- The Washington Times - Wednesday, November 16, 2005


DALLAS — Medical specialists 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.

Biotechnology scientists from Cytograft Tissue Engineering Inc., reported Tuesday that two kidney dialysis patients from Argentina have received the world’s first blood vessels grown in a laboratory from snippets of their own skin.

Other potential uses for the vessels are to prevent limb amputations from poor leg circulation in diabetics, and heart bypass operations when patients don’t have good veins or arteries to create new detours around blocked vessels. The 40,000 children born with defective blood vessels are other prospects.

“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 invested $2.5 million in the tiny California company’s work.

The method doesn’t involve stem cells, thus 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. The 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, and are then 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.

Still, that means that only patients whose needs are known that far 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 do so. 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,” Mr. McAllister said.

Patients often run out of healthy vessels that can be cut out and moved to form a shunt, and synthetic vessels often develop complications.

“Living biological tissues have a capacity to heal … pieces of plastic don’t,” Mr. McAllister said. Such problems led scientists to put the first “home-grown” vessels into a 56-year-old Buenos Aires woman in May and a 61-year-old man in September.

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], so it’s a huge, huge economic burden,” Mr. McAllister said. The company plans to ask the Food and Drug Administration to allow them to do a study in the United States next year.

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