PEG-Plasma Hydrogels Increase Epithelialization Using A Human Ex Vivo Skin Model
Randolph Stone, II, John Wall, Kyle Florell, Shanmugasundaram Natesan, Robert Christy.
US Army Institute of Surgical Research, Fort Sam Houston, TX, USA.
Background: Ex vivo wound healing models are an alternative to in vitro cell culture and are better at investigating proliferation, differentiation, and migration of cells in their natural three dimensional environment. The purpose of this study was to establish an ex vivo model from discarded human skin to evaluate therapies aimed at improving wound healing. Methods: An 8-10 mm biopsy “wound” was created in the center of a 6-well insert sized piece of discarded skin and incubated with media maintained at the epidermal/dermal border to keep the epidermis air exposed. Three hydrogels [collagen, polyethylene glycol (PEG)-fibrin, or PEG-plasma] were tested in the wounds. Microscopy images were captured to measure the epithelialization. After 14 days, the tissue was fixed and stained for cytokeratin 10 (CK-10), alpha smooth muscle actin (α-SMA), and wheat germ (WG). Results: Collagen treated wounds resulted in minimal cellular proliferation and migration. The PEG-plasma hydrogel treated wounds epithelialized faster than other groups at days 8, 11, and 14 (76.8, 90.7, 97.4 vs. 34.1, 41.6, 54.9%, p<0.01, respectively vs. PEG-fibrin). Sections co-stained with WG and α-SMA indicated cells from the normal tissue had infiltrated and proliferated into the PEGylated hydrogels. On top of the PEG-plasma hydrogels, a 5-7 cell layer thick CK-10 positive stratified epidermis was observed. Conclusions: The PEG-plasma hydrogels allowed the wounds to epithelialize with a stratified epidermis at a faster rate than wounds treated with other biomaterials. Development of a practical ex vivo skin model is superior to other standard in vitro cell culture and can be used as a screening tool to study wound healing to minimize the number of animals used in research.
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