heart attack

The present and future of regenerative medicine

/ Kevin McCormack / Leave a comment

One of the great pleasures of my job is getting to meet the high school students who take part in our SPARK or Summer Internship to Accelerate Regenerative Medicine Knowledge program. It’s a summer internship for high school students where they get to spend a couple of months working in a world class stem cell and gene therapy research facility. The students, many of whom go into the program knowing very little about stem cells, blossom and produce work that is quite extraordinary.

One such student is Tan Ieng Huang, who came to the US from China for high school. During her internship at U.C. San Francisco she got to work in the lab of Dr. Arnold Kriegstein. He is the Founding Director of the Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research at the University of California, San Francisco. Not only did she work in his lab, she took the time to do an interview with him about his work and his thoughts on the field.

It’s a fascinating interview and shows the creativity of our SPARK students. You will be seeing many other examples of that creativity in the coming weeks. But for now, enjoy the interview with someone who is a huge presence in the field today, by someone who may well be a huge presence in the not too distant future.

‘a tête-à-tête with Prof. Arnold Kriegstein’

The Kriegstein lab team: Photo courtesy UCSF

Prof. Arnold Kriegstein is the Founding Director of the Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research at the University of California, San Francisco. Prof. Kriegstein is also the Co-Founder and Scientific Advisor of Neurona Therapeutics which seeks to provide effective and safe cell therapies for chronic brain disorder. A Clinician by training, Prof. Kriegstein has been fascinated by the intricate workings of the human brain. His laboratory focuses on understanding the transcriptional and signaling networks active during brain development, the diversity of neuronal cell types, and their fate potential. For a long time, he has been interested in harnessing this potential for translational and therapeutic intervention.

During my SEP internship I had the opportunity to work in the Kriegstein lab. I was in complete awe. I am fascinated by the brain. During the course of two months, I interacted with Prof. Kriegstein regularly, in lab meetings and found his ideas deeply insightful. Here’s presenting some excerpts from some of our discussions, so that it reaches many more people seeking inspiration!

Tan Ieng Huang (TH): Can you share a little bit about your career journey as a scientist?

Prof. Arnold Kriegstein (AK): I wanted to be a doctor when I was very young, but in high school I started having some hands-on research experience. I just loved working in the lab. From then on, I was thinking of combining those interests and an MD/PhD turned out to be an ideal course for me. That was how I started, and then I became interested in the nervous system. Also, when I was in high school, I spent some time one summer at Rockefeller University working on a project that involved operant conditioning in rodents and I was fascinated by behavior and the role of the brain in learning and memory. That happened early on, and turned into an interest in cortical development and with time, that became my career.

TH: What was your inspiration growing up, what made you take up medicine as a career?

AK: That is a little hard to say, I have an identical twin brother. He and I used to always share activities, do things together. And early on we actually became eagle scouts, sort of a boy scout activity in a way. In order to become an eagle scout without having to go through prior steps, we applied to a special program that the scouts had, which allowed us to shadow physicians in a local hospital. I remember doing that at a very young age. It was a bit ironic, because one of the evenings, they showed us films of eye surgery, and my brother actually fainted when they made an incision in the eye. The reason it makes me laugh now is because my brother became an eye surgeon many years later. But I remember our early experience, we both became very fascinated by medicine and medical research.

Tan Ieng and Dr. Arnold Kriegstein at UCSF

TH: What inspired you to start the Eli and Edythe Broad Center of Regeneration Medicine and Stem Cell Research Institute?

AK: My interest in brain development over the years became focused on earlier stages of development and eventually Neurogenesis, you know, how neurons are actually generated during early stages of in utero brain development. In the course of doing that we discovered that the radial glial cells, which have been thought for decades to simply guide neurons as they migrate, turned out to actually be the neural stem cells, they were making the neurons and also guiding them toward the cortex. So, they were really these master cells that had huge importance and are now referred to as neural stem cells. But at that time, it was really before the stem cell field took off. But because we studied neurogenesis, because I made some contributions to understanding how the brain develops from those precursors or progenitor cells, when the field of stem cells developed, it was very simple for me to identify as someone who studied neural stem cells. I became a neural stem cell scientist. I started a neural stem cell program at Columbia University when I was a Professor there and raised 15 million dollars to seed the program and hired new scientists. It was shortly after that I was approached to join UCSF as the founder of a new stem cell program. And it was much broader than the nervous system; it was a program that covered all the different tissues and organ systems.

TH: Can you tell us a little bit about how stem cell research is contributing to the treatment of diseases? How far along are we in terms of treatments?

AK: It’s taken decades, but things are really starting to reach the clinic now. The original work was basic discovery done in research laboratories, now things are moving towards the clinic. It’s a really very exciting time. Initially the promise of stem cell science was called Regenerative medicine, the idea of replacing injured or worn-out tissues or structures with new cells and new tissues, new organs, the form of regeneration was made possible by understanding that there are stem cells that can be tweaked to actually help make new cells and tissues. Very exciting process, but in fact the main progress so far hasn’t been replacing worn out tissues and injured cells, but rather understanding diseases using human based model of disease. That’s largely because of the advent of induced pluripotent stem cells, a way of using stem cells to make neurons or heart cells or liver cells in the laboratory, and study them both in normal conditions during development and in disease states. Those platforms which are relatively easy to make now and are pretty common all over the world allow us to study human cells rather than animal cells, and the hope is that by doing that we will be able to produce conventional drugs and treatments that work much better than ones we had in the past, because they will be tested in actual human cells rather than animal cells.

TH: That is a great progress and we have started using human models because even though there are similarities with animal models, there are still many species-specific differences, right?

AK: Absolutely, in fact, one of the big problems now in Big Pharma, you know the drug companies, is that they invest millions and sometimes hundreds of millions of dollars in research programs that are based on successes in treating mice, but patients don’t respond the same way. So the hope is that by starting with a treatment that works on human cells it might be more likely that the treatment will work on human patients.

TH: What are your thoughts on the current challenges and future of stem cell research?

AK: I think this is an absolute revolution in modern medicine, the advent of two things that are happening right now, first the use of induced pluripotent stem cells, the ability to make pluripotent cells from adult tissue or cells from an individual allows us to use models of diseases that I mentioned earlier from actual patients. That’s one major advance. And the other is gene editing, and the combination of gene editing and cell-based discovery science allows us to think of engineering cells in ways that can make them much more effective as a form of cell therapy and those cell therapies have enormous promise. Right now, they are being used to treat cancer, but in the future, they might be able to treat heart attack, dementia, neurodegenerative diseases, ALS, Parkinson’s disease, a huge list of disorders that are untreatable right now or incurable. They might be approached by the combination of cell-based models, cell therapies, and gene editing.

TH: I know there are still some challenges right now, like gene editing has some ethical issues because people don’t know if there can be side effects after the gene editing, what are your thoughts?

AK: You know, like many other technologies there are uncertainties, and there are some issues. Some of the problems are off-target effects, that is you try to make a change in one particular gene, and while doing that you might change other genes in unexpected ways and cause complications. But we are understanding that more and more now and can make much more precise gene editing changes in just individual genes without affecting unanticipated areas of the genome. And then there are also the problems of how to gene-edit cells in a safe way. There are certain viral factors that can be used to introduce the gene editing apparatus into a cell, and sometimes if you are doing that in a patient, you can also have unwanted side effects from the vectors that you are using, often they are modified viral vectors. So, things get complicated very quickly when you start trying to treat patients, but I think these are all tractable problems and I think in time they will all be solved. It will be a terrific, very promising future when it comes to treating patients who are currently untreatable.

TH: Do you have any advice for students who want to get into this field?

AK: Yes, I think it’s actually never been a better time and I am amazed by the technologies that are available now. Gene editing that I mentioned before but also single cell approaches, the use of single cell multiomics revealing gene expression in individual cells, the molecular understanding of how individual cells are formed, how they are shaped, how they change from one stage to another, how they can be forced into different fates. It allows you to envision true Regenerative medicine, improving health by healing or replacing injured or diseased tissues. I think this is becoming possible now, so it’s a very exciting time. Anyone who has an interest in stem cell biology or new ways of treating diseases, should think about getting into a laboratory or a clinical setting. I think this time is more exciting than it’s ever been.

TH: So excited to hear that, because in school we have limited access to the current knowledge, the state-of-art. I want to know what motivates you every day to do Research and contribute to this field?

AK: Well, you know that I have been an MD/PhD, as I mentioned before, in a way, there are two different reward systems at play. In terms of the PhD and the science, it’s the discovery part that is so exciting. Going in every day and thinking that you might learn something that no one has ever known before and have a new insight into a mechanism of how something happens, why it happens. Those kinds of new insights are terrifically satisfying, very exciting. On the MD side, the ability to help patients and improve peoples’ lives is a terrific motivator. I always wanted to do that, was very driven to become a Neurologist and treat both adult and pediatric patients with neurological problems. In the last decade or so, I’ve not been treating patients so much, and have focused on the lab, but we have been moving some of our discoveries from the laboratory into the clinic. We have just started a clinical trial, of a new cell-based therapy for epilepsy in Neurona Therapeutics, which is really exciting. I am hoping it will help the patients but it’s also a chance to actually see something that started out as a project in the laboratory become translated into a therapy for patients, so that’s an achievement that has really combined my two interests, basic science, and clinical medicine. It’s a little late in life but not too late, so I’m very excited about that.

Tan Ieng Huang, Kriegstein Lab, SEP Intern, CIRM Spark Program 2022

Using stem cells and smart machines to warn of heart problems

/ Kevin McCormack / 1 Comment

Despite advances in treatments in recent years heart disease remains the leading cause of death in the US. It accounts for one in three deaths in this country, and many people are not even aware they have a problem until they have a heart attack.

One of the early warning signs of danger is a heart arrhythmia; that’s when electrical signals that control the hearts beating don’t work properly and can result in the heart beating too fast, too slow, or irregularly. However, predicting who is at risk of these arrhythmias is difficult. Now new research may have found a way to change that.

A research team at the Institute of Molecular and Cell Biology in Singapore combined stem cells with machine learning, and developed a way to predict arrhythmias, with a high degree of accuracy.

The team used stem cells to create different batches of cardiomyocytes or heart muscle cells. Some of these batches were healthy heart cells, but some had arrhythmias caused by different problems such as a genetic disorder or drug induced.

They then trained a machine learning program to use videos to scan the 3,000 different groups of cells. By studying the different beating patterns of the cells, and then using the levels of calcium in the cells, the machine was able to predict, with 90 percent accuracy, which cells were most likely to experience arrhythmias.

The researchers say their approach is faster, simpler and more accurate than current methods of trying to predict who is at risk for arrhythmias and could have a big impact on our ability to intervene before the individual suffers a fatal heart attack.

The research was published in the journal Stem Cell Reports.

The California Institute for Regenerative Medicine has invested more than $180 million in more than 80 different projects, including four clinical trials, targeting heart disease.

CIRM funds clinical trials targeting heart disease, stroke and childhood brain tumors

/ Kevin McCormack / Leave a comment
Gary Steinberg (Jonathan Sprague)

Heart disease and stroke are two of the leading causes of death and disability and for people who have experienced either their treatment options are very limited. Current therapies focus on dealing with the immediate impact of the attack, but there is nothing to deal with the longer-term impact. The CIRM Board hopes to change that by funding promising work for both conditions.

Dr. Gary Steinberg and his team at Stanford were awarded almost $12 million to conduct a clinical trial to test a therapy for motor disabilities caused by chronic ischemic stroke.  While “clot busting” therapies can treat strokes in their acute phase, immediately after they occur, these treatments can only be given within a few hours of the initial injury.  There are no approved therapies to treat chronic stroke, the disabilities that remain in the months and years after the initial brain attack.

Dr. Steinberg will use embryonic stem cells that have been turned into neural stem cells (NSCs), a kind of stem cell that can form different cell types found in the brain.  In a surgical procedure, the team will inject the NSCs directly into the brains of chronic stroke patients.  While the ultimate goal of the therapy is to restore loss of movement in patients, this is just the first step in clinical trials for the therapy.  This first-in-human trial will evaluate the therapy for safety and feasibility and look for signs that it is helping patients.

Another Stanford researcher, Dr. Crystal Mackall, was also awarded almost $12 million to conduct a clinical trial to test a treatment for children and young adults with glioma, a devastating, aggressive brain tumor that occurs primarily in children and young adults and originates in the brain.  Such tumors are uniformly fatal and are the leading cause of childhood brain tumor-related death. Radiation therapy is a current treatment option, but it only extends survival by a few months.

Dr. Crystal Mackall and her team will modify a patient’s own T cells, an immune system cell that can destroy foreign or abnormal cells.  The T cells will be modified with a protein called chimeric antigen receptor (CAR), which will give the newly created CAR-T cells the ability to identify and destroy the brain tumor cells.  The CAR-T cells will be re-introduced back into patients and the therapy will be evaluated for safety and efficacy.

Joseph Wu Stanford

Stanford made it three in a row with the award of almost $7 million to Dr. Joe Wu to test a therapy for left-sided heart failure resulting from a heart attack.  The major issue with this disease is that after a large number of heart muscle cells are killed or damaged by a heart attack, the adult heart has little ability to repair or replace these cells.  Thus, rather than being able to replenish its supply of muscle cells, the heart forms a scar that can ultimately cause it to fail.  

Dr. Wu will use human embryonic stem cells (hESCs) to generate cardiomyocytes (CM), a type of cell that makes up the heart muscle.  The newly created hESC-CMs will then be administered to patients at the site of the heart muscle damage in a first-in-human trial.  This initial trial will evaluate the safety and feasibility of the therapy, and the effect upon heart function will also be examined.  The ultimate aim of this approach is to improve heart function for patients suffering from heart failure.

“We are pleased to add these clinical trials to CIRM’s portfolio,” says Maria T. Millan, M.D., President and CEO of CIRM.  “Because of the reauthorization of CIRM under Proposition 14, we have now directly funded 75 clinical trials.  The three grants approved bring forward regenerative medicine clinical trials for brain tumors, stroke, and heart failure, debilitating and fatal conditions where there are currently no definitive therapies or cures.”

A new way to evade immune rejection in transplanting cells

/ Kevin McCormack / 2 Comments
Immune fluorescence of HIP cardiomyocytes in a dish; Photo courtesy of UCSF

Transplanting cells or an entire organ from one person to another can be lifesaving but it comes with a cost. To avoid the recipient’s body rejecting the cells or organ the patient has to be given powerful immunosuppressive medications. Those medications weaken the immune system and increase the risk of infections. But now a team at the University of California San Francisco (UCSF) have used a new kind of stem cell to find a way around that problem.

The cells are called HIP cells and they are a specially engineered form of induced pluripotent stem cell (iPSC). Those are cells that can be turned into any kind of cell in the body. These have been gene edited to make them a kind of “universal stem cell” meaning they are not recognized by the immune system and so won’t be rejected by the body.

The UCSF team tested these cells by transplanting them into three different kinds of mice that had a major disease; peripheral artery disease; chronic obstructive pulmonary disease; and heart failure.

The results, published in the journal Proceedings of the National Academy of Science, showed that the cells could help reduce the incidence of peripheral artery disease in the mice’s back legs, prevent the development of a specific form of lung disease, and reduce the risk of heart failure after a heart attack.

In a news release, Dr. Tobias Deuse, the first author of the study, says this has great potential for people. “We showed that immune-engineered HIP cells reliably evade immune rejection in mice with different tissue types, a situation similar to the transplantation between unrelated human individuals. This immune evasion was maintained in diseased tissue and tissue with poor blood supply without the use of any immunosuppressive drugs.”

Deuse says if this does work in people it may not only be of great medical value, it may also come with a decent price tag, which could be particularly important for diseases that affect millions worldwide.

“In order for a therapeutic to have a broad impact, it needs to be affordable. That’s why we focus so much on immune-engineering and the development of universal cells. Once the costs come down, the access for all patients in need increases.”

/ Kevin McCormack / 1 Comment

Two voices, one message, watch out for predatory stem cell clinics

Last week two new papers came out echoing each other about the dangers of bogus “therapies” being offered by predatory stem cell clinics and the risks they pose to patients.

The first was from the Pew Charitable Trusts entitled: ‘Harms Linked to Unapproved Stem Cell Interventions Highlight Need for Greater FDA Enforcement’ with a subtitle: ‘Unproven regenerative medical products have led to infections, disabilities, and deaths.’

That pretty much says everything you need to know about the report, and in pretty stark terms; need for greater FDA enforcement and infections, disabilities and deaths.

Just two days later, as if in response to the call for greater enforcement, the Food and Drug Administration (FDA) came out with its own paper titled: ‘Important Patient and Consumer Information About Regenerative Medicine Therapies.’ Like the Pew report the FDA’s paper highlighted the dangers of unproven and unapproved “therapies” saying it “has received reports of blindness, tumor formation, infections, and more… due to the use of these unapproved products.”

The FDA runs down a list of diseases and conditions that predatory clinics claim they can cure without any evidence that what they offer is even safe, let alone effective. It says Regenerative Medicine therapies have not been approved for the treatment of:

  • Arthritis, osteoarthritis, rheumatism, hip pain, knee pain or shoulder pain.
  • Blindness or vision loss, autism, chronic pain or fatigue.
  • Neurological conditions like Alzheimer’s and Parkinson’s.
  • Heart disease, lung disease or stroke.

The FDA says it has warned clinics offering these “therapies” to stop or face the risk of legal action, and it warns consumers: “Please know that if you are being charged for these products or offered these products outside of a clinical trial, you are likely being deceived and offered a product illegally.”

It tells consumers if you are offered one of these therapies – often at great personal cost running into the thousands, even tens of thousands of dollars – you should contact the FDA at ocod@fda.hhs.gov.

The Pew report highlights just how dangerous these “therapies” are for patients. They did a deep dive into health records and found that between 2004 and September 2020 there were more than 360 reported cases of patients experiencing serious side effects from a clinic that offered unproven and unapproved stem cell procedures.

Those side effects include 20 deaths as well as serious and even lifelong disabilities such as:

  • Partial or complete blindness (9).
  • Paraplegia (1).
  • Pulmonary embolism (6).
  • Heart attack (5).
  • Tumors, lesions, or other growths (16).
  • Organ damage or failure in several cases that resulted in death.

More than one hundred of the patients identified had to be hospitalized.

The most common type of procedures these patients were given were stem cells taken from their own body and then injected into their eye, spine, hip, shoulder, or knee. The second most common was stem cells from a donor that were then injected.

The Pew report cites the case of one California-based stem cell company that sold products manufactured without proper safety measures, “including a failure to properly screen for communicable diseases such as HIV and hepatitis B and C.” Those products led to at least 13 people being hospitalized due to serious bacterial infection in Texas, Arizona, Kansas, and Florida.

Shocking as these statistics are, the report says this is probably a gross under count of actual harm caused by the bogus clinics. It says the clinics themselves rarely report adverse events and many patients don’t report them either, unless they are so serious that they require medical intervention.

The Pew report concludes by saying the FDA needs more resources so it can more effectively act against these clinics and shut them down when necessary. It says the agency needs to encourage doctors and patients to report any unexpected side effects, saying: “devising effective strategies to collect more real-world evidence of harm can help the agency in its efforts to curb the growth of this unregulated market and ensure that the regenerative medicine field develops into one that clinicians and patients can trust and safely access.”

We completely support both reports and will continue to work with the FDA and anyone else opposed to these predatory clinics. You can read more here about what we have been doing to oppose these clinics, and here is information that will help inform your decision if you are thinking about taking part in a stem cell clinical trial but are not sure if it’s a legitimate one.

Scientists at UC Davis discover a way to help stem cells repair heart tissue

/ Yimy Villa / Leave a comment
Researchers Phung Thai (left) and Padmini Sirish were part of a research team seeking stem cell solutions to heart failure care.  Image Credit: UC Davis

Repairing the permanent damage associated with a heart attack or long-term heart disease has been a challenge that scientists have been trying to tackle for a long time. Heart failure affects approximately 5.7 million people in the U.S and it is estimated that this number will increase to 9 million by the year 2030. At a biological level, the biggest challenge to overcome is cell death and thickening of muscles around the heart.

Recently, using stem cells to treat heart disease has shown some promise. However, little progress has been made in this area because the inflammation associated with heart disease decreases the chances of stem cell survival. Fortunately, Dr. Nipavan Chiamvimonvat and her team of researchers at UC Davis have found an enzyme inhibitor that may help stem cells repair damaged heart tissue.

Dr. Nipavan Chiamvimonvat
 Image Credit: UC Davis

The enzyme the team is looking at, known as soluble epoxide hydrolase (or sEH for short), is a known factor in joint and lung disease and is associated with inflammation. The inhibitor Dr. Chiamvimonvat and her team are studying closely is called TPPU and it is meant to block sEH.

In their study, the UC Davis team used human-induced pluripotent stem cells (hiPSCs), a kind of stem cell made by reprogramming skin or blood cells that then has the ability to form all cell types. In this case, the hiPSCs were turned into heart muscle cells.

To evaluate the effectiveness of TPPU, the team then induced heart attacks in six groups of mice. A group of these mice was treated with a combination of TPPU and the newly created heart muscle cells.  The team found that the mice treated with this combination approach had the best outcomes in terms of increased engraftment and survival of transplanted stem cells. Additionally, this group also had less heart muscle thickening and improved heart function. 

The next step for Dr. Chiamvimonvat and her team is to conduct more animal testing in order to obtain the data necessary to test this therapy in clinical trials.

In a press release, Dr. Chiamvimonvat discusses the importance of research and its impact on patients.

““It is my dream as a clinician and scientist to take the problems I see in the clinic to the lab for solutions that benefit our patients.”

The full study was published in Stem Cells Translational Medicine.

 

Of Mice and Men, and Women Too; Stem cell stories you might have missed

/ Kevin McCormack / Leave a comment
Mice brains can teach us a lot

Last week’s news headlines were dominated by one big story, the use of a stem cell transplant to effectively cure a person of HIV. But there were other stories that, while not quite as striking, did also highlight how the field is advancing.

A new way to boost brain cells (in mice!)

It’s hard to fix something if you don’t really know what’s wrong in the first place. It would be like trying to determine why a car is not working just by looking at the hood and not looking inside at the engine. The human brain is far more complex than a car so trying to determine what’s going wrong is infinitely more challenging. But a new study could help give us a new option.

Researchers in Luxembourg and Germany have developed a new computer model for what’s happening inside the brain, identifying what cells are not operating properly, and fixing them.

Antonio del Sol, one of the lead authors of the study – published in the journal Cell – says their new model allows them to identify which stem cells are active and ready to divide, or dormant. 

“Our results constitute an important step towards the implementation of stem cell-based therapies, for instance for neurodegenerative diseases. We were able to show that, with computational models, it is possible to identify the essential features that are characteristic of a specific state of stem cells.”

The work, done in mice, identified a protein that helped keep brain stem cells inactive in older animals. By blocking this protein they were able to help “wake up” those stem cells so they could divide and proliferate and help regenerate the aging brain.

And if it works in mice it must work in people right? Well, that’s what they hope to see next.

Deeper understanding of fetal development

According to the Mayo Clinic between 10 and 20 percent of known pregnancies end in miscarriage (though they admit the real number may be even higher) and our lack of understanding of fetal development makes it hard to understand why. A new study reveals a previously unknown step in this development that could help provide some answers and, hopefully, lead to ways to prevent miscarriages.

Researchers at the Karolinska Institute in Sweden used genetic sequencing to follow the development stages of mice embryos. By sorting those different sequences into a kind of blueprint for what’s happening at every stage of development they were able to identify a previously unknown phase. It’s the time between when the embryo attaches to the uterus and when it begins to turn these embryonic stem cells into identifiable parts of the body.

Qiaolin Deng, Karolinska Institute

Lead researcher Qiaolin Deng says this finding provides vital new evidence.

“Being able to follow the differentiation process of every cell is the Holy Grail of developmental biology. Knowledge of the events and factors that govern the development of the early embryo is indispensable for understanding miscarriages and congenital disease. Around three in every 100 babies are born with fetal malformation caused by faulty cellular differentiation.”

The study is published in the journal Cell Reports.

Could a new drug discovery reduce damage from a heart attack?

Every 40 seconds someone in the US has a heart attack. For many it is fatal but even for those who survive it can lead to long-term damage to the heart that ultimately leads to heart failure. Now British researchers think they may have found a way to reduce that likelihood.

Using stem cells to create human heart muscle tissue in the lab, they identified a protein that is activated after a heart attack or when exposed to stress chemicals. They then identified a drug that can block that protein and, when tested in mice that had experienced a heart attack, they found it could reduce damage to the heart muscle by around 60 percent.

Prof Michael Schneider, the lead researcher on the study, published in Cell Stem Cell, said this could be a game changer.

“There are no existing therapies that directly address the problem of muscle cell death and this would be a revolution in the treatment of heart attacks. One reason why many heart drugs have failed in clinical trials may be that they have not been tested in human cells before the clinic. Using both human cells and animals allows us to be more confident about the molecules we take forward.”

Creating a platform to help transplanted stem cells survive after a heart attack

/ Kevin McCormack / 1 Comment

heart

Developing new tools to repair damaged hearts

Repairing, even reversing, the damage caused by a heart attack is the Holy Grail of stem cell researchers. For years the Grail seemed out of reach because the cells that researchers transplanted into heart attack patients didn’t stick around long enough to do much good. Now researchers at Stanford may have found a way around that problem.

In a heart attack, a blockage cuts off the oxygen supply to muscle cells. Like any part of our body starved off oxygen the muscle cells start to die, and as they do the body responds by creating a layer of scars, effectively walling off the dead tissue from the surviving healthy tissue.  But that scar tissue makes it harder for the heart to effectively and efficiently pump blood around the body. That reduced blood flow has a big impact on a person’s ability to return to a normal life.

In the past, efforts to transplant stem cells into the heart had limited success. Researchers tried pairing the cells with factors called peptides to help boost their odds of surviving. That worked a little better but most of the peptides were also short-lived and weren’t able to make a big difference in the ability of transplanted cells to stick around long enough to help the heart heal.

Slow and steady approach

Now, in a CIRM-funded study published in the journal Nature Biomedical Engineering, a team at Stanford – led by Dr. Joseph Wu – believe they have managed to create a new way of delivering these cells, one that combines them with a slow-release delivery mechanism to increase their chances of success.

The team began by working with a subset of bone marrow cells that had been shown in previous studies to have what are called “pro-survival factors.” Then, working in mice, they identified three peptides that lived longer than other peptides. That was step one.

Step two involved creating a matrix, a kind of supporting scaffold, that would enable the researchers to link the three peptides and combine them with a delivery system they hoped would produce a slow release of pro-survival factors.

Step three was seeing if it worked. Using fluorescent markers, they were able to show, in laboratory tests, that unlinked peptides were rapidly released over two or three days. However, the linked peptides had a much slower release, lasting more than 15 days.

Out of the lab and into animals

While these petri dish experiments looked promising the big question was could this approach work in an animal model and, ultimately, in people. So, the team focused on cardiac progenitor cells (CPCs) which have shown potential to help repair damaged hearts, but which also have a low survival rate when transplanted into hearts that have experienced a heart attack.

The team delivered CPCs to the hearts of mice and found the cells without the pro-survival matrix didn’t last long – 80 percent of the cells were gone four days after they were injected, 90 percent were gone by day ten. In contrast the cells on the peptide-infused matrix were found in large numbers up to eight weeks after injection. And the cells didn’t just survive, they also engrafted and activated the heart’s own survival pathways.

Impact on heart

The team then tested to see if the treatment was helping improve heart function. They did echocardiograms and magnetic resonance imaging up to 8 weeks after the transplant surgery and found that the mice treated with the matrix combination had a statistically improved left ventricular function compared to the other mice.

Jayakumar Rajadas, one of the authors on the paper told CIRM that, because the matrix was partly made out of collagen, a substance the FDA has already approved for use in people, this could help in applying for approval to test it in people in the future:

“This paper is the first comprehensive report to demonstrate an FDA-compliant biomaterial to improve stem cell engraftment in the ischemic heart. Importantly, the biomaterial is collagen-based and can be readily tested in humans once regulatory approval is obtained.”

 

How mice and zebrafish are unlocking clues to repairing damaged hearts

/ Kevin McCormack / Leave a comment

Bee-Gees

The Bee Gees, pioneers in trying to find ways to mend a broken heart. Photograph: Michael Ochs Archives

This may be the first time that the Australian pop group the Bee Gees have ever been featured in a blog about stem cell research, but in this case I think it’s appropriate. One of the Bee Gees biggest hits was “How can you mend a broken heart” and while it was a fine song, Barry and Robin Gibb (who wrote the song) never really came up with a viable answer.

Happily some researchers at the University of Southern California may succeed where Barry and Robin failed. In a study, published in the journal Nature Genetics, the USC team identify a gene that may help regenerate damaged heart tissue after a heart attack.

When babies are born they have a lot of a heart muscle cell called a mononuclear diploid cardiomyocyte or MNDCM for short. This cell type has powerful regenerative properties and so is able to rebuild heart muscle. However, as we get older we have less and less MNDCMs. By the time most of us are at an age where we are most likely to have a heart attack we are also most likely to have very few of these cells, and so have a limited ability to repair the damage.

Michaela Patterson, and her colleagues at USC, set out to find ways to change that. They found that in some adult mice less than 2 percent of their heart cells were MNDCMs, while other mice had a much higher percentage, around 10 percent. Not surprisingly the mice with the higher percentage of MNDCMs were better able to regenerate heart muscle after a heart attack or other injury.

So the USC team – with a little help from CIRM funding – dug a little deeper and did a genome-wide association study of these mice, that’s where they look at all the genetic variants in different individuals to see if they can spot common traits. They found one gene, Tnni3k, that seems to play a key role in generating MNDCMs.

Turning Tnni3K off in mice resulted in higher numbers of MNDCMs, increasing their ability to regenerate heart muscle. But when they activated Tnni3k in zebrafish it reduced the number of MNDCMs and impaired the fish’s ability to repair heart damage.

While it’s a long way from identifying something interesting in mice and zebrafish to seeing if it can be used to help people, Henry Sucov, the senior author on the study, says these findings represent an important first step in that direction:

“The activity of this gene, Tnni3k, can be modulated by small molecules, which could be developed into prescription drugs in the future. These small molecules could change the composition of the heart over time to contain more of these regenerative cells. This could improve the potential for regeneration in adult hearts, as a preventative strategy for those who may be at risk for heart failure.”

 

 

 

Using skin cells to repair damaged hearts

/ Kevin McCormack / Leave a comment

heart-muscle

Heart muscle  cells derived from skin cells

When someone has a heart attack, getting treatment quickly can mean the difference between life and death. Every minute delay in getting help means more heart cells die, and that can have profound consequences. One study found that heart attack patients who underwent surgery to re-open blocked arteries within 60 minutes of arriving in the emergency room had a six times greater survival rate than people who had to wait more than 90 minutes for the same treatment.

Clearly a quick intervention can be life-saving, which means an approach that uses a patient’s own stem cells to treat a heart attack won’t work. It simply takes too long to harvest the healthy heart cells, grow them in the lab, and re-inject them into the patient. By then the damage is done.

Now a new study shows that an off-the-shelf approach, using donor stem cells, might be the most effective way to go. Scientists at Shinshu University in Japan, used heart muscle stem cells from one monkey, to repair the damaged hearts of five other monkeys.

In the study, published in the journal Nature, the researchers took skin cells from a macaque monkey, turned those cells into induced pluripotent stem cells (iPSCs), and then turned those cells into cardiomyocytes or heart muscle cells. They then transplanted those cardiomyocytes into five other monkeys who had experienced an induced heart attack.

After 3 months the transplanted monkeys showed no signs of rejection and their hearts showed improved ability to contract, meaning they were pumping blood around the body more powerfully and efficiently than before they got the cardiomyocytes.

It’s an encouraging sign but it comes with a few caveats. One is that the monkeys used were all chosen to be as close a genetic match to the donor monkey as possible. This reduced the risk that the animals would reject the transplanted cells. But when it comes to treating people, it may not be feasible to have a wide selection of heart stem cell therapies on hand at every emergency room to make sure they are a good genetic match to the patient.

The second caveat is that all the transplanted monkeys experienced an increase in arrhythmias or irregular heartbeats. However, Yuji Shiba, one of the researchers, told the website ResearchGate that he didn’t think this was a serious issue:

“Ventricular arrhythmia was induced by the transplantation, typically within the first four weeks. However, this post-transplant arrhythmia seems to be transient and non-lethal. All five recipients of [the stem cells] survived without any abnormal behaviour for 12 weeks, even during the arrhythmia. So I think we can manage this side effect in clinic.”

Even with the caveats, this study demonstrates the potential for a donor-based stem cell therapy to treat heart attacks. This supports an approach already being tested by Capricor in a CIRM-funded clinical trial. In this trial the company is using donor cells, derived from heart stem cells, to treat patients who developed heart failure after a heart attack. In early studies the cells appear to reduce scar tissue on the heart, promote blood vessel growth and improve heart function.

The study from Japan shows the possibilities of using a ready-made stem cell approach to helping repair damage caused by a heart attacks. We’re hoping Capricor will take it from a possibility, and turn it into a reality.

If you would like to read some recent blog posts about Capricor go here and here.