THE MOLECULES FOUND within a microenviron—ment—such as an area of injury—may be found in the form of peptides or proteins or may be bound to other cells. An understanding of microenviron—mental influence on stem cells requires an interdisciplinary approach among engineering, science, and different areas of biology. Such an understanding is needed as part of the mechanism leading to successful stem cell therapy.

Proposed therapies with stem cells require several experimental considerations. A major issue relates to the rejection of implanted stem cells when they are taken from one donor and then given to another recipient. This type of stem cell transfer is referred as allogeneic transplantation. The major cause of rejection is the polymorphism found within major histocompatibility class 2 (MHC-2). This indicates that it ...