Mathematical Investigation of the Interactions Between the Inflammatory Response and Mechanical Aspects of Dermal Wound Repair

Abstract

Dermal wound repair involves complex interactions between cells, cytokines and mechanics to close injuries to the skin. In particular, we investigate the contribution of fibroblasts, myofibroblasts, TGF , collagen and local tissue mechanics to wound repair in the human dermis. We develop a morphoelastic model where a realistic representation of tissue mechanics is key, and a fibrocontractive model that involves a reasonable approximation to the true kinetics of the important bioactive species. We use each of these descriptions to elucidate the mechanisms that generate pathologies such as hypertrophic scars, contractures and keloids. We find that for hypertrophic scar and contracture development, factors regulating the myofibroblast phenotype are critical, with heightened myofibroblast activation, reduced myofibroblast apoptosis or prolonged inflammation all predicted as mediators for scar hypertrophy and contractures. Prevention of these pathologies is predicted when myofibroblast apoptosis is induced, myofibroblast activation is blocked or TGF is neutralised. To investigate keloid invasion, we develop a caricature representation of the fibrocontractive model and find that TGF spread is the driving factor behind keloid growth. Blocking activation of TGF is found to cause keloid regression. Thus, we recommend myofibroblasts and TGF as targets for clinicians when developing intervention strategies for prevention and cure of fibrotic scars.