Using stem cells to fix bad behavior in the brain

 

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Gladstone Institutes Steven Finkbeiner and Gaia Skibinski: Photo courtesy Chris Goodfellow, Gladstone Institutes

Diseases of the brain have many different names, from Alzheimer’s and Parkinson’s to ALS and Huntington’s, but they often have similar causes. Researchers at the Gladstone Institutes in San Francisco are using that knowledge to try and find an approach that might be effective against all of these diseases. In a new CIRM-funded study, they have identified one protein that could help do just that.

Many neurodegenerative diseases are caused by faulty proteins, which start to pile up and cause damage to neurons, the brain cells that are responsible for processing and transmitting information. Ultimately, the misbehaving proteins cause those cells to die.

The researchers at the Gladstone found a way to counter this destructive process by using a protein called Nrf2. They used neurons from humans (made from induced pluripotent stem cells – iPSCs – hence the stem cell connection here) and rats. They then tested these cells in neurons that were engineered to have two different kinds of mutations found in  Parkinson’s disease (PD) plus the Nrf2 protein.

Using a unique microscope they designed especially for this study, they were able to track those transplanted neurons and monitor what happened to them over the course of a week.

The neurons that expressed Nrf2 were able to render one of those PD-causing proteins harmless, and remove the other two mutant proteins from the brain cells.

In a news release to accompany the study in The Proceedings of the National Academy of Sciences, first author Gaia Skibinski, said Nrf2 acts like a house-cleaner brought in to tidy up a mess:

“Nrf2 coordinates a whole program of gene expression, but we didn’t know how important it was for regulating protein levels until now. Over-expressing Nrf2 in cellular models of Parkinson’s disease resulted in a huge effect. In fact, it protects cells against the disease better than anything else we’ve found.”

Steven Finkbeiner, the senior author on the study and a Gladstone professor, said this model doesn’t just hold out hope for treating Parkinson’s disease but for treating a number of other neurodegenerative problems:

“I am very enthusiastic about this strategy for treating neurodegenerative diseases. We’ve tested Nrf2 in models of Huntington’s disease, Parkinson’s disease, and ALS, and it is the most protective thing we’ve ever found. Based on the magnitude and the breadth of the effect, we really want to understand Nrf2 and its role in protein regulation better.”

The next step is to use this deeper understanding to identify other proteins that interact with Nrf2, and potentially find ways to harness that knowledge for new therapies for neurodegenerative disorders.

Stem Cell Stories that caught our eye: a womb with a view, reversing aging and stabilizing stem cells

Here are some stem cell stories that caught our eye this past week. Some are groundbreaking science, others are of personal interest to us, and still others are just fun.

Today we bring you a trifecta of stem cell stories that were partially funded by grants from CIRM.

A womb with a view: using 3D imaging to observe embryo implantation. Scientists have a good understanding of how the beginning stages of pregnancy happen. An egg cell from a woman is fertilized by a sperm cell from a man and the result is a single cell called a zygote. Over the next week, the zygote divides into multiple cells that form the developing embryo. At the end of that period, the embryo hatches out of its protective membrane and begins implanting itself into the lining of the mother’s uterus.

It’s possible to visualize the early stages of embryo development in culture dishes, which has helped scientists understand the biological steps required for an embryo to survive and develop into a healthy fetus. However, something that is not easy to observe is the implantation stage of the embryo in the uterus. This process is complex and involves a restructuring of the uterine wall to accommodate the developing embryo. As you can imagine, replicating these events would be extremely complicated and difficult to do in a culture dish, and current imaging techniques aren’t adequate either.

That’s where new CIRM-funded research from a team at UCSF comes to the rescue. They developed a 3D imaging technology and combined it with a previously developed “tissue clearing” method, which uses chemicals to turn tissues translucent, to provide clear images of the uterine wall during embryo implantation in mice. Their work was published this week in the journal Development.

According to a UCSF news release,

“Using their new approach, the team observed that the uterine lining becomes extensively folded as it approaches its window of receptivity for an embryo to implant. The geometry of the folds in which the incoming embryos dwell is important, the team found, as genetic mutants with defects in implantation have improper patterns of folding.”

Ultimately, the team aims to use their new imaging technology to get an inside scoop on how to prevent or treat pregnancy disorders and also how to improve the outcome of pregnancies by in vitro fertilization.

Senior author on the study, UCSF professor Diana Laird concluded:

“This new view of early pregnancy lets us ask fundamentally new questions about how the embryo finds its home within the uterus and what factors are needed for it to implant successfully. Once we can understand how these processes happen normally, we can also ask why certain genetic mutations cause pregnancies to fail, to study the potential dangers of environmental toxins such as the chemicals in common household products, and even why metabolic disease and obesity appears to compromise implantation.”

If you want to see this womb with a view, check out the video below.

Watch these two videos for more information:

Salk scientists reverse signs of aging in mice. For our next scintillating stem cell story, we’re turning back the clock – the aging clock that is. Scientists from the Salk Institute in La Jolla, reported an interesting method in the journal Cell  that reverses some signs of aging in mice. They found that periodic expression of embryonic stem cell genes in skin cells and mice could reverse some signs of aging.

The Salk team made use of cellular reprogramming tools developed by the Nobel Prize winning scientist Shinya Yamanaka. He found that four genes normally expressed in embryonic stem cells could revert adult cells back to a pluripotent stem cell state – a process called cellular reprogramming. Instead of turning adult cells back into stem cells, the Salk scientists asked whether the Yamanaka factors could instead turn back the clock on older, aging cells – making them healthier without turning them back into stem cells or cancer-forming cells.

The team found that they could rejuvenate skin cells from mice without turning them back into stem cells if they turned on the Yamanaka genes on for a short period of time. These skin cells were taken from mice that had progeria – a disease that causes them to age rapidly. Not only did their skin cells look and act younger after the treatment, but when the scientists used a similar technique to turn on the Yamanaka genes in progeria mice, they saw rejuvenating effects in the mice including a more rapid healing and regeneration of muscle and pancreas tissue.

(Left) impaired muscle repair in aged mice; (right) improved muscle regeneration in aged mice subjected to reprogramming. (Salk Institute)

(Left) impaired muscle repair in aged mice; (right) improved muscle regeneration in aged mice subjected to reprogramming. (Salk Institute)

The senior author on the study, Salk Professor Juan Carlos Izpisua Belmonte, acknowledged in a Salk news release that this is early stage work that focuses on animal models, not humans:

“Obviously, mice are not humans and we know it will be much more complex to rejuvenate a person. But this study shows that aging is a very dynamic and plastic process, and therefore will be more amenable to therapeutic interventions than what we previously thought.”

This story was very popular, which is not surprising as aging research is particularly fascinating to people who want to live longer lives. It was covered by many news outlets including STATnews, Scientific American and Science Magazine. I also recommend reading Paul Knoepfler’s journal club-style blog on the study for an objective take on the findings and implications of the study. Lastly, you can learn more about the science of this work by watching the movie below by the Salk.

Movie:

Stabilizing unstable stem cells. Our final stem cell story is brought to you by scientists from the UCLA Broad Stem Cell Research Center. They found that embryonic stem cells can harbor genetic instabilities that can be passed on to their offspring and cause complications, or even disease, later in life. Their work was published in two separate studies in Cell Stem Cell and Cell Reports.

The science behind the genetic instabilities is too complicated to explain in this blog, so I’ll refer you to the UCLA news release for more details. In brief, the UCLA team found a way to reverse the genetic instability in the stem cells such that the mature cells that they developed into turned out healthy.

As for the future impact of this research, “The research team, led by Kathrin Plath, found a way to correct the instability by resetting the stem cells from a later stage of development to an earlier stage of development. This fundamental discovery could have great impact on the creation of healthy tissues to cure disease.”

Understanding two heart problems by studying the domino effect of one gene network

Although heart muscle cells, or cardiomyocytes, are specialized to help pump blood to the organs, they nonetheless carry all the genetic instructions for becoming a nerve cell, an intestinal cell, a liver or any cell type in the body. But at the moment in time that the fetal heart begins to develop, master switch proteins, called transcription factors, act like the first tile in an extremely complex pattern of dominos and set off a chain of events which lead to the activation of heart muscle specific genes in cardiomyocytes as well as the silencing of genes important for the development other cells types.

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cardiomyocytes

It’s truly amazing that this process comes together to create functioning hearts in the about 355,000 babies that are born in the world each day. But it isn’t always flawless as heart defects occur in about 1% of all live births. By studying a family with a history of heart defects, scientists at the Gladstone Institutes have gained a deeper understanding of how gene networks go awry,  causing heart defects as well as heart disease later in life. This CIRM-funded work was published today in Cell.

Half the children in the family studied by the Gladstone team were born with a hole in the wall between the two chambers of the heart. Back in 2003, the family approached Deepak Srivastava, head of the cardiovascular institute at Gladstone, for help. A genetic analysis by Srivastava’s team found that all of the affected children carried a mutation in the GATA4 gene, which encodes a heart specific transcription factor protein. Seven years later the children developed heart disease that led to weaker heart pumping. Although the two heart problems were not related, they suspected both were caused by the GATA4 mutation and sought to understand how that could be the case.

Srivastava’s team sought to understand how the GATA4 mutation could be causing both health problems. They collected skin samples from the affected children and generated cardiomyocytes using the induced pluripotent stem cell technique. Cells were also collected from the children’s healthy siblings. In the laboratory, the cells were analyzed for how well they functioned, such as their ability to contract. All of these tests showed that the cells carrying the GATA4 mutation had impaired function compared to the healthy cells. These findings provide a basis for the heart disease found in the children during their teens.

In terms of the heart wall defect, the team examined the GATA4 protein’s interaction with the protein TBX5, another transcription factor that is also mutated in cases of this defect. Both proteins regulate genes by directly binding to DNA as well as interacting with each other. In cells with the defective GATA4, the research discovered TBX5 did not bind well to the DNA. The lack of TBX5 led to a disruption in the activation of genes that play a role in the development of the heart wall.

TBX5 and GATA4 also work together in cardiomyocytes to silence genes that play a role in other cell types. But the scientists found that the because the GATA4 mutation hindered its interaction with TBX5, those non-heart specific genes we’re no longer repressed causing further disruption to proper cardiomyocyte development. Srivastava summed up these results in an institute press release:

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Deepak Srivastava

“By studying the patients’ heart cells in a dish, we were able to figure out why their hearts were not pumping properly. Investigating their genetic mutation revealed a whole network of genes that went awry, first causing septal [heart wall] defects and then the heart muscle dysfunction.”

Now, because GATA4 and TBX5 are those first domino tiles in very intricate networks of genes, targeting those proteins for future therapy development wouldn’t be wise. Their effects are so widespread that blocking their actions would do more harm than good. But finding drugs that might affect only a branch of GATA4/TBX5 actions could result in new therapy approaches to heart defects and disease.

deepak-yen-sin-22 Deepak Srivastava and Yen-Sin Ang [Photo: Chris Goodfellow, Gladstone Institutes]

Yen-Sin Ang, the first author on the report, thinks these finding could prove fruitful for other diseases as well:

“It’s amazing that by studying genes in a two-dimensional cluster of heart cells, we were able to discover insights into a disease that affects a complicated three-dimensional organ. We think this conceptual framework could be used to study other diseases caused by mutations in proteins that serve as master regulators of whole gene networks.”

California’s stem cell agency rounds up the year with two more big hits

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CIRM Board meeting with  Jake Javier, CIRM Chair Jonathan Thomas, Vice Chair Sen. Art Torres (Ret.) and President/CEO Randy Mills

It’s traditional to end the year with a look back at what you hoped to accomplish and an assessment of what you did. By that standard 2016 has been a pretty good year for us at CIRM.

Yesterday our governing Board approved funding for two new clinical trials, one to help kidney transplant patients, the second to help people battling a disease that destroys vision. By itself that is a no small achievement. Anytime you can support potentially transformative research you are helping advance the field. But getting these two clinical trials over the start line means that CIRM has also met one of its big goals for the year; funding ten new clinical trials.

If you had asked us back in the summer, when we had funded only two clinical trials in 2016, we would have said that the chances of us reaching ten trials by the end of the year were about as good as a real estate developer winning the White House. And yet……..

Helping kidney transplant recipients

The Board awarded $6.65 million to researchers at Stanford University who are using a deceptively simple approach to help people who get a kidney transplant. Currently people who get a transplant have to take anti-rejection medications for the rest of their life to prevent their body rejecting the new organ. These powerful immunosuppressive medications are essential but also come with a cost; they increase the risk of cancer, infection and heart disease.

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CIRM President/CEO Randy Mills addresses the CIRM Board

The Stanford team will see if it can help transplant patients bypass the need for those drugs by injecting blood stem cells and T cells (which play an important role in the immune system) from the kidney donor into the kidney recipient. The hope is by using cells from the donor, you can help the recipient’s body more readily adjust to the new organ and reduce the likelihood the body’s immune system will attack it.

This would be no small feat. Every year around 17,000 kidney transplants take place in the US, and many people who get a donor kidney experience fevers, infections and other side effects as a result of taking the anti-rejection medications. This clinical trial is a potentially transformative approach that could help protect the integrity of the transplanted organ, and improve the quality of life for the kidney recipient.

Fighting blindness

The second trial approved for funding is one we are already very familiar with; Dr. Henry Klassen and jCyte’s work in treating retinitis pigmentosa (RP). This is a devastating disease that typically strikes before age 30 and slowly destroys a person’s vision. We’ve blogged about it here and here.

Dr. Klassen, a researcher at UC Irvine, has developed a method of injecting what are called retinal progenitor cells into the back of the eye. The hope is that these cells will repair and replace the cells damaged by RP. In a CIRM-funded Phase 1 clinical trial the method proved safe with no serious side effects, and some of the patients also reported improvements in their vision. This raised hopes that a Phase 2 clinical trial using a larger number of cells in a larger number of patients could really see if this therapy is as promising as we hope. The Board approved almost $8.3 million to support that work.

Seeing is believing

How promising? Well, I recently talked to Rosie Barrero, who took part in the first phase clinical trial. She told me that she was surprised how quickly she started to notice improvements in her vision:

“There’s more definition, more colors. I am seeing colors I haven’t seen in years. We have different cups in our house but I couldn’t really make out the different colors. One morning I woke up and realized ‘Oh my gosh, one of them is purple and one blue’. I was by myself, in tears, and it felt amazing, unbelievable.”

Amazing was a phrase that came up a lot yesterday when we introduced four people to our Board. Each of the four had taken part in a stem cell clinical trial that changed their lives, even saved their lives. It was a very emotional scene as they got a chance to thank the group that made those trials, those treatments possible.

We’ll have more on that in a future blog.

 

 

 

 

With an eye toward 2020, CIRM looks at clinical milestones achieved in 2016

strategy-wideOne year ago, CIRM announced its strategic plan for the next five years. It’s a bold vision to maximize our impact in stem cell research by accelerating stem cell treatments to patients with unmet medical needs.

Our strategic plan, which can be found on our website, details how CIRM will invest in five main program areas including infrastructure, education, discovery, translation and clinical research. While CIRM has invested in these areas in the past, we are doing so now with a renewed focus to make sure our efforts have a lasting impact in California and more importantly for patients.

Now that a year has passed, it’s time to review our progress and look ahead to the next four years.

Our Progress

2016 was a very productive year. On the infrastructure side, CIRM successfully launched the Translating and Accelerating Centers, awarding both grants to QuintilesIMS. The Translating Center supports preclinical research that’s ready to advance to clinical trials but still needs approval by the US Food and Drug Administration (FDA). The Accelerating Center picks up where the Translating Center leaves off and offers support and management services for clinical trial projects to ensure that they succeed. Collectively called The Stem Cell Center, the goal of this new infrastructure is to increase efficiency and shorten the time it takes to get human stem cell trials up and running.

On the research side in 2016, CIRM funded over 70 promising stem cell projects ranging from education to discovery, translational and clinical projects. While of these areas are important to invest in, CIRM has shifted its focus to funding clinical trials in hopes that one or more of these trials will develop into an approved therapy for patients. So far, we’ve funded 25 trials, 22 of which are currently active since CIRM was established.

In our strategic plan, we gave ourselves the aggressive goal of funding 50 new clinical trials by 2020, which equates to 10 new trials per year. So far in 2016, we’ve funded eight clinical trials and tomorrow at our December ICOC meeting, our Governing Board will determine whether we meet our yearly clinical milestone of 10 trials by considering two more for funding.

The first trial is testing a stem cell treatment that could improve the outcome of kidney transplants. For normal kidney transplants, the recipient is required to take immunosuppressive drugs to prevent their body from rejecting the donated organ. This clinical trial aims to bypass the need for these drugs, which carry an increased risk of cancer, infection and heart disease, by injecting blood stem cells and other immune cells from the kidney donor into the patient receiving the kidney. You can read more about this proposed trial here.

The second clinical trial is a stem cell derived therapy to improve vision in patients with a degenerative eye disease called retinitis pigmentosa. This disease destroys the light sensing cells at the back of the eye and has no cure. The trial hopes that by transplanting stem cell derived retinal progenitor cells into the back of the eye, these injected cells will secrete factors that will keep the cells in the eye healthy and possibly improve a patient’s vision. You can read more about this proposed trial here.

Our Future

No matter the outcome at tomorrow’s Board meeting, I think our agency should be proud of its accomplishments since launching our strategic plan. The eight clinical trials we’ve funded this year are testing stem cell therapies for diseases including muscular dystrophy, kidney disease, primary immune diseases, and multiple types of cancer and blood disorders.

At this pace, it seems likely that we will achieve many of the goals in our strategic plan including our big goal of 50 new clinical trials. But pride and a sense of accomplishment are not what CIRM is ultimately striving for. Our mission and the reason why we exist are to help people and improve their lives. I’ll leave you with a quote from our President and CEO Randy Mills:

CIRM CEO and President, Randy Mills.

Randy Mills

“In everything we do there is a real sense of urgency, because lives are at stake. Our Board’s support for these programs highlights how every member of the CIRM team shares that commitment to moving the most promising research out of the lab and into patients as quickly as we can.”


Related Links:

How stem cells are helping change the face of medicine, one pioneering patient at a time

One of the many great pleasures of my job is that I get to meet so many amazing people. I get to know the researchers who are changing the face of medicine, but even more extraordinary are the people who are helping them do it, the patients.

Attacking Cancer

Karl

Karl Trede

It’s humbling to meet people like Karl Trede from San Jose, California. Karl is a quiet, witty, unassuming man who when the need arose didn’t hesitate to put himself forward as a medical pioneer.

Diagnosed with throat cancer in 2006, Karl underwent surgery to remove the tumor. Several years later, his doctors told him it had returned, only this time it had spread to his lungs. They told him there was no effective treatment. But there was something else.

“One day the doctor said we have a new trial we’re going to start, would you be interested? I said “sure”. I don’t believe I knew at the time that I was going to be the first one, but I thought I’d give it a whirl.”

Karl was Patient #1 in a clinical trial at Stanford University that was using a novel approach to attack cancer stem cells, which have the ability to evade standard anti-cancer treatments and cause the tumors to regrow. The team identified a protein, called CD47, that sits on the surface of cancer stem cells and helps them evade being gobbled up and destroyed by the patient’s own immune system. They dubbed CD47 the “don’t eat me” signal and created an antibody therapy they hoped would block the signal, leaving the cancer and the cancer stem cells open to attack by the immune system.

The team did pre-clinical testing of the therapy, using mice to see if it was safe. Everything looked hopeful. Even so, this was still the first time it was being tested in a human. Karl said that didn’t bother him.

“It was an experience for me, it was eye opening. I wasn’t real concerned about being the first in a trial never tested in people before. I said we know that there’s no effective treatment for this cancer, it’s not likely but it’s possible that this could be the one and if nothing else, if it doesn’t do anything for me hopefully it does something so they learn for others.”

It’s that kind of selflessness that is typical of so many people who volunteer for clinical trials, particularly Phase 1 trials, where a treatment is often being tried in people for the first time ever. In these trials, the goal is to make sure the approach is safe, so patients are given a relatively small dose of the therapy (cells or drugs) and told ahead of time it may not do any good. They’re also told that there could be some side effects, potentially serious, even life-threatening ones. Still, they don’t hesitate.

Improving vision

Rosie Barrero certainly didn’t hesitate when she got a chance to be part of a clinical trial testing the use of stem cells to help people with retinitis pigmentosa, a rare progressive disease that destroys a person’s vision and ultimately leaves them blind.

Rosalinda Barrero

Rosie Barrero

“I was extremely excited about the clinical trial. I didn’t have any fear or trepidation about it, I would have been happy being #1, and I was #6 and that was fine with me.”

 

Rosie had what are called retinal progenitor cells injected into her eye, part of a treatment developed by Dr. Henry Klassen at the University of California, Irvine. The hope was that those cells would help repair and perhaps even replace the light-sensing cells damaged by the disease.

Following the stem cell treatment, gradually Rosie noticed a difference. It was small things at first, like being able to make out the colors of cups in her kitchen cupboard, or how many trash cans were outside their house.

“I didn’t expect to see so much, I thought it would be minor, and it is minor on paper but it is hard to describe the improvement. It’s visible, it’s visible improvement.”

These are the moments that researchers like Henry Klassen live for, and have worked so tirelessly for. These are the moments that everyone at CIRM dreams of, when the work we have championed, supported and funded shows it is working, shows it is changing people’s lives.

One year ago this month our governing Board approved a new Strategic Plan, a detailed roadmap of where we want to go in the coming years. The plan laid out some pretty ambitious goals, such as funding 50 new clinical trials in the next 5 years, and at our Board meeting next week we’ll report on how well we are doing in terms of hitting those targets.

People like Karl and Rosie help motivate us to keep trying, to keep working as hard as we can, to achieve those goals. And if ever we have a tough day, we just have to remind ourselves of what Rosie said when she realized she could once again see her children.

“Seeing their faces. It’s pretty incredible. I always saw them with my heart so I just adore them, but now I can see them with my eye.”


Related Links:

Translating great stem cell ideas into effective therapies

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CIRM funds research trying to solve the Alzheimer’s puzzle

In science, there are a lot of terms that could easily mystify people without a research background; “translational” is not one of them. Translational research simply means to take findings from basic research and advance them into something that is ready to be tested in people in a clinical trial.

Yesterday our Governing Board approved $15 million in funding for four projects as part of our Translational Awards program, giving them the funding and support that we hope will ultimately result in them being tested in people.

Those projects use a variety of different approaches in tackling some very different diseases. For example, researchers at the Gladstone Institutes in San Francisco received $5.9 million to develop a new way to help the more than five million Americans battling Alzheimer’s disease. They want to generate brain cells to replace those damaged by Alzheimer’s, using induced pluripotent stem cells (iPSCs) – an adult cell that has been changed or reprogrammed so that it can then be changed into virtually any other cell in the body.

CIRM’s mission is to accelerate stem cell treatments to patients with unmet medical needs and Alzheimer’s – which has no cure and no effective long-term treatments – clearly represents an unmet medical need.

Another project approved by the Board is run by a team at Children’s Hospital Oakland Research Institute (CHORI). They got almost $4.5 million for their research helping people with sickle cell anemia, an inherited blood disorder that causes intense pain, and can result in strokes and organ damage. Sickle cell affects around 100,000 people in the US, mostly African Americans.

The CHORI team wants to use a new gene-editing tool called CRISPR-Cas9 to develop a method of editing the defective gene that causes Sickle Cell, creating a healthy, sickle-free blood supply for patients.

Right now, the only effective long-term treatment for sickle cell disease is a bone marrow transplant, but that requires a patient to have a matched donor – something that is hard to find. Even with a perfect donor the procedure can be risky, carrying with it potentially life-threatening complications. Using the patient’s own blood stem cells to create a therapy would remove those complications and even make it possible to talk about curing the disease.

While damaged cartilage isn’t life-threatening it does have huge quality of life implications for millions of people. Untreated cartilage damage can, over time lead to the degeneration of the joint, arthritis and chronic pain. Researchers at the University of Southern California (USC) were awarded $2.5 million to develop an off-the-shelf stem cell product that could be used to repair the damage.

The fourth and final award ($2.09 million) went to Ankasa Regenerative Therapeutics, which hopes to create a stem cell therapy for osteonecrosis. This is a painful, progressive disease caused by insufficient blood flow to the bones. Eventually the bones start to rot and die.

As Jonathan Thomas, Chair of the CIRM Board, said in a news release, we are hoping this is just the next step for these programs on their way to helping patients:

“These Translational Awards highlight our goal of creating a pipeline of projects, moving through different stages of research with an ultimate goal of a successful treatment. We are hopeful these projects will be able to use our newly created Stem Cell Center to speed up their progress and pave the way for approval by the FDA for a clinical trial in the next few years.”

A single protein can boost blood stem cell regeneration

Today, CIRM-funded scientists from the UCLA Broad Stem Cell Research Center reported  in Nature Medicine that hematopoietic stem cells (HSCs) – blood stem cells that generate the cell in your blood and immune system – get a helping hand after injury from cells in the bone marrow called bone progenitor cells. By secreting a protein called dickkopf-1 (Dkk1), bone progenitor cells improve the recovery and survival of blood stem cells in a culture dish and in mice whose immune systems are suppressed by irradiation.

These findings build upon a related study published by the same UCLA team last month showing that deleting a single gene in HSCs boosts blood stem cell regeneration. We covered this initial story previously on the Stem Cellar, and you can refer to it for background on the importance of stimulating the regenerative capacity of HSCs in patients that need bone marrow transplants or have undergone radiation therapy for cancer.

Dkk1 boost blood stem cell regeneration

Senior author on the study, UCLA Professor Dr. John Chute, wanted to understand how the different cell types in the bone marrow environment, or niche, interact with HSCs to enhance their ability to recover from injury and regenerate the immune system. As mentioned earlier, he and his team found that bone progenitor cells secrete Dkk1 protein in response to injury caused by exposing mice to full body irradiation. Dkk1 promoted blood stem cell regeneration in the mice and increased their survival rates.

I inquired with Dr. Chute about this seemingly beneficial relationship between HSCs and cells in the bone marrow niche.

Dr. John Chute, UCLA

Dr. John Chute, UCLA

“The precise functions of bone cells, stromal cells and endothelial cells in regulating blood stem cell fate are not completely understood,” said Dr. Chute. “Our prior studies demonstrated that endothelial cells are necessary for blood stem cell regeneration after irradiation.  The current study suggests that bone progenitor cells are also necessary for normal blood stem cell regeneration after irradiation, and that this activity is mediated by secretion of Dkk1 by the bone progenitor cells.”

He further commented in a UCLA press release:

“The cellular niche is like the soil that surrounds the stem cell ‘seed’ and helps it grow and proliferate. Our hypothesis was that the bone progenitor cell in the niche may promote hematopoietic stem cell regeneration after injury.”

Not only did Dkk1 improve HSC regeneration in irradiated mice, it also boosted the regeneration of HSCs that were irradiated in a culture dish. On the other hand, when Dkk1 was deleted from HSCs in irradiated mice, the HSCs did not recover and regenerate. Diving in deeper, the team found that Dkk1 promotes blood stem cell regeneration by direct action on the stem cells and by indirectly increasing the secretion of the stem cell growth factor EGF by bone marrow blood vessels. Taken together, the team concluded that Dkk1 is necessary for blood stem cell recovery following injury/irradiation.

After radiation, blood cells (purple) regenerated in bone marrow when mice were given DKK1 intravenously (left), but not in those that received saline solution (right). (UCLA/Nature Medicine)

After radiation, blood cells (purple) regenerated in bone marrow when mice were given DKK1 (left), but not in those that received saline solution (right). (UCLA/Nature Medicine)

Future applications for blood stem cell regeneration

When I asked Dr. Chute how his current study on Dkk1 and HSCs relates to his previous study on boosting HSC regeneration by deleting a gene called Grb10, he explained:

“In this paper we discovered the role of a niche cell-derived protein, Dkk1, and how it promotes blood stem cell regeneration after myelosuppression in mice.  In the Cell Reports paper, we described our discovery of an adaptor protein, Grb10, which is expressed by blood stem cells and the inhibition of which also promotes blood stem cell regeneration after myelosuppression. So, these are two novel molecular mechanisms that regulate blood stem cell regeneration that could be therapeutically targeted.”

Both studies offer new strategies for promoting blood stem cell regeneration in patients who need to replenish their blood and immune systems following radiation treatments or bone marrow transplants.

Dr. Chute concluded:

“We are very interested in translating our observations into the clinic for the purpose of accelerating hematologic recovery in patients receiving chemotherapy or undergoing hematopoietic stem cell transplantation.”


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Stem cell stories that caught our eye: glowing stem cells and new insights into Zika and SCID

Here are some stem cell stories that caught our eye this past week. Some are groundbreaking science, others are of personal interest to us, and still others are just fun.

Glowing stem cells help scientists understand how cells work. (Karen Ring)
It’s easy to notice when something is going wrong. It’s a lot harder to notice when something is going right. The same thing can be said for biology. Scientists dedicate their careers to studying unhealthy cells, trying to understand why people get certain diseases and what’s going wrong at the cellular level to cause these problems. But there is a lot to be said for doing scientific research on healthy cells so that we can better understand what’s happening when cells start to malfunction.

A group from the Allen Institute for Cell Science is doing just this. They used a popular gene-editing technology called CRISPR/Cas9 to genetically modify human stem cell lines so that certain parts inside the cell will glow different colors when observed under a fluorescent microscope. Specifically, the scientists inserted the genetic code to produce fluorescent proteins in both the nucleus and the mitochondria of the stem cells. The final result is a tool that allows scientists to study how stem cells specialize into mature cells in various tissues and organs.

Glowing human stem cells. The edges of the cells are shown in purple while the DNA in the cell’s nucleus is in blue. (Allen Institute for Cell Science).

Glowing human stem cells. The edges of the cells are shown in purple while the DNA in the cell’s nucleus is in blue. (Allen Institute for Cell Science).

The director of stem cells and gene editing at the Allen Institute, Ruwanthi Gunawardane, explained how their technology improves upon previous methods for getting cells to glow in an interview with Forbes:

 “We’re trying to understand how the cell behaves, how it functions, but flooding it with some external protein can really mess it up. The CRISPR system allows us to go into the DNA—the blueprint—and insert a gene that allows the cell to express the protein in its normal environment. Then, through live imaging, we can watch the cell and understand how it works.”

The team has made five of these glowing stem cell lines available for use by the scientific community through the Coriell Institute for Medical Research (which also works closely with the CIRM iPSC Initiative). Each cell line is unique and has a different cellular structure that glows. You can learn more about these cell lines on the Coriell Allen Institute webpage and by watching this video:

 

Zika can take multiple routes to infect a child’s brain. (Kevin McCormack)
One of the biggest health stories of 2016 has been the rapid, indeed alarming, spread of the Zika virus. It went from an obscure virus to a global epidemic found in more than 70 countries.

The major concern about the virus is its ability to cause brain defects in the developing brain. Now researchers at Harvard have found that it can do this in more ways than previously believed.

Up till now, it was believed that Zika does its damage by grabbing onto a protein called AXL on the surface of brain cells called neural progenitor cells (NPCs). However, the study, published in the journal Cell Stem Cell, showed that even when AXL was blocked, Zika still managed to infiltrate the brain.

Using induced pluripotent stem cell technology, the researchers were able to create NPCs and then modify them so they had no AXL expression. That should, in theory, have been able to block the Zika virus. But when they exposed those cells to the virus they found they were infected just as much as ordinary brain cells exposed to the virus were.

Caption: Zika virus (light blue) spreads through a three-dimensional model of a developing brain. Image by Max Salick and Nathaniel Kirkpatrick/Novartis

Caption: Zika virus (light blue) spreads through a three-dimensional model of a developing brain. Image by Max Salick and Nathaniel Kirkpatrick/Novartis

In a story in the Harvard Gazette, Kevin Eggan, one of the lead researchers, said this shows scientists need to re-think their approach to countering the virus:

“Our finding really recalibrates this field of research because it tells us we still have to go and find out how Zika is getting into these cells.”

 

Treatment for a severe form of bubble baby disease appears on the horizon. (Todd Dubnicoff)
Without treatment, kids born with bubble baby disease typically die before reaching 12 months of age. Formally called severe combined immunodeficiency (SCID), this genetic blood disorder leaves infants without an effective immune system and unable to fight off even minor infections. A bone marrow stem cell transplant from a matched sibling can treat the disease but this is only available in less than 20 percent of cases and other types of donors carry severe risks.

In what is shaping up to be a life-changing medical breakthrough, a UCLA team has developed a stem cell/gene therapy treatment that corrects the SCID mutation. Over 40 patients have participated to date with a 100% survival rate and CIRM has just awarded the team $20 million to continue clinical trials.

There’s a catch though: other forms of SCID exist. The therapy described above treats SCID patients with a mutation in a gene responsible for producing a protein called ADA. But an inherited mutation in another gene called Artemis, leads to a more severe form of SCID. These Artemis-SCID infants have even less success with a standard bone marrow transplant compared to those with ADA-SCID. Artemis plays a role in DNA damage repair something that occurs during the chemo and radiation therapy sessions that are often necessary for blood marrow transplants. So Artemis-SCID patients are hyper-sensitive to the side of effects of standard treatments.

A recent study by UCSF scientists in Human Gene Therapy, funded in part by CIRM, brings a lot of hope to these Artemis-SCID patient. Using a similar stem cell/gene therapy method, this team collected blood stem cells from the bone marrow of mice with a form of Artemis-SCID. Then they added a good copy of the human Artemis gene to these cells. Transplanting the blood stem cells back to mice, restored their immune systems which paves the way for delivering this approach to clinic to also help the Artemis-SCID patients in desperate need of a treatment.

Key Steps Along the Way To Finding Treatments for HIV on World AIDS Day

Today, December 1st,  is World AIDS Day. It’s a day to acknowledge the progress that is being made in HIV prevention and treatment around the world but also to renew our commitment to a future free of HIV. This year’s theme is Leadership. Commitment. Impact.  At CIRM we are funding a number of projects focused on HIV/AIDS, so we asked Jeff Sheehy, the patient advocate for HIV/AIDS on the CIRM Board to offer his perspective on the fight against the virus.

jeff-sheehy

At CIRM we talk about and hope for cures, but our actual mission is “accelerating stem cell treatments to patients with unmet medical needs.”

For those of us in the HIV/AIDS community, we are tremendously excited about finding a cure for HIV.  We have the example of Timothy Brown, aka the “Berlin Patient”, the only person cured of HIV.

Multiple Shots on Goal

Different approaches to a cure are under investigation with multiple clinical trials.  CIRM is funding three clinical trials using cell/gene therapy in attempts to genetically modify blood forming stem cells to resist infection with HIV.  While we hope this leads to a cure, community activists have come together to urge a look at something short of a “home run.”

A subset of HIV patients go on treatment, control the virus in their blood to the point where it can’t be detected by common diagnostic tests, but never see their crucial immune fighting CD4 T cells return to normal levels after decimation by HIV.

For instance, I have been on antiretroviral therapy since 1997.  My CD4 T cells had dropped precipitously, dangerous close to the level of 200.  At that level, I would have had an AIDS diagnosis and would have been extremely vulnerable to a whole host of opportunistic infections.  Fortunately, my virus was controlled within a few weeks and within a year, my CD T cells had returned to normal levels.

For the immunological non-responders I described above, that doesn’t happen.  So while the virus is under control, their T cell counts remain low and they are very susceptible to opportunistic infections and are at much greater risk of dying.

Immunological non-responders (INRs) are usually patients who had AIDS when they were diagnosed, meaning they presented with very low CD4 T cell counts.  Many are also older.  We had hoped that with frequent testing, treatment upon diagnosis and robust healthcare systems, this population would be less of a factor.  Yet in San Francisco with its very comprehensive and sophisticated testing and treatment protocols, 16% of newly diagnosed patients in 2015 had full blown AIDS.

Until we make greater progress in testing and treating people with HIV, we can expect to see immunological non-responders who will experience sub-optimal health outcomes and who will be more difficult to treat and keep alive.

Boosting the Immune System

A major cell/gene trial for HIV targeted this population.  Their obvious unmet medical need and their greater morbidity/mortality balanced the risks of first in man gene therapy.  Sangamo, a CIRM grantee, used zinc finger nucleases to snip out a receptor, CCR5, on the surface of CD4 T cells taken from INR patients.  That receptor is a door that HIV uses to enter cells.  Some people naturally lack the receptor and usually are unable to be infected with HIV.  The Berlin Patient had his entire immune system replaced with cells from someone lacking CCR5.

Most of the patients in that first trial saw their CD4 T cells rise sharply.  The amount of HIV circulating in their gut decreased.  They experienced a high degree of modification and persistence in T stem cells, which replenish the T cell population.  And most importantly, some who regularly experienced opportunistic infections such as my friend and study participant Matt Sharp who came down with pneumonia every winter, had several healthy seasons.

Missed Opportunities

Unfortunately, the drive for a cure pushed development of the product in a different direction.  This is in large part to regulatory challenges.  A prior trial started in the late 90’s by Chiron tested a cytokine, IL 2, to see if administering it could increase T cells.  It did, but proving that these new T cells did anything was illusive and development ceased.  Another cytokine, IL 7, was moving down the development pathway when the company developing it, Cytheris, ceased business.  The pivotal trial would have required enrolling 4,000 participants, a daunting and expensive prospect.  This was due to the need to demonstrate clinical impact of the new cells in a diverse group of patients.

Given the unmet need, HIV activists have looked at the Sangamo trial, amongst others, and have initiated a dialogue with the FDA.  Activists are exploring seeking orphan drug status since the population of INRs is relatively small.

Charting a New Course

They have also discussed trial designs looking at markers of immune activity and discussed potentially identifying a segment of INRs where clinical efficacy could be shown with far, far fewer participants.

Activists are calling for companies to join them in developing products for INRs.  I’ve included the press release issued yesterday by community advocates below.

With the collaboration of the HIV activist community, this could be a unique opportunity for cell/gene companies to actually get a therapy through the FDA. On this World AIDS Day, let’s consider the value of a solid single that serves patients in need while work continues on the home run.

NEWS RELEASE: HIV Activists Seek to Accelerate Development of Immune Enhancing Therapies for Immunologic Non-Responders.

Dialogues with FDA, scientists and industry encourage consideration of orphan drug designations for therapies to help the immunologic non-responder population and exploration of novel endpoints to reduce the size of efficacy trials.

November 30, 2016 – A coalition of HIV/AIDS activists are calling for renewed attention to HIV-positive people termed immunologic non-responders (INRs), who experience sub-optimal immune system reconstitution despite years of viral load suppression by antiretroviral therapy. Studies have shown that INR patients remain at increased risk of illness and death compared to HIV-positive people who have better restoration of immune function on current drug therapies. Risk factors for becoming an INR include older age and a low CD4 count at the time of treatment initiation. To date, efforts to develop immune enhancing interventions for this population have proven challenging, despite some candidates from small companies showing signs of promise.

“We believe there is an urgent need to find ways to encourage and accelerate development of therapies to reduce the health risks faced by INR patients,” stated Nelson Vergel of the Program for Wellness Restoration (PoWeR), who initiated the activist coalition. “For example, Orphan Drug designations[i] could be granted to encourage faster-track approval of promising therapies.  These interventions may eventually help not only INRs but also people with other immune deficiency conditions”.

Along with funding, a major challenge for approval of any potential therapy is proving its efficacy. While INRs face significantly increased risk of serious morbidities and mortality compared to HIV-positive individuals with more robust immune reconstitution, demonstrating a reduction in the incidence of these outcomes would likely require expensive and lengthy clinical trials involving thousands of individuals. Activists are therefore encouraging the US Food & Drug Administration (FDA), industry and researchers to evaluate potential surrogate markers of efficacy such as relative improvements in clinical problems that may be more frequent in INR patients, such as upper respiratory infections, gastrointestinal disease, and other health issues.

“Given the risks faced by INR patients, every effort should be made to assess whether less burdensome pathways toward approval are feasible, without compromising the regulatory requirement for compelling evidence of safety and efficacy”, said Richard Jefferys of the Treatment Action Group.

The coalition is advocating that scientists, biotech and pharmaceutical companies pursue therapeutic candidates for INRs. For example, while gene and anti-inflammatory therapies for HIV are being assessed in the context of cure research, there is also evidence that they may have potential to promote immune reconstitution and reduce markers associated with risk of morbidity and mortality in INR patients. Therapeutic research should also be accompanied by robust study of the etiology and mechanisms of sub-optimal immune responses.

“While there is, appropriately, a major research focus on curing HIV, we must be alert to evidence that candidate therapies could have benefits for INR patients, and be willing to study them in this context”, argued Matt Sharp, a coalition member and INR who experienced enhanced immune reconstitution and improved health and quality of life after receiving an experimental gene therapy.

The coalition has held an initial conference call with FDA to discuss the issue. Minutes are available online.

The coalition is now aiming to convene a broader dialogue with various drug companies on the development of therapies for INR patients. Stakeholders who are interested in becoming involved are encouraged to contact coalition representatives.

[i] The Orphan Drug Act incentivizes the development of treatments for rare conditions. For more information, see:  http://www.fda.gov/ForIndustry/DevelopingProductsforRareDiseasesConditions/ucm2005525.htm

For more information:

Richard Jefferys

Michael Palm Basic Science, Vaccines & Cure Project Director
Treatment Action Group richard.jefferys@treatmentactiongroup.org

Nelson Vergel, Program for Wellness Restoration programforwellness@gmail.com