Blood vessels grown in lab offer hope for diabetic care
BY MARILYNN MARCHIONE
ASSOCIATED PRESS
November 16, 2005
DALLAS -- Two kidney dialysis patients from Argentina have received the world's first blood vessels grown in a lab dish from snippets of their own skin, a promising step toward helping people with a variety of diseases.
Doctors hope the technique someday will offer a source of arteries and veins for people with diabetes and poor circulation and patients of heart bypass or dialysis.
Scientists from Cytograft Tissue Engineering Inc., a San Francisco Bay-area biotechnology company, reported on it Tuesday at an American Heart Association conference in Dallas.
"We think this is extraordinarily promising. We think that there are a number of patients who would benefit from tissue-engineered vessels," said Dr. Elizabeth Nabel, director of the National Heart, Lung and Blood Institute, which has poured $2.5 million into the tiny company's work.
People with certain chronic conditions, such as dialysis patients, often run out of healthy vessels. Growing them involves taking a piece of skin and a vein, less than a quarter-inch square, from the back of the hand.
It's placed in a lab dish and nurtured with growth enhancers.
Two types of tissue are grown. One forms the tough structure or backbone of the vessel, and another lines it and helps it to function.
Sheets of this tissue are produced -- "You can cover your desk with a sheet," said Todd McAllister, a scientist and cofounder of the company -- and then stacked and rolled into vessels 6 to 8 inches long.
That takes six to nine months, but faster development should become possible, said Nicholas L'Heureux, the company's chief scientific officer who invented the method.
Still, that means that only patients whose needs are known ahead of time could be considered. The focus now is on diabetics who need dialysis, machines to filter wastes from their blood because their failing kidneys no longer can. They number 285,000 in the United States and double that worldwide.
To enable dialysis, doctors create a shunt, a kind of short-circuit that connects an artery and vein, which is tapped into three times a week for the procedure. "The problem is, as you puncture that over and over and over, the vessel tends to fail," McAllister said.
Patients often run out of healthy vessels that can be cut out and moved to form a shunt, and synthetic vessels often don't last long and can develop complications.
Such problems led scientists to put the first so-called homegrown vessels in a 56-year-old Buenos Aires woman in May and a 61-year-old man in September.
The woman's new vessel has withstood needle punctures three times a week for six months and the man's, for almost three. "They're holding up," L'Heureux said.
The lab-grown vessels are expected to cost less than $10,000.
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