Chapter 16 – Growth Factors

Tissue remodeling is an essential process in the maintenance and survival of all organisms throughout life. Tissue remodeling occurs throughout the entire span of injury, repair and wound healing. Early studies clarified the sequence and time course of appearance of different cell types and their changing phenotypes in healing wounds. However, the mechanisms that regulate the tissue remodeling that constitutes the wound healing process remain incompletely understood. An essential component of the regulatory processes that drive tissue remodeling includes the different growth factors and the cytokines that dictate cell type and tissue specificity of responses that drive tissue remodeling. The regulation of their gene expression is the critical component that establishes the timing and sequence of appearance of the tissue remodeling that leads to the healed wound. Coordination of these properties effectively defines the wound healing process. Remarkable progress over the past few years has resulted from the identification, isolation, cloning, and characterization of the properties of growth factors and cytokines and their use in wound healing models. The most important lesson learned from their use appears to be that the growth factors and cytokines are important in initiating and accelerating the normal processes involved from injury to repair. The growth factors are the ‘trigger’ that opens sequential activation of downstream pathways of critical importance to the progressive tissue remodeling that leads to the healed wound.