Repairing and replacing damaged tissue has traditionally had several problems. One major problem is the shortage of enough donor tissue. Another is that the immune system sees the new implanted tissue as foreign, and has an inflammatory response. Or even worse: Completely rejects the grafted tissue.
In the 1990s, a new field emerged, hoping to solve these problems by engineering the new replacement tissue in the lab. The materials used would be designed to bypass the body’s immune defense systems, among other things, by using stem cells. This is the field of Tissue Engineering (TE).