From Rutgers University: “Targeting Key Gene Could Help Lead to Down Syndrome Treatment”

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From Rutgers University

May 22, 2019

Todd Bates
848-932-0550
todd.bates@rutgers.edu

Rutgers-led team uses stem cell-based disease models to pinpoint gene linked to impaired memory in Down syndrome.

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A living 3D “organoid” model of the brain generated from Down syndrome human stem cells. Photo: Ranjie Xu/Rutgers University-New Brunswick.

Targeting a key gene before birth could someday help lead to a treatment for Down syndrome by reversing abnormal embryonic brain development and improving cognitive function after birth, according to a Rutgers-led study.

Using stem cells that can turn into other cells in the brain, researchers developed two experimental models – a living 3D “organoid” model of the brain and a mouse brain model with implanted human cells – to investigate early brain development linked to Down syndrome, according to the study in the journal Cell Stem Cell. The study focused on human chromosome 21 gene OLIG2.

“Our results suggest the OLIG2 gene is potentially an excellent prenatal therapeutic target to reverse abnormal embryonic brain development, rebalance the two types of neurons in the brain – excitatory and inhibitory, and a healthy balance is critical – as well as improve postnatal cognitive function,” said Peng Jiang, assistant professor in the Department of Cell Biology and Neuroscience at Rutgers University–New Brunswick.

Usually, a baby is born with 46 chromosomes, but babies with Down syndrome have an extra copy of chromosome 21. That changes how a baby’s body and brain develops, which can lead to mental and physical challenges, according to the U.S. Centers for Disease Control and Prevention. Down syndrome is the most common chromosomal condition diagnosed in the United States, affecting about one in 700 babies, and about 6,000 infants are born each year with the condition.

The researchers obtained skin cells collected from Down syndrome patients and genetically reprogrammed those cells to human-induced pluripotent stem cells (hiPSCs). Resembling embryonic stem cells, the special cells can develop into many different types of cells, including brain cells, during early life and growth and are useful tools for drug development and disease modeling, according to the National Institutes of Health.

Using brain cells derived from stem cells with an extra copy of chromosome 21, the scientists developed the 3D brain organoid model, which resembles the early developing human brain. They also developed the mouse brain model, with stem cell-derived human brain cells implanted into the mouse brain within a day after the mice were born. They found that inhibitory neurons – which make your brain function smoothly – were overproduced in both models, and adult mice had impaired memory. They also found that the OLIG2 gene plays a critical role in those effects and that inhibiting it led to improvements.

The combination of the brain organoid and mouse brain model could be used to study other neurodevelopmental disorders such as autism spectrum disorder. It may also help scientists better understand the mechanisms in Alzheimer’s disease. Down syndrome patients often develop early-onset Alzheimer’s disease, Jiang noted.

The study’s lead author is Ranjie Xu, a postdoctoral researcher in Jiang’s lab. Other Rutgers co-authors include Hyosung Kim, a former post-doc in Jiang’s lab; Ronald P. Hart, a professor in the Department of Cell Biology and Neuroscience at Rutgers–New Brunswick; Zhiping P. Pang, an associate professor in the Department of Neuroscience and Cell Biology at Rutgers Robert Wood Johnson Medical School, and Jing-Jing Liu, a former post-doc in Pang’s lab. Scientists at the University of Texas Health Science Center, Kent State University, and University of Nebraska Medical Center contributed to the study.

See the full article here .


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Rutgers, The State University of New Jersey, is a leading national research university and the state’s preeminent, comprehensive public institution of higher education. Rutgers is dedicated to teaching that meets the highest standards of excellence; to conducting research that breaks new ground; and to providing services, solutions, and clinical care that help individuals and the local, national, and global communities where they live.

Founded in 1766, Rutgers teaches across the full educational spectrum: preschool to precollege; undergraduate to graduate; postdoctoral fellowships to residencies; and continuing education for professional and personal advancement.

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From Rutgers University: “Rutgers Researchers Discover Crucial Link Between Brain and Gut Stem Cells”

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From Rutgers University

April 15, 2019

Patti Verbanas
848-932-0551
patti.verbanas@rutgers.edu

Study paves the way for better detection and treatment of neurodegenerative diseases and colorectal cancers.

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Their findings show that the insulin-like growth factor II gene is essential for multiple types of adult stem cells that are critical for cognitive function and renewing the lining of the small intestine in adults.

The organs in our bodies house stem cells that are necessary to regenerate cells when they become damaged, diseased or too old to function. Researchers at Rutgers University have identified a new factor that is essential for maintaining the stem cells in the brain and gut and whose loss may contribute to anxiety and cognitive disorders and to gastrointestinal diseases.

The study, published in the journal Stem Cell Reports, reveals the importance of the insulin-like growth factor II gene in adult stem cell maintenance in these two organs. The gene provides key support for the existence of two, functionally distinct sets of stem cells in the intestine, whose unregulated self-renewal and proliferation may contribute to colorectal cancers.

“The role that the insulin-like growth factor II gene plays in adult stem cells has been largely unknown. This growth factor was previously regarded as dispensable in adults,” said co-author Steven Levison, director of the Laboratory for Regenerative Neurobiology at Rutgers New Jersey Medical School. “The discovery that there is a factor — this gene product — that is common between more than one adult stem cell population is remarkable.”

The findings indicate that this growth factor is essential for multiple types of adult stem cells, including those critical for cognitive function, sense of smell and for renewing the lining of the small intestine in adults.

In the study, the researchers removed the gene from adult mice either rapidly over five days or more slowly over 15 days. In the intestine, the fast deletion of the gene led to a rapid loss of fast-cycling stem cells that replenish the gut lining, leading to dramatic weight loss and death within a week. A slower deletion of the gene allowed the mice to survive due to the recruitment of a second, and more inactive, population of gut stem cells, whose existence has been debated. Additionally, the study revealed that half of the stem cells in two regions of the brain that house neural stem cells were lost, causing deficits in learning and memory, increased anxiety and a loss of the sense of smell.

“When the gene was removed acutely, the stem cells in glands in the inner surface of the small intestine could not continue their normal cycle of continued cell replacement, causing organ failure,” said co-author Teresa Wood, a professor at Rutgers New Jersey Medical School. “However, when the gene was deleted slowly, it gave the other stem cells an opportunity to take over for the lost stem cells.”

Other Rutgers co-authors were Qiang Feng, Shravanthi Chidambaram, Jaimie M. Testai, Ekta Kumari, Deborah E. Rothbard, Tara Cominski, Kevin Pang and Nan Gao. The intestinal studies were performed in Gao’s lab at Rutgers University–Newark.

See the full article here .


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Rutgers, The State University of New Jersey, is a leading national research university and the state’s preeminent, comprehensive public institution of higher education. Rutgers is dedicated to teaching that meets the highest standards of excellence; to conducting research that breaks new ground; and to providing services, solutions, and clinical care that help individuals and the local, national, and global communities where they live.

Founded in 1766, Rutgers teaches across the full educational spectrum: preschool to precollege; undergraduate to graduate; postdoctoral fellowships to residencies; and continuing education for professional and personal advancement.

As a ’67 graduate of University college, second in my class, I am proud to be a member of

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From UCLA Newsroom: “UCLA scientists make cells that enable the sense of touch”


UCLA Newsroom

January 11, 2018
Sarah C.P. Williams

Researchers are the first to create sensory interneurons from stem cells.

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Human embryonic stem cell-derived neurons (green) showing nuclei in blue. Left: with retinoic acid added. Right: with retinoic acid and BMP4 added, creating proprioceptive sensory interneurons (pink). UCLA Broad Stem Cell Research Center/Stem Cell Reports.

Researchers at the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA have, for the first time, coaxed human stem cells to become sensory interneurons — the cells that give us our sense of touch. The new protocol could be a step toward stem cell–based therapies to restore sensation in paralyzed people who have lost feeling in parts of their body.

The study, which was led by Samantha Butler, a UCLA associate professor of neurobiology and member of the Broad Stem Cell Research Center, was published today in the journal Stem Cell Reports.

Sensory interneurons, a class of neurons in the spinal cord, are responsible for relaying information from throughout the body to the central nervous system, which enables the sense of touch. The lack of a sense of touch greatly affects people who are paralyzed. For example, they often cannot feel the touch of another person, and the inability to feel pain leaves them susceptible to burns from inadvertent contact with a hot surface.

“The field has for a long time focused on making people walk again,” said Butler, the study’s senior author. “‘Making people feel again doesn’t have quite the same ring. But to walk, you need to be able to feel and to sense your body in space; the two processes really go hand in glove.”

In a separate study, published in September by the journal eLife, Butler and her colleagues discovered how signals from a family of proteins called bone morphogenetic proteins, or BMPs, influence the development of sensory interneurons in chicken embryos. The Stem Cell Reports research applies those findings to human stem cells in the lab.

When the researchers added a specific bone morphogenetic protein called BMP4, as well as another signaling molecule called retinoic acid, to human embryonic stem cells, they got a mixture of two types of sensory interneurons. DI1 sensory interneurons give people proprioception — a sense of where their body is in space — and dI3 sensory interneurons enable them to feel a sense of pressure.

The researchers found the identical mixture of sensory interneurons developed when they added the same signaling molecules to induced pluripotent stem cells, which are produced by reprogramming a patient’s own mature cells such as skin cells. This reprogramming method creates stem cells that can create any cell type while also maintaining the genetic code of the person they originated from. The ability to create sensory interneurons with a patient’s own reprogrammed cells holds significant potential for the creation of a cell-based treatment that restores the sense of touch without immune suppression.

Butler hopes to be able to create one type of interneuron at a time, which would make it easier to define the separate roles of each cell type and allow scientists to start the process of using these cells in clinical applications for people who are paralyzed. However, her research group has not yet identified how to make stem cells yield entirely dI1 or entirely dI3 cells — perhaps because another signaling pathway is involved, she said.

The researchers also have yet to determine the specific recipe of growth factors that would coax stem cells to create other types of sensory interneurons.

The group is currently implanting the new dI1 and dI3 sensory interneurons into the spinal cords of mice to understand whether the cells integrate into the nervous system and become fully functional. This is a critical step toward defining the clinical potential of the cells.

“This is a long path,” Butler said. “We haven’t solved how to restore touch but we’ve made a major first step by working out some of these protocols to create sensory interneurons.”

The research was supported by grants from the California Institute for Regenerative Medicine and its Cal State Northridge–UCLA Bridges to Stem Cell Research program, the National Institutes of Health and the UCLA Broad Stem Cell Research Center.

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This can-do perspective has brought us 12 Nobel Prizes, 12 Rhodes Scholarships, more NCAA titles than any university and more Olympic medals than most nations. Our faculty and alumni helped create the Internet and pioneered reverse osmosis. And more than 100 companies have been created based on technology developed at UCLA.

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From Stanford University – Engineering: “An advance in stem-cell development could help lead to new therapies”

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Stanford University – Engineering

November 02, 2017
Andrew Myers

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Stem cells hold the promise of being able to cure ills ranging from spinal cord injuries to cancers. | Image by: luismmolina/Getty Images

In many ways, stem cells are the divas of the biological world. On the one hand, these natural shapeshifters can transform themselves into virtually any type of cell in the body. In that regard, they hold the promise of being able to cure ills ranging from spinal cord injuries to cancers.

On the other hand, said associate professor of materials science and engineering Sarah Heilshorn, stem cells, like divas, are also mercurial and difficult to work with.

“We just don’t know how to efficiently and effectively grow massive numbers of stem cells and keep them in their regenerative state,” Heilshorn said. “This has prevented us from making more progress in creating therapies.”

Until now, that is. In a recent paper in Nature Materials, Heilshorn described a solution to the dual challenges of growing and preserving neural stem cells in a state where they are still able to mature into many different cell types. The first challenge is that growing stem cells in quantity requires space. Like traditional farming, it is a two-dimensional affair. If you want more wheat, corn or stem cells, you need more surface area. Culturing stem cells, therefore, requires a lot of relatively expensive laboratory real estate, not to mention the energy and nutrients necessary to pull it all off.

The second challenge is that once they’ve divided many times in a lab dish, stem cells do not easily remain in the ideal state of readiness to become other types of cells. Researchers refer to this quality as “stemness.” Heilshorn found that for the neural stem cells she was working with, maintaining the cells’ stemness requires the cells to be touching.

Heilshorn’s team was working with a particular type of stem cell that matures into neurons and other cells of the nervous system. These types of cells, if produced in sufficient quantities, could generate therapies to repair spinal cord injuries, counteract traumatic brain injury or cure some of the most severe degenerative disorders of the nervous system, like Parkinson’s and Huntington’s diseases.

Seeking stemness

Heilshorn’s solution involves the use of better materials in which to grow stem cells. Her lab has developed new polymer-based gels that allow the cells to be grown in three dimensions instead of two. This new 3-D process takes up less than 1 percent of the lab space required by current stem cell culturing techniques. And because cells are so tiny, the 3-D gel stack is just a single millimeter tall, roughly the thickness of a dime.

“For a 3-D culture, we need only a 4-inch-by-4-inch plot of lab space, or about 16 square inches. A 2-D culture requires a plot four feet by four feet, or about 16 square feet,” more than 100-times the space, according to first author Chris Madl, a recent doctoral graduate in bioengineering from Heilshorn’s lab

In addition to the dramatic savings of lab space, the new process demands fewer nutrients and less energy, as well.

The gels the team developed allow the stem cells to remodel the long molecules and maintain physical contact with one another to preserve critical communication channels between cells. “The simple act of touching is key to communication between stem cells and to maintaining stemness. If stem cells can’t remodel the gels, they can’t touch one another,” Madl explained.

“The stem cells don’t exactly die if they can’t touch, but they lose that ability to regenerate that we really need for therapeutic success,” Heilshorn added.

Striking results

This need for neural stem cell to remodel their environment differs from what Heilshorn has found in working with other types of stem cells. For those cells, it is the stiffness of the gels – not the ability to remodel – that is the key factor in maintaining stemness. It is as if for these other types of stem cells, gels must mimic the rigidity of the tissue in which the cells will eventually be transplanted. Not so with neural progenitors, said Heilshorn.

“Neural cell stemness is not sensitive to stiffness and that was a big surprise to us,” she said.

The result was so striking and unexpected that Heilshorn, at first, didn’t believe her own results. The lab ended up testing three entirely different gels to see if their conclusion held, an unusual supplementary step in this kind of research. With each new material, they saw that those that could be remodeled produced quality stem cells; those that could not be remodeled had a negative effect on stemness.

Next up on Heilshorn’s research agenda is to create gels that can be injected directly from the lab dish into the body. The possibilities have her feeling optimistic about stem cell therapies again. For a time, she said, it felt as if the field had hit a wall, as initial excitement for regeneration gave way to uninspiring results in the clinic. With her new finding, she said, it feels like new things may be just around the corner.

“There’s this convergence of biological knowledge and engineering principles in stem cell research that has me hopeful we might finally actually solve some big problems,” she said.

See the full article here .

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From UC Davis: “Neural Stem Cells Steered by Electric Fields in Rat Brain”

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UC Davis

July 11, 2017
Andy Fell
ahfell@ucdavis.edu

Min Zhao
minzhao@ucdavis.edu

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Transplants of neural stem cells might be used to treat brain injuries, but how to get them to the right location? UC Davis researcher Min Zhao and Junfeng Feng, a neurosurgeon at Ren Ji Hospital, Shanghai, showed that they can steer transplanted stem cells (green, in inset on right) to one part of a rat’s brain using electrical fields. (Image: Junfeng Feng)

Electric fields can be used to guide neural stem cells transplanted into the brain toward a specific location. The research, published July 11 in the journal Stem Cell Reports, opens possibilities for effectively guiding stem cells to repair brain damage.

Professor Min Zhao at the University of California, Davis, School of Medicine’s Institute for Regenerative Cures studies how electric fields can guide wound healing. Damaged tissues generate weak electric fields, and Zhao’s research has shown how these electric fields can attract cells into wounds to heal them.

“One unmet need in regenerative medicine is how to effectively and safely mobilize and guide stem cells to migrate to lesion sites for repair,” Zhao said. “Inefficient migration of those cells to lesions is a significant roadblock to developing effective clinical applications.”

Junfeng Feng, a neurosurgeon at Ren Ji Hospital, Shanghai Jiao Tong University and Shanghai Institute of Head Trauma, visited Zhao’s lab to study how electric fields might guide stem cells implanted in the brain.

Natural neural stem cells — cells that can develop into other brain tissues — are found deep in the brain, in the subventricular zone and hippocampus. To repair damage to the outer layers of the brain (the cortex), they have to migrate some distance, especially in the large human brain. Transplanted stem cells might also have to migrate some way to find an area of damage.

Stem cells move ‘upstream’

Feng and Zhao developed a model of stem cell transplants in rats. They placed human neural stem cells in the rostral migration stream — a pathway in the rat brain that carries cells toward the olfactory bulb, which governs the animal’s sense of smell. Cells move along this pathway partly carried by the flow of cerebrospinal fluid and partly guided by chemical signals.

By applying an electric field within the rat’s brain, they found that they could get the transplanted stem cells to swim “upstream” against the fluid flow and natural cues and head for other locations within the brain.

The transplanted stem cells were still in their new locations weeks or months after treatment.

“Electrical mobilization and guidance of stem cells in the brain therefore provides a potential approach to facilitate stem cell therapies for brain diseases, stroke and injuries,” Zhao said.

Additional authors on the paper are: at UC Davis, Lei Zhang, Jing Liu, Bruce Lyeth and Jan Nolta; Ji-Yao Jiang, Ren Ji Hospital, Shanghai Jiao Tong University and Shanghai Institute of Head Trauma; and Michael Russell, Aaken Laboratories, Davis. The work was supported by the California Institute for Regenerative Medicine with additional support from NIH, NSF and Research to Prevent Blindness Inc.

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From HUJI: “First ‘haploid’ human stem cells could change the face of medical research; earn Kaye Innovation Award”

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Doctoral student and Kaye Innovation Award winner Ido Sagi at the Hebrew University of Jerusalem (Credit: Hebrew University)

28/06/2017

Potential for regenerative medicine and cancer research earns doctoral student Ido Sagi a Kaye Innovation Award

Stem cell research holds huge potential for medicine and human health. In particular, human embryonic stem cells (ESCs), with their ability to turn into any cell in the human body, are essential to the future prevention and treatment of disease.

One set or two? Diploid versus haploid cells

Most of the cells in our body are diploid, which means they carry two sets of chromosomes — one from each parent. Until now, scientists have only succeeded in creating haploid embryonic stem cells — which contain a single set of chromosomes — in non-human mammals such as mice, rats and monkeys. However, scientists have long sought to isolate and replicate these haploid ESCs in humans, which would allow them to work with one set of human chromosomes as opposed to a mixture from both parents.

This milestone was finally reached when Ido Sagi, working as a PhD student at the Hebrew University of Jerusalem’s Azrieli Center for Stem Cells and Genetic Research, led research that yielded the first successful isolation and maintenance of haploid embryonic stem cells in humans. Unlike in mice, these haploid stem cells were able to differentiate into many other cell types, such as brain, heart and pancreas, while retaining a single set of chromosomes.

With Prof. Nissim Benvenisty, Director of the Azrieli Center, Sagi showed that this new human stem cell type will play an important role in human genetic and medical research. It will aid our understanding of human development – for example, why we reproduce sexually instead of from a single parent. It will make genetic screening easier and more precise, by allowing the examination of single sets of chromosomes. And it is already enabling the study of resistance to chemotherapy drugs, with implications for cancer therapy.

Diagnostic kits for personalized medicine

Based on this research, Yissum, the Technology Transfer arm of the Hebrew University, launched the company New Stem, which is developing a diagnostic kit for predicting resistance to chemotherapy treatments. By amassing a broad library of human pluripotent stem cells with different mutations and genetic makeups, NewStem plans to develop diagnostic kits for personalized medication and future therapeutic and reproductive products.

2017 Kaye innovation Award

In recognition of his work, Ido Sagi was awarded the Kaye Innovation Award for 2017.

The Kaye Innovation Awards at the Hebrew University of Jerusalem have been awarded annually since 1994. Isaac Kaye of England, a prominent industrialist in the pharmaceutical industry, established the awards to encourage faculty, staff and students of the Hebrew University to develop innovative methods and inventions with good commercial potential, which will benefit the university and society.

Ido Sagi received BSc summa cum laude in Life Sciences from the Hebrew University, and currently pursues a PhD at the laboratory of Prof. Nissim Benvenisty at the university’s Department of Genetics in the Alexander Silberman Institute of Life Sciences. He is a fellow of the Adams Fellowship of the Israel Academy of Sciences and Humanities, and has recently received the Rappaport Prize for Excellence in Biomedical Research. Sagi’s research focuses on studying genetic and epigenetic phenomena in human pluripotent stem cells, and his work has been published in leading scientific journals, including Nature, Nature Genetics and Cell Stem Cell.

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The Hebrew University of Jerusalem, founded in 1918 and opened officially in 1925, is Israel’s premier university as well as its leading research institution. The Hebrew University is ranked internationally among the 100 leading universities in the world and first among Israeli universities.

The recognition the Hebrew University has attained confirms its reputation for excellence and its leading role in the scientific community. It stresses excellence and offers a wide array of study opportunities in the humanities, social sciences, exact sciences and medicine. The university encourages multi-disciplinary activities in Israel and overseas and serves as a bridge between academic research and its social and industrial applications.

The Hebrew University has set as its goals the training of public, scientific, educational and professional leadership; the preservation of and research into Jewish, cultural, spiritual and intellectual traditions; and the expansion of the boundaries of knowledge for the benefit of all humanity.

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From HMS: “Staving Off Stem Cell Cancer Risk”

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Harvard University

Harvard Medical School

Harvard Medical School

April 26, 2017 [Never saw this one.]
HANNAH ROBBINS

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Image: BlackJack3D/Getty Images

Regenerative medicine using human pluripotent stem cells to grow transplantable tissue outside the body carries the promise to treat a range of intractable disorders, such as diabetes and Parkinson’s disease.

As stem cell lines grow in a lab dish, however, they often acquire mutations in the TP53 (p53) gene, an important tumor suppressor responsible for controlling cell growth and division, according to new research from a team at Harvard Medical School, the Harvard Stem Cell Institute and the Stanley Center for Psychiatric Research at the Broad Institute of MIT and Harvard.

The findings suggest that genetic sequencing technologies should be used to screen stem cell cultures so that those with mutated cells can be excluded from scientific experiments and clinical therapies. If such methods are not employed, the researchers said, it could lead to an elevated cancer risk in patients receiving transplants.

The paper, published online in the journal Nature on April 26, comes at just the right time, the researchers said, as experimental treatments using human pluripotent stem cells are ramping up across the country.

“Our results underscore the need for the field of regenerative medicine to proceed with care,” said the study’s co-corresponding author, Kevin Eggan, a principal faculty member at HSCI and director of stem cell biology at the Stanley Center.

The team said that the new research should not discourage the pursuit of experimental treatments, but instead should be heeded as a call to rigorously screen all cell lines for mutations at various stages of development as well as immediately before transplantation.

“Fortunately,” said Eggan, this additional series of genetic quality-control checks “can be readily performed with precise, sensitive and increasingly inexpensive sequencing methods.”

Hidden mutations

Researchers can use human stem cells to recreate human tissue in the lab. Eggan’s lab in Harvard University’s Department of Stem Cell and Regenerative Biology uses human stem cells to study the mechanisms of brain disorders, including amyotrophic lateral sclerosis, intellectual disability and schizophrenia.

Eggan has also been working with Steve McCarroll, associate professor of genetics at HMS and director of genetics at the Stanley Center, to study how genes shape the biology of neurons, which can be derived from human stem cells.

McCarroll’s lab recently discovered a common precancerous condition in which a blood stem cell in the body acquires a so-called pro-growth mutation and then outcompetes a person’s normal stem cells, becoming the dominant generator of that person’s blood cells. People with this condition are 12 times more likely to develop blood cancer later in life.

The current study’s lead authors, Florian Merkle and Sulagna Ghosh, collaborated with Eggan and McCarroll to test whether laboratory-grown stem cells might be vulnerable to an analogous process.

“Cells in the lab, like cells in the body, acquire mutations all the time,” said McCarroll, co-corresponding author of the study. “Mutations in most genes have little impact on the larger tissue or cell line. But cells with a pro-growth mutation can outcompete other cells, become very numerous and ‘take over’ a tissue.”

“We found that this process of clonal selection—the basis of cancer formation in the body—is also routinely happening in laboratories.”

A p53 problem

To find acquired mutations, the researchers performed genetic analyses on 140 stem cell lines. Twenty-six lines had been developed for therapeutic purposes using Good Manufacturing Practices, a quality control standard set by regulatory agencies in multiple countries. The remaining 114 were listed on the NIH registry of human pluripotent stem cells.

“While we expected to find some mutations, we were surprised to find that about 5 percent of the stem cell lines we analyzed had acquired mutations in a tumor-suppressing gene called p53,” said Merkle.

Nicknamed the “guardian of the genome,” p53 controls cell growth and cell death. People who inherit p53 mutations develop a rare disorder called Li-Fraumeni syndrome, which confers a near 100 percent risk of developing cancer in a wide range of tissue types.

The specific mutations that the researchers observed are dominant negative mutations, meaning that when present on even one copy of p53, they compromise the function of the normal protein. The same dominant negative mutations are among the most commonly observed mutations in human cancers.

“They are among the worst p53 mutations to have,” said co-lead author Ghosh.

The researchers performed a sophisticated set of DNA analyses to rule out the possibility that these mutations had been inherited rather than acquired as the cells grew in the lab.

Ensuring safety

In subsequent experiments, the scientists found that p53 mutant cells outperformed and outcompeted nonmutant cells in the lab dish. In other words, a culture with a million healthy cells and one p53 mutant cell, said Eggan, could quickly become a culture of only mutant cells.

“The spectrum of tissues at risk for transformation when harboring a p53 mutation includes many of those that we would like to target for repair with regenerative medicine using human pluripotent stem cells,” said Eggan.

Those organs include the pancreas, brain, blood, bone, skin, liver and lungs.

However, Eggan and McCarroll emphasized that now that this phenomenon has been found, inexpensive gene-sequencing tests will allow researchers to identify and remove from the production line cell cultures with concerning mutations that might prove dangerous after transplantation.

The researchers point out in their paper that screening approaches already exist to identify these p53 mutations and others that confer cancer risk. Such techniques are being used in cancer diagnostics.

In fact, an ongoing clinical trial that is transplanting cells derived from induced pluripotent stem cells (iPSCs) is using gene sequencing to ensure the transplanted cell products are free of dangerous mutations.

This work was supported by the Harvard Stem Cell Institute, the Stanley Center for Psychiatric Research, the Rosetrees Trust, the Azrieli Foundation, the Howard Hughes Medical Institute, the Wellcome Trust, the Medical Research Council, the Academy of Medical Sciences and grants from the National Institutes of Health (HL109525, 5P01GM099117, 5K99NS08371, HG006855, MH105641).

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Established in 1782, Harvard Medical School began with a handful of students and a faculty of three. The first classes were held in Harvard Hall in Cambridge, long before the school’s iconic quadrangle was built in Boston. With each passing decade, the school’s faculty and trainees amassed knowledge and influence, shaping medicine in the United States and beyond. Some community members—and their accomplishments—have assumed the status of legend. We invite you to access the following resources to explore Harvard Medical School’s rich history.

Harvard University campus

Harvard is the oldest institution of higher education in the United States, established in 1636 by vote of the Great and General Court of the Massachusetts Bay Colony. It was named after the College’s first benefactor, the young minister John Harvard of Charlestown, who upon his death in 1638 left his library and half his estate to the institution. A statue of John Harvard stands today in front of University Hall in Harvard Yard, and is perhaps the University’s best known landmark.

Harvard University has 12 degree-granting Schools in addition to the Radcliffe Institute for Advanced Study. The University has grown from nine students with a single master to an enrollment of more than 20,000 degree candidates including undergraduate, graduate, and professional students. There are more than 360,000 living alumni in the U.S. and over 190 other countries.

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