Houston establishes itself as a pioneer in regenerative medicine
Inside Doris Taylor’s lab at the Texas Heart Institute are ethereal white pig hearts, stripped of their cells and now a blank slate of an organ.
Removing cells from an organ is fairly simple for scientists like Taylor. Rebuilding the organ by injecting stem cells is the tricky part.
But that’s exactly what Taylor hopes to do: grow a human heart by injecting human stem cells into a “decellularized” organ.
“It’s very cool, the stuff we’re doing,” Taylor told the Houston Chronicle a few years ago.
While Houston is internationally known for being at the apex of cancer treatment, the city is also quickly establishing itself as a leader in regenerative medicine.
At its core, the regenerative medicine is focused on finding new ways to help the body repair itself, often through the use of stem cells.
For example, scientists at Houston Methodist are hoping to someday restore hand function to paralyzed patients by using stem cells to help repair the spinal cord. Baylor College of Medicine is invested in research that might prevent cerebral palsy by coaxing cells into the brain to produce myelin, which foster communication between nerve cells. Children with brain injuries are benefitting from stem cell research at UT Health Science Center at Houston Medical School.
At the Texas Heart Institute, a dream team of scientists that includes Taylor are studying various ways to compel damaged hearts to self-repair, including zeroing in on the best stem cells to use for treatment.
“Our goal in research at the Texas Heart Institute is ultimately to prevent cardiovascular disease, and along those lines make it tolerable for people to relieve symptoms, their pain and help improve their overall lifestyle,” said James T. Willerson, the Institute’s president. “And this is the important piece of it. I think it’s one of the most important things we do.
The use of stem cells in medicine has evolved rapidly since a pair of Canadian scientists first confirmed the existence of stem cells in 1961.
Stem cells are found both in early stage embryos and in adults, in the blood marrow and elsewhere. They are of particular interest to scientists because of their ability to easily divide and develop into various types of cells, sometimes repairing damaged cells.
Because of their potential to repair damaged organs, Willerson got interested in stem cells in the 1990′s and began working with them in animal research.
In 2000, that research took a monumental leap when he and a Brazilian colleague, Emerson C. Perin, got approval to perform the first ever injection of human stem cells into 14 patients suffering from advanced heart failure in Rio de Janeiro.
Using a specialized catheter, Willerson and Perin injected stem cells taken from the patient’s bone marrow and injected them into 15 sites in the heart.
Within a year, the results were nothing short of amazing.
“Some that couldn’t walk from here to the door were now jogging on the beach in Rio, not very fast, but quite an improvement,” Willerson said.
That study was the first of its kind in the world and in 2004 Willerson and Perin asked the Food and Drug Administration for permission to replicate it in the U.S.
After much scrutiny, permission was granted and 20 patients in various throes of heart failure were injected with their own stem cells.
That study taught them not all stem cells were created equal. Stem cells that come from people under the age of 60 tend to perform better.
Perin, who is now the medical director of the Institute’s Stem Cell Center, has focused his research on a more specialized type of stem cells known as mysenchymal cells.
In a 2015, he was the lead author on a study that found injecting 150 million precursor mysenchymal cells into patients with severe heart failure prevented future heart attacks, death, and worsening heart failure.
“That’s almost unheard of,” Willerson said. “And this was a very sick group of people.”
Working with stem cells is not without controversy, particularly if that means using embryonic stem cells.
In 2006, a Japanese researcher found a way to reprogram adult stem cells to behave like embryonic stem cells. These cells known as induced pluripotent stem cells (iPSC) became a game changer by removing some of the moral objections over research with fetal tissue.
The technology to create iPSC’s combined with a brand new genome editing tool known as CRISPR-Cas9 are giving scientists a new way to detect genetic mutations and possibly fix flaws that in the past caused debilitating diseases.
“I would say the sky is the limit,” said Ben Deneen, an associate professor at Baylor College of Medicine’s Stem Cells and Regenerative Medicine Center.
Deneen’s research is focused on coaxing cells in the brain to make myelin, which is often damaged when an infant suffers a loss of oxygen to the brain. When that happens, cerebral palsy or multiple sclerosis occurs.
It’s just one example of a regenerative medicine that doesn’t involve injecting stem cells directly into a damaged organ.
Scientists at Houston Methodist’s Center for Neuroregeneration are also looking at new ways to trigger the brain to repair itself in hopes of someday helping people with severe paralysis recover the use of their hands.
“When you survey people who have had severe strokes or are quadriplegics, they most want to see function of their hands restored,” said Phil Horner, the Center’s director. “Way down that list is walking.”
Historically, scientists have had to rely on wires to stimulate the parts of the brain that control movement. But that method tends to cause scarring and isn’t a good long-term fix for patients.
That’s why Horner and others are excited about using new mechanisms to stimulate the brain such as lights, and magnetic fields.
“To me it’s an extremely exciting time,” Horner said. “Instead of the old trial and error ways of the past, we’re starting to approach the brain like engineers. We are moving toward being able to re-engineer specific pathways in the brain. It’s radically different way of helping patients.”