AN INVESTIGATION OF THE EFFECT OF CHITOSAN-BASED MATERIALS ON SKIN WOUND HEALING

Abstract

Chronic wounds fail to undergo an orderly and timely reparative process. Currently, there are no effective treatments for chronic wounds. The heparan sulphate (HS) proteoglycan (HSPG), perlecan, plays an important role in healing chronic wounds through binding and signalling of growth factors. Biomimetic materials that mimic naturally occurring HS may find application in the delivery of growth factors for skin wound healing. Chitosan is a polysaccharide with a similar structure to HS, with the exception of sulphate modifications. This thesis explored the effect of chitosan-arginine (CH-Arg), a water soluble form of chitosan, modified with different levels of sulphate substitution on skin wound healing. Specifically, this thesis investigated the effect of sulphated CH-Arg on the expression of extracellular matrix (ECM) components including perlecan produced by human keratinocytes dermal fibroblasts in 2D and 3D skin models. Perlecan produced by both skin cell types was full-length perlecan decorated with HS and chondroitin sulphate (CS) chains. In addition, smaller fragments of perlecan were present in the fibroblast samples. Exposure to highly sulphated CH-Arg (HS-CH-Arg) increased the perlecan expression in both skin cell types. CH-Arg-based materials did not alter the proliferation of either skin cell type, while sulphated CH-Arg significantly (p <0.05) enhanced keratinocyte migration, demonstrating that the sulphated CH-Arg materials promoted keratinocyte migration. An in vitro skin model was established with similar expression in basement membrane components, proteoglycans and glycosaminoglycans to human adult skin, as well as a well-developed mimicked epidermis. CH-Arg-based materials significantly (p <0.05) enhanced the epidermal thickness, indicating their role in epidermal formation. In addition, sulphated CH-Arg enhanced the expression of perlecan, laminin β1, collagen type IV, syndecans-1 and -4 and HS with the exception of serglycin. Thus, CH-Arg-based materials have the potential to mimic HS and promote skin wound healing with respect to enhancing re-epithelialisation and the formation of ECM molecules.