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Grow-Your-Own Blood Vessels May Be Coming -- San Francisco Biotech Uses Patients' Skin, Vein

Posted on: Tuesday, 22 November 2005, 12:00 CST

By Marilynn Marchione Associated Press / Mark Watson contributed

DALLAS - Medical experts hope they have found a technique that will someday offer a new source of blood vessels for diabetics with poor circulation and patients needing dialysis.

Scientists from Cytograft Tissue Engineering Inc., a San Francisco Bay-area biotechnology company, reported Tuesday that two kidney dialysis patients from Argentina have received the world's first blood vessels grown in a lab from snippets of their own skin.

"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.

The method doesn't involve stem cells and therefore is not politically or ethically contentious.

It involves taking a piece of skin and a vein, less than a quarter-inch square, from the back of the hand. This tissue snippet is placed in a lab dish and nurtured with growth enhancers that help it produce substances such as collagen and elastin, which give tissues their shape and texture.

Two types of tissue are grown: one that forms the tough structure or backbone of the vessel and another that lines it and helps it to function.

Sheets of this tissue are produced, stacked and rolled into vessels 6 to 8 inches long, said Todd McAllister, a scientist and co- founder of the company.

This takes six to nine months, but faster development should be possible once ways are found to do the work on a commercial scale, said Nicholas L'Heureux, the company's chief scientific officer who invented the method.

Still, that means only patients whose needs are known that far ahead of time could be considered. The focus now is on diabetics who need dialysis to filter wastes from their blood because of kidney failure. They number 285,000 in the United States and twice 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 to be moved to form a shunt, and synthetic vessels often don't last long and develop complications.

Such problems led scientists to put the first "home-grown" 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.

However, Dr. Richard Weisel, a Toronto General Hospital cardiac surgeon not involved but familiar with the work, said more long- term results are needed before anyone can know whether this is a good solution.

The lab-grown vessels are expected to cost under $10,000. By comparison, "Medicare pays $4 billion to $5 billion annually to maintain grafts (shunts) ," McAllister said.

Other potential uses for the vessels are to prevent limb amputations from poor leg circulation in diabetics, and heart bypass operations where patients don't have good veins or arteries to create new detours around blocked vessels.

The Argentina study will test the vessels in 25 diabetics; another study expected to start soon in England will involve 25 heart bypass patients.

Company officials said they'll ask the U.S. Food and Drug Administration to allow a study in the United States in 2006.

On the Web

American Heart Association: americanheart.org.

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Regional impact

Memphis could help with process

Memphis could become a center for the manufacture of blood vessels from patients' own tissue, said Dr. Lisa Jennings, director of the University of Tennessee Health Science Center's Vascular Biology Center, which works on blood cells, blood vessels, vascular disease and Memphis' emerging biotech sector.

Existing expertise

Researchers in the Center already focus on new devices that may be used in patients undergoing non-invasive coronary intervention, bypass grafting for larger arteries and on biological mechanisms key in vascular injury response, such as atherosclerosis and diabetes, she said.

"Combined with the capability of FedEx to transport these vessels to hospitals in the US and in the world within a matter of hours, it is an opportunity for the Memphis medical research and clinical community to partner with the business community."

- Mark Watson

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Source: Commercial Appeal, The

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