High-Tech Treatments for the Heart
Researchers Grow New Arteries, Heart Cells
Nov. 18, 2002 (Chicago) -- For patients with advanced heart disease the best treatment may be homegrown: cells from muscles, skin, and bone marrow that are "engineered" to grow into new, healthy arteries or injected into injured heart tissue to restore function.
Several researchers in the U.S. and Europe are working in this rapidly developing field of tissue engineering and cellular transplantation and some of them where on hand at the opening day of the American Heart Association's Scientific Sessions 2002 to discuss their breakthrough work.
Most people who have blocked arteries in their hearts or legs undergo bypass surgery in which veins are sewn into the heart so that blood can "bypass" the blocked artery. The veins are taken from other areas of the body -- but veins are limited in supply. People with severe disease can literally "run out of available blood vessels," says Todd McAllister, MD, tissue engineering researcher. With surgery no longer an option, these patients face painful, disabling disease.
But McAllister says that he has found a way to grow new veins from skin cells -- a method that could produce "an endless supply of veins."
McAllister says he has already "grown" new blood vessels and tested the effectiveness of the vessels in dogs. Those results are so encouraging that he plans human studies in 12 to 18 months.
The idea, he says, is to take a small piece of skin -- about the size of a postage stamp -- as a source for cells that are then coaxed into growing together to form a sheet of new tissue that is eventually shaped into "vessels" for surgical implant.
McAllister, president and CEO of Cytograft Tissue Engineering in Novato, California, tells WebMD that his team of researchers is not the first group to attempt heart repairs using engineered tissue, but his approach has a significant difference: the vessels are grown from the patient's own cells and once fully grown, these new vessels have no synthetic or artificial parts.
In the study, which was unveiled at the meeting, cells collected from 11 dogs with advanced heart disease were placed in a special solution that promotes cell growth.
As soon as the cells grew into a thin sheet, they were wrapped around a thin, stainless steel tube about the size of a blood vessel. The tissue continued to grow or mature until it took on the shape of the tube. At that point the tube was carefully removed and the vessel was ready for surgical implant.
McAllister says the whole process from skin biopsy to finished blood vessel takes about three months, but once the vessel is grown it remains healthy and viable for surgical bypass for up to six months.
In his experiment, the dogs were monitored for up to 14 days after surgery. During that time the vessels functioned as well as native blood vessels with no clots or blockages, says McAllister. The vessels were then surgically removed and examined. Again, McAllister said, the vessels were virtually indistinguishable form healthy, native blood vessels.