The art and science of using biological tissue grafts from animal and human
sources for various ailments is nascent. Various research groups around the
world are actively investigating the potential prostheses of biological
origin. Biological tissue grafts are rendered acellular through various
methods of processing and fabrication before they are used for the specific
purpose. The remainder is a scaffold that offers framework for host cellular
repopulation and revascularization. Different methods of fixation have been
explored over several decades to render the biological grafts suitable for
use with or without extraction of cells. Therefore, methods such as
glutaraldehyde and polyepoxide crosslinking treatments and dye-mediated
photooxidation have been developed to stabilize and deantigenize the tissue
while attempting to maintain its natural mechanical properties. Also,
residual cellular components in a bioprosthetic material have been
associated with undesired effects, such as calcification and immunological
recognition, and thus have been the motivation for various decellularization
processes. The effects of these stabilization and decellularization
treatments on mechanical, biological and chemical properties of treated
tissues have been investigated, specifically with regard to calcification,
immunogenicity, and cytotoxicity concerns. Naturally derived biological
scaffolds offer many mechanical, chemical and biological advantages over
synthetic materials, and thus hold tremendous potential for use in tissue
engineering therapies. Therefore the rationale of using biological grafts in
usable forms is gaining importance in order to avoid unwanted chronic
inflammatory reactions. This review article discusses the need for such
bioprosthetics and the potential role for natural tissues in various
applications.