Blood-Sucking Machine May Put Leeches Out of Work

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Doctors often try surgery to remove the clot, restore blood flow and keep the new tissue from dying, "but if that doesn't work, the only medical option is leeches," Connor said.

The leech is actually a highly sophisticated medical tool.

The wormlike creature has three jaws, each with about 100 teeth. Its bite resembles the Mercedes Benz symbol—a circle, formed by the sucker, with three spokes inside from the three jaws.

The leech creates or attaches to a wound and sucks up to five times its body weight of blood. It secretes its own anesthetic, so the bite doesn't hurt. It also secretes an anti-coagulant that keeps the wound bleeding for hours, allowing blood to continue to flow and nourish the tissue.

A Mechanical Alternative

"We thought we could probably recreate those three simple steps" with a machine, Hartig said.

Michael Conforti, a veterinarian who works at the VA and UW Hospitals and Clinics, worked with Connor and Hartig to design the device, a bell-shaped glass cup with tubes running through it to suction out blood.

A porous tip, implanted just beneath the skin, rotates to inhibit coagulation and clotting, keeping the tissue irrigated. It also releases the anti-coagulant heparin and props the wound open a little so it doesn't clot.

In three to ten days, the body usually has healed enough to form sufficient new veins to adequately drain blood from the new tissue. Unlike leeches, which feed for only about half an hour before being sated, the mechanical leech is insatiable and can remove greater quantities of blood for as long as needed.

The UW scientists have been testing the device on dozens of pigs, and say use in humans is probably two to three years away.

"It's a very difficult process. There are both mechanical aspects of the project and biologic aspects," Conforti said. "We've got good enough results to keep pressing on."

Meanwhile, doctors continue to use live leeches, obtained from one of two U.S. companies or a few universities that propagate their own.

Biopharm, a company based in Wales, in Great Britain, raises medicinal leeches in a lab and supplies about 1,000 U.S. hospitals, said Lisa Darmo, a spokeswoman for the Carolina Biological Supply Co., which distributes the leeches in this country.

New York-based Leeches U.S.A. gets them from their native habitats in eastern Europe, she said.

"We used to import them from France," but now get them from commercial suppliers, said Matloub.

He said patients at Froedtert have had varying reactions to being treated with leeches.

"The farmers don't care. They look at them, they have seen them. But some of the patients, they don't want to see it, they say it's really gross, so we have to shield them" while the leech does its work, he said.

If a mechanical alternative were developed, "it would be a very good thing," he said.

Copyright 2001, Milwaukee Journal Sentinel

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