Implantable patch may mend ailing hearts

September 16, 2009

Cell therapists— Dr. Steven Goldman (right) and pre-doctoral fellow Jordan Lancaster view a microscope image of an implantable, synthetic mesh patch seeded with living heart cells. (Photo by Daniel Stolte/U. of Arizona).

It was one of the cooler videos posted recently on National Public Radio's "Science Friday" website: A mesh patch, the size of a thumbnail, appears to dance rhythmically, as if shaking to a Latin beat.

What's driving the motion? Heart muscle cells, beating in the same direction and at the same tempo, seeded onto the polymer patch. The research—presented at an American Heart Association meeting in July—shows what may be a key strategy in cardiac care of the future.

Study leader Dr. Steven Goldman, chief of cardiology at the Tucson VA and a professor at the University of Arizona, says the biodegradable patch would be seeded with cells and implanted onto the heart to deliver a therapeutic boost. The idea would be to help rebuild dead muscle tissue after a heart attack and revitalize the hearts of people with chronic heart failure.

The patch itself is made by a California company called Theregen. In its basic form, it contains living human cells called fibroblasts. These are the building blocks for connective tissue. In early clinical trials, the patch spurred the growth of new blood vessels in the heart. In animal studies in Goldman's lab, it improved heart function after heart attack.

Study was 'proof of concept'

In the new VA study, Goldman's group showed that the patch can be a viable platform for living heart cells—in this case, heart muscle cells taken from newborn rats. Seeded onto the patch in sufficient number, they resume beating just as they did in the animal. They even beat in unison—at the same speed and in the same direction. "Within 72 hours, you can see the entire scaffold contracting," said Jordan Lancaster, a pre-doctoral fellow in Goldman's lab, in an interview with NPR. Goldman, added, "The fact that they beat synchronously and the whole thing contracts, means the cardiomyocytes [heart muscle cells] are talking to each other."

Lancaster notes, "This neonatal work was a proof of concept that we could seed the cells in a way that would allow them to survive and communicate with each other." How would the work translate into patient care? The patch would need to be seeded with cells that would divide, multiply and grow into mature heart tissue. Several types of cardiac stem cells have already been tried in humans. Lancaster mentions induced pluripotent stem cells, or IPS cells, as one option. These cells are genetically engineered in the lab from non-stem cells found in various tissues in the body. "You can harvest them, ideally, from the patient's own skin or even fat tissue, and culture them to have these cardiomyocyte-like features," he says.

Cells thrive on patch

The main point, say the researchers, is that the patch is a good environment for cells to thrive in—like seedlings placed in rich, fertile potting soil. "Think of it as a delivery system," explains Goldman. "Any type of cell could be put on the patch."

That could help get around obstacles that have thwarted other approaches. In past clinical trials, researchers have tried injecting cardiac stem cells directly into the heart, or squirting them into the arteries that supply blood to the heart. But not enough of the cells survive. "Delivery can be a huge problem in cell therapy," says Lancaster. "We think the patch method could promote cell survival and growth."

This article originally appeared in the September 2009 issue of VA Research Currents.