Transplantation of acellular dermis and keratinocytes cultured on porous biodegradable microcarriers into full-thickness skin injuries on athymic rats.

In search of an optimal transplantation regime for sufficient dermal and epidermal regeneration after a full-thickness skin injury, wounds on athymic rats were grafted with split-thickness skin grafts or acellular human dermis followed by transplantation with human keratinocytes either in single-cell suspension or cultured on porous biodegradable microcarriers. After 2 weeks, all wounds grafted with acellular human dermis showed a well organised and vascularised dermal component and reepithelialisation on the grafted dermal matrix was complete 21 days after transplantation with human keratinocytes. Wounds grafted with human keratinocytes seeded on biodegradable microcarriers or split-thickness skin grafts displayed over time (i.e. 16-21 days post-transplantation) a significantly thicker epithelial cell layer in comparison to wounds grafted with keratinocytes in single-cell suspensions or microcarriers not seeded with cells. Furthermore, measurements of dermal thickness in the closed wounds 21 days after grafting showed a significantly thicker and well organised neodermal component in wounds transplanted with keratinocytes seeded on microcarriers or split-thickness skin grafts compared to all other wounds. Positive immunostaining towards von Willebrand factor revealed the plausible proangiogenic effects of transplantation with keratinocytes seeded on microcarriers. Analysis of representative tissue sections after fluorescence in situ hybridisation visualised that grafted human keratinocytes were present in the epidermal layers covering the wounds 16 and 21 days after transplantation, strongly indicating preservation of cell viability. These results shows that the use of biodegradable microcarriers in the culture of autologous keratinocytes for treatment of full-thickness wounds not only facilitate the cultivation, transportation and transplantation processes but also enhances the dermal regeneration induced by a dermal scaffold which results in a clinical result that is significantly superior to the one obtained when keratinocytes are transplanted in a single-cell suspension.