Gel for joint repair is in the works

May 30, 1999|By Robert Cooke | Robert Cooke,Newsday

Anyone with creaky knees or other painful joints may someday get repairs made with an injectable plastic that gradually grows replacement cartilage, scientists report.

A research team at the Massachusetts Institute of Technology has developed a plastic material containing living cartilage cells, designed for injection into troubled joints. The plastic hardens when subjected to ultraviolet light, providing a pliable "glue" that holds the cells in place while they grow.

The basic idea is to replace or repair old, damaged joint tissue with slick new cartilage, smoothing the movement of limbs and erasing chronic pain. After new cartilage has grown, the plastic dissolves and disappears, the researchers said.

"This substance basically replaces cartilage," said Jennifer Elisseeff, a chemistry graduate student at MIT. "This is a method of cartilage tissue engineering that makes it easier to implant a hydrogel" for therapeutic purposes, she explained.

The plastic, or hydrogel, is injected in liquid form, and it turns into a pliable solid when subjected to a beam of ultraviolet light. In time, it dissolves away, leaving just the implanted cartilage.

So far, the mix of plastic and cartilage cells works as expected in tests. The cartilage cells have also been shown to grow, but the system has not yet been tried in living joints, not even in experimental animals.

The research is being done by Elisseeff in collaboration with Robert Langer, a professor at MIT. They are trying to develop and commercialize the joint-saving process in association with a San Diego firm, Advanced Tissue Sciences Inc. Elisseeff said she began pursuing the idea of creating injectable cartilage four years ago, after hearing plastic surgeons at nearby Massachusetts General Hospital express a need for better control of cartilage emplacement. She came up with the idea that light shining through the skin could be used to trigger the hydrogel to set exactly where it's needed.

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