Stem Cell Patch Restores Vision in Patients with Age-Related Macular Degeneration

Stem cell-derived retinal pigmented epithelial cells. Cell borders are green and nuclei are red. (Photo Credit: Dennis Clegg, UCSB Center for Stem Cell Biology and Engineering)

Two UK patients suffering from vision loss caused by age-related macular degeneration (AMD) have regained their sight thanks to a stem cell-based retinal patch developed by researchers from UC Santa Barbara (UCSB). The preliminary results of this promising Phase 1 clinical study were published yesterday in the journal Nature Biotechnology.

AMD is one of the leading causes of blindness and affects over six million people around the world. The disease causes the blurring or complete loss of central vision because of damage to an area of the retina called the macula. There are different stages (early, intermediate, late) and forms of AMD (wet and dry). The most common form is dry AMD which occurs in 90% of patients and is characterized by a slow progression of the disease.

Patching Up Vision Loss

In the current study, UCSB researchers engineered a retinal patch from human embryonic stem cells. These stem cells were matured into a layer of cells at the back of the eye, called the retinal pigment epithelium (RPE), that are damaged in AMD patients. The RPE layer was placed on a synthetic patch that is implanted under the patient’s retina to replace the damaged cells and hopefully improve the patient’s vision.

The stem cell-based eyepatches are being implanted in patients with severe vision loss caused by the wet form of AMD in a Phase 1 clinical trial at the Moorfields Eye Hospital NHS Foundation Trust in London, England. The trial was initiated by the London Project to Cure Blindness, which was born from a collaboration between UCSB Professor Peter Coffey and Moorsfields retinal surgeon Lyndon da Cruz. Coffey is a CIRM grantee and credited a CIRM Research Leadership award as one of the grants that supported this current study.

The trial treated a total of 10 patients with the engineered patches and reported 12-month data for two of these patients (a woman in her 60s and a man in his 80s) in the Nature Biotech study. All patients were given local immunosuppression to prevent the rejection of the implanted retinal patches. The study reported “three serious adverse events” that required patients to be readmitted to the hospital, but all were successfully treated. 12-months after treatment, the two patients experienced a significant improvement in their vision and went from not being able to read at all to reading 60-80 words per minute using normal reading glasses.

Successfully Restoring Sight

Douglas Waters, the male patient reported on, was diagnosed with wet AMD in July 2015 and received the treatment in his right eye a few months later. He spoke about the remarkable improvement in his vision following the trial in a news release:

“In the months before the operation my sight was really poor, and I couldn’t see anything out of my right eye. I was struggling to see things clearly, even when up-close. After the surgery my eyesight improved to the point where I can now read the newspaper and help my wife out with the gardening. It’s brilliant what the team have done, and I feel so lucky to have been given my sight back.”

This treatment is “the first description of a complete engineered tissue that has been successfully used in this way.” It’s exciting not only that both patients had a dramatic improvement in their vision, but also that the engineered patches were successful at treating an advanced stage of AMD.

The team will continue to monitor the patients in this trial for the next five years to make sure that the treatment is safe and doesn’t cause tumors or other adverse effects. Peter Coffey highlighted the significance of this study and what it means for patients suffering from AMD in a UCSB news release:

Peter Coffey

“This study represents real progress in regenerative medicine and opens the door to new treatment options for people with age-related macular degeneration. We hope this will lead to an affordable ‘off-the-shelf’ therapy that could be made available to NHS patients within the next five years.”

Inspiring Video: UC Irvine Stem Cell Trial Gives Orange County Woman Hope in Her Fight Against ALS

Stephen Hawking

Last week, we lost one of our greatest, most influential scientific minds. Stephen Hawking, a famous British theoretical physicist and author of “A Brief History of Time: From the Big Bang to Black Holes”, passed away at the age of 76.

Hawking lived most of his adult life in a wheelchair because he suffered from amyotrophic lateral sclerosis (ALS). Also known as Lou Gehrig’s disease, ALS causes the degeneration of the nerve cells that control muscle movement.

When Hawking was diagnosed with ALS at the age of 21, he was told he only had three years to live. But Hawking defied the odds and went on to live a life that not only revolutionized our understanding of the cosmos, but also gave hope to other patients suffering from this devastating degenerative disease.

A Story of Hope

Speaking of hope, I’d like to share another story of an Orange County woman name Lisa Wittenberg who was recently diagnosed with ALS. Her story was featured this week on KTLA5 news and is also available on the UC Irvine Health website.

VIDEO: UCI Health stem cell trial helps Orange County woman fight neurodegenerative disease ALS. Click on image to view video in new window.

In this video, Lisa describes how quickly ALS changed her life. She was with her family sledding in the snow last winter, and only a year later, she is in a wheelchair unable to walk. Lisa got emotional when she talked about how painful it is for her to see her 13-year-old son watch her battle with this disease.

But there is hope for Lisa in the form of a stem cell clinical trial at the UC Irvine CIRM Alpha Stem Cell Clinic. Lisa enrolled in the Brainstorm study, a CIRM-funded phase 3 trial that’s testing a mesenchymal stem cell therapy called NurOwn. BrainStorm Cell Therapeutics, the company sponsoring this trial, is isolating mesenchymal stem cells from the patient’s own bone marrow. The stem cells are then cultured in the lab under conditions that convert them into biological factories secreting a variety of neurotrophic factors that help protect the nerve cells damaged by ALS. The modified stem cells are then transplanted back into the patient where they will hopefully slow the progression of the disease.

Dr. Namita Goyal, a neurologist at UC Irvine Health involved in the trial, explained in the KTLA5 video that they are hopeful this treatment will give patients more time, and optimistic that in some cases, it could improve some of their symptoms.

Don’t Give Up the Fight

The most powerful part of Lisa’s story to me was the end when she says,

“I think it’s amazing that I get to fight, but I want everybody to get to fight. Everybody with ALS should get to fight and should have hope.”

Not only is Lisa fighting by being in this ground-breaking trial, she is also participated in the Los Angeles marathon this past weekend, raising money for ALS research.

More patients like Lisa will get the chance to fight as more potential stem cell treatments and drugs enter clinical trials. Videos like the one in this blog are important for raising awareness about available clinical trials like the Brainstorm study, which, by the way, is still looking for more patients to enroll (contact information for this trial can be found on the website here). CIRM is also funding another stem cell trial for ALS at the Cedars-Sinai Medical Center. You can read more about this trial on our website.

Lisa’s powerful message of fighting ALS and having hope reminds me of one of Stephen Hawking’s most famous quotes, which I’ll leave you with:

“Remember to look up at the stars and not down at your feet. Try to make sense of what you see and wonder about what makes the Universe exist. Be curious. And however difficult life may seem, there is always something you can do and succeed at. It matters that you don’t just give up.”

Related Links:

Stem Cell Round: Improving memory, building up “good” fat, nanomedicine

Stem Cell Photo of the Week

roundup03618In honor of brain awareness week, our featured stem cell photo is of the brain! Scientists at the Massachusetts General Hospital and Harvard Stem Cell Institute identified a genetic switch that could potentially improve memory during aging and symptoms of PTSD. Shown in this picture are dentate gyrus cells (DGC) (green) and CA3 interneurons (red) located in the memory-forming area of the brain known as the hippocampus. By reducing the levels of a protein called abLIM3 in the DGCs of older mice, the researchers were able to boost the connections between DGCs and CA3 cells, which resulted in an improvement in the memories of the mice. The team believes that targeting this protein in aging adults could be a potential strategy for improving memory and treating patients with post-traumatic stress disorder (PTSD). You can read more about this study in The Harvard Gazette.

New target for obesity.
Fat cells typically get a bad rap, but there’s actually a type of fat cell that is considered “healthier” than others. Unlike white fat cells that store calories in the form of energy, brown fat cells are packed with mitochondria that burn energy and produce heat. Babies have brown fat, so they can regulate their body temperature to stay warm. Adults also have some brown fat, but as we get older, our stores are slowly depleted.

In the fight against obesity, scientists are looking for ways to increase the amount of brown fat and decrease the amount of white fat in the body. This week, CIRM-funded researchers from the Salk Institute identified a molecule called ERRg that gives brown fat its ability to burn energy. Their findings, published in Cell Reports, offer a new target for obesity and obesity-related diseases like diabetes and fatty liver disease.

The team discovered that brown fat cells produce the ERRg molecule while white fat cells do not. Additionally, mice that couldn’t make the ERRg weren’t able to regulate their body temperature in cold environments. The team concluded in a news release that ERRg is “involved in protection against the cold and underpins brown fat identity.” In future studies, the researchers plan to activate ERRg in white fat cells to see if this will shift their identity to be more similar to brown fat cells.


Mice that lack ERR aren’t able to regulate their body temperature and are much colder (right) than normal mice (left). (Image credit Salk Institute)

Tale of two nanomedicine stories: making gene therapies more efficient with a bit of caution (Todd Dubnicoff).
This week, the worlds of gene therapy, stem cells and nanomedicine converged for not one, but two published reports in the journal American Chemistry Society NANO.

The first paper described the development of so-called nanospears – tiny splinter-like magnetized structures with a diameter 5000 times smaller than a strand of human hair – that could make gene therapy more efficient and less costly. Gene therapy is an exciting treatment strategy because it tackles genetic diseases at their source by repairing or replacing faulty DNA sequences in cells. In fact, several CIRM-funded clinical trials apply this method in stem cells to treat immune disorders, like severe combined immunodeficiency and sickle cell anemia.

This technique requires getting DNA into diseased cells to make the genetic fix. Current methods have low efficiency and can be very damaging to the cells. The UCLA research team behind the study tested the nanospear-delivery of DNA encoding a gene that causes cells to glow green. They showed that 80 percent of treated cells did indeed glow green, a much higher efficiency than standard methods. And probably due to their miniscule size, the nanospears were gentle with 90 percent of the green glowing cells surviving the procedure.

As Steve Jonas, one of the team leads on the project mentions in a press release, this new method could bode well for future recipients of gene therapies:

“The biggest barrier right now to getting either a gene therapy or an immunotherapy to patients is the processing time. New methods to generate these therapies more quickly, effectively and safely are going to accelerate innovation in this research area and bring these therapies to patients sooner, and that’s the goal we all have.”

While the study above describes an innovative nanomedicine technology, the next paper inserts a note of caution about how experiments in this field should be set up and analyzed. A collaborative team from Brigham and Women’s Hospital, Stanford University, UC Berkeley and McGill University wanted to get to the bottom of why the many advances in nanomedicine had not ultimately led to many new clinical trials. They set out looking for elements within experiments that could affect the uptake of nanoparticles into cells, something that would muck up the interpretation of results.


imaging of female human amniotic stem cells incubated with nanoparticles demonstrated a significant increase in uptake compared to male cells. (Green dots: nanoparticles; red: cell staining; blue: nuclei) Credit: Morteza Mahmoudi, Brigham and Women’s Hospital.

In this study, they report that the sex of cells has a surprising, noticeable impact on nanoparticle uptake. Nanoparticles were incubated with human amniotic stem cells derived from either males or females. The team showed that the female cells took up the nanoparticles much more readily than the male cells.  Morteza Mahmoudi, PhD, one of the authors on the paper, explained the implications of these results in a press release:

“These differences could have a critical impact on the administration of nanoparticles. If nanoparticles are carrying a drug to deliver [including gene therapies], different uptake could mean different therapeutic efficacy and other important differences, such as safety, in clinical data.”


CIRM-funded clinical trial takes a combination approach to treating deadly blood cancers

Stained blood smear shows enlarged chronic lymphocytic leukemia cells among normal red blood cells. (UCSD Health)

A diagnosis of cancer often means a tough road ahead, with surgery, chemotherapy and radiation used to try and kill the tumor. Even then, sometimes cancer cells manage to survive and return later, spreading throughout the body. Now researchers at UC San Diego and Oncternal Therapeutics are teaming up with a combination approach they hope will destroy hard-to-kill blood cancers like leukemia.

The combination uses a monoclonal antibody called cirmtuzumab (so called because CIRM funding helped develop it) and a more traditional anti-cancer therapy called ibrutinib. Here’s how it is hoped this approach will work.

Ibrutinib is already approved by the US Food and Drug Administration (FDA) to treat blood cancers such as leukemia and lymphoma. But while it can help, it doesn’t always completely eradicate all the cancer cells. Some cancer stem cells are able to lie dormant during treatment and then start proliferating and spreading the cancer later. That’s why the team are pairing ibrutinib with cirmtuzumab.

In a news release announcing the start of the trial, UCSD’s Dr. Thomas Kipps,  said they hope this one-two punch combination will be more effective.

Thomas Kipps, UCSD

“As a result {of the failure to kill all the cancer cells}, patients typically need to take ibrutinib indefinitely, or until they develop intolerance or resistance to this drug. Cirmtuzumab targets leukemia and cancer stem cells, which are like the seeds of cancer. They are hard to find and difficult to destroy. By blocking signaling pathways that promote neoplastic-cell growth and survival, cirmtuzumab may have complementary activity with ibrutinib in killing leukemia cells, allowing patients potentially to achieve complete remissions that permit patients to stop therapy altogether.”

Because this is an early stage clinical trial, the goal is to first make sure the approach is safe, and second to identify the best dose and treatment schedule for patients.

The researchers hope to recruit 117 patients around the US. Some will get the cirmtuzumab and ibrutinib combination, some will get ibrutinib alone to see if one approach is more effective than the other.

CIRM has a triple investment in this research. Not only did our funding help develop cirmtuzumab, but CIRM is also funding this clinical trial and one of the trial sites is at UCSD, one of the CIRM Alpha Stem Cell Clinics.

CIRM’s Dr. Ingrid Caras says this highlights our commitment to our mission of accelerating stem cell therapies to patients with unmet medical needs.

“Our partnership with UC San Diego and the Alpha Stem Cell Clinics has enabled this trial to more quickly engage potential patient-participants. Being among the first to try new therapies requires courage and CIRM is grateful to the patients who are volunteering to be part of this clinical trial.”

Related Links:

It’s World Kidney Day: Highlighting CIRM’s Investments in Treating Kidney Failure

WKD-Logo-HiToday is World Kidney Day. Hundreds of events across the globe are taking place “to raise awareness of the importance of our kidneys to our overall health and to reduce the frequency and impact of kidney disease and its associated health problems worldwide.” (Side note: in recognition that today is also International Women’s Day, World Kidney Day’s theme this year is “Kidney’s & Women: Include, Value, Empower.)

To honor this day, we’re highlighting how CIRM is playing its part in that mission. The infographic below provides big picture summaries of the four CIRM-funded clinical trials that are currently testing stem cell-based therapies for kidney failure, a condition that affects well over 600,000 Americans.

When a person’s kidneys fail, their body can no longer filter out waste products and extra fluid from the blood which leads to life-threatening complications. About 30% of those affected in the U.S. have organ transplants. Due to the limited availability of donor organs, the other 70% need dialysis, a blood filtration therapy, that requires several trips a week to a special clinic.

Both treatment options have serious limitations. Organ recipients have to take drugs that prevent organ rejections for the rest of their lives. Over time, these drugs are toxic and can increase a patient’s risk of infection, heart disease, cancer and diabetes. In the case of dialysis treatment, the current procedure uses a plastic tube called a shunt to connect to a patient’s vein. These shunts are far from ideal and can lead to infection, blood clots and can be rejected by the patient’s immune system. These complications probably play a role in the average life expectancy of 5-10 years for dialysis patients.

Four CIRM-funded clinical trials aim to circumvent these drawbacks. Humacyte has received over $24 million from the Agency to support two clinical trials that are testing an alternative to the plastic shunt used in dialysis treatment. The company has developed a bioengineered vessel that is implanted in the patient’s arm and over time is populated with the patient’s own stem cells which develop into a natural blood vessel. The trials will determine if the bioengineered vessel is superior to the shunt in remaining open for longer periods of time and with lower incidence of interventions due to blood clots and infections.

The other two CIRM-funded trials, one headed by Stanford University and the other by Medeor Therapeutics, aims to eliminate the need for long-life, anti-rejection medicine after kidney transplant. Both trials use a similar strategy: blood stem cells and immune cells from the organ donor are infused into the patient receiving the organ. If all goes as planned, those donor cells will engraft into and mix with the recipient’s immune system, making organ rejection less likely and ending the need for immune-system suppressing drugs.

For more details visit our Clinical Trial Dashboard.


A shot in the arm for people with bad knees


Almost every day I get an email or phone call from someone asking if we have a stem cell therapy for bad knees. The inquiries are from people who’ve been told they need surgery to replace joints damaged by age and arthritis. They’re not alone. Every year around 600,000 Americans get a knee replacement. That number is expected to rise to three million by 2030.

Up till now my answer to those calls and emails has been ‘I’m sorry, we don’t have anything’. But a new CIRM-funded study from USC stem cell scientist Denis Evseenko says that may not always be the case.


The ability to regenerate joint cartilage cells instead of surgically replacing joints would be a big boon for future patients. (Photo/Nancy Liu, Denis Evseenko Lab, USC Stem Cell)

Evseenko and his team have discovered a molecule they have called Regulator of Cartilage Growth and Differentiation or RCGD 423. This cunning molecule works in two different ways. One is to reduce the inflammation that many people with arthritis have in their joints. The second is to help stimulate the regeneration of the cartilage destroyed by arthritis.

When they tested RCGD 423 in rats with damaged cartilage, the rats cartilage improved. The study is published in the Annals of Rheumatic Diseases.

In an article in USC News, Evseenko, says there is a lot of work to do but that this approach could ultimately help people with osteoarthritis or juvenile arthritis.

“The goal is to make an injectable therapy for an early to moderate level of arthritis. It’s not going to cure arthritis, but it will delay the progression of arthritis to the damaging stages when patients need joint replacements, which account for a million surgeries a year in the U.S.”

Breaking the isolation of rare diseases

Rare disease day

Rare Disease Day in Sacramento, California

How can something that affects 30 million Americans, one in ten people in the US, be called rare? But that’s the case with people who have a rare disease. There are around 7,000 different diseases that are categorized as rare because they affect fewer than 200,000 people. Less than five percent of these diseases have a treatment.

That’s why last Wednesday, in cities across the US, members of the rare disease community gathered to call for more support, more research, and more help for families battling these diseases. Their slogan tells their story, ‘Alone we are rare; Together we are strong.’

At the Rare Disease Day rally in Sacramento, California, I met Kerry Rivas. Kerry’s son Donovan has a life-threatening condition called Shprintzen-Goldberg Syndrome. Talk about rare. There are only 70 documented cases of the syndrome worldwide. Just getting a diagnosis for Donovan took years.

DonovanDonovan suffers from a lot of problems but the most serious affect his heart, lungs and spinal cord. Getting him the care he needs is time consuming and expensive and has forced Kerry and her family to make some big sacrifices. Even so they work hard to try and see that Donovan is able to lead as normal a life as is possible.

While the disease Kerry’s son has is rarer than most, everyone at Rare Disease Day had a similar story, and an equal commitment to doing all they can to be an effective advocate. And their voices are being heard.

To honor the occasion the US Food and Drug Administration (FDA) announced it was partnering with the National Organization of Rare Diseases (NORD) to hold listening sessions involving patients and FDA medical reviewers.

In a news release Peter L. Saltonstall, President and CEO of NORD, said:

“These listening sessions will provide FDA review division staff with better insight into what is important to patients in managing their diseases and improving their quality of life. It is important for FDA to understand, from the patient perspective, disease burden, management of symptoms, daily impact on quality of life, and patients’ risk tolerance. Patients and caregivers bring a pragmatic, realistic perspective about what they are willing to deal with in terms of potential risks and benefits for new therapies.”

FDA Commissioner Dr. Scott Gottlieb said his agency is committed to doing everything possible to help the rare disease community:

“Despite our successes, there are still no treatments for the vast proportion of rare diseases or conditions. FDA is committed to do what we can to stimulate the development of more products by improving the consistency and efficiency of our reviews, streamlining our processes and supporting rare disease research.”

At CIRM we are also committed to doing all we can to help the cause. Many of the diseases we are currently funding in clinical trials are rare diseases like ALS or Lou Gehrig’s disease, SCID, spinal cord injury and sickle cell disease.

Many pharmaceutical companies are shy about funding research targeting these diseases because the number of patients involved is small, so the chances of recouping their investment or even making a profit is small.

At CIRM we don’t have to worry about those considerations. Our focus is solely on helping those in need. People like Donovan Rivas.

Friday Roundup: A better kind of blood stem cell transplant; Encouraging news from spinal cord injury trial; Finding an “elusive” cell that could help diabetics

Cool Instagram image of the week:

Pancreatic Progenitors

Diabetes Research Institute scientists have confirmed that the unique stem cells reside within large ducts of the human pancreas. Two such ducts (green) surrounded by three islets (white) are shown. [Diabetes Research Institute Foundation]

Chemo- and radiation-free blood stem cell transplant showing promise

Bubble baby disease, also known as severe combined immunodeficiency (SCID), is an inherited disorder that leaves newborns without an effective immune system. Currently, the only approved treatment for SCID is a blood stem cell transplant, in which the patient’s defective immune system cells are eliminated by chemotherapy or radiation to clear out space for cells from a healthy, matched donor. Even though the disease can be fatal, physicians loathe to perform a stem cell transplant on bubble baby patients:

Shizuru“Physicians often choose not to give chemotherapy or radiation to young children with SCID because there are lifelong effects: neurological impairment, growth delays, infertility, risk of cancer, etc.,” says Judith Shizuru, MD, PhD, professor of medicine at Stanford University.

To avoid these complications, Dr. Shizuru is currently running a CIRM-funded clinical trial testing a gentler approach to prepare patients for blood stem cell transplants. She presented promising, preliminary results of the trial on Tuesday at the annual meeting of Stanford’s Center for Definitive and Curative Medicine.

Trial participants are receiving a protein antibody called CD117 before their stem cell transplant. Previous studies in animals showed that this antibody binds to the surface of blood stem cells and blocks the action of a factor which is required for stem cell survival. This property of CD117 provides a means to get rid of blood stem cells without radiation or chemotherapy.

Early results in two participants indicate that, 6 and 9 months after receiving the CD117 blood stem cell transplants, the donor cells have successfully established themselves in the patients and begun making immune cells.

Spinal cord injury trial reports more promising results:

AsteriasRegular readers of our blog will already know about our funding for the clinical trial being run by Asterias Biotherapeutics to treat spinal cord injuries. The latest news from the company is very encouraging, in terms of both the safety and effectiveness of the treatment.

Asterias is transplanting stem cells into patients who have suffered recent injuries that have left them paralyzed from the neck down. It’s hoped the treatment will restore connections at the injury site, allowing patients to regain some movement and feeling in their hands and arms.

This week the company announced that of the 25 patients they have treated there have been no serious side effects. In addition:

  • Magnetic Resonance Imaging (MRI) scans show that in more than 90 percent of the patients the cells appear to show signs of engraftment
  • At least 75 percent of those treated have recovered at least one motor level, and almost 20 percent have recovered two levels

In a news release, Michael Mulroy, Asterias’ President and CEO, said:

“The positive safety profile to date, the evidence supporting engraftment of the cells post-implantation, and the improvements we are seeing in upper extremity motor function highlight the promising findings coming from this Phase 1/2a clinical trial, which will guide us as we work to design future studies.”

There you are! Finding the “elusive” human pancreatic progenitor cells – the story behind our cool Instagram image of the week.

Don’t you hate it when you lose something and can’t find it? Well imagine the frustration of scientists who were looking for a group of cells they were sure existed but for decades they couldn’t locate them. Particularly as those cells might help in developing new treatments for diabetes.

Diabetes-Research-Institute_University-of-Miami-Miller-School-of-MedicineWell, rest easy, because scientists at the Diabetes Research Institute at the University of Miami finally found them.

In a study, published in Genetic Engineering and Biotechnology News, the researchers show how they found these progenitor cells in the human pancreas, tucked away in the glands and ducts of the organ.

In type 1 diabetes, the insulin-producing cells in the pancreas are destroyed. Finding these progenitor cells, which have the ability to turn into the kinds of cells that produce insulin, means researchers could develop new ways to regenerate the pancreas’ ability to function normally.

That’s a long way away but this discovery could be an important first step along that path.

Gladstone scientists tackle heart failure by repairing the heart from within

Modern medicine often involves the development of a drug or treatment outside the body, which is then given to a patient to fix, improve or even prevent their condition. But what if you could regenerate or heal the body using the cells and tissue already inside a patient?

Scientists at the Gladstone Institutes are pursuing such a strategy for heart disease. In a CIRM-funded study published today in the journal Cell, the team identified four genes that can stimulate adult heart muscle cells, called cardiomyocytes, to divide and proliferate within the hearts of living mice. This discovery could be further developed as a strategy to repair cardiac tissue damage caused by heart disease and heart attacks.

Regenerating the Heart

Heart disease is the leading cause of death in the US and affects over 24 million people around the world. When patients experience a heart attack, blood flow is restricted to the heart, and parts of the heart muscle are damaged or die due to the lack of oxygen. The heart is unable to regenerate new healthy heart muscle, and instead, cardiac fibroblasts generate fibrous scar tissue to heal the injury. This scar tissue impairs the heart’s ability to pump blood, causing it to work harder and putting patients at risk for future heart failure.

Deepak Srivastava, President of the Gladstone Institutes and a senior investigator there, has dedicated his life’s research to finding new ways to regenerate heart tissue. Previously, his team developed methods to reprogram mouse and human cardiac fibroblasts into beating cardiomyocytes in hopes of one day restoring heart function in patients. The team is advancing this research with the help of a CIRM Discovery Stage research grant, which will aid them in developing a gene therapy product that delivers reprogramming factors into scar tissue cells to regenerate new heart muscle.

In this new study, Srivastava took a slightly different approach and attempted to coax cardiomyocytes, rather than cardiac fibroblasts, to divide and regenerate the heart. During development, fetal cardiomyocytes rapidly divide to create heart tissue. This regenerative ability is lost in adult cardiomyocytes, which are unable to divide because they’ve already exited the cell cycle (a series of phases that a cell goes through that ultimately results in its division).

Deepak Srivastava (left) and first author Tamer Mohamed (right). Photo credits: Diana Rothery.

Unlocking proliferative potential

Srivastava had a hunch that genes specifically involved in the cell division could be used to jump-start an adult cardiomyocyte’s re-entry into the cell cycle. After some research, they identified four genes (referred to as 4F) involved in controlling cell division. When these genes were turned on in adult cardiomyocytes, the cells started to divide and create new heart tissue.

This 4F strategy worked in mouse and rat cardiomyocytes and also was successful in stimulating cell division in 15%-20% of human cardiomyocytes. When they injected 4F into the hearts of mice that had suffered heart attacks, they observed an improvement in their heart function after three months and a reduction in the size of the scar tissue compared to mice that did not receive the injection.

The team was able to further refine their method by replacing two of the four genes with chemical inhibitors that had similar functions. Throughout the process, the team did not observe the development of heart tumors caused by the 4F treatment. They attributed this fact to the short-term expression of 4F in the cardiomyocytes. However, Srivastava expressed caution towards using this method in a Gladstone news release:

“In human organs, the delivery of genes would have to be controlled carefully, since excessive or unwanted cell division could cause tumors.”

First stop heart, next stop …

This study suggests that it’s possible to regenerate our tissues and organs from within by triggering adult cells to re-enter the cell cycle. While more research is needed to ensure this method is safe and worthy of clinical development, it could lead to a regenerative treatment strategy for heart failure.

Srivastava will continue to unravel the secrets to the proliferative potential of cardiomyocytes but predicts that other labs will pursue similar methods to test the regenerative potential of adult cells in other tissues and organs.

“Heart cells were particularly challenging because when they exit the cell cycle after birth, their state is really locked down—which might explain why we don’t get heart tumors. Now that we know our method is successful with this difficult cell type, we think it could be used to unlock other cells’ potential to divide, including nerve cells, pancreatic cells, hair cells in the ear, and retinal cells.”

Related Links:

Scientists repair spinal cord injuries in monkeys using human stem cells

Human neuronal stem cells extend axons (green). (Image UCSD)

An exciting development for spinal cord injury research was published this week in the journal Nature Medicine. Scientists from the University of San Diego School of Medicine transplanted human neural progenitor cells (NPCs) into rhesus monkeys that had spinal cord injuries. These cells, which are capable of turning into other cells in the brain, survived and robustly developed into nerve cells that improved the monkeys’ use of their hands and arms.

The scientists grafted 20 million human NPCs derived from embryonic stem cells into two-week-old spinal cord lesions in the monkeys. These stem cells were delivered with growth factors to improve their survival and growth. The monkeys were also treated with immunosuppressive drugs to prevent their immune system from rejecting the human cells.

After nine months, they discovered that the NPCs had developed into nerve cells within the injury site that extended past the injury into healthy tissue. These nerve extensions are called axons, which allow nerves to transmit electrical signals and instructions to other brain cells. During spinal cord injury, nerve cells and their axon extensions are damaged. Scientists have found it difficult to regenerate these damaged cells because of the inhibitory growth environment created at the injury site. You can compare it to the build-up of scar tissue after a heart attack. The heart has difficulty regenerating healthy heart muscle, which is instead replaced by fibrous scar tissue.

Excitingly, the UCSD team was able to overcome this hurdle in their current study. When they transplanted human NPCs with growth factors into the monkeys, they found that the cells were not affected by the inhibitory environment of the injury and were able to robustly develop into nerve cells and send out axon extensions.

Large numbers of human axons (green) emerge from a lesion/graft sites. Many axons travel along the interface (indicated by arrows) between spinal cord white matter (nerve fibers covered with myelin) and spinal cord gray matter (nerves without the whitish myelin sheathing). Image courtesy of Mark Tuszynski, UC San Diego School of Medicine.

The senior scientist on the study, Dr. Mark Tuszynski, explained how their findings in a large animal model are a huge step forward for the field in a UCSD Health news release:

“While there was real progress in research using small animal models, there were also enormous uncertainties that we felt could only be addressed by progressing to models more like humans before we conduct trials with people. We discovered that the grafting methods used with rodents didn’t work in larger, non-human primates. There were critical issues of scale, immunosuppression, timing and other features of methodology that had to be altered or invented. Had we attempted human transplantation without prior large animal testing, there would have been substantial risk of clinical trial failure, not because neural stem cells failed to reach their biological potential but because of things we did not know in terms of grafting and supporting the grafted cells.”

Dr. Tuszynski is a CIRM-grantee whose earlier research involved optimizing stem cell treatments for rodent models of spinal cord injury. We’ve blogged about that research previously on the Stem Cellar here and here.

Tuszynski recently was awarded a CIRM discovery stage research grant to develop a candidate human neural stem cell line that is optimized to repair the injured spinal cord and can be used in human clinical trials. He expressed cautious optimism about the future of this treatment for spinal cord injury patients emphasizing the need for patience and more research before arriving at clinical trials:

“We seem to have overcome some major barriers, including the inhibitory nature of adult myelin against axon growth. Our work has taught us that stem cells will take a long time to mature after transplantation to an injury site, and that patience will be required when moving to humans. Still, the growth we observe from these cells is remarkable — and unlike anything I thought possible even ten years ago. There is clearly significant potential here that we hope will benefit humans with spinal cord injury.”

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