But what really excites Zon, director of the Stem Cell research program at Boston Children’s Hospital, is the power of the chemical screening platform he and his colleagues used. Described last week in the journal Cell, it found a cocktail of three compounds that induced human muscle cells to grow—in just a matter of weeks. Zon believes it could fast-track drug discovery for multiple disorders. Full story »
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Researchers have struggled to find the right approach to regeneration. Cell transplants have been tried, but the cells don’t engraft well long term and haven’t shown efficacy. Gene therapy to spur regeneration has been tested in animals, but dosage is hard to control and there’s a risk of genes going where they shouldn’t, causing tumors and other problems. Protein drugs have been tried, but they have short half-lives, being degraded or eliminated by the body before they can do much good. They are also hard to target to the heart.
A more recent approach to cardiac regeneration is to stimulate the body itself—and, specifically, progenitor cells— to repair the heart from within. Full story »
In 2006, Shinya Yamanaka, MD, PhD, discovered a way to reprogram mature skin cells back to a stem cell state so they can be converted into any cell type a scientist is interested in studying. That work earned him last year’s Nobel Prize in Physiology or Medicine.
Yamanaka’s discovery raised the tantalizing question of whether similar reprogramming ever occurs in nature. In fact, it does, discovered David Breault, MD, PhD, an endocrinologist at Boston Children’s Hospital and a member of the Harvard Stem Cell Institute. In the journal Developmental Cell, Breault recently showed that the adrenal gland uses cellular reprogramming (called lineage conversion) for daily maintenance and to repair itself after injury.
“This is going to be important for how we think of tissue maintenance and regeneration,” Breault says. Full story »
Stem cells are well-known for their ability to differentiate, or transform, into different types of cells. Two types of stem cells—embryonic stem cells and induced pluripotent stem cells—are able to ultimately change into any human cell. But that doesn’t mean all stem cells in these groups are equal: They have certain molecular features that bias them toward transforming into particular cell types. The ability to predict a stem cell’s differentiation bias would enable scientists to select a specific embryonic or induced pluripotent cell line to create cells for different applications—like grooming some youth athletes for football, others for basketball.
Zhang’s lab has identified a gene that acts as a powerful biomarker—physical or chemical characteristic whose appearance heralds a particular process—predicting a pluripotent stem cell’s tendency to differentiate into endoderm, cells on the inner layer of an embryo that become lung, digestive tract, pancreas and liver cells. It could be the first of a family of genetic biomarkers that guide scientists trying to create different cells and tissues for regenerative medicine. Full story »
In 2008, Gregory and his colleagues showed how a factor called Lin28, which is associated with numerous cancers, makes a cell more prone to revert to a less specialized, stem-like state.
Lin28 acts by preventing maturation of Let-7—an ancient family of microRNAs found in creatures from humans to worms. Let-7 is the yin to Lin28’s yang: it causes stem cells to differentiate (embryonic stem cells, which are completely unspecialized, have very low levels of it). If a cell’s Let-7 can’t mature, it can’t differentiate; instead, it remains stem-like and can potentially become cancerous.
Suppressing Lin28 with RNA interference (RNAi) has been shown to suppress tumor growth. But Lin28 is difficult to target with drugs. Full story »
Now, we have a potential therapeutic target to accomplish this: a family of microRNAs called miR-17-92 that regulates cardiomyocyte proliferation. In Circulation Research earlier this month, a team led by Kühn’s research colleague Da-Zhi Wang, PhD, demonstrates its potential. Full story »
As a hematologist, I see all too many children battling blood disorders that are essentially untreatable. Babies with immune deficiencies living life in a virtual bubble, hospitalized again and again for infections their bodies can’t fight. Children disabled by strokes caused by sickle cell disease, or suffering through sickle cell crises that drug treatments can’t completely prevent. Children whose only recourse is to risk a bone marrow transplant—if a suitably matched donor can even be found.
Over the past 20 years, my lab and that of George Daley, MD, PhD, at Boston Children’s Hospital have worked hard to give these children a one-time, potentially curative option—a treatment that begins with patients’ own cells and doesn’t require finding a match. Full story »
I recently took my 6-year-old son to a Family Science Day, hosted by the 2013 American Association for the Advancement of Science (AAAS) Annual Meeting in Boston. He was most excited by a model airplane made out of parts that had been generated with a 3D printer. The scientist, from MIT, explained to us how this technology works: Instead of generating 2D printouts by spraying ink onto paper, 3D printing technologies assemble 3D objects layer by layer from a digital model, generally using molten plastics or metals.
3D printing is quickly being adopted by many professions, from architects and jewelers who want to build mock-ups for clients, to manufacturers of products like bikes, cars or airplanes. Soon we might all have 3D printers in our homes: The kids could design and print their own toys, while the grownups might use the technology to generate replacement parts for minor home improvement jobs (our broken shower faucet knob comes to mind). Full story »
For more than 100 years, people have been debating whether human hearts can grow after birth by generating new contractile muscle cells, known as cardiomyocytes. Recently, Bernhard Kühn, MD, at Boston Children’s Hospital and his colleagues added fuel to the debate—and hope for regenerative therapies for diseased hearts—with their findings that infants, children and adolescents are indeed capable of generating new cardiomyocytes.
Research in the 1930s and 1940s suggested that cardiomyocyte division may continue after birth, and recent investigations in zebrafish and newborn mice presented the possibility that some young animals can regenerate heart muscle through muscle cell division. Still, for many years, the accepted dogma among physicians and researchers was that human hearts grow after birth only through existing cells growing larger.
“This is a very sticky subject in cardiology,” says Kühn. Not only do long-held scientific beliefs die hard, but the ability to directly study heart cell growth in humans has been limited. “Healthy human hearts are hard to come by,” he says. Full story »
For the Cáceres family of Argentina, it’s a joyous holiday homecoming. Agustín, who received gene therapy at 5½ months of age, journeyed with his family to Boston for a check-up and got a clean bill of health.
Agustín was born with the rare immune-deficiency disorder SCID-X1. More popularly known as “bubble boy” disease, it left him defenseless against infections, unable to make enough T-cells to fight them off. His baptism was the only time his family could come near him, all wearing masks, gloves and gowns. His infancy was spent in isolation with his mother.
Now, at age 2½, Agustín has been cleared to go to nursery school, ride a bus and attend large family gatherings without fear of contracting a life-threatening infection. When we caught up with him, he was chasing and tumbling with his older brother Jeremías while waiting to bid farewell to his care team. Full story »