| Cutaneous wound healing is a well-orchestrated process leading to reestablishment of normal function of skin within few weeks. However, in diabetic and elderly patients, this process is compromised leading to development of non-healing ulcers. Despite the introduction of numerous treatment modalities, chronic wounds remain a significant healthcare problem. This dissertation is focused on development of innovative approaches for stimulation of cutaneous wound healing. Specifically, we use Low Level Light Therapy (LLLT) and novel bioactive extracellular matrix protein fragments. LLLT is known for over 40 years but its efficacy remains controversial and the mechanisms of its activity are poorly understood. Our work in mouse models of cutaneous wound healing demonstrates that both coherent and non-coherent light can stimulate cellular responses to injury, identifies the most effective wavelength of light (820 nm) and establishes that there are significant variations in response to treatment between different strains of mice. We demonstrate that LLLT fosters fibroblast to myofibroblast transition and promotes wound contraction. While contraction is an important part of the healing process, its stimulation in human subjects might not be desirable as excessive contraction can lead to reduction of skin elasticity and loss of function. Therefore, next we focused on development of wound healing modalities that could enhance wound healing without stimulation of contraction. Previously it has been shown that collagenase from Clostridium histolyticum promotes cellular responses to injury both in vitro and in vivo. We hypothesize that stimulation of repair occurs via collagenase-mediated release of matrixassociated bioactive moieties. We used endothelial ECM degraded by bacterial collagenase and immunoprecipitated with anti-collagen antibodies to identify these biologically active peptides. We isolated several fragments of collagen IV, fibrillin 1, tenascin X and created a novel peptide as a combination between fibrillin 1 and tenascin X. The peptides increase rates of microvascular endothelial cell proliferation by 50% and in vitro angiogenesis by 200% when compared to serum-stimulated controls. Moreover, we demonstrate that combinatorial peptide, applied into the wound bed of healing impaired cyclophosphamide treated mice enhances responses to injury. Current studies are aimed at revealing the molecular mechanisms regulating peptide-induced wound healing. |
