08/12/97 - 12:24 AM ET - Click reload often for latest version
The first tissue successfully engineered and made available to people was skin.
Scientists have been developing skin substitutes for almost 20 years. Advanced Tissue Sciences Inc. of La Jolla, Calif., was the first company to get a tissue-engineered skin product to the market. It was approved for commercial use in March by the Food and Drug Administration.
The product, Dermagraft TC, is used for severe burns as a temporary covering for wounds. It was designed as an alternative to cadaver skin, which had been the best treatment doctors could offer.
About 2 million people suffer burns each year; 13,000 require skin grafts. About 1,500 suffer burns over 20% of their bodies. With such extensive burns, skin grafting isn't feasible and skin substitutes are required.
The Dermagraft TC skin product is made from cells of the foreskins of newborns. The cells, called dermal fibroblasts, are grown on a mesh that serves as a three-dimensional scaffold, says Gail Naughton, co-inventor of the product and company president. As the cells grow over the scaffold, they secrete human skin collagen, growth factors and structural proteins. A synthetic outer skin layer is then added.
The skin substitute is placed on deep burns where the patient's skin is too badly destroyed to regenerate on its own. The substitute helps hold in body fluids that would otherwise ooze from the exposed areas; it helps maintain body temperature and it serves as a barrier against infection. Naughton says it can be kept on the body without changing for about three months; cadaver skin is usually rejected after a week or two.
The company has a second skin product under expedited review by the FDA. It is intended as a permanent graft for treating diabetic foot ulcers, which affect about 800,000 people a year. The product is designed to promote healing and help prevent amputations.
Other companies involved in skin engineering:
Newer, multilayered skin that contains several different cell types like natural skin are expected to be developed over the next decade.
The second major tissue type to make it to market will be cartilage. Most companies are experimenting with cartilage cells, and several are only months away from human studies.
Genzyme already has a cartilage product made from a patient's own cells. Advanced Tissue Sciences also is developing cartilage, using cadaver cells as a source. The company is expected to begin human studies in the USA and Europe later this year.
