Stem cell stories that caught our eye: new CRISPR fix for sickle cell disease, saving saliva stem cells, jumping genes in iPSCs and lung stem cells.

An end run around sickle cell disease with CRISPR
The CRISPR-based gene editing technique has got to be the hottest topic in biomedical research right now. And I sense we’re only at the tip of the iceberg with more applications of the technology popping up almost every week. Just two days ago, researchers at the Dana Farber Cancer Institute in Boston reported in Nature that they had identified a novel approach to correcting sickle cell disease (SCD) with CRISPR.

A mutation in the globlin gene leads to sickled red blood cells that clog up blood vessels

A mutation in the globlin gene leads to sickled red blood cells that clog up blood vessels (image: CIRM video)

Sickle cell anemia is a devastating blood disorder caused by a single, inherited DNA mutation in the adult form of the hemoglobin gene (which is responsible for making blood). A CIRM-funded team at UCLA is getting ready to start testing a therapy in clinical trials that uses a similar but different gene editing tool to correct this mutation. Rather than directly fixing the SCD mutation as the UCLA team is doing, the Dana Farber team focused on a protein called BCL11A. Acting like a molecular switch during development, BCL11A shifts hemoglobin production from a fetal to an adult form. The important point here is that the fetal form of hemoglobin can substitute for the adult form and is unaffected by the SCD mutation.

So using CRISPR gene editing, they deleted a section of DNA from a patient’s blood stem cells that reduced BCL11A and increased production of the fetal hemoglobin. This result suggests the technique can, to pardon the football expression, do an end run around the disease.

But if there’s already a recipe for directly fixing the SCD mutation, why bother with this alternate CRISPR DNA deletion method? In a press release Daniel Bauer, one of the project leaders, explains the rationale:

“It turns out that blood stem cells, the ultimate targets for this kind of therapy, are much more resistant to genetic repair than to genetic disruption.”

Whatever the case, we’re big believers in the need to have several shots on goal to help ensure a victory for patients.

Clinical trial asks: does sparing salivary stem cells protect against severe dry mouth?
I bet you rarely think about or appreciate your saliva. But many head and neck cancer patients who undergo radiation therapy develop severe dry mouth caused by damage to their salivary glands. It doesn’t sound like a big deal, but in reality, the effects of dry mouth are life-changing. A frequent need to drink water disrupts sleep and leads to chronic fatigue. And because saliva is crucial for preventing tooth decay, these patients often lose their teeth. Eating and speaking are also very difficult without saliva, which cause sufferers to retreat from society.

Help may now be on the way. On Wednesday, researchers from University of Groningen in the Netherlands reported in Science Translational Medicine the identification of stem cells in a specific region within the large salivary glands found near each ear. In animal experiments, the team showed that specifically irradiating the area where the salivary stem cells lie shuts down saliva production. And in humans, the amount of radiation to this area is linked to the severity of dry mouth symptoms.

Doctors have confirmed that focusing the radiation therapy beams can minimize exposure to the stem cell-rich regions in the salivary glands. And the research team has begun a double-blind clinical trial to see if this modified radiation treatment helps reduce the number of dry mouth sufferers. They’re looking to complete the trial in two to three years.

Keeping a Lid on Jumping Genes
Believe it or not, you have jumping genes in your cells. The scientific name for them is retrotransposons. They are segments of DNA that can literally change their location within your chromosomes.

While retrotransposons have some important benefits such as creating genetic diversity, the insertion or deletion of DNA sequences can be bad news for a cell. Such events can cause genetic mutations and chromosome instability, which can lead to an increased risk of cancer growth or cell death.

To make its jump, the DNA sequence of a retrotransposon is copied with the help of an intermediary RNA (the green object in the picture below). A special enzyme converts the RNA back into DNA and this new copy of the retrotransposon then gets inserted at a new spot in the cell’s chromosomes.

Retrotransposons: curious pieces of DNA that can be transcribed into RNA, copied into DNA, and inserted to a new spot in your chromosomes.

The duplication and insertion of transposons into our chromosomes can be bad news for a cell

Most of our cells keep this gene jumping activity in check by adding inhibitory chemical tags to the retrotransposon DNA sequence. Still, researchers have observed that in unspecialized cells, like induced pluripotent stem (iPS) cells, these inhibitory chemical tags are reduced significantly.

So you’d think that iPS cells would be prone to the negative consequences of retrotransposon reactivation and unleashed jumping genes. But in a CIRM-funded paper published on Monday in Nature Structural and Molecular Biology, UC Irvine researchers show that despite the absence of those inhibitory chemical tags, the retrotransposon activity is reduced due to the presence of microRNA (miRNA), in this case miRNA-128. This molecule binds and blocks the retrotransposon’s RNA intermediary so no duplicate jumping gene is made.

The team’s hope is that by using miRNA-128 to curb the frequency of gene jumping, they can reduce the potential for mutations and tumor growth in iPS cells, a key safety step for future iPS-based clinical trials.

Great hope for lung stem cells
Chronic lung disease is the third leading cause of death in the U.S. but sadly doctors don’t have many treatment options except for a full lung transplant, which is a very risky procedure with very limited sources of donated organs. For these reasons, there is great interest in better understanding the location and function of lung stem cells. Harnessing the regenerative abilities of these cells may lead to more alternatives for people with end stage lung disease.

In a BioMedicine Development commentary that’s geared for our scientist readers, UCSF researchers summarize the evidence for stem cell population in the lung. We’re proud to say that one of the lead authors, Matt Donne, is a former CIRM Scholar.

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The Ogawa-Yamanaka Prize Crowns Its First Stem Cell Champion

A world of dark

Imagine if you woke up one day and couldn’t see. Your life would change drastically, and you would have to painfully relearn how to function in a world that heavily relies on sight.

A retina of a patient with macular degeneration. (Photo credit: Paul Parker/SPL)

A retina of a patient with macular degeneration. (Photo credit: Paul Parker/SPL)

While most people don’t lose their sight overnight, many suffer from visual impairments that slowly happen over time. Glaucoma, cataracts, and macular degeneration are examples of debilitating eye diseases that eventually lead to blindness.

With almost 300 million people world wide with some form of visual impairment, there’s urgency in the scientific community to develop safe therapies for clinical applications. One of the most promising strategies is using human induced pluripotent stem (iPS) cells derived from patients to generate cell types suitable for transplantation into the human eye.

However, this task is more easily said than done. Safety, regulatory, and economical concerns make the process of translating iPS cell therapies from the bench into the clinic an enormous challenge worthy only of a true scientific champion.

A world of light

Dr. Masayo Takahashi

Dr. Masayo Takahashi

Meet Dr. Masayo Takahashi. She is a faculty member at the RIKEN Centre for Developmental Biology, a prominent female scientist in Japan, and a bona fide stem cell champion. Her mission is to cure diseases of blindness using iPS cell technology.

Since the Nobel Prize-winning discovery of iPS cells by Dr. Shinya Yamanaka eight years ago, Dr. Takahashi has made fast work using this technology to generate specific cells from human iPS cells that can be transplanted into patients to treat an eye disease called macular degeneration. This disease results in the degeneration of the retina, an area in the back of the eye that receives light and translates the information to your brain to produce sight.

Dr. Takahashi generates cells called retinal pigment epithelial (RPE) cells from human iPS cells that can replace lost or dying retinal cells when transplanted into patients with macular degeneration. What makes this therapy so exciting is that Dr. Takahashi’s iPS-derived RPE cells appear to be relatively safe and don’t cause an immune system reaction or cause tumors when transplanted into humans.

Because of the safety of her technology, and the unfulfilled needs of millions of patients with eye diseases, Dr. Takahashi made it her goal to take iPS cells into humans within five years of Dr. Yamanaka’s discovery.

Ogawa-Yamanaka Stem Cell Prize

It’s no surprise that Dr. Takahashi succeeded in her ambitious goal. Her cutting edge work has led to the first clinical trial using iPS cells in humans, specifically treating patients with macular degeneration. In September 2014, the first patient, a 70-year-old Japanese woman, received a transplant of her own iPS-derived RPE cells and no complications were reported.

Currently, the trial is on hold “as part of a safety validation step and in consideration of anticipated regulatory changes to iPS cell research in Japan” according to a Gladstone Institute news release. Nevertheless, this first iPS cell trial in humans has overcome significant regulatory hurdles, has set an important precedent for establishing the safety of stem cell therapies, and has given scientists hope that iPS cell therapies can become a reality.

Dr. Deepak Srivastava presents Dr. Takahashi with the Ogawa-Yamanaka Prize.

Dr. Deepak Srivastava presents Dr. Takahashi with the Ogawa-Yamanaka Prize.

For her accomplishments, Dr. Takahashi was recently awarded the first ever Ogawa-Yamanaka Stem Cell Prize and honored at a special event held at the Gladstone Institutes in San Francisco yesterday. This prize was established by a generous gift from Mr. Hiro Ogawa in collaboration with Dr. Shinya Yamanaka and Dr. Deepak Srivastava at the Gladstone Institutes. The award recognizes scientists who conduct translational iPS cell research that will eventually be applied to patients in the clinic.

In an interview with CIRM, Dr. Deepak Srivastava, the Director of the Gladstone Institute of Cardiovascular Disease and the Roddenberry Center for Stem Cell Biology and Medicine at Gladstone, described the prestigious prize and the ceremony held at the Gladstone to honor Dr. Takahashi:

Dr. Deepak Srivastava

The Ogawa-Yamanaka prize prize is meant to incentivize and honor those whose work is advancing the translational use of stem cells for regenerative medicine. Dr. Masayo Takahashi is a pioneer in pushing the technology of iPS cell-derived cell types and actually introducing them into people. She’s the very first person in the world to successfully overcome all the regulatory barriers and the scientific barriers to introduce this new type of stem cell into a patient. And she’s done so for a condition of blindness called macular degeneration, which affects millions of people world wide, and for which there are very few treatments currently. We are honoring her with this prize for her pioneering efforts at making this technology one that can be applied to patients.

The new world that iPS cells will bring

As part of the ceremony, Dr. Takahashi gave a scientific talk on the new world that iPS cells will bring for patients with diseases that lack cures, including those with visual impairments. The Stem Cellar team was lucky enough to interview Dr. Takahashi as well as attend her lecture during the Gladstone ceremony. We will cover both her talk and her interview with CIRM in an upcoming blog.

The Stem Cellar team at CIRM was excited to attend this momentous occasion, and to know that CIRM-funding has supported many researchers in the field of iPS cell therapy and regenerative medicine. We would like to congratulate Dr. Takahashi on her impressive and impactful accomplishments in this area and look forward to seeing progress in iPS cell trial for macular degeneration.


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Brain Stem Cells in a Dish to the Rescue


Image credit:

The best way to impress your friends at the next party you attend might be to casually mention that scientists can grow miniature brain models in a dish using human stem cells. Sure, that might scare away some people, but when you explain how these tiny brain models can be used to study many different neurological diseases and could help identify new therapies to treat these diseases, your social status could sky rocket.

Recently, a group at UC San Diego used human stem cells to model a rare neurological disorder and identified a drug molecule that might be able to fix it. This work was funded in part by CIRM, and it was published today in the journal Molecular Psychiatry.

The disorder is called MECP2 duplication syndrome. It’s caused by a duplication of the MECP2 gene located in the X chromosome, and is genetically inherited as an X-linked disorder, meaning the disease is much more common in males. Having extra copies of this gene causes a number of unfortunate symptoms including reduced muscle tone (hypotonia), intellectual disabilities, impaired speech, seizures, and developmental delays, to name a few. So far, treatments for this disorder only help ease the symptoms and do not cure the disease.

The group from UCSD decided to model this disease using induced pluripotent stem cells (iPSCs) derived from patients with MECP2 duplication syndrome. iPSCs can form any cell type in the body, and the group used this to their advantage by coaxing the iPSCs into the specific type of nerve cell affected by the disorder. Their hard work was rewarded when they observed that the diseased nerve cells acted differently than normal nerve cells without the disease.

In fact, the diseased nerve cells generated more connections with other nearby nerve cells, and this altered their ability to talk to each other and perform their normal functions. The senior author Alysson Muotri described the difference as an “over-synchronization of the neuronal networks”, meaning that they were more active and tended to fire their signals in unison.

After establishing a relevant nerve cell model of MECP2 duplication disorder, the group tested out a library of drug molecules and identified a new drug candidate that was able to rescue the diseased nerve cells from their “over-synchronized” activity.

The senior author Alysson Muotri commented on the study in a press release:

Alysson Muotri (Photo by David Ahntholz)  

This work is encouraging for several reasons. First, this compound had never before been considered a therapeutic alternative for neurological disorders. Second, the speed in which we were able to do this. With mouse models, this work would likely have taken years and results would not necessarily be useful for humans.


The press release goes on to describe how Muotri and his team plan to push their preclinical studies using human stem-cell based models forward in hopes of entering clinical trials in the near future.


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Study Identifies Safer Stem Cell Therapies

To reject or not reject, that is the question facing the human immune system when new tissue or cells are transplanted into the body.

Stem cell-therapy promises hope for many debilitating diseases that currently have no cures. However, the issue of immune rejection has prompted scientists to carefully consider how to develop safe stem cell therapies that will be tolerated by the human immune system.

Before the dawn of induced pluripotent stem cells (iPSCs), embryonic stem cells (ESCs) were suggested as a potential source for transplantable cells and tissue. However, ESCs run into a couple of issues, including their origin, and the fact that ESC-derived cells likely would be rejected when transplanted into most areas of a human due to differences in genetic backgrounds.

The discovery of iPSCs in the early 2000’s gave new hope to the field of stem cell therapy. By generating donor cells and tissue from a patient’s own iPSCs, transplanting those cells/tissue back into the same individual shouldn’t – at least theoretically – cause an immune reaction. This type of transplantation is called “autologous” meaning that the stem cell-derived cells have the same genetic background as the person.

Unfortunately, scientists have run up against a roadblock in iPSC-derived stem cell therapy. They discovered that even cells derived from a patient’s own iPSCs can cause an immune reaction when transplanted into that patient. The answers as to why this occurs remained largely unanswered until recently.

In a paper published last week in Cell Stem Cell, scientists from the University of California, San Diego (UCSD) reported that different mature cell types derived from human iPSCs have varying immunogenic effects (the ability to cause an immune reaction) when transplanted into “humanized” mice that have a human immune system. This study along with the research conducted to generate the humanized mice was funded by CIRM grants (here, here).

In this study, retinal pigment epithelial cells (RPE) and skeletal muscle cells (SMC) derived from human iPSCs were transplanted into humanized mice. RPEs were tolerated by the immune system while SMCs were rejected. (Adapted from Zhao et al. 2015)

Scientists took normal mice and replaced their immune system with a human one. They then took human iPSCs generated from the same human tissue used to generate the humanized mice and transplanted different cell types derived from the iPSCs cells into these mice.

Because they were introducing cells derived from the same source of human tissue that the mouse’s immune system was derived from, in theory, the mice should not reject the transplant. However, they found that many of the transplants did indeed cause an immune reaction.

Interestingly, they found that certain mature cell types derived from human iPSCs created a substantial immune reaction while other cell types did not. The authors focused on two specific cell types, smooth muscle cells (SMC) and retinal pigment epithelial cells (RPE), to get a closer look at what was going on.

iPSC-derived smooth muscle cells created a large immune response when transplanted into humanized mice. However, when they transplanted iPSC-derived retinal epithelial cells (found in the retina of the eye), they didn’t see the same immune reaction. As a control, they transplanted RPE cells made from human ESCs, and as expected, they saw an immune response to the foreign ESC-derived RPE cells.


iPSC derived RPE cells (green) do not cause an immune reaction (red) after transplantation into humanized mice while H9 embryonic stem cell derived RPE cells do. (Zhao et al. 2015)

When they looked further to determine why the humanized mice rejected the muscle cells but accepted the retinal cells, they found that SMCs had a different gene expression profile and higher expression of immunogenic molecules. The iPSC-derived RPE cells had low expression of these same immunogenic molecules, which is why they were well tolerated in the humanized mice.

Results from this study suggest that some cell types generated from human iPSCs are safer for transplantation than others, an issue which can be addressed by improving the differentiation techniques used to produce mature cells from iPSCs. This study also suggests that iPSC-derived RPE cells could be a safe and promising stem cell therapy for the treatment of eye disorders such as age-related macular degeneration (AMD). AMD is a degenerative eye disease that can cause vision impairment or blindness and usually affects older people over the age of 50. Currently there is no treatment for AMD, a disease that affects approximately 50 million people around the world. (However there is a human iPSC clinical trial for AMD out of the RIKEN Center for Developmental Biology in Japan that has treated one patient but is currently on hold due to safety issues.)

The senior author on this study, Dr. Yang Xu, commented on the importance of this study in relation to AMD in a UCSD press release:

Dr. Yang Xu

Dr. Yang Xu

Immune rejection is a major challenge for stem cell therapy. Our finding of the lack of immune rejection of human iPSC-derived retinal pigment epithelium cells supports the feasibility of using these cells for treating macular degeneration. However, the inflammatory environment associated with macular degeneration could be an additional hurdle to be overcome for the stem cell therapy to be successful.

Xu makes an important point by acknowledging that iPSC-derived RPE cells aren’t a sure bet for curing AMD just yet. More research needs to be done to address other issues that occur during AMD in order for this type of stem cell therapy to be successful.


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Stem cell stories that caught our eye: A groove for healing hearts, model for muscular dystrophy and the ice bucket worked

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.

A tight groove could help heal a heart.  We have written several posts with the theme “It takes a village to raise a stem cell.” If you want a stem cell to mature into a desired tissue you have to pay attention to all aspects of its environment—both the chemicals around it and the physical space.

A team at the Imperial College London has provided the latest chapter to this tale. It turns out if you want stem cells to consistently turn into long fibers of heart muscle, besides providing them with the right chemical signals making them grow in long narrow grooves on lab plate also helps. They got a two-fold increase in heart muscle cells compared to stem cells grown on a flat lab plate.

They’re now trying to figure out why the etched silicon chips worked so well for generating heart muscle. The journal Biomaterials and Regenerative Medicine published the work and the web portal myScience picked up the university’s press release.

Stem cell model for muscular dystrophy. In the past, when scientists have looked at muscle samples from patients with Duchenne muscular dystrophy (DMD) to see why they have the characteristic muscle weakening, they ‘ve arrived at the scene of the crime too late. At that point, the cellular missteps had already occurred and all that is left to observe was the damage.

Healthy muscle cells express dystrophin (green), not cells from DMD patients (middle), but treated stem cells from patients do (right)

Healthy muscle cells express dystrophin (green), not cells from DMD patients (middle), but treated stem cells from patients do (right)

So, a team at Kyoto University reprogrammed a patient’s cells to create iPS type stem cells. They then used genetic cues to direct the stem cells to become muscle and watched to see how what went wrong as this process happened.

“Our model allows us to use the same genetic background to study the early stage of pathogenesis which was not possible in the past,” said first author Emi Shoji.

The research published in Scientific Reports and highlighted in a university press release picked up by MedicalXpress documented the level of inappropriate influx of calcium into the cells and showed that a specific cell surface receptor channel was to blame. That receptor will now become a target for new drug therapy for DMD pateints.

Ice bucket results.  The ALS Association raised $220 million in the past year for amyotrophic lateral sclerosis, or Lou Gehrig’s disease, by getting people to dump bucket of ice water over their heads and then make a donation. More important, in just a year a major paper funded by the proceeds of the ice bucket challenge has shown a defect in the nerves of ALS patients and shown that correcting the defect makes the cells healthier. Those are pretty fast results for science.

In a paper published in the prestigious journal Science a team at Johns Hopkins found that one protein, TDP-43, was not doing its job well. When they genetically modified stem cell from ALS patients to correct that defect the cells worked properly. YahooFinance ran a story about the challenge and the new research.

“If we are able to mimic TDP-43’s function in the human neurons of ALS patients, there’s a good chance that we could slow down progression of the disease!” said Jonathan Ling, a researcher on the team. “And that’s what we’re putting all our efforts into right now.”

Of the initial $115 million raised during the early months of the challenge, 67 percent went to research, 20 percent to patient services, and nine percent to public and professional education. Just four percent went to overhead costs of fund raising.

China says it’s cracking down on clinics. I spend a considerable amount of time suggesting callers to our agency be very cautious about considering spending large sums of money to go overseas to get unregulated and unproven stem cell treatment. So, I was pleased to read this morning’s news that China’s top health authority issued regulation to control some of the most questionable clinics.

The regulations reported in China Daily note that any treatments using stem cells for conditions other than proven uses in blood diseases would be considered experimental and could only be conducted in approved hospitals. It noted conditions touted by clinics there including epilepsy, cerebral palsy, spinal cord injury and autism.

“Only eligible hospitals can perform the practice as a clinical trial for research purpose and it must not be charged or advertised. Anyone caught breaking the rules will be punished according to the new regulation,” said Zhang Linming, a senior official of the science and technology department of the commission.

Stem cell stories that caught our eye: potentially safer cell reprogramming, hair follicle cells become nerve and liver 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.

A potentially safer way to reprogram cells. Ever since then soon-to-be Nobel Prize winner Shinya Yamanaka showed how to reprogram adult cells to an embryonic stem cell-like state labs around the world have jumped on that band wagon. But many of their experiments have not just been using those cells but rather looking for ways to make them more efficiently and possibly safer for clinical use.

The four “Yamanaka factors” traditionally used to make what are now called induced pluripotent stem cells (iPSCs) include genes that can induce cancer. So, folks have been justifiably nervous about using cells derived from iPSCs in patients.

Today in the journal Science two different Chinese teams report slightly different methods of using only chemicals to reprogram skin cells directly into nerves. One team worked at the Shanghai Institutes for Biological Sciences and the other worked at Peking University.

“In comparison with using transgenic reprogramming factors, the small molecules that are used in this chemical approach are cell permeable; cost-effective; and easy to synthesize, preserve, and standardize; and their effects can be reversible,” Hongkui Deng of the Peking team said in a press release used to write a piece in the International Business Times.


Stem cells in hair follicles may repair nerve. The base of our hair follicles contains skin stem cells as you would expect, but it also contains cells with markers suggesting they come from the area of the embryo known as the neural crest. A team at the University of Newcastle in the U.K. tested those cells to see if they have stem cell properties and they do.

They were able to use those cells to create Schwann cells, support cells that our bodies use to repair nerves and help with certain systems like sensation. The team’s Schwann cells interacted with nerve cells in lab dishes the way natural cells do in the body.

“We observed that the bulge, a region within hair follicles, contains skin stem cells that are intermixed with cells derived from the neural crest – a tissue known to give rise to Schwann cells,” said Maya Sieber-Blum, in a university press release picked up by Yahoo. “This observation raised the question whether these neural crest-derived cells are also stem cells and whether they could be used to generate Schwann cells.”

They showed that the cells can indeed become Schwann cells. The researchers now want to see if their cells can repair nerve damage in an animal model.

Prior work at Stanford had turned embryonic stem cells into liver cells.

Prior work at Stanford had turned embryonic stem cells into liver cells.

Drink up. Liver stem cells found. The liver creates new liver cells quite readily, whether damaged by alcohol or other factors. But no one has known exactly where the new cells come from, with most researchers assuming the remaining health cells divide to create new tissue. But a team at Stanford suggested that the liver works too hard for that to be the case. In order to remove all the toxins that come its way adult liver cells have amplified certain chromosomes, and team leader Roel Nusse said that would make them unable to divide and create new cells.

So, his team set out to track down previously elusive liver stem cells. They bred mice that had cells that would have a green florescent glow if they carried a protein usually found only on stem cells. They indeed did find stem cells and tracked them as the animals matured and saw them both divide to create more stem cells and mature into adult liver cells.

“We’ve solved a very old problem,” said Nusse, who is a Howard Hughes investigator. “We’ve shown that like other tissues that need to replace lost cells, the liver has stem cells that both proliferate and give rise to mature cells, even in the absence of injury or disease.”

The Hughes Institute issued a press release and the International Business Times wrote the story and illustrated it with a photo from CIRM’s Flickr site.

Earliest stem cells made in lab; provide “extraordinary” potential

Embryonic stem cells are classified as pluripotent cells because they are able (“potent”) to mature into almost every (“pluri”) cell type. Thanks to Nobel Prize winner Shinya Yamanaka, researchers have been able to reprogram fully matured cells, like skin or blood, into embryonic stem cell-like induced pluripotent stem cells (iPS). The technique has revolutionized stem cell science, providing human models of disease and the prospect of personalized cell therapies.


Human embryo about to complete 1st cell division. Each of these cells are totipotent: they have the ability (“potent”) can give rise to all (“toti”) the cell types of the developing embryo including placenta and umbilical cord. (Image credit: The Endowment for Human Development)

And yet it has remained unknown if reprogramming cells resembling so-called totipotent cells is possible. Unlike iPS or embryonic stem cells, totipotent cells have complete shape-shifting abilities in that they can give rise to all (“toti”) the cell types of the developing embryo including the placenta and umbilical cord. They appear briefly during the earliest stages of development when the fertilized embryo is made up of just one or a few cells. Could lab-derived totipotent cells provide an equally or even more powerful research tool than iPS cells?

The stem cell field is now in position to ask that question. This week scientists from French Institute of Health and Medical Research (INSERM) and the Max Planck Institute in Germany report in Nature Structural Biology that they successfully induced mouse embryonic stem cells to take on totipotent characteristics.


That question mark over the blue arrow can be removed after this week’s report that pluripotent stem cells can be induced to take on characteristics of totipotent cells. (image credit: IGBMC)

To achieve this feat, the scientists started with the known observation that a small amount of totipotent cells spontaneously appear when growing pluripotent stem cells in petri dishes. They are called 2C-like cells because of their likeness to the cells of the two-cell embryo. The team isolated those 2C cells and carefully compared them to the pluripotent embryonic stem cells. They noticed the DNA in 2C cells had a looser structure, which indicates more flexibility to switch on many different genes in a cell. With this information, they found that a protein called CAF1 known to play a role in making a tighter DNA structure, and inhibiting genes, was reduced in the totipotent 2C cells.

By experimentally blocking the function of CAF1 in pluripotent cells, the tightened DNA structure was loosened, leading to more genes being switched on and inducing a totipotent state. With these cells in hand, the team can now examine their possible impact on accelerating progress in regenerative medicine. Maria-Elena Torres-Padilla, the lead scientist on the project, pointed out in a press release the significance of these cells for future studies:

“Totipotency is a much more flexible state than the pluripotent state and its potential applications are extraordinary.”

Mini-Brains Help Unlock Autism’s Secrets

Some diseases like sickle cell anemia, an inherited blood disorder, can be traced to a single known genetic mutation. But other diseases like autism spectrum disorder (ASD), are so varied in their symptoms and severity that pinpointing the underlying cause is extremely complicated. People with autism typically have difficulties communicating with the world around them, unable to fully process both verbal and non-verbal language, and plagued by repetitive behaviors. Some rare forms of autism appear to be inherited but over 80% of cases are idiopathic, a fancy term for “we don’t know what causes it.”

Process for making organoid

Process for making organoid “mini-brains” from iPS cells derived from patient skin samples (image credit: Keval Tilva, wikipedia)

Last week, a research team at the Yale School of Medicine published data in Cell that appears to unveil some of the mystery behind autism. The scientists relied on induced pluripotent stem cells (iPS) derived from skin samples of people with severe forms of ASD. Rather than maturing the stem cells into a flat layer of brain cells, or neurons, on a plastic petri dish, the Yale team stirred the cells in a bioreactor. This technique allows the cells to mature in a small three-dimensional clump, which self organizes into so-called brain “organoids” or “mini-brains.” The structure of these mini-brains resembles the portions of the developing fetal human brain, the stage at which autism is thought to arise.

An analysis of the mini-brains found no underlying genetic mutations. Instead, the team identified genes involved with cell growth and neuron development that were turned on higher in the ASD vs. non-ASD mini-brains. A closer look at cell growth showed that inhibitory neurons, responsible for keeping nerve signals in check, were increased in number in the ASD mini-brains. Teasing out this discovery further pinpointed a protein, called FOXG1, which was responsible for the increased cell growth of the inhibitory neurons.

Fluorescent microscopy images of minibrain organoids derived from ASD patients (right) and unaffected family members (left). The red and green color indicate the increased presence of inhibitory neurons in the ASD minibrain (right). (Image credit: Mariani et al. Cell Volume 162, Issue 2, p375–390.

Fluorescent microscopy images of minibrain organoids derived from ASD patients (right) and unaffected family members (left). The red and green color indicate the increased presence of inhibitory neurons in the ASD minibrain (right). (Image credit: Mariani et al. Cell Volume 162, Issue 2, p375–390, Fig 4I.)

Here’s the interesting part if you’re still with me: of the four patient samples used in this study, higher levels of FOXG1 protein correlated with more severe ASD. And blocking the production of FOXG1 in the ASD mini-brains reduced the inhibitory neurons back to normal levels. Although this initial finding doesn’t directly link FOXG1 and autism, the results suggest a common disease mechanism: that autism may arise by over producing FOXG1 which in turn creates too many inhibitory neurons during brain development and somehow disrupts connections between neurons.

In an interview with The Scientist, CIRM-funded grantee Alysson Muotri of UCSD, who also studies autism using patient derived iPS cells, finds this possible commonality in ASD remarkable:

“These are patients with idiopathic autism that do not share any genetic causes, and yet the authors find phenotypes shared between their cells. That’s impressive. If someone had asked me, I would have said, ‘You won’t find anything in common, it’s probably going to be a mixed bag.’ But no . . . there seems to be key things that are dysregulated in all of them.”

Stem cell stories that caught our eye: fixing defects we got from mom, lung repair and staunching chronic nerve pain

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.

Two ways to clean up mitochondrial defects. Every student gets it drilled into them that we get half our genes from mom and half from dad, but that is not quite right. Mom’s egg contains a few genes outside the nucleus in the so-called powerhouse of the cell, the mitochondria that we inherit only from mom. The 13 little genes in that tiny organelle that are responsible for energy use can wreak havoc when they are mutated. Now, a multi-center team working in Oregon and California has developed two different ways to create stem cells that match the DNA of specific patients in everyway except those defective mitochondrial genes.

The various mitochondrial mutations tend to impact one body system more than others. The end goal for the current research is to turn those stem cells into healthy tissue that can be transplanted into the area most impacted by the disease in a specific patient. That remains some years away, but this is a huge step in providing therapies for this group of diseases.

Currently, we have two ways of making stem cells that match the DNA of a patient, which hopefully result in transplantable cells that can avoid immune rejection. One is to reprogram adult tissue into induced pluripotent (iPS type) stem cells and the other uses the techniques called Somatic Cell Nuclear Transfer (SCNT), often called therapeutic cloning. The current research did both.

The team converted the SCNT stem cells into various needed tissues such as these nerve precursor cells.

The team converted the SCNT stem cells into various needed tissues such as these nerve precursor cells.

The iPS work relied on the fact that our tissues are mosaics because of the way mitochondria get passed on when cells divide. So not all cells show mitochondrial mutations in people with “mito disease” —how impacted families tend to refer to it, as I found out through a distant cousin with a child valiantly struggling with one form of the disease. Because each iPS stem cell line arises from one cell, the researchers could do DNA analysis on each cell line and sort for ones with few or no mutations, resulting in healthy stem cells, which could become healthy transplant tissue.

But for some patients, there are just too many mutations. For those the researchers inserted the DNA from the patient into a healthy donor egg containing healthy mitochondria using SCNT. The result: again healthy stem cells.

“To families with a loved one born with a mitochondrial disease waiting for a cure, today we can say that a cure is on the horizon,” explained co-senior author Shoukhrat Mitalipov at the Oregon Stem Cell Center in a story in Genetic Engineering News. “This critical first step toward treating these diseases using gene therapy will put us on the path to curing them and unlike unmatched tissue or organ donations, combined gene and cell therapy will allow us to create the patients’ own healthy tissue that will not be rejected by their bodies.”

ScienceDaily ran the Oregon press release, HealthCanal ran the press release from the Salk Institute in La Jolla home of the other co-senior author Juan Carlos Izpisua Belmonte, whose lab CIRM funds for other projects. And Reuters predictably did a piece with a bit more focus on the controversy around cloning. Nature published the research paper on Wednesday.

Stem cells to heal damaged lungs. Lung doctors dealing with emphysema, cystic fibrosis and other lung damage may soon take a page from the playbook of cancer doctors who transplant bone marrow stem cells. A team at Israel’s Weizmann Institute has tested a similar procedure in mice with damaged lungs and saw improved lung function

Transplanted lung cells continued to grow at six weeks (left) and 16 weeks (right).

Transplanted lung cells continued to grow at six weeks (left) and 16 weeks (right).

Stem cells are homebodies. They tend to hang out in their own special compartments we call the stem cell niche, and if infused elsewhere in the body will return home to the niche. Bone marrow transplants make use of that tendency in two ways. Doctors wipe out the stem cells in the niche so that there is room there when stem cells previously harvested from the patient or donor cells are infused after therapy.

The Weizmann team did this in the lungs by developing a method to clear out the lung stem cell niche and isolating a source of stem cells capable of generating new lung tissue that could be infused. They now need to perfect both parts of the procedure. ScienceDaily ran the institute’s press release.

Stem cells for chronic pain due to nerve damage. Neuropathy, damaged nerves caused by diabetes, chemotherapy or injury tends to cause pain that resists treatment. A team at Duke University in North Carolina has shown that while a routine pain pill might provide relief for a few hours, a single injection of stem cells provided relief for four to five weeks—in mice.

They used a type of stem cell found in bone marrow known to have anti-inflammatory properties called Bone Marrow Stromal Cells (BMSCs). They infused the cells directly into the spinal cavity in mice that had induced nerve damage. They found that one chemical released by the stem cells, TGF Beta1, was present in the spinal fluid of the treated animals at higher than normal levels. This finding becomes a target for further research to engineer the BMSCs so that they might be even better at relieving pain. ScienceNewsline picked up the Duke press release about the research published in the Journal of Clinical Investigation.

Giving stem cells the right physical cues produced micro hearts, maybe a tool to avoid birth defects

Heart defects, one of the leading types of birth defects, often result from drugs mom is taking, but we have not had a good model of developing fetal hearts to test drugs for these side effects. Now, a team at the University of California, Berkeley and the Gladstone Institutes has created micro heart chambers in a lab dish by providing the starting stem cells with the right physical cues. And they found these mini-hearts can predict birth defects.

Different types of cells required to make functioning heart tissue show up as different colors here.

Different types of cells required to make functioning heart tissue show up as different colors here.

As we have written before, it takes a neighborhood to raise a stem cell into a wanted adult cell. While most lab cultures maturing stem cells into adult tissue are flat, the developing fetal heart grows in an environment with many physical cues, both chemical and pressure. The Berkeley team added a chemical layer to the cell culture dish and etched it to provide added physical cues. The result produced both connective tissue and heart muscle that were organized into micro heart chambers that could beat.

“We believe it is the first example illustrating the process of a developing human heart chamber in vitro,” said Kevin Healy, co-senior author of the study at UC Berkeley. “This technology could help us quickly screen for drugs likely to generate cardiac birth defects, and guide decisions about which drugs are dangerous during pregnancy.”

The team took the added step of testing a drug known to cause birth defects, thalidomide. When the stem cells were growing with the drug added to the culture, they did not develop into the same micro chambers.

The Berkeley bioengineers started with stem cells reprogrammed from adult skin tissue in the CIRM-funded lab of Bruce Conklin at the Gladstone, the other co-senior author on the paper. These iPS-type stem cells were essential to the project.

“The fact that we used patient-derived human pluripotent stem cells in our work represents a sea change in the field,” said Healy. “Previous studies of cardiac micro-tissues primarily used harvested rat cardiomyocytes, which is an imperfect model for human disease.”


Berkeley issued a press release on the work and Popular Science wrote a piece on it complete with a fun embedded video of the beating tissue. The journal Nature Communication ran the original research publication today.