In Vivo Synthesis of Tissues and Organs

With increasing fetal development, the mechanism of mammalian wound healing transitions from regeneration to a repair process characterized by organized wound contraction and scar synthesis. Recently, a variety of tissue-engineering constructs have been developed to block the contraction and scar formation mechanisms of repair, and to induce regeneration following injury with similar mechanisms of action observed for both the skin and peripheral nervous system (PNS). Such constructs, mostly scaffolds that are analogs of extracellular matrix and possess specific biological activity, have become the basis of studies of in vivo synthesis of tissues and organs. In this article, we provide an overview of mammalian wound healing processes following severe injury as well as a description of the tissue triad and the regenerative capacity of the three distinct tissue types that comprise the triad. We also discuss the critical structural elements of an active extracellular matrix analog that induces regeneration, and describe the use of standardized wound models for study of in vivo regeneration processes. We conclude this review describing recent data from studies utilizing active extracellular matrix analogs (scaffolds) that have shown regenerative activity.