A little history in the making by helping the tiniest patients

Dr. Diana Farmer stands with Dr. Aijun Wang and their UC Davis research team.

It’s appropriate that at the start of Women’s History Month, UC Davis’ Dr. Diana Farmer is making a little history of her own. She launched the world’s first clinical trial using stem cells to treat spina bifida before the child is born.

Spina bifida is a birth defect caused when a baby’s spinal cord fails to develop properly in the womb. In myelomeningocele, the most severe form of spina bifida, a portion of the spinal cord or nerves is exposed in a sac through an opening in the spine. Most people with myelomeningocele have changes in their brain structure, leg weakness, and bladder and bowel dysfunction. 

Illustration of spina bifida

While surgery can help, Dr. Farmer says it is far from perfect: “Currently, the standard of care for our patients is fetal surgery, which, while promising, still leaves more than half of children with spina bifida unable to walk independently. There is an extraordinary need for a treatment that prevents or lessens the severity of this devastating condition. Our team has spent more than a decade working up to this point of being able to test such a promising therapy.” 

The team at UC Davis – in a CIRM-funded study – will use a stem cell “patch” that is placed over the exposed spinal cord, then surgically close the opening, hopefully allowing the stem cells to regenerate and protect the spinal cord.

In a news release Dr. Aijun Wang, a stem cell bioengineer, says the team has been preparing for this trial for years, helping show in animals that it is safe and effective. He is hopeful it will prove equally safe and effective in people: “Our cellular therapy approach, in combination with surgery, should encourage tissue regeneration and help patients avoid devastating impairments throughout their lives.” 

Dr. Farmer says the condition, while rare, disproportionately affects Latinx babies and if the procedure works could have an enormous impact on their lives and the lives of their families: “A successful treatment for MMC would relieve the tremendous emotional and economic cost burden on families. We know it initially costs approximately $532,000 per child with spina bifida. But the costs are likely several million dollars more due to ongoing treatments, not to mention all the pain and suffering, specialized childcare, and lost time for unpaid caregivers such as parents.”

Here is video of two English bulldogs who had their spinal injuries repaired at UC Davis using stem cells. This was part of the research that led to the clinical trial led by Dr. Farmer and Dr. Wang.

Stem cell gene therapy for Fabry disease shows positive results in patients

Darren Bidulka rests after his modified blood stem cells were transplanted into him at the Foothills Medical Centre in Calgary in 2017, allowing him to stop his enzyme therapy. (From left): Dr. Jeffrey Medin, Medical College of Wisconsin, Dr. Aneal Khan, the experimental trial lead in Calgary, and Darren Bidulka. Image Credit: Darren Bidulka

Fabry disease is an X-linked genetic disorder that can damage major organs and shorten lifespan. Without a functional version of a gene called GLA, our bodies are unable to make the correct version of an enzyme that breaks down a fat, and that in turn can lead to problems in the kidneys, heart and brain. It is estimated that one person in 40,000 to 60,000 has the disease and it affects men more severely than women since men only have one copy of the X chromosome. Current treatment consists of enzyme therapy infusions every two weeks but there is currently no cure for Fabry disease. 

However, a Canadian research team is conducting the world’s first pilot study to treat Fabry disease using a stem cell gene therapy approach. The researchers collected the patient’s own blood stem cells and used gene therapy to insert copies of the fully functional gene into the stem cells, allowing them to make the correct version of the enzyme. The newly modified stem cells were then transplanted back into each patient.

Five men participated in this trial and the results so far have been very encouraging. After treatment with the stem cell gene therapy, all patients began producing the corrected version of the enzyme to near normal levels within one week. With these initial results, all five patients were allowed to stop their biweekly enzyme therapy infusions. So far, only three patients decided to do so and are stable.

In a news release, Darren Bidulka, the first patient to be treated in the study, talked about how life changing this stem cell gene therapy has been for him.

“I’m really happy that this worked. What an amazing result in an utterly fascinating experience. I consider this a great success. I can lead a more normal life now without scheduling enzyme therapy every two weeks. This research is also incredibly important for many patients all over the world, who will benefit from these findings.”

CIRM is no stranger to stem cell gene therapy and its potential having funded clinical trials in various areas such as severe combined immunodeficiency (bubble baby disease), cystinosis, sickle cell disease, and various others. The broad range of genetic diseases it has been used in to treat patients further highlights its importance in scientific research.

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

Scientists look at how the lung and brain respond differently to SARS-CoV-2 infection

UC San Diego School of Medicine researchers found approximately 10-fold higher SARS-CoV-2 infection (green) in lung organoids (left), compared to brain organoids (right). Image courtesy of UCSD Health

Since the start of the coronavirus pandemic early last year, scientists all over the world are still trying to better understand SARS-CoV-2, the virus that causes COVID-19. Although the more commonly known symptoms involve respiratory issues, there have been other long term problems observed in recovered patients. These consist of heart issues, fatigue, and neurological issues such as loss of taste and smell and “brain fog”.

To better understand this, Dr. Tariq Rana and a team of researchers at the UC San Diego School of Medicine are using stem cells to create lung and brain organoids to better understand how the virus interacts with the various organ systems and to better develop therapies that block infection. Organoids are 3D models made of cells that can be used to analyze certain features of the human organ being modeled. Although they are far from perfect replicas, they can be used to study physical structure and other characteristics. 

The team’s lung and brain organoids produced molecules ACE2 and TMPRSS2, which sit like doorknobs on the outer surfaces of cells. SARS-CoV-2 is able to use these doorknobs to enter cells and establish infection.

Dr. Rana and his team then developed a pseudovirus, a noninfectious version of SARS-CoV-2, and attached a fluorescent label, allowing them to measure how effectively the virus binds in human lung and brain organoids as well as to evaluate the cells’ response. The team was surprised to see an approximately 10-fold higher SARS-CoV-2 infection in lung organoids compared to brain organoids. Additionally, treatment with TMPRSS2 inhibitors reduced infection levels in both organoids.

Besides differences in infection levels, the lung and brain organoids also differed in their responses to the virus. Infected lung organoids pumped out molecules intended to summon help from the immune system while infected brain organoids upped their production of molecules that plays a fundamental role in pathogen recognition and activation of the body’s own immune defenses.

In a news release from UC San Diego Health, Dr. Rana elaborates on the results of his study.

“We’re finding that SARS-CoV-2 doesn’t infect the entire body in the same way. In different cell types, the virus triggers the expression of different genes, and we see different outcomes.”

The next steps for Rana and his team is to develop SARS-CoV-2 inhibitors and test out how well they work in organoid models derived from people of a variety of racial and ethnic backgrounds that represent California’s diverse population. To carry out this research, CIRM awarded Dr. Rana a grant of $250,000, which is part of the $5 million in emergency funding for COVID-19 research that CIRM authorized at the beginning of the pandemic.

The full results of this study can be found in Stem Cell Reports.

Scientists use stem cells to create Neanderthal-like “mini-brain”

Alysson R. Muotri, Ph.D.

The evolution of modern day humans has always been a topic that has been shrouded in mystery. Some of what is known is that Neanderthals, an archaic human species that lived on this planet up until about 11,700 years ago, interbred with our species (Homo sapiens) at some point in time. Although their brains were about as big as ours, anthropologists think they must have worked differently due to the fact that they never achieved the sophisticated technology and artistry modern humans have.

Since brains do not fossilize, it has been challenging to see how these two early human species have changed over time. To help answer this question, Dr. Alysson Muotri and his team at UC San Diego created so-called “mini-brains” using stem cells and gene editing technology to better understand how the Neanderthal brain might have functioned.

For this study, Dr. Muotri and his team closely evaluated the differences in genes between modern day humans and Neanderthals. They found a total of 61 different genes, but for this study focused on one in particular that plays a role in influencing early brain development.

Brain organoids that carry a Neanderthal gene.
Image courtesy of the Muotri Lab and UCSD

Using gene editing technology, the team introduced the Neanderthal version of the gene into human stem cells. These stem cells, which have the ability to become various cell types, were then used to create brain cells. These cells eventually formed brain organoids or “mini-brains”, 3D models made of cells that can be used to analyze certain features of the human brain. Although they are far from perfect replicas, they can be used to study physical structure and other characteristics. In a previous CIRM funded study, Dr. Muotri had used “mini-brains” to model an autism spectrum disorder and help test treatments.

Dr. Muotri and his team found that the Neanderthal-like brain organoids looked very different than modern human brain organoids, having a distinctly different shape. Upon further analysis, the team found that modern and Neanderthal-like brain organoids also differed in the way their cells grow. Additionally, the way in which connections between neurons formed as well as the proteins involved in forming these connections differed between the two organoids. Finally, electrical impulses displayed higher activity at earlier stages, but didn’t synchronize in networks in Neanderthal-like brain organoids.

According to Muotri, the neural network changes in Neanderthal-like brain organoids mimic the way newborn primates acquire new abilities more rapidly than human newborns.

In a news release from UCSD, Dr. Muotri discusses the next steps in advancing this research.

“This study focused on only one gene that differed between modern humans and our extinct relatives. Next we want to take a look at the other 60 genes, and what happens when each, or a combination of two or more, are altered. We’re looking forward to this new combination of stem cell biology, neuroscience and paleogenomics.”

The full results of this study were published in Science.

Biotechnology companies join forces in developing treatment for X-SCID

Jasper Therapeutics, Inc., a biotechnology company focused on blood stem cell therapies, and Graphite Bio, Inc., a biotechnology company focused on gene editing therapies to treat or cure serious diseases, announced a research and clinical collaboration for a treatment for X-SCID.

X-SCID, which stands for X-linked severe combined immunodeficiency, is a genetic disorder that interferes with the normal development of the immune system, leaving infants vulnerable to infections that most people can easily fight off. One treatment for X-SCID involves a blood stem cell transplant, in which the patient’s defective stem cells are wiped out with chemotherapy or radiation to make room for normal blood stem cells to take their place. Unfortunately, the problem with chemotherapy or radiation in young infants is that it can lead to lifelong effects such as neurological impairment, growth delays, infertility, and risk of cancer.

Fortunately, Jasper Therapeutics has developed JSP191, a non-toxic alternative to chemotherapy and radiation. It is an antibody that works by targeting and removing the defective blood forming stem cells. The approach has previously been used in a CIRM-funded clinical trial ($20M award) for X-SCID.

Graphite Bio has developed GPH201, the first-in-human investigational blood stem cell treatment that will be evaluated as a potential cure for patients suffering from X-SCID. GPH201 is generated using precise and efficient gene editing technology, It works by directly replacing a defective gene that causes problems with the immune system. The hope is that GPH201 will ultimately lead to the production of fully functional, healthy immune cells.

The ultimate goal of this collaboration is to use JSP191 as the non-toxic alternative to chemotherapy in patients in order to remove their defective blood stem cells. After that, the gene editing blood stem cell technology developed by Graphite Bio can be introduced to patients in order to treat X-SCID. The two companies have agreed to collaborate on research, and potentially a clinical study, evaluating JSP191 as the non-toxic conditioning agent for GPH201.

In a press release, Josh Lehrer, M.Phil., M.D., chief executive officer at Graphite Bio, expressed excitement about the collaboration between the two companies.

“This collaboration with Jasper demonstrates our shared commitment to pioneering novel therapeutic approaches with the potential to significantly improve the treatment experiences of individuals with devastating conditions who stand to benefit from gene replacement therapies, initially for patients with XSCID. GPH201 harnesses our targeted gene integration platform to precisely target the defective gene that causes XSCID and replace it with a normal copy.”

In the same press release, Bill Lis, executive chairman and CEO of Jasper Therapeutics, also expressed optimism in regards to the two companies teaming up.

“Our collaboration with Graphite Bio is an exciting opportunity to further advance the field of curative gene correction by combining a targeted gene integration platform with our first-in-class targeted CD117 antibody, JSP191, that has already demonstrated preliminary clinical efficacy and safety as a conditioning agent in X-SCID patients and those with blood cancers undergoing allogeneic hematopoietic stem cell transplant.”

Graphite Bio is also developing gene editing technology to help treat sickle cell disease.  It is currently supported by a CIRM  late stage preclinical grant ($4.8M award). Th goal is to complete the final preclinical studies, which will allow Graphite Bio to start clinical studies of the sickle cell disease gene therapy in sickle cell patients in 2021.

DNA therapeutic treats blood cancer in mice and begins human clinical trial

The left image represents a microscopic view of the bone marrow of a myeloma-bearing mouse treated with control, and the right image represents the same for a myeloma-bearing mouse treated with ION251, an experimental therapeutic. The red dots represent the IRF4 protein within human myeloma cells, which are much sparser after ION251 treatment. Image credit: UC San Diego Health

Multiple myeloma is the second most common blood cancer in the United States, with more than 32,000 new cases predicted in 2020.  Unfortunately, many patients with this type of blood cancer eventually develop resistance to multiple types of treatments.  This phenomenon is partially due to the fact that cancer stem cells, which have the ability to evade traditional therapies and then self-renew, help drive the disease.

It is for this reason that a team of researchers, at the UC San Diego School of Medicine and Ionis Pharmaceuticals, are developing a therapy that can destroy these malignant stem cells, thereby preventing the cancer from coming back.  With support from CIRM, the team developed an approach that interacts with IRF4, a gene that allows myeloma stem cells and tumor cells to grow and survive chemotherapy and radiation.  They have engineered an oligonucleotide, a short DNA molecule, to prevent IRF4 from functioning.  The therapy, known as ION251, lowered disease burden, reduced the amount of myeloma stem cells, and increased survival when tested in mice bearing human myeloma.  These results have enabled the team to start a Phase I clinical trial to see if this approach is safe and effective in people with myeloma.

To study the disease and test ION251, the team transplanted human myeloma cells into mice that lack an immune system and thus won’t reject human cells.  Ten mice received the ION251 treatment and an additional ten mice received a control treatment.  After receiving the ION251 therapy, the treated mice had significantly fewer myeloma cells after two to six weeks of treatment.  Additionally, 70 to 100 percent of the treated mice survived, whereas none of the untreated control mice did. 

In a news release from UC San Diego Health, Dr. Leslie Crews, co-senior author and assistant professor at the UCSD School of Medicine, elaborated on the promising results from the mouse study.

“The results of these preclinical studies were so striking that half the microscopy images we took to compare bone marrow samples between treated and untreated mice kept coming back blank — in the treated mice, we couldn’t find any myeloma cells left for us to study.  It makes the science more difficult, but it gives me hope for patients.”

The Phase I clinical trial to assess the safety of ION251, sponsored by Ionis Pharmaceuticals, is now recruiting participants at Moores Cancer Center at UC San Diego Health and elsewhere. More information on this can be viewed by clicking the link here.

The full results of this study were published in the journal Cell Stem Cell.

CIRM funded researchers discover link between Alzheimer’s gene and COVID-19

Dr. Yanhong Shi (left) and Dr. Vaithilingaraja Arumugaswami (right)

All this month we are using our blog and social media to highlight a new chapter in CIRM’s life, thanks to the voters approving Proposition 14. We are looking back at what we have done since we were created in 2004, and also looking forward to the future. Today we focus on groundbreaking CIRM funded research related to COVID-19 that was recently published.

It’s been almost a year since the world started hearing about SARS-CoV-2, the virus that causes COVID-19.  In our minds, the pandemic has felt like an eternity, but scientists are still discovering new things about how the virus works and if genetics might play a role in the severity of the virus.  One population study found that people who have ApoE4, a gene type that has been found to increase the risk of developing Alzheimer’s, had higher rates of severe COVID-19 and hospitalizations.

It is this interesting observation that led to important findings of a study funded by two CIRM awards ($7.4M grant and $250K grant) and conducted by Dr. Yanhong Shi at City of Hope and co-led by Dr. Vaithilingaraja Arumugaswami, a member of the UCLA Broad Stem Cell Research Center.  The team found that the same gene that increases the risk for Alzheimer’s disease can increase the susceptibility and severity of COVID-19.

At the beginning of the study, the team was interested in the connection between SARS-CoV-2 and its effect on the brain.  Due to the fact that patients typically lose their sense of taste and smell, the team theorized that there was an underlying neurological effect of the virus.  

The team first created neurons and astrocytes.  Neurons are cells that function as the basic working unit of the brain and astrocytes provide support to them.  The neurons and astrocytes were generated from induced pluripotent stem cells (iPSCs), which are a kind of stem cell that can become virtually any type of cell and can be created by “reprogramming” the skin cells of patients.  The newly created neurons and astrocytes were then infected with SARS-CoV-2 and it was found that they were susceptible to infection.

Next, the team used iPSCs to create brain organoids, which are 3D models that mimic certain features of the human brain.  They were able to create two different organoid models: one that contained astrocytes and one without them.  They infected both brain organoid types with the virus and discovered that those with astrocytes boosted SARS-CoV-2 infection in the brain model. 

The team then decided to further study the effects of ApoE4 on susceptibility to SARS-CoV-2.  They did this by generating neurons from iPSCs “reprogrammed” from the cells of an Alzheimer’s patient.  Because the iPSCs were derived from an Alzheimer’s patient, they contained ApoE4.  Using gene editing, the team modified some of the ApoE4 iPSCs created so that they contained ApoE3, which is a gene type considered neutral.  The ApoE3 and ApoE4 iPSCs were then used to generate neurons and astrocytes.

The results were astounding.  The ApoE4 neurons and astrocytes both showed a higher susceptibility to SARS-CoV-2 infection in comparison to the ApoE3 neurons and astrocytes.  Moreover, while the virus caused damage to both ApoE3 and ApoE4 neurons, it appeared to have a slightly more severe effect on ApoE4 neurons and a much more severe effect on ApoE4 astrocytes compared to ApoE3 neurons and astrocytes. 

“Our study provides a causal link between the Alzheimer’s disease risk factor ApoE4 and COVID-19 and explains why some (e.g. ApoE4 carriers) but not all COVID-19 patients exhibit neurological manifestations” says Dr. Shi. “Understanding how risk factors for neurodegenerative diseases impact COVID-19 susceptibility and severity will help us to better cope with COVID-19 and its potential long-term effects in different patient populations.”

In the last part of the study, the researchers tested to see if the antiviral drug remdesivir inhibits virus infection in neurons and astrocytes.  They discovered that the drug was able to successfully reduce the viral level in astrocytes and prevent cell death.  For neurons, it was able to rescue them from steadily losing their function and even dying. 

The team says that the next steps to build on their findings is to continue studying the effects of the virus and better understand the role of ApoE4 in the brains of people who have COVID-19.  Many people that developed COVID-19 have recovered, but long-term neurological effects such as severe headaches are still being seen months after. 

“COVID-19 is a complex disease, and we are beginning to understand the risk factors involved in the manifestation of the severe form of the disease” says Dr. Arumugaswami.  “Our cell-based study provides possible explanation to why individuals with Alzheimer’s’ disease are at increased risk of developing COVID-19.”

The full results to this study were published in Cell Stem Cell.

A look back: CIRM funded trial aims to help patients suffering from chronic viral infections

Dr. Michael Pulsipher

All this month we are using our blog and social media to highlight a new chapter in CIRM’s life, thanks to the voters approving Proposition 14. We are looking back at what we have done since we were created in 2004, and also looking forward to the future. Today we look at a way of making blood stem cell transplants safer and more readily available

Blood stem cell transplants have provided lifechanging treatments to individuals.  This statement is observed firsthand in several patients in CIRM funded trials for X-linked Chronic Granulomatous Disease (X-CGD), Sickle Cell Disease (SCD), and Severe Combined Immunodeficiency (SCID).  The personal journeys of Evangelina Padilla-Vaccaro, Evie Junior, and Brenden Whittaker speak volumes for the potential this treatment holds.  In these trials, defective blood stem cells from the patient are corrected outside the body and then returned to the patient in a transplant procedure.

Unfortunately, there is still a certain degree of risk that accompanies this procedure.  Before a blood stem cell transplant can be performed,  diseased or defective blood stem cells in the patient’s bone marrow need to be removed using chemotherapy or radiation to make room for the transplant.  This leaves the patient temporarily without an immune system and at risk for a life-threatening viral infection.  Additionally, viral infections pose a serious risk to patients with immune deficiency disorders, with viruses accounting upwards of 40% of deaths in these patients.

That’s why in October 2017, the CIRM ICOC Board awarded $4.8M to fund a clinical trial conducted by Dr. Michael Pulsipher at the Children’s Hospital of Los Angeles.  Dr. Pulsipher and his team are using virus-specific T cells (VSTs), a special type of cell that plays an important role in the immune response, to treat immunosuppressed or immune deficient patients battling life-threatening viral infections.  This trial includes patients with persistent viral infections after having received a blood stem cell transplant as well as those with immune deficiency disorders that have not yet received a blood stem cell transplant.  The VSTs used in this trial specifically treat cytomegalovirus (CMV), Epstein-Barr virus (EBV), and adenovirus infections.  They are manufactured using cells from healthy donors and are banked so as to be readily available when needed. 

One challenge of receiving a stem cell transplant can be finding a patient and donor that are a close or identical match.  This is done by looking at specific human leukocyte antigens (HLA), which are protein molecules we inherit from our parents.  To give you an idea of how challenging this can be, you only have a 25% chance of being an HLA identical match with your sibling. 

Because VSTs are temporary soldiers that are administered to fight the viral infection and then disappear, Dr. Pulsipher and his team are using partially HLA-matched VSTs to treat patients in their trial.  Previous studies have indicated that partially HLA-matched T-cells can be effective in treating patients.  The availability of partially HLA-matched VST banks that can be used “off the shelf” improves accessibility and shortens the time for patients to receive VST therapy, which will save lives.

To learn more about Dr. Pulsipher’s work, please view the video below:

A Month of CIRM: Where we’ve been, where we’re going

All this month we are using our blog and social media to highlight a new chapter in CIRM’s life, thanks to the voters approving Proposition 14. We are looking back at what we have done since we were created in 2004, and also looking forward to the future. We kick off this event with a letter from our the Chair of our Board, Jonathan Thomas.

When voters approved Proposition 14 last November, they gave the Stem Cell Agency a new lease on life and a chance to finish the work we began with the approval of Proposition 71 in 2004. It’s a great honor and privilege. It’s also a great responsibility. But I think looking back at what we have achieved over the last 16 years shows we are well positioned to seize the moment and take CIRM and regenerative medicine to the next level and beyond.

When we started, we were told that if we managed to get one project into a clinical trial by the time our money ran out we would have done a good job. As of this moment we have 68 clinical trials that we have funded plus another 31 projects in clinical trials where we helped fund crucial early stage research. That inexorable march to therapies and cures will resume when we take up our first round of Clinical applications under Prop 14 in March.

But while clinical stage projects are the end game, where we see if therapies really work and are safe in people, there’s so much more that we have achieved since we were created. We have invested $900 million in  basic research, creating a pipeline of the most promising stem cell research programs, as well as investing heavily on so-called “translational” projects, which move projects from basic science to where they’re ready to apply to the Food and Drug Administration (FDA) to begin clinical trials.

We have funded more than 1,000 projects, with each one giving us valuable information to help advance the science. Our funding has helped attract some of the best stem cell scientists in the world to California and, because we only fund research in California, it has persuaded many companies to either move here or open offices here to be eligible for our support. We have helped create the Alpha Stem Cell Clinics, a network of leading medical centers around the state that have the experience and expertise to deliver stem cell therapies to patients. All of those have made California a global center in the field.

That result is producing big benefits for the state. An independent Economic Impact Analysis reported that by the end of 2018 we had already helped generate an extra $10.7 billion in new sales revenue and taxes for California, hundreds of millions more in federal taxes and created more than 56,000 new jobs.

As if that wasn’t enough, we have also:

  • Helped develop the largest iPSC research bank in the world.
  • Created the CIRM Center of Excellence in Stem Cell Genomics to accelerate fundamental understanding of human biology and disease mechanisms.
  • Helped fund the construction of 12 world class stem cell institutes throughout the state.
  • Reached a unique partnership with the National Heart, Lung and Blood Institutes to find a cure for sickle cell disease.
  • Used our support for stem cell research to leverage an additional $12 billion in private funding for the field.
  • Enrolled more than 2700 patients in CIRM funded clinical trials

In many ways our work is just beginning. We have laid the groundwork, helped enable an extraordinary community of researchers and dramatically accelerated the field. Now we want to get those therapies (and many more) over the finish line and get them approved by the FDA so they can become available to many more people around the state, the country and the world.

We also know that we have to make these therapies available to all people, regardless of their background and ability to pay. We have to ensure that underserved communities, who were often left out of research in the past, are an integral part of this work and are included in every aspect of that research, particularly clinical trials. That’s why we now require anyone applying to us for funding to commit to engaging with underserved communities and to have a written plan to show how they are going to do that.

Over the coming month, you will hear more about some of the remarkable things we have managed to achieve so far and get a better sense of what we hope to do in the future. We know there will be challenges ahead and that not everything we do or support will work. But we also know that with the team we have built at CIRM, the brilliant research community in California and the passion and drive of the patient advocate community we will live up to the responsibility the people of California placed in us when they approved Proposition 14.

“Mini-brains” model an autism spectrum disorder and help test treatments

Alysson Muotri, PhD, professor and director of the Stem Cell Program at UC San Diego School of Medicine
and member of the Sanford Consortium for Regenerative Medicine.
Image credit: UC San Diego Health

Rett syndrome is a rare form of autism spectrum disorder that impairs brain development and causes problems with movement, speech, and even breathing. It is caused by mutations in a gene called MECP2 and primarily affects females. Although there are therapies to alleviate symptoms, there is currently no cure for this genetic disorder.

With CIRM funding ($1.37M and $1.65M awards), Alysson Muotri, PhD and a team of researchers at the University of California San Diego School of Medicine and Sanford Consortium for Regenerative Medicine have used brain organoids that mimic Rett syndrome to identify two drug candidates that returned the “mini-brains” to near-normal. The drugs restored calcium levels, neurotransmitter production, and electrical impulse activity.

Brain organoids, also referred to as “mini-brains”, are 3D models made of cells that can be used to analyze certain features of the human brain. Although they are far from perfect replicas, they can be used to study changes in physical structure or gene expression over time.

Dr. Muotri and his team created induced pluripotent stem cells (iPSCs), a type of stem cell that can become virtually any type of cell. For the purposes of this study, they were created from the skin cells of Rett syndrome patients. The newly created iPSCs were then turned into brain cells and used to create “mini-brains”, thereby preserving each Rett syndrome patient’s genetic background. In addition to this, the team also created “mini-brains” that artificially lack the MECP2 gene, mimicking the issues with the same gene observed in Rett syndrome.

Lack of the MECP2 gene changed many things about the “mini-brains” such as shape, neuron subtypes present, gene expression patterns, neurotransmitter production, and decreases in calcium activity and electrical impulses. These changes led to major defects in the emergence of brainwaves.

To correct the changes caused by the lack of the MECP2 gene, the team treated the brain organoids with 14 different drug candidates known to affect various brain cell functions. Of all the drugs tested, two stood out: nefiracetam and PHA 543613. The two drugs resolved nearly all molecular and cellular symptoms observed in the Rett syndrome “mini-brains”, with the number active neurons doubling post treatment.

The two drugs were previously tested in clinical trials for the treatment of other conditions, meaning they have been shown to be safe for human consumption.

In a news release from UC San Diego Health, Dr. Muotri stresses that although the results for the two drugs are promising, the end treatment for Rett syndrome may require a multi-drug cocktail of sorts.

“There’s a tendency in the neuroscience field to look for highly specific drugs that hit exact targets, and to use a single drug for a complex disease. But we don’t do that for many other complex disorders, where multi-pronged treatments are used. Likewise, here no one target fixed all the problems. We need to start thinking in terms of drug cocktails, as have been successful in treating HIV and cancers.”

The full results of this study were published in EMBO Molecular Medicine.