

There is a wide selection of topics from “Driving Towards a Cure” – which looks at some pioneering work being done in research targeting type 1 diabetes and HIV/AIDS – to Cancer Clinical Trials, that looks at therapies for multiple myeloma, brain cancer and leukemia.

The COVID-19 pandemic also proved the background for two detailed discussions on our funding for projects targeting the coronavirus, and for how the lessons learned from the pandemic can help us be more responsive to the needs of underserved communities.

Here’s the agenda for the day and with each topic there’s a link to the video of the presentation and conversation.

Thursday October 8, 2020

View Recording: CIRM Fellows Trainees

9:00am Welcome Mehrdad Abedi, MD, UC Davis Health, ASCC Program Director  

Catriona Jamieson, MD,  View Recording: ASCC Network Value Proposition

9:10am Session I:  Cures for Rare Diseases Innovation in Action 

Moderator: Mark Walters, MD, UCSF, ASCC Program Director 

Don Kohn, MD, UCLA – View Recording: Severe combined immunodeficiency (SCID) 

Mark Walters, MD, UCSF, ASCC Program Director – View Recording: Thalassemia 

Pawash Priyank, View Recording: Patient Experience – SCID

Olivia and Stacy Stahl, View Recording: Patient Experience – Thalassemia

10 minute panel discussion/Q&A 

BREAK

9:55am Session II: Addressing Unmet Medical Needs: Driving Towards a Cure 

Moderator: John Zaia, MD, City of Hope, ASCC Program Direction 

Mehrdad Abedi, MD, UC Davis Health, ASCC Program Director – View Recording: HIV

Manasi Jaiman, MD, MPH, ViaCyte, Vice President, Clinical Development – View Recording: Diabetes

Jeff Taylor, Patient Experience – HIV

10 minute panel discussion/Q&A 

BREAK

10:40am Session III: Cancer Clinical Trials: Networking for Impact 

Moderator: Catriona Jamieson, MD, UC San Diego, ASCC Program Director 

Daniela Bota, MD, PhD, UC Irvine, ASCC Program Director – View Recording:  Glioblastoma 

Michael Choi, MD, UC San Diego – View Recording: Cirmtuzimab

Matthew Spear, MD, Poseida Therapeutics, Chief Medical Officer – View Recording: Multiple Myeloma  

John Lapham, Patient Experience –  View Recording: Chronic lymphocytic leukemia (CLL) 

10 minute panel discussion/Q&A 

BREAK

11:30am Session IV: Responding to COVID-19 and Engaging Communities

Two live “roundtable conversation” sessions, 1 hour each.

Roundtable 1: Moderator Maria Millan, MD, CIRM 

CIRM’s / ASCC Network’s response to COVID-19 Convalescent Plasma, Cell Therapy and Novel Vaccine Approaches

Panelists

Michael Matthay, MD, UC San Francisco: ARDS Program

Rachael Callcut, MD, MSPH, FACS, UC Davis: ARDS Program 

John Zaia, MD, City of Hope: Convalescent Plasma Program 

Daniela Bota, MD, PhD, UC Irvine: Natural Killer Cells as a Treatment Strategy 

Key questions for panelists: 

  • Describe your trial or clinical program?
  • What steps did you take to provide access to disproportionately impacted communities?
  • How is it part of the overall scientific response to COVID-19? 
  • How has the ASCC Network infrastructure accelerated this response? 

Brief Break

Roundtable 2: Moderator Ysabel Duron, The Latino Cancer Institute and Latinas Contra Cancer

View Recording: Roundtable 2

Community Engagement and Lessons Learned from the COVID Programs.  

Panelists

Marsha Treadwell, PhD, UC San Francisco: Community Engagement  

Sheila Young, MD, Charles R. Drew University of Medicine and Science: Convalescent Plasma Program in the community

David Lo, MD, PhD,  UC Riverside: Bringing a public health perspective to clinical interventions

Key questions for panelists: 

  • What were important lessons learned from the COVID programs? 
  • How can CIRM and the ASCC Network achieve equipoise among communities and engender trust in clinical research? 
  • How can CIRM and the ASCC Network address structural barriers (e.g. job constrains, geographic access) that limit opportunities to participate in clinical trials?

Repairing damaged muscles

Close-up of the arm of a 70-year-old male patient with a torn biceps muscle as a result of a bowling injury; Photo courtesy Science Photo Library

In the time of coronavirus an awful lot of people are not just working from home they’re also working out at home. That’s a good thing; exercise is a great way to boost the immune system, stay healthy and deal with stress. But for people used to more structured workouts at the gym it can come with a downside. Trying new routines at home that look easy on YouTube, but are harder in practice could potentially increase the risk of injury.

A new study from Japan looks at what happens when you damage a muscle. It won’t help it heal faster, but it will at least let you understand what is happening inside your body as you sit there with ice on your arm and ibuprofen in your hand.

The researchers found that when you damage a muscle, for example by trying to lift too much weight or doing too many repetitions of one exercise, the damaged muscle fibers leak substances that activate nearby “satellite” stem cells. These satellite cells then flock to the site of the injury and help repair the muscle.

The team, from Kumamoto University and Nagasaki University in Japan, named the leaking substances “Damaged myofiber-derived factors” (DMDFs) – personally I think “Substances Leaked by Injured Muscles (SLIM) would be a much cooler acronym, but that’s just me. Gaining a deeper understanding of how DMDFs work might help lead to therapies for older people who have fewer satellite muscle cells, and also for conditions like muscular dystrophy and age-related muscular fragility (sarcopenia), where the number and function of satellite cells decreases.

In an article in Science Daily, Professor Yusuke Ono, the leader of the study, says it’s possible that DMDFs play an even greater role in the body:

“In this study, we proposed a new muscle injury-regeneration model. However, the detailed molecular mechanism of how DMDFs activate satellite cells remains an unclear issue for future research. In addition to satellite cell activation, DMDF moonlighting functions are expected to be diverse. Recent studies have shown that skeletal muscle secretes various factors that affect other organs and tissues, such as the brain and fat, into the bloodstream, so it may be possible that DMDFs are involved in the linkage between injured muscle and other organs via blood circulation. We believe that further elucidation of the functions of DMDFs could clarify the pathologies of some muscle diseases and help in the development of new drugs.”

The study appears in the journal Stem Cell Reports.

Partners in health

From left to right: Heather Dahlenburg, Jan Nolta, Jeannine Logan White, Sheng Yang
From left to right: Heather Dahlenburg, staff research associate; Jan Nolta, director of the Stem Cell Program; Jeannine Logan White, advanced cell therapy project manager; Sheng Yang, graduate student, Bridges Program, Humboldt State University, October 18, 2019. (AJ Cheline/UC Davis)

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.

In 2016, led by Fred Meyers, a professor in the School of Medicine, UC Davis launched the Center for Precision Medicine and Data Sciences, bringing together innovations such as genomics and biomedical data sciences to create individualized treatments for patients.

Last year, the university launched the Gene Therapy Center, part of the IMPACT Center program.

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.

Several cell and gene therapies have progressed to the point that ongoing clinical trials are being conducted at UC Davis for diseases, including sickle-cell anemia, retinopathy, muscle injury, dysphasia, advanced cancer, and Duchenne muscular dystrophy, among others.

“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.

.Joseph Anderson

Joseph Anderson

“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

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.

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.

Battling COVID and turning back the clock on stem cell funding

Coronavirus

Battling the virus that causes COVID-19 is something that is top of everyone’s mind right now. That’s why CIRM is funding 17 different projects targeting the virus. But one of the most valuable tools in helping develop vaccines against a wide variety of diseases in the past is now coming under threat. We’ll talk about both issues in a live broadcast we’re holding on Wednesday, October 14th at noon (PDT).

That date is significant because it’s Stem Cell Awareness Day and we thought it appropriate to host a meeting looking at two of the most important issues facing the field.

The first part of the event will focus on the 17 projects that CIRM is funding that target COVID-19. This includes three clinical trials aiming to treat people who have been infected with the virus and are experiencing some of the more severe effects, such as damaged lungs.

We’ll also look at some of the earlier stage research that includes:

  • Work to help develop a vaccine
  • Using muscle stem cells to help repair damage to the diaphragm in patients who have spent an extended period on a ventilator
  • Boosting immune system cells to help fight the virus

The second part of the event will look at ways that funding for stem cell research at the federal level is once again coming into question. The federal government has already imposed new restrictions on funding for fetal tissue research, and now there are efforts in Congress to restrict funding for embryonic stem cell research.

The impacts could be significant. Fetal tissue has been used for decades to help develop some of the most important vaccines used today including rubella, chickenpox, hepatitis A, and shingles. They have also been used to make approved drugs against diseases including hemophilia, rheumatoid arthritis, and cystic fibrosis.

We’ll look at some of the reasons why we are seeing these potential restrictions on the medical research and what impact they could have on the ability to develop new treatments for the coronavirus and other deadly diseases.

You can watch the CIRM Stem Cell Awareness Day live event by going here: https://www.youtube.com/c/CIRMTV/videos at noon on Wednesday, October 14th.

Feel free to share news about this event with anyone you think might be interested.

We look forward to seeing you there.

Perseverance: from theory to therapy. Our story over the last year – and a half

Some of the stars of our Annual Report

It’s been a long time coming. Eighteen months to be precise. Which is a peculiarly long time for an Annual Report. The world is certainly a very different place today than when we started, and yet our core mission hasn’t changed at all, except to spring into action to make our own contribution to fighting the coronavirus.

This latest CIRM Annual Reportcovers 2019 through June 30, 2020. Why? Well, as you probably know we are running out of money and could be funding our last new awards by the end of this year. So, we wanted to produce as complete a picture of our achievements as we could – keeping in mind that we might not be around to produce a report next year.

Dr. Catriona Jamieson, UC San Diego physician and researcher

It’s a pretty jam-packed report. It covers everything from the 14 new clinical trials we have funded this year, including three specifically focused on COVID-19. It looks at the extraordinary researchers that we fund and the progress they have made, and the billions of additional dollars our funding has helped leverage for California. But at the heart of it, and at the heart of everything we do, are the patients. They’re the reason we are here. They are the reason we do what we do.

Byron Jenkins, former Naval fighter pilot who battled back from his own fight with multiple myeloma

There are stories of people like Byron Jenkins who almost died from multiple myeloma but is now back leading a full, active life with his family thanks to a CIRM-funded therapy with Poseida. There is Jordan Janz, a young man who once depended on taking 56 pills a day to keep his rare disease, cystinosis, under control but is now hoping a stem cell therapy developed by Dr. Stephanie Cherqui and her team at UC San Diego will make that something of the past.

Jordan Janz and Dr. Stephanie Cherqui

These individuals are remarkable on so many levels, not the least because they were willing to be among the first people ever to try these therapies. They are pioneers in every sense of the word.

Sneha Santosh, former CIRM Bridges student and now a researcher with Novo Nordisk

There is a lot of information in the report, charting the work we have done over the last 18 months. But it’s also a celebration of everyone who made it possible, and our way of saying thank you to the people of California who gave us this incredible honor and opportunity to do this work.

We hope you enjoy it.

Promising results from CIRM-funded projects

Severe Leukocyte Adhesion Deficiency-1 (LAD-1) is a rare condition that causes the immune system to malfunction and reduces its ability to fight off viruses and bacteria. Over time the repeated infections can take a heavy toll on the body and dramatically shorten a person’s life. But now a therapy, developed by Rocket Pharmaceuticals, is showing promise in helping people with this disorder.

The therapy, called RP-L201, targets white blood cells called neutrophils which ordinarily attack and destroy invading particles. In people with LAD-1 their neutrophils are dangerously low. That’s why the new data about this treatment is so encouraging.

In a news release, Jonathan Schwartz, M.D., Chief Medical Officer of Rocket, says early results in the CIRM-funded clinical trial, show great promise:

“Patients with severe LAD-I have neutrophil CD18 expression of less than 2% of normal, with extremely high mortality in early childhood. In this first patient, an increase to 47% CD18 expression sustained over six months demonstrates that RP-L201 has the potential to correct the neutrophil deficiency that is the hallmark of LAD-I. We are also pleased with the continued visible improvement of multiple disease-related skin lesions. The second patient has recently been treated, and we look forward to completing the Phase 1 portion of the registrational trial for this program.”

The results were released at the 23rd Annual Meeting of the American Society of Gene and Cell Therapy.

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These microscopic images show gene expression in muscle stem and progenitor cells as they mature from early development to adulthood (left to right). As part of this process, the cells switch from actively expressing one key gene (green) to another (violet); this is accompanied by the growth of muscle fibers (red).
Photo courtesy: Cell Stem Cell/UCLA Broad Stem Cell Research Center

When you are going on a road-trip you need a map to help you find your way. It’s the same with stem cell research. If you are going to develop a new way to treat devastating muscle diseases, you need to have a map to show you how to build new muscle stem cells. And that’s what researchers at the Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research at UCLA – with help from CIRM funding – have done.

The team took muscle progenitor cells – which show what’s happening in development before a baby is born – and compared them to muscle stem cells – which control muscle development after a baby is born. That enabled them to identify which genes are active at what stage of development.

In a news release, April Pyle, senior author of the paper, says this could open the door to new therapies for a variety of conditions:

“Muscle loss due to aging or disease is often the result of dysfunctional muscle stem cells. This map identifies the precise gene networks present in muscle progenitor and stem cells across development, which is essential to developing methods to generate these cells in a dish to treat muscle disorders.”

The study is published in the journal Cell Stem Cell.

Study shows that exercise rejuvenates muscle stem cells of old mice

Dr. Thomas Rando, Stanford University

While we’re all at home and practicing social distancing during this global pandemic, it has become a challenge to get in daily exercise. Aside from outward physical appearance, what other benefits does exercise hold? Dr. Thomas Rando and his team at Stanford University explored this question in more detail in a CIRM supported animal study.

The Stanford research team found that exercise played a key role in restoring the youthful properties in the muscle stem cells of old mice. Muscle stem cells play an important role in tissue regeneration. They are usually on standby alongside muscle fibers in a resting state known as quiescence until called upon to repair damage.

For this study, the researchers wanted to see if voluntary exercise had an effect on the muscle stem cells in mice. Older mice that were 20 months old, the equivalent of 60-70 human years, were given an exercise wheel where they were allowed to run at will. Younger mice that were 3-4 months old, the equivalent of 20-30 human years, were also given an exercise wheel and allowed to run at will. A separate group of younger and older mice were given a wheel that didn’t rotate to compare them with the groups of mice that exercised.

They found that the older animals that had exercised regularly were significantly better at repairing muscle damage compared to their counterparts that did not exercise. However, this exercise benefit was not observed between the younger group of mice.

The researchers also transplanted the muscle stem cells from the older mice that had exercised into younger mice that had not exercised. They found that the muscle stem cells from the older mice contributed more to the repair process than did those from the non-exercising mice.

What was also surprising is that injecting blood from an old mouse that had exercised into an old mouse that hadn’t created a similar benefit in the muscle stem cells. This finding suggests that exercise simulates the production of some factors that then circulate in the blood and enhance the function of older stem cells.

Lastly, the researchers were ably to identify a molecular pathway that activates the resting muscle stem cells in response to damage.

In a press release, Dr. Rando discusses how this discovery could potentially lead to the development of a drug that could rejuvenate muscle stem cells.

“If we could develop a drug that mimics this effect, we may be able to experience the benefit without having to do months of exercise.”

The full results of this study were published in Nature Metabolism.

Deep dive into muscle repair yields new strategies to combat Duchenne muscular dystrophy

Researchers at the Sanford Burnham Prebys Medical Discovery Institute (SBP) reported new findings this week that may lead to novel therapeutic strategies for people suffering from Duchenne muscular dystrophy (DMD). DMD, a muscle-wasting disease that affects 1 in 7250 males aged 5 to 24 years in the United States, is caused by a genetic mutation leading to the lack of a protein called dystrophin. Without dystrophin, muscle cells become fragile and are easily damaged. Instead of self-repair, the muscles are replaced by scar tissue, a process called fibrosis that leads to muscle degeneration and wasting.

DMD_KhanAcademy

Dystrophin, a protein that maintains the structural integrity of muscle fibers, is missing in people with DMD. Image credit: Khan Academy

Boys with DMD first show signs of muscle weakness between ages 3-5 and often stop walking by the time they’re teenagers. Eventually the muscles critical for breathing and heart function stop working. Average life expectancy is 26 and there is no cure.

The SBP scientists are aiming to treat DMD by boosting muscle repair in affected individuals. But to do that, they sought to better understand how muscle regeneration works in the first place. In the current study, they focused their efforts on so-called fibro/adipogenic precursor (FAP) cells which, in response to acute injury, appear to play a role in stimulating muscle stem cells to divide and replace damaged muscle in healthy individuals. But FAPs are also implicated in the muscle wasting and scarring that’s seen in DMD.

By examining the gene activity of single FAP cells from mouse models of acute injury and DMD, the researchers identified a sub-population of FAP cells (sub-FAPs). Further study of these sub-FAPs showed that during early stages of muscle regeneration, these cells promote muscle stem cell activation but then at later stages, sub-FAPs – identified by a cell surface protein called Vcam1 – stimulate fibrosis. It turns out that during healthy acute muscle injury, the sub-FAPs with cell-surface Vcam1 protein are readily eaten up and removed by immune cells thereby avoiding muscle fibrosis. But in the DMD mouse model, removal of these sub-FAPs is impaired and instead collagen deposits and muscle fibrosis occur which are hallmarks of the progressive degeneration seen in DMD.

Barbora Malecova, Ph.D., a first author of the study, explained the implications of these results in a press release:

“This study elucidates the cellular and molecular pathogenesis of muscular dystrophy. These results indicate that removing or modulating the activity of Vcam1-positive sub-FAPs, which promote fibrosis, could be an effective treatment for DMD.”

The lab, led by Pier Lorenzo Puri, M.D., next will explore the possibility of finding drugs that target the Vcam1 sub-FAPs which in turn could help prevent fibrosis in DMD.

The study, funded in part by CIRM, appears in Nature Communications. CIRM is also funding a Phase 2 clinical trial testing a stem cell-based therapy that aims to improve the life-threatening heart muscle degeneration that occurs in DMD patients.

The Five Types of Stem Cells

When I give an “Intro to Stem Cells” presentation to, say, high school students or to a local Rotary Club, I begin by explaining that there are three main types of stem cells: (1) embryonic stem cells (ESCs) (2) adult stem cells and (3) induced pluripotent stem cells (iPSCs). Well, like most things in science, it’s actually not that simple.

To delve a little deeper into the details of characterizing stem cells, I recommend checking out a video animation produced by BioInformant, a stem cell market research company. The video is introduced in a blog, “Do you know the 5 types of stem cells?” by Cade Hildreth, BioInformant’s founder and president.

Stem-Cell-Types

Image credit: BioInformant

Hildreth’s list categorizes stem cells by the extent of each type’s shape-shifting abilities. So while we sometimes place ESCs and iPSCs in different buckets because the methods for obtaining them are very different, in this list, they both belong to the pluripotent stem cell type. Pluri (“many”) – potent (“potential”) refers to the ability of both stem cell types to specialize into all of the cell types in the body. They can’t, though, make the cells of the placenta and other extra-embryonic cells too. Those ultimate blank-slate stem cells are called toti (“total”) – potent (“potential”).

When it comes to describing adult stem cells in my talks, I often lump blood stem cells together with muscle stem cells because they are stem cells that are present within us throughout life. But based on their ability to mature into specialized cells, these two stem cell types fall into two different categories in Hildreth’s list:  blood stem cells which can specialize into closely related cell types – the various cell types found in the blood – are considered “oligopotent” while muscle stem cells are “unipotent” because the can only mature into one type of cell, a muscle cell.

For more details on the five types of stem cells based on their potential to specialize, head over to the BioInformant blog. And scroll to the very bottom for the video animation which can also viewed on FaceBook.