Stories about: stem cell research

Tissue models of heart disease provide testing ground for treatments

Pink heart circuit board EKG-shutterstock_322058528Scientists are now able to create cardiac heart muscle cells from patients with heart disease. But cells alone aren’t enough to fully study cardiac disorders — especially rhythm disorders that require the activity of multiple cells assembled into tissues.

William Pu, MD, of Boston Children’s Hospital’s Heart Center and his team are honing the art of modeling heart disease in a dish. With an accurate lab model, they hope to test drug therapies without posing a risk to living patients (or even live animals).

Together with researchers at Harvard’s Wyss Institute, Pu’s lab recently modeled a rare rhythm disorder called catecholaminergic polymorphic ventricular tachycardia (CPVT). CPVT is a dangerous disease in which the heart’s rhythm can suddenly jolt abnormally without warning. Undetectable on a resting electrocardiogram (EKG), CPVT does not affect patients at rest. However, exercise or emotional upset trigger high levels of adrenaline, which can lead to life-threatening arrhythmia, cardiac arrest and possibly sudden death.

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Meet the researcher behind “heart on a chip”

Pu and wife and waterfallFrom a series on researchers and innovators at Boston Children’s Hospital.

With all of the recent buzz about precision medicine, it’s no wonder that William Pu, MD is gaining recognition for his innovative application of stem cell science and gene therapy to study Barth syndrome, a type of heart disease that severely weakens heart muscle. Pu’s research was recently recognized by the American Heart Association as one of the top ten cardiovascular disease research advances of 2014.

Can you describe your work and its potential impact on patient care?

We modeled a form of heart-muscle disease in a dish. To do this, we converted skin cells from patients with a genetic heart muscle disease into stem cells, which we then instructed to turned into cardiomyocytes (heart-muscle cells) that have the genetic defect. We then worked closely with bioengineers to fashion the cells into contracting tissues, a “heart-on-a-chip.”

How was the idea that sparked this innovation born?

This innovation combined the fantastic, ground-breaking advances from many other scientists. It is always best to stand on the shoulders of giants.

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Seeding medical innovation: The Technology Development Fund

Monique Yoakim Turk Technology Development FundMonique Yoakim-Turk, PhD, is a partner of the Technology Development Fund and associate director of the Technology and Innovation Development Office at Boston Children’s Hospital

Since 2009, Boston Children’s Hospital has committed $6.2 million to support 58 hospital innovations ranging from therapeutics, diagnostics, medical devices and vaccines to regenerative medicine and healthcare IT projects. What a difference six years makes.

The Technology Development Fund (TDF) was proposed to Boston Children’s senior leadership in 2008 after months of research. As a catalyst fund, the TDF is designed to transform seed-stage academic technologies at the hospital into independently validated, later-stage, high-impact opportunities sought by licensees and investors. In addition to funds, investigators get access to mentors, product development experts and technical support through a network of contract research organizations and development partners. TDF also provides assistance with strategic planning, intellectual property protection, regulatory requirements and business models.

Seeking some “metrics of success” beyond licensing numbers and royalties (which can come a decade or so after a license), I asked recipients of past TDF awards to report back any successes that owed at least in part to data generated with TDF funds. While we expected some of the results, we would have never anticipated such a large impact.

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Stem cell medicine gets a “roadmap” and a quality assurance tool

cell fate map Boston subway
Credit: Samantha Morris, PhD, Boston Children’s Hospital

If you’ve lost your way on the Boston subway, you need only consult a map to find the best route to your destination. Now stem cell engineers have a similar map to guide the making of cells and tissues for disease modeling, drug testing and regenerative medicine. It’s a computer algorithm known as CellNet.

As in this map on the cover of Cell, a cell has many possible destinations or “fates,” and can arrive at them through three main stem cell engineering methods:

reprogramming (dialing a specialized cell, such as a skin cell, back to a stem-like state with full tissue-making potential)
differentiation (pushing a stem cell to become a particular cell type, such as a blood cell)
direct conversion (changing one kind of specialized cell to another kind)

Freely available on the Internet, CellNet provides clues to which methods of cellular engineering are most effective—and acts as a much-needed quality control tool.

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The hope and promise of stem cells: A TED tutorial

At TEDx Longwood this spring, Leonard Zon, MD, founder and director of the Stem Cell Program at Boston Children’s Hospital, took the stage. In his enthusiastic yet humble style, he took the audience on a journey that included time-lapse video of zebrafish embryos developing, a riff by Jay Leno and a comparison of stem cell “engraftment” to a college kid coming home after finals: “You sleep for three days, and on day 4, you wake up and you’re in your own bed.” Three takeaways:

1)   Stem cells made from our own skin cells can help find new therapeutics. With the right handling, they themselves can be therapeutics, producing healthy muscle, insulin-secreting cells, pretty much anything we need. (So far, this has just been done in mice.)

2)   Zebrafish, especially when they’re see-through, can teach us how stem cells work and can be used for mass screening of potential drugs. The Zon Lab boasts 300,000 of these aquarium fish, and can mount robust “clinical trials” with 100 fish per group.

3)   Drugs discovered via zebrafish are in human clinical trials right now: A drug to enhance cord blood transplants for leukemia or lymphoma, and an anti-melanoma drug originally used to treat arthritis.

Zon, who co-founded the biopharm company Fate Therapeutics, will be part of a judging panel of clinicians and venture capitalists for the Innovation Tank at Boston Children’s Global Pediatric Innovation Summit + Awards (Oct. 30-31). Don’t miss it!

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Regrowing corneas: It’s all about finding the stem cells

A restored cornea grown from human ABCB5-positive limbal stem cells
A restored, clear cornea grown from ABCB5-positive limbal stem cells. (Image courtesy of the researchers)
Severe burns, chemical injury and certain diseases can cause blindness by clouding the eyes’ corneas and killing off a precious population of stem cells that help maintain them. In the past, doctors have tried to regrow corneal tissue by transplanting cells from limbal tissue—found at the border between the cornea and the white of the eye. But they didn’t know whether the tissue contained enough of the active ingredient: limbal stem cells.

How cancer research led to a regenerative treatment for blindness.

Results have therefore been mixed. “Limbal stem cells are very rare, and successful transplants are dependent on these rare cells,” says Bruce Ksander, PhD, of the Massachusetts Eye and Ear/Schepens Eye Research Institute. “If you have a limbal stem cell deficiency and receive a transplant that does not contain stem cells, the cornea will become opaque again.”

Limbal stem cells have been sought for over a decade. That’s where a “tracer” molecule called ABCB5—first studied in the context of cancer—comes in.

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Getting the most of mesenchymal stem cell transplants

Fat cells from mesenchymal stem cell transplant
The fat cells shown in yellow are descended from transplanted human mesenchymal stem cells (green) inside of a mouse after co-transplantation. The red stain shows native mouse fat cells.(Courtesy Juan Melero-Martin)
Joseph Caputo originally wrote this post for the Harvard Stem Cell Institute (HSCI). Vector editor Nancy Fliesler contributed.

Stem cell scientists had what first appeared to be an easy win for regenerative medicine when they discovered mesenchymal stem cells several decades ago. These cells, found in the bone marrow, can give rise to bone, fat and muscle tissue, and have been used in hundreds of clinical trials for tissue repair.

Uses range from tissue protection in heart attack and stroke to immune modification in multiple sclerosis and diabetes. Unfortunately, the results of these trials have been underwhelming. One challenge is that these stem cells don’t stick around in the body long enough to benefit the patient.

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Recapturing the liver’s fountain of youth

fountain of youth stem cellsThis post is condensed from a report from the Harvard Stem Cell Institute.

The liver has been a model of tissue regeneration for decades, and it’s well known that a person’s liver cells can duplicate in response to injury. Even if three-quarters of the liver is surgically removed, duplication alone can return the organ to its normal functioning mass. It’s why people are able to donate part of their liver to someone in need—like this mother to her son who was born with biliary atresia.

But what about people with more chronic liver damage? Researchers led by Fernando Camargo, PhD, of the Harvard Stem Cell Institute and Boston Children’s Hospital’s Stem Cell Program, have new evidence in mice that it may be possible to repair such liver disease by forcing mature liver cells to turn back the clock and revert to a stem cell-like state, able to generate functional liver progenitor cells to replace damaged tissue.

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‘Heart on a chip’ suggests a surprising treatment for a rare genetic disease

heart chip BarthIt was the variability that intrigued pediatric cardiologist William Pu, MD, about his patient with heart failure. The boy suffered from a rare genetic mitochondrial disorder called Barth syndrome. While he ultimately needed a heart transplant, his heart function seemed to vary day-to-day, consistent with reports in the medical literature.

“Often patients present in infancy with severe heart failure, then in childhood it gets much better, and in the teen years, much worse,” says Pu, of the Cardiology Research Center at Boston Children’s Hospital. “This reversibility suggests that this is a disease we should really be able to fix.”

Though it needs much more testing, a potential fix may now be in sight for Barth syndrome, which has no specific treatment and also causes skeletal muscle weakness and low white-blood-cell counts. It’s taken the work of multiple labs collaborating across institutional lines.

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Can blood cells be rebooted into blood stem cells?

Hematopoietic hierarchy blood development stem cells
The classic hematopoietic hierarchy. What if we could turn those arrows around?

Think, for a moment, of a cell as a computer, with its genome as its software, working to give cells particular functions. One set of genetic programs turns a cell into a heart cell, another set creates a neuron, still another a lymphocyte and so on.

The job of controlling which programs get booted up, and when, falls in part to transcription factors—genes that act like molecular switches to turn other genes on and off.

Derrick Rossi, PhD, spends a lot of his time thinking about transcription factors. A stem cell and blood development researcher in Boston Children’s Hospital’s Program in Cellular and Molecular Medicine, Rossi believes that transcription factors hold the power to achieve one of the most sought-after goals in regenerative medicine: producing, from other cell types, transplantable hematopoietic stem cells (HSCs).

“There are about 50,000 HSC transplants every year,” Rossi explains, noting that the success of a transplant is highly dependent on the number of cells a patient receives from her donor. “But HSCs only comprise about one in every 20,000 cells in the bone marrow.

“If we could generate autologous HSCs from a patient’s other cells,” he continues, “it could be transformative for transplant medicine and for our ability to model diseases of blood development.”

As they reported April 24 in Cell, Rossi and his collaborators have taken a significant step toward that goal: Using a cocktail of eight transcription factors, they reprogrammed mature mouse blood cells into what they have dubbed induced HSCs (iHSCs).

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