TransCyte (Advanced Tissue Sciences Inc. La Jolla, CA), a bioactive skin substitute, was granted premarket approval (PMA) by the FDA in 1997 for "for use as a temporary wound covering for surgically excised full-thickness and deep partial-thickness thermal burn wounds in patients who require such a covering prior to autograft placement." TranCyte was not indicated for chronic wounds. TransCyte consists of human dermal fibroblasts grown on nylon mesh, combined with a synthetic epidermal layer. TransCyte can be used as a temporary covering over full thickness and some partial-thickness burns until autografting is possible. It can also be used as a temporary covering for some burn wounds that heal without autografting. TransCyte is packaged and shipped in a cryo-preserved state to burn treatment centers. The surgeon then thaws the product and stretches it over a burn site. In about 7 to 14 days, the TransCyte starts peeling off, and the surgeon trims it away as it peels.