Stem cell stories that caught our eye: drug safety for heart cells, worms hijack plant stem cells & battling esophageal cancer

Devising a drug safety measuring stick in stem cell-derived heart muscle cells
One of the mantras in the drug development business is “fail early”. That’s because most of the costs of getting a therapy to market occur at the later stages when an experimental treatment is tested in clinical trials in people. So, it’s best for a company’s bottom line and, more importantly, for patient safety to figure out sooner rather than later if a therapy has dangerous toxic side effects.

Researchers at Stanford reported this week in Science Translational Medicine on a method they devised that could help weed out cancer drugs with toxic effects on the heart before the treatment is tested in people.

In the lab, the team grew beating heart muscle cells, or cardiomyocytes, from induced pluripotent stem cells derived from both healthy volunteers and kidney cancer patients. A set of cancer drugs called tyrosine kinase inhibitors which are known to have a range of serious side effects on the heart, were added to the cells. The effect of the drugs on the heart cell function were measured with several different tests which the scientists combined into a single “safety index”.

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A single human induced pluripotent stem cell-derived cardiomyocyte. Cells such as these were used to assess tyrosine kinase inhibitors for cardiotoxicity in a high-throughput fashion. Credit: Dr. Arun Sharma at Dr. Joseph Wu’s laboratory at Stanford University

They found that the drugs previously shown to have toxic effects on patients’ hearts had the worst safety index values in the current study. And because these cells were in a lab dish and not in a person’s heart, the team was able to carefully examine cell activity and discovered that the toxic effects of three drugs could be alleviated by also adding insulin to the cells.

As lead author Joseph Wu, director of the Stanford Cardiovascular Institute, mentions in a press release, the development of this drug safety index could provide a powerful means to streamline the drug development process and make the drugs safer:

“This type of study represents a critical step forward from the usual process running from initial drug discovery and clinical trials in human patients. It will help pharmaceutical companies better focus their efforts on developing safer drugs, and it will provide patients more effective drugs with fewer side effects”

Worm feeds off of plants by taking control of their stem cells
In what sounds like a bizarre mashup of a vampire movie with a gardening show, a study reported this week pinpoints how worms infiltrate plants by commandeering the plants’ own stem cells. Cyst nematodes are microscopic roundworms that invade and kill soybean plants by sucking out their nutrients. This problem isn’t a trivial matter since nematodes wreak billions of dollars of damage to the world’s soybean crops each year. So, it’s not surprising that researchers want to understand how exactly these critters attack the plants.

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A nematode, the oblong object on the left, activates the vascular stem cell pathway in the developing nematode feeding site on a plant root. Credit: Xiaoli Guo, University of Missouri

Previous studies by Melissa Goellner Mitchum, a professor at the University of Missouri, had shown that the nematodes release protein fragments, called peptides, near a plant’s roots that help divert the flow of plant nutrients to the worm.

“These parasites damage root systems by creating a unique feeding cell within the roots of their hosts and leeching nutrients out of the soybean plant. This can lead to stunting, wilting and yield loss for the plant,” Mitchum explained in a press release.

In the current PLOS Pathogens study, Mitchum’s team identified another peptide produced by the nematode that is identical to a plant peptide that instructs stem cells to form the plant equivalent of blood vessels. This devious mimicking of the plant peptides is what allows the nematode to trick the plant stem cells into building vessels that reroute the plants’ nutrients directly to the worm.

Mitchum described the big picture implications of this fascinating discovery:

“Understanding how plant-parasitic nematodes modulate host plants to their own benefit is a crucial step in helping to create pest-resistant plants. If we can block those peptides and the pathways nematodes use to overtake the soybean plant, then we can enhance resistance for this very valuable global food source.”

Finding vulnerabilities in treatment-resistant esophageal cancer stem cells

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Illustration of radiation therapy for esophageal cancer.
Credit: Cancer Research UK

The incidence of esophageal cancer has increased more than any other disease over the past 30 years. And while some patients respond well to chemotherapy and radiation treatment, most do not because the cancer becomes resistant to these treatments.

Focusing on cancer stem cells, researchers at Trinity College Dublin have identified an approach that may overcome treatment resistance.

Within tumors are thought to lie cancer stem cells that, just like stem cells, have the ability to multiply indefinitely. Even though they make up a small portion of a tumor, in some patients the cancer stem cells evade the initial rounds of treatment and are responsible for the return of the cancer which is often more aggressive. Currently, there’s no effective way to figure out how well a patient with esophageal cancer will response to treatment.

In the current study published in Oncotarget, the researchers found that a genetic molecule called miR-17 was much less abundant in the esophageal cancer stem cells. In fact, the cancer stem cells with the lowest levels of miR-17, were the most resistant to radiation therapy. The researchers went on to show that adding back miR-17 to the highly resistant cells made them sensitive again to the radiation. Niamh Lynam-Lennon, the study’s first author, explained in a press release that these results could have direct clinical applications:

“Going forward, we could use synthetic miR-17 as an addition to radiotherapy to enhance its effectiveness in patients. This is a real possibility as a number of other synthetic miR-molecules are currently in clinical trials for treating other diseases.”

Stem Cell Stories That Caught our Eye: Making blood and muscle from stem cells and helping students realize their “pluripotential”

Stem cells offer new drug for blood diseases. A new treatment for blood disorders might be in the works thanks to a stem cell-based study out of Harvard Medical School and Boston Children’s hospital. Their study was published in the journal Science Translational Medicine.

The teams made induced pluripotent stem cells (iPSCs) from the skin of patients with a rare blood disorder called Diamond-Blackfan anemia (DBA) – a bone marrow disease that prevents new blood cells from forming. iPSCs from DBA patients were then specialized into blood progenitor cells, the precursors to blood cells. However, these precursor cells were incapable of forming red blood cells in a dish like normal precursors do.

Red blood cells were successfully made via induced pluripotent stem cells from a Diamond-Blackfan anemia patient. Image: Daley lab, Boston Children’s

Red blood cells were successfully made via induced pluripotent stem cells from a Diamond-Blackfan anemia patient. Image: Daley lab, Boston Children’s

The blood progenitor cells from DBA patients were then used to screen a library of compounds to identify drugs that could get the DBA progenitor cells to develop into red blood cells. They found a compound called SMER28 that had this very effect on progenitor cells in a dish. When the compound was tested in zebrafish and mouse models of DBA, the researchers observed an increase in red blood cell production and a reduction of anemia symptoms.

Getting pluripotent stem cells like iPSCs to turn into blood progenitor cells and expand these cells into a population large enough for drug screening has not been an easy task for stem cell researchers.

Co-first author on the study, Sergei Doulatov, explained in a press release, “iPS cells have been hard to instruct when it comes to making blood. This is the first time iPS cells have been used to identify a drug to treat a blood disorder.”

In the future, the researchers will pursue the questions of why and how SMER28 boosts red blood cell generation. Further work will be done to determine whether this drug will be a useful treatment for DBA patients and other blood disorders.

 

Students realize their “pluripotential”. In last week’s stem cell stories, I gave a preview about an exciting stem cell “Day of Discovery” hosted by USC Stem Cell in southern California. The event happened this past Saturday. Over 500 local middle and high school students attended the event and participated in lab tours, poster sessions, and a career resource fair. Throughout the day, they were engaged by scientists and educators about stem cell science through interactive games, including the stem cell edition of Family Feud and a stem cell smartphone videogame developed by USC graduate students.

In a USC press release, Rohit Varma, dean of the Keck School of Medicine of USC, emphasized the importance of exposing young students to research and scientific careers.

“It was a true joy to welcome the middle and high school students from our neighboring communities in Boyle Heights, El Sereno, Lincoln Heights, the San Gabriel Valley and throughout Los Angeles. This bright young generation brings tremendous potential to their future pursuits in biotechnology and beyond.”

Maria Elena Kennedy, a consultant to the Bassett Unified School District, added, “The exposure to the Keck School of Medicine of USC is invaluable for the students. Our students come from a Title I School District, and they don’t often have the opportunity to come to a campus like the Keck School of Medicine.”

The day was a huge success with students posting photos of their experiences on social media and enthusiastically writing messages like “stem cells are our future” and “USC is my goal”. One high school student acknowledged the opportunity that this day offers to students, “California currently has biotechnology as the biggest growing sector. Right now, it’s really important that students are visiting labs and learning more about the industry, so they can potentially see where they’re going with their lives and careers.”

You can read more about USC’s Stem Cell Day of Discovery here. Below are a few pictures from the event courtesy of David Sprague and USC.

Students have fun with robots representing osteoblast and osteoclast cells at the Stem Cell Day of Discovery event held at the USC Health Sciences Campus in Los Angeles, CA. February 4th, 2017. The event encourages students to learn more about STEM opportunities, including stem cell study and biotech, and helps demystify the fields and encourage student engagement. Photo by David Sprague

Students have fun with robots representing osteoblast and osteoclast cells at the USC Stem Cell Day of Discovery. Photo by David Sprague

Dr. Francesca Mariana shows off a mouse skeleton that has been dyed to show bones and cartilage at the Stem Cell Day of Discovery event held at the USC Health Sciences Campus in Los Angeles, CA. February 4th, 2017. The event encourages students to learn more about STEM opportunities, including stem cell study and biotech, and helps demystify the fields and encourage student engagement. Photo by David Sprague

Dr. Francesca Mariana shows off a mouse skeleton that has been dyed to show bones and cartilage. Photo by David Sprague

USC masters student Shantae Thornton shows students how cells are held in long term cold storage tanks at -195 celsius at the Stem Cell Day of Discovery event held at the USC Health Sciences Campus in Los Angeles, CA. February 4th, 2017. The event encourages students to learn more about STEM opportunities, including stem cell study and biotech, and helps demystify the fields and encourage student engagement. Photo by David Sprague

USC masters student Shantae Thornton shows students how cells are held in long term cold storage tanks at -195 celsius. Photo by David Sprague

Genesis Archila, left, and Jasmine Archila get their picture taken at the Stem Cell Day of Discovery event held at the USC Health Sciences Campus in Los Angeles, CA. February 4th, 2017. The event encourages students to learn more about STEM opportunities, including stem cell study and biotech, and helps demystify the fields and encourage student engagement. Photo by David Sprague

Genesis Archila, left, and Jasmine Archila get their picture taken at the USC Stem Cell Day of Discovery. Photo by David Sprague

New stem cell recipes for making muscle: new inroads to study muscular dystrophy (Todd Dubnicoff)

Embryonic stem cells are amazing because scientists can change or specialize them into virtually any cell type. But it’s a lot easier said than done. Researchers essentially need to mimic the process of embryo development in a petri dish by adding the right combination of factors to the stem cells in just the right order at just the right time to obtain a desired type of cell.

Making human muscle tissue from embryonic stem cells has proven to be a challenge. The development of muscle, as well as cartilage and bone, are well characterized and known to form from an embryonic structure called a somite. Researches have even been successful working out the conditions for making somites from animal stem cells. But those recipes didn’t work well with human stem cells.

Now, a team of researchers at the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA has overcome this roadblock by carrying out a systematic approach using human tissue. As described in Cell Reports, the scientists isolated somites from early human embryos and studied their gene activity. By comparing somites that were just beginning to emerge with fully formed somites, the researchers pinpointed differences in gene activity patterns. With this data in hand, the team added factors to the cells that were known to affect the activity of those genes. Through some trial and error, they produced a recipe – different than those used in animal cells – that could convert 90 percent of the human stem cells into somites in only four days. Those somites could then readily transform into muscle or bone or cartilage.

This new method for making human muscle will be critical for the lab’s goal to develop therapies for Duchenne muscular dystrophy, an incurable muscle wasting disease that strikes young boys and is usually fatal by their 20’s.

The new protocol turned 90 percent of human pluripotent stem cells into somite cells in just four days; those somite cells then generated (left to right) cartilage, bone and muscle cells.  Image: April Pyle Lab/UCLA

The new protocol turned 90 percent of human pluripotent stem cells into somite cells in just four days; those somite cells then generated (left to right) cartilage, bone and muscle cells. Image: April Pyle Lab/UCLA

“Apples to Apples” analysis: induced pluripotent stem cell (iPSC) method doesn’t increase mutations

It’s full steam ahead for the development of induced pluripotent stem cell (iPSC)-derived clinical trials. That’s according to a group at the National Human Genome Research Institute in Bethesda, Maryland who report this week in PNAS that the process of reprogramming a skin cell into the embryonic stem cell-like state of an iPSC does not itself cause an increased number of genetic mutations.

logo_nhgriEver since the technique was first devised ten years ago, there has been a lot of excitement about applying IPSCs to cell therapies for patients with unmet medical needs. Unlike human embryonic stem cells (hESCs) which are generated through the destruction of a fertilized embryo, iPSCs avoid ethical concerns because they’re obtained using adult cells like blood or skin. And the fact they’re patient specific carries the additional advantage of delivering iPSC-derived therapies back to the same patient with less concerns of rejection by the immune system.

Still, the use of iPSC-derived therapies has certainly not been worry-free and their translation into human clinical trials has been slow. One big concern is that the process of reprogramming inherently causes cell stress leading to an increased rate of genetic mutations in the cells. An abnormal number of mutations is bad news for cell therapies because they could carry an increased risk of becoming cancerous after being injected into a patient – an event that would end up causing more harm than good. Previous DNA sequencing studies comparing iPSCs with their cell source (skin, blood, etc.) identified many new sequence mutations in the iPSCs. But other studies suggested that many of those mutations already existed in the source cells and so they were essentially inherited during the iPSC process.

The team in this study sought out a definitive answer by tackling this mutation question using an “apples to apples” approach. To explain their approach, let’s first understand a technical detail about the iPSC method. When the iPSC reprogramming factors are added to the adult skin cells, the process is not efficient and only a few become iPSCs. Single iPSCs are then isolated and allowed to divide and make clones of themselves. This population of cells is called a cell “line” and takes several rounds of cell division to multiply into enough numbers to analyze their DNA sequence.

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Credit: Darryl Leja and Ernesto Del Aguila III, NHGRI

So the researchers decided to also go through the process of making cell lines from the original skin cells but in this set they did not add the iPSC reprogramming factors. Now, they could compare the fate of DNA sequences in skin cell lines with and without the iPSC reprogramming method. The sequencing results showed that mutations occurred at the same rate in both the skin cell lines and the iPSC cell lines. This direct comparison suggests that iPSCs aren’t any less stable than non-reprogrammed cells. This finding bodes well for moving ahead with iPS-derived clinical trials. That’s certainly the perspective Erika Mijin Kwon, a co-author on the publication:

“Based on this data, we plan to start using iPSCs to gain a deeper understanding of how diseases start and progress,” said Kwon, in a press release. “We eventually hope to develop new therapies to treat patients with leukemia using their own iPSCs. We encourage other researchers to embrace the use of iPSCs.”

Stories that caught our eye: stem cell transplants help put MS in remission; unlocking the cause of autism; and a day to discover what stem cells are all about

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Motor neurons

Stem cell transplants help put MS in remission: A combination of high dose immunosuppressive therapy and transplant of a person’s own blood stem cells seems to be a powerful tool in helping people with relapsing-remitting multiple sclerosis (RRMS) go into sustained remission.

Multiple sclerosis (MS) is an autoimmune disorder where the body’s own immune system attacks the brain and spinal cord, causing a wide variety of symptoms including overwhelming fatigue, blurred vision and mobility problems. RRMS is the most common form of MS, affecting up to 85 percent of people, and is characterized by attacks followed by periods of remission.

The HALT-MS trial, which was sponsored by the National Institute of Allergy and Infectious Diseases (NIAID), took the patient’s own blood stem cells, gave the individual chemotherapy to deplete their immune system, then returned the blood stem cells to the patient. The stem cells created a new blood supply and seemed to help repair the immune system.

Five years after the treatment, most of the patients were still in remission, despite not taking any medications for MS. Some people even recovered some mobility or other capabilities that they had lost due to the disease.

In a news release, Dr. Anthony Fauci, Director of NIAID, said anything that holds the disease at bay and helps people avoid taking medications is important:

“These extended findings suggest that one-time treatment with HDIT/HCT may be substantially more effective than long-term treatment with the best available medications for people with a certain type of MS. These encouraging results support the development of a large, randomized trial to directly compare HDIT/HCT to standard of care for this often-debilitating disease.”

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Scripps Research Institute

Using stem cells to model brain development disorders. (Karen Ring) CIRM-funded scientists from the Scripps Research Institute are interested in understanding how the brain develops and what goes wrong to cause intellectual disabilities like Fragile X syndrome, a genetic disease that is a common cause of autism spectrum disorder.

Because studying developmental disorders in humans is very difficult, the Scripps team turned to stem cell models for answers. This week, in the journal Brain, they published a breakthrough in our understanding of the early stages of brain development. They took induced pluripotent stem cells (iPSCs), made from cells from Fragile X syndrome patients, and turned these cells into brain cells called neurons in a cell culture dish.

They noticed an obvious difference between Fragile X patient iPSCs and healthy iPSCs: the patient stem cells took longer to develop into neurons, a result that suggests a similar delay in fetal brain development. The neurons from Fragile X patients also had difficulty forming synaptic connections, which are bridges that allow for information to pass from one neuron to another.

Scripps Research professor Jeanne Loring said that their findings could help to identify new drug therapies to treat Fragile X syndrome. She explained in a press release;

“We’re the first to see that these changes happen very early in brain development. This may be the only way we’ll be able to identify possible drug treatments to minimize the effects of the disorder.”

Looking ahead, Loring and her team will apply their stem cell model to other developmental diseases. She said, “Now we have the tools to ask the questions to advance people’s health.”

A Day to Discover What Stem Cells Are All about.  (Karen Ring) Everyone is familiar with the word stem cells, but do they really know what these cells are and what they are capable of? Scientists are finding creative ways to educate the public and students about the power of stem cells and stem cell research. A great example is the University of Southern California (USC), which is hosting a Stem Cell Day of Discovery to educate middle and high school students and their families about stem cell research.

The event is this Saturday at the USC Health Sciences Campus and will feature science talks, lab tours, hands-on experiments, stem cell lab video games, and a resource fair. It’s a wonderful opportunity for families to engage in science and also to expose young students to science in a fun and engaging way.

Interest in Stem Cell Day has been so high that the event has already sold out. But don’t worry, there will be another stem cell day next year. And for those of you who don’t live in Southern California, mark your calendars for the 2017 Stem Cell Awareness Day on Wednesday, October 11th. There will be stem cell education events all over California and in other parts of the country during that week in honor of this important day.

 

 

Growing a rat pancreas in a mouse with stem cells & CRISPR: a solution for the organ shortage crisis?

Right now, about 120,000 Americans are on a waiting list for an organ transplant and 22 will die today before any organs become available. The plain truth is there aren’t enough organ donors to meet the demand. And according to the U.S. Department of Health and Human Services, the number of available organ donors has remained static over the past decade. How can we overcome this crisis?

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The need for organ transplants is growing but the number of donors is stagnant. Image: U.S. Dept. Human Health Services

One answer may be stem cells. These “blank slate” cells can specialize into virtually any cell type in the body which has many scientists pursuing the holy grail of stem cell research: creating an unlimited supply of human organs. Today, a team of Salk Institute scientists report in Cell that they’ve taken an early but important step toward that goal by showing it’s possible to grow rat organs within a mouse. The results bode well for not only organ transplants but also for the study of human development and disease.

Chimera – monster or medical marvel?
Our regular Stem Cellar readers will be familiar with several fascinating studies using stem cell-based 3D bioprinters or bioscaffolds which aim to one day enable the manufacturing of human tissues and organs. Instead of taking this engineering approach, the Salk team seeks a strategy in which chimeric animals are bred to grow human organs. The term “chimeric” is borrowed from Greek mythology that told tales of the chimera, a monster with a lion’s heads, a goat’s body and a serpent’s tail.

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The chimera of Greek Mythology: part lion, goat and snake. Image: Wikimedia Commons

The team’s first set of experiments explored the feasibility of this method by first focusing on rat-mouse chimeras. Reprogramming skin cells collected from rat tails, the scientists generated induced pluripotent stem cells (iPSCs) – cells with the embryonic stem cell-like ability to become any cell type – and injected them into very early stage mouse embryos. The embryos were then implanted into surrogate female mice and successfully carried to term. Examination of the resulting mouse pups showed that their tissues and organs contained a patchwork of both rat and mouse cells.

And for my next trick, I will make a rat pancreas in a mouse
Now, if the ultimate goal is to grow organs that are 100% human in a host animal, an organ that merely has a random patchwork human cells would miss the mark. To show there’s a way around this problem, the Salk team used the CRISPR gene-editing technique to generate mouse embryos that lacked a gene that’s critical for the development of the pancreas. Without the gene, no pancreas forms and the mice died shortly after birth. But when the rat iPSCs were integrated into the gene edited mice embryos, the rat cells picked up the slack as the embryo developed, resulting in chimeric mice with rat pancreases.

Using the same CRISPR gene editing strategy, the researchers also grew rat hearts, and if you can believe it, rat eyes in the chimeric mice. On top of that, the mice in these experiments were healthy with most reaching adulthood and one living two years, an elderly age for mice.

A first step toward growing patient-specific human organs in large animals
One small, actually big, problem is that mice are much too little to serve as chimeric hosts for human organs. So the team repeated these mixed species experiments in pigs which are much better matched to humans. In this case, they added human iPSCs to the pig embryos, implanted them into female pigs and let the embryos develop for four weeks. Although it wasn’t as efficient as the rat-mouse chimeras, the researchers did indeed observe human cells that had incorporated into the chimera and were showing the early signs of specializing in different cell types within the implanted pig embryos.

This work is the first time human iPSCs have been incorporated into large animal species (they also got it to work with cattle) and many years of lab work remain before this approach can help solves the organ shortage crisis. But the potential applications are spellbinding. Imagine a patient in need of an organ transplant: a small skin biopsy is collected to make iPSCs and, using this chimeric animal approach, a patient-derived organ could be grown.

Juan Carlos Izpisua Belmonte, the study’s team leader, talked about this possibility and more in a press release:

“Of course, the ultimate goal of chimeric research is to learn whether we can use stem-cell and gene-editing technologies to generate genetically-matched human tissues and organs, and we are very optimistic that continued work will lead to eventual success. But in the process we are gaining a better understanding of species evolution as well as human embryogenesis and disease that is difficult to get in other ways.”

Ethical concerns
Now, if the idea of breeding pigs or cows with human organs make you a little uneasy, you aren’t alone.  In fact, the National Institutes of Health announced in 2015 that they had halted funding research that introduces human stem cells into other animals. They want more time “to evaluate the state of the science in this area, the ethical issues that should be considered, and the relevant animal welfare concerns associated with these types of studies.”  To read more discussion on this topic, read this MIT Technology Review article from a year ago.

 

Stories that caught our eye: $20.5 million in new CIRM discovery awards, sickle cell disease cell bank, iPSC insights

CIRM Board launches a new voyage of Discovery (Kevin McCormack).
Basic or early stage research is the Rodney Dangerfield of science; it rarely gets the respect it deserves. Yesterday, the CIRM governing Board showed that it not only respects this research, but also values its role in laying the foundation for everything that follows.

The CIRM Board approved 11 projects, investing more than $20.5 million in our Discovery Quest, early stage research program. Those include programs using gene editing techniques to develop a cure for a rare but fatal childhood disease, finding a new approach to slowing down the progress of Parkinson’s disease, and developing a treatment for the Zika virus.

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Electron micrograph of Zika virus (red circles). Image: CDC/Cynthia Goldsmith

The goal of the Discovery Quest program is to identify and explore promising new stem cell therapies or technologies to improve patient care.

In a news release Randy Mills, CIRM’s President & CEO, said we hope this program will create a pipeline of projects that will ultimately lead to clinical trials:

“At CIRM we never underestimate the importance of early stage scientific research; it is the birth place of groundbreaking discoveries. We hope these Quest awards will not only help these incredibly creative researchers deepen our understanding of several different diseases, but also lead to new approaches on how best to use stem cells to develop treatments.”

Creating the world’s largest stem cell bank for sickle cell disease (Karen Ring).
People typically visit the bank to deposit or take out cash, but with advancements in scientific research, people could soon be visiting banks to receive life-saving stem cell treatments. One of these banks is already in the works. Scientists at the Center for Regenerative Medicine (CReM) at Boston Medical Center are attempting to generate the world’s largest stem cell bank focused specifically on sickle cell disease (SCD), a rare genetic blood disorder that causes red blood cells to take on an abnormal shape and can cause intense pain and severe organ damage in patients.

To set up their bank, the team is collecting blood samples from SCD patients with diverse ethnic backgrounds and making induced pluripotent stem cells (iPSCs) from these samples. These patient stem cell lines will be used to unravel new clues into why this disease occurs and to develop new potential treatments for SCD. More details about this new SCD iPSC bank can be found in the latest edition of the journal Stem Cell Reports.

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Gustavo Mostoslavsky, M.D., PH.D., Martin Steinberg, M.D., George Murphy PH.D.
Photo: Boston Medical Center

In a news release, CReM co-founder and Professor, Gustavo Mostoslavsky, touched on the future importance of their new stem cell bank:

“In addition to the library, we’ve designed and are using gene editing tools to correct the sickle hemoglobin mutation using the stem cell lines. When coupled with corrected sickle cell disease specific iPSCs, these tools could one day provide a functional cure for the disorder.”

For researchers interested in using these new stem cell lines, CReM is making them available to researchers around the world as part of the NIH’s NextGen Consortium study.

DNA deep dive reveals ways to increase iPSC efficiency (Todd Dubnicoff)
Though the induced pluripotent stem (iPS) cell technique was first described ten years ago, many researchers continue to poke, prod and tinker with the method which reprograms an adult cell, often from skin, into an embryonic stem cell-like state which can specialize into any cell type in the body. Though this breakthrough in stem cell research is helping scientists better understand human disease and develop patient-specific therapies, the technique is hampered by its low efficiency and consistency.

This week, a CIRM-funded study from UCLA reports new insights into the molecular changes that occur during reprogramming that may help pave the way toward better iPS cell methods. The study, published in Cell, examined the changes in DNA during the reprogramming process.

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Senior authors Kathrin Plath and Jason Ernst and first authors Petko Fiziev and Constantinos Chronis.
Photo: UCLA

In a skin cell, the genes necessary for embryonic stem cell-like, or pluripotent, characteristics are all turned off. One way this shut down in gene activity occurs is through tight coiling of the DNA where the pluripotent genes are located. This physically blocks proteins called transcriptions factors from binding the DNA and activating those pluripotent genes within skin cells. On the other hand, regions of DNA carrying skin-related genes are loosely coiled, so that transcription factors can access the DNA and turn on those genes.

The iPS cell technique works by artificially adding four pluripotent transcriptions factors into skin cells which leads to changes in DNA coiling such that skin-specific genes are turned off and pluripotent genes are turned on. The UCLA team carefully mapped the areas where the transcription factors are binding to DNA during the reprogramming process. They found that the shut down of the skin genes and activation of the pluripotent genes occurs at the same time. The team also found that three of the four iPS cell factors must physically interact with each other to locate and activate the areas of DNA that are responsible for reprogramming.

Using the findings from those experiments, the team was able to identify a fifth transcription factor that helps shut down the skin-specific gene more effectively and, in turn, saw a hundred-fold increase in reprogramming efficiency. These results promise to help the researchers fine-tune the iPS cell technique and make its clinical use more practical.

Has the promise of stem cells been overstated?

One of the most famous stem cell scientists in the world said on Monday that the promise of stem cell treatments has in some ways been overstated.

In an interview with the New York Times, Dr. Shinya Yamanaka, one of the recipients of the 2012 Nobel Prize in Medicine for his discovery of induced pluripotent stem cells (iPS cells), said, “we can help just a small portion of patients by stem cell therapy.”

Shinya Yamanaka. (Image source: Ko Sasaki, New York Times)

Shinya Yamanaka. (Image source: Ko Sasaki, New York Times)

He explained that there are only 10 target diseases that he believes will benefit directly from stem cell therapies including, “Parkinson’s, retinal and corneal diseases, heart and liver failure, diabetes, spinal cord injury, joint disorders and some blood disorders. But maybe that’s all. The number of human diseases is enormous.”

This is a big statement coming from a key opinion leader in the field of stem cell research, and it’s likely to spur a larger conversation on the future of stem cell treatments.

Yamanaka also touched on another major point in his interview – progress takes time.

In the ten years since his discovery of iPS cells, he and other scientists have learned the hard way that the development of stem cell treatments can be time consuming. While autologous iPS cell treatments (making stem cell lines from a patient and transplanting them back into that patient) have entered clinical trials to treat patients with macular degeneration, a disease that causes blindness, the trials have been put on hold until the safety of the stem cell lines being used are confirmed.

At the World Alliance Forum in November, Yamanaka revealed that generating a single patient iPS cell line can cost up to one million dollars which isn’t feasible for the 1000’s of patients who need them. He admitted that the fate of personalized stem cell medicine, which once seemed so promising, now seems unrealistic because it’s time consuming and costly.

But with any obstacle, there is always a path around it. Under Yamanaka’s guidance, Japan is generating donor iPS cell lines that can be used to treat a large portion of the Japanese population. Yamanaka said that 100 lines would cover 100 million people in Japan and that 200 lines would be enough to cover the US population. iPS cell banks are being generated around the world, meaning that one day the millions of people suffering from the target diseases Yamanaka mentioned could be treated or even cured. Would this not fulfill a promise that was made about the potential of stem cell treatments?

Which brings me to my point, I don’t believe the promise of stem cells has been overstated. I think that it has yet to be realized, and it will take more research and more time to get there. As a community, we need to be understanding, patient, and supportive.

In my opinion (as a scientist aside from my role at CIRM), I believe that Yamanaka’s interview failed to reveal his optimism about the future of stem cell treatments. What I took from Yamanaka’s comments is that stem cell treatments can help a small number of patients with specific diseases right now. That’s not to say that stem cell research won’t produce promising treatments for other diseases in the future.

Retinal diseases and blood disorders are easier to target with stem cell treatments because only one type of cell needs to be replaced. It makes sense to tackle those diseases first and make sure that these stem cell treatments are effective and safe in patients before we focus on more complicated diseases where multiple cell types or organs are involved.

Part of the reason why scientists are unsure whether stem cell treatments can treat complex diseases is because we still don’t know the details of what causes these diseases. After we know more about what’s going wrong, including all the cell types and molecules involved, research might reveal new ways that stem cells could be used to help treat those diseases. Or on the other hand, stem cells could be used to model those diseases to help discover new drug treatments.

I’ve heard Yamanaka talk many times and recently I heard him speak at the World Alliance Forum in November, where he said that the two biggest hurdles we are facing for stem cell treatments to be successful is time and cost. After we overcome these hurdles, his outlook was optimistic that stem cell treatments could improve people’s lives. But he stressed that these advances will take time.

He shared a similar sentiment at the very end of the NY Times interview by referencing his father’s story and the decades it took to cure hepatitis C,

“You know, my father had a small factory. He injured his leg in the factory when I was in junior high. He had a transfusion, and he got hepatitis C. He passed away in 1989. Twenty-five years later, just two years ago, scientists developed a very effective cure. We now have a tablet. Three months and the virus is gone — it’s amazing. But it took 25 years. iPS cells are only 10 years old. The research takes time. That’s what everybody needs to understand.”

Yamanaka says more time is needed for stem cell treatments to become effective cures, but CIRM has already witnessed success. In our December Board meeting, we heard from two patients who were cured of genetic blood diseases by stem cell treatments that CIRM funded. One of them was diagnosed with severe combined immunodeficiency (SCID) and the other had chronic granulomatous disease (CGD). Both had their blood stem cells genetically engineered to removed disease-causing mutations and then transplanted back into their body to create a healthy immune system and cure them of their disease.

Hearing how grateful these patients and their families were to receive life-saving stem cell treatments and how this research brings new hope to other patients suffering from the same diseases, in my mind, fulfills the promise of stem cell research and makes funding stem cell treatments worth it.

I believe we will hear more and more of these success stories in the next decade and CIRM will most certainly play an important role in this future. There are others in the field who share a similar optimism for the future of stem cell treatments. Hank Greely, the Director for Law and the Biosciences at Stanford University, said in an interview with the Sacramento Bee about the future of CIRM,

Hank Greely, Stanford University

Hank Greely, Stanford University

“The next few years should determine just how good California’s investment has been. It is encouraging to see CIRM supporting so many clinical trials; it will be much more exciting when – and I do expect ‘when’ and not ‘if’ – one of those trials leads to an approved treatment.”

 


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Stories that caught our eye: frail bones in diabetics, ethics of future IVF, Alzheimer’s

The connection between diabetes and frail bones uncovered
Fundamentally, diabetes is defined by abnormally high blood sugar levels. But that one defect over time carries an increased risk for a wide range of severe health problems. For instance, compared to healthy individuals, type 2 diabetics are more prone to poorly healing bone fractures – a condition that can dramatically lower one’s quality of life.

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Bones of the healthy animals (top) form larger calluses during healing which lead to stronger repaired bones. Bones of the diabetic mice (bottom) have smaller calluses and the healed bones are more brittle. Image: Stanford University

To help these people, researchers are trying to tease out how diabetes impacts bone health. But it’s been a complicated challenge since there are many factors at play. Is it from potential side effects of diabetes drugs? Or is the increased body weight associated with type 2 diabetes leading to decreased bone density? This week a CIRM-funded team at Stanford pinpointed skeletal stem cells, a type of adult stem cell that goes on to make all the building blocks of the bone, as important pieces to this scientific puzzle.

Reporting in Science Translational Medicine, the team, led by Michael Longaker – co-director of Stanford’s Institute for Stem Cell Biology and Regenerative Medicine – found that, compared to healthy animals, type 2 diabetic mice have a reduced number of skeletal stem cells after bone fracture. A study of the local cellular “neighborhood” of these stem cells showed that the diabetic mice also had a reduction in the levels of a protein called hedgehog. Blocking hedgehog activity in healthy mice led to the slow bone healing seen in the diabetic mice. More importantly, boosting hedgehog levels near the site of the fracture in diabetic mice lead to bone healing that was just as good as in the healthy mice.

To see if this result might hold up in humans, the team analyzed hedgehog levels in bone samples retrieved from diabetics and non-diabetics undergoing joint replacement surgeries. Sure enough, hedgehog was depleted in the diabetic bone exactly reflecting the mouse results.

Though more studies will be needed to develop a hedgehog-based treatment in humans, Longaker talked about the exciting big picture implications of this result in a press release:

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Michael Longaker

“We’ve uncovered the reason why some patients with diabetes don’t heal well from fractures, and we’ve come up with a solution that can be locally applied during surgery to repair the break. Diabetes is rampant worldwide, and any improvement in the ability of affected people to heal from fractures could have an enormously positive effect on their quality of life.”

 

Getting the ethics ahead of the next generation of fertility treatments
The Business Insider ran an article this week with a provocative title, “Now is the time to talk about creating humans from stem cells.” I initially read too much into that title because I thought the article was advocating the need to start the push for the cloning of people. Instead, author Rafi Letzter was driving at the importance for concrete, ethical discussion right now about stem cell technologies for fertility treatments that may not be too far off.

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These mice were born from artificial eggs that were made from stem cells in a dish.
It’s great news for infertility specialist but carries many ethical dilemmas. 
(Image: K. Hayashi, Kyushu University)

In particular, he alludes to a paper from October (read our blog about it) that reported the creation of female mouse eggs from stem cells. These eggs were fertilized, implanted into the mother and successfully developed into living mice. What’s more, one set of stem cells were derived from mouse skin samples via the induced pluripotent stem cell method. This breakthrough could one day make it possible for an infertile woman to simply go through a small skin biopsy or mouth swab to generate an unlimited number of eggs for in vitro fertilization (IVF). Just imagine how much more efficient, less invasive and less costly this procedure could be compared to current IVF methods that require multiple hormone injections and retrieval of eggs from a woman’s ovaries.

But along with that hope for couples who have trouble conceiving a child comes a whole host of ethical issues. Here, Letzter refers to a perspective letter published on Wednesday in Science Translation Medicine by scientists and ethicists about this looming challenge for researchers and policymakers.

It’s an important read that lays out the current science, the clinical possibilities and regulatory and ethical questions that must be addressed sooner than later. In an interview with Letzter, co-author Eli Adashi, from the Alpert Medical School at Brown University, warned against waiting too long to heed this call to action:

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Eli Adashi

“Let’s start the [ethical] conversation now. Like all conversations it will be time consuming. And depending how well we do it, and we’ve got to do it well, it will be demanding. It will not be wise to have that conversation when you’re seeing a paper in Science or Nature reporting the complete process in a human. That would not be wise on our collective part. We should be as much as possible ready for that.”

 

 

Tackling Frontotemporal dementia and Alzheimer’s by hitting the same target.
To develop new disease therapies, you usually need to understand what is going wrong at a cellular level. In some cases, that approach leads to the identification of a specific protein that is either missing or in short supply. But this initial step is just half the battle because it may not be practical to make a drug out of the protein itself. So researchers instead search for other proteins or small molecules that lead to an increase in the level of the protein.

A CIRM-funded project at the Gladstone Institutes has done just that for the protein called progranulin. People lacking one copy of the progranulin gene carry an increased risk for  frontotemporal dementia (FTD), a degenerative disease of the brain that is the most common cause of dementia in people under 60 years of age. FTD symptoms are often mistaken for Alzheimer’s. In fact, mutations in progranulin are also associated with Alzheimer’s.

Previous studies have shown that increasing levels of progranulin in animals with diseases that mimic FTP and Alzheimer’s symptoms can reverse symptoms. But little was known how progranulin protein levels were regulated in the cells. Amanda Mason, the lead author on the Journal of Biological Chemistry report, explained in a press release how they tackled this challenge:

“We wanted to know what might regulate the levels of progranulin. Many processes in biology are controlled by adding or removing a small chemical group called phosphate, so we started there.”

These phosphate groups hold a lot of energy in their chemical bonds and can be harnessed to activate or turn off the function of proteins and DNA. The team systematically observed the effects of enzymes that add and remove phosphate groups and zeroed in on one called Ripk1 that leads to increases in progranulin levels. Now the team has set their sights on Ripk1 as another potential target for developing a therapeutic that could be effective against both FTP and Alzheimer’s. Steve Finkbeiner, the team lead, gave a big picture perspective on these promising results:

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Steve Finkbeiner

“This is an exciting finding. Alzheimer’s disease was discovered over 100 years ago, and we have essentially no drugs to treat it. To find a possible new way to treat one disease is wonderful. To find a way that might treat two diseases is amazing.”

 

Eye on the prize: two stem cell studies restore vision in blind mice

For the 39 million people in the world who are blind, a vision-restoring therapy would be the ultimate prize. So far, this prize has remained out of reach, but two studies published this week have entered the ring as promising contenders in the fight against blindness.

In the red corner, we have a study published in Stem Cell Reports from the RIKEN Institute in Japan led by scientist Masayo Takahashi. Her team restored vision in blind mice with an advanced stage of retinal disease by transplanting sheets of light-sensing photoreceptor cells that were made from induced pluripotent stem cells (iPSCs).

In the blue corner, we have a study published in Cell Stem Cell from the Buck Institute in California led by scientist Deepak Lamba. His team restored long-term vision in blind mice by transplanting embryonic stem cell-derived photoreceptor cells and preventing the immune system from rejecting the transplant.

Transplanting Retinal sheets

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Synaptic integration of graft retina into model mouse
Credit: RIKEN

Let’s first talk about the Riken study led by Masayo Takahashi. She is well known for her pioneering work on iPSC-derived treatments for macular degeneration – a disease that damages the retina and causes blindness.

In previous work, Takahashi and her team transplanted sheets of mouse stem cell-derived retinal progenitor cells, which mature into light-sensing cells called photoreceptors, into the eyes of mice. The cells within the sheet formed connections with the resident cells in the mouse eye, proving the feasibility of transplanting retinal sheets to restore vision.

In their current study, published in Stem Cell Reports, Takahashi’s team found that the retinal sheets could restore vision in mice that had a very severe form of retinal disease that left them unable to see light. After the mice received the retinal transplants, they responded to light, which they were unable to do previously. Like their other findings, they found that the cells in the transplant made connections with the host cells in the eye including nerve cells that send light-sensing signals to the brain.

First author on the study, Michiko Mandai explained the importance of their findings and their future plans in a news release,

“These results are a proof of concept for using iPSC-derived retinal tissue to treat retinal degeneration. We are planning to proceed to clinical trials in humans after a few more necessary studies using human iPSC-derived retinal tissue in animals. Clinical trials are the only way to determine how many new connections are needed for a person to be able to ‘see’ again.”

While excited by their results, Mandai and the rest of the RIKEN team aren’t claiming the prize for a successful treatment that will cure blindness in people just yet. Mandai commented,

“We cannot expect to restore practical vision at the moment. We will start from seeing a simple light, then possibly move on to larger figures in the next stage.”

Blocking the immune system

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Image showing transplanted GFP-expressing human stem cell derived photoreceptors (green) integrated in a host rodent retina stained for Otx2 (red).
Credit Jie Zhu, Buck Institute for Research on Aging

In the Buck Institute study, Lamba and his team took on the challenge of answering a controversial question about why retinal cell transplants typically don’t survive long-term in the eye. Some scientists think that the transplanted cells die off over time because they don’t integrate into the eye while others think that they are rejected and killed off by the immune system.

To answer this question, Lamba transplanted human embryonic stem cell-derived retinal cells into immunodeficient mice that lacked a protein receptor that’s vital for a functioning immune system. The retinal cells transplanted into immunodeficient mice survived much better than retinal cells transplanted into normal mice and developed into ten times as many photoreceptors that integrated themselves into the host eye.

Their next step was to transplant the retinal cells into mice that were blind and also lacked the same immune receptor as the other mice. After the transplant, the blind mice became responsive to light and showed brain activity associated with sensing light. Their newfound ability to see lasted for nine months to a year following the transplant.

Lamba believes that backing down the immune response is responsible for the long-term vision restoration in the blind mice. He explained the importance of their findings in a Buck Institute news release,

“That finding gives us a lot of hope for patients, that we can create some sort of advantage for these stem cell therapies so it won’t be just a transient response when these cells are put in, but a sustained vision for a long time. Even though the retina is often considered to be ‘immune privileged,’ we have found that we can’t ignore cell rejection when trying to transplant stem cells into the eye.”

In the future, Lamba will explore the potential for using drugs that target the specific protein receptor they blocked earlier to improve the outcome of embryonic stem cell-derived retinal transplants,

“We can also potentially identify other small molecules or recombinant proteins to reduce this interleukin 2 receptor gamma activity in the body – even eye-specific immune responses – that might reduce cell rejection. Of course it is not validated yet, but now that we have a target, that is the future of how we can apply this work to humans.”

Who will be the winner?

The Buck Institute study is interesting because it suggests that embryonic stem cell-based transplants combined with immunosuppression could be a promising strategy to improve vision in patients. But it also begs the question of whether the field should focus instead on iPSC-based therapies where a patient’s own stem cells are used to make the transplanted cells. This strategy would side step the immune response and prevent patients from a taking a lifetime of immunosuppressive drugs.

However, I’m not saying that RIKEN’s iPSC-based strategy is necessarily the way to go for treating blindness (at least not yet). It takes a lot of time and money to make iPSC lines and it’s not feasible given our current output to generate iPSC lines for every blind patient.

So, it sounds like a winner in this fight to cure blindness won’t be announced any time soon. In the meantime, both teams need to conduct further preclinical studies before they can move on to testing these treatments in human clinical trials.

Here at CIRM, we’re funding a promising Phase 1 clinical trial sponsored by jCyte for a form of blindness called Retinis Pigmentosa. Based on preliminary results with a small cohort of patient, the treatment seems safe and may even be showing hints of effectiveness in some patients.

Ultimately, more is better. As the number of stem cell clinical trials for blindness grows, the sooner we can find out which therapies work best for which patients.

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.