Copyright
IIT Kharagpur
Abstract
Acellular artificial skin grafts are indifferent to the wound pathobiologic conditions and merely evoke a regenerative response. Review of wound biology suggests that pH of wound milieu varies with the severity and pathobiologic condition and hence can be used as a novel clue for wound pathobiology responsive therapy.
The thesis pertains to the development of growth factors loaded artificial skin graft capable of providing customized sustained delivery of growth factors to the wound site in a programmed way by sensing the in situ pH variation of wound milieu. For this purpose, acid soluble goat tendon collagen (GTC) was selected as matrix material and poly(N-isopropyl acrylamide-co-acrylic acid) [poly (NIPAAm-co-AAc)] was chosen as sustained pH responsive delivery system for programmed delivery of epidermal growth factor (EGF) and vascular endothelial growth factor (VEGF).
Physicochemical characterization of GTC showed its close molecular and structural resemblance to calf skin collagen. Comprehensive analysis of adhesion, traction, and proliferation of murine primary dermal fibroblast cells (MF) on GTC modified substrate ensured better cytocompatibility of GTC in comparison to collagen of bovine origin. Analysis of the release profiles of growth factors from poly(NIPAAm- co-AAc) hydrogel pointed out pH responsive sustained non Fickian release, governed by pH dependant electrostatic repulsion mediated structural change of the molecular network of polymer matrix. Growth factors loaded graft was fabricated by coupling poly(NIPAAm-co-AAc) polymer gel (containing EGF and VEGF) with freeze-dried collagen three dimensional scaffold. Results of physical characterization (microarchitechture, tensile strength and swelling) and subsequent biocompatibility study endorsed its compliance as scaffold for skin graft. Immunogenicity and systemic toxicity of the graft was assessed in vivo in mice model and results showed no significant adverse reactions. Efficacy of the acellular graft was tested in vivo in murine excisional full thickness wound model and compared with conventional sustained growth factor therapy. Histological and immunohistological analysis showed that graft possess potent skin regeneration property and augment healing stages like epithelization, and angiogenesis. In conclusion, growth factor loaded wound pH responsive smart skin graft can lead to new therapeutic modalities for effective skin regeneration.
Key words: Wound pH, Goat collagen, Skin graft, Hydrogel, Growth factor
