Regeneration pattern of blood vessels and nerves in cultured keratinocyte grafts assessed by confocal laser scanning microscopy.

Abstract

The aim of this study was to investigate the pattern of both neovascularization and reinnervation, and the relationship between the two processes, in keratodermal grafts, using confocal laser scanning microscopy, at different time points during the healing process. Keratodermal grafts were prepared in pigs by combining autologous dermis with cultured autologous keratinocytes. Immunohistochemistry was carried out on thick cryostat sections (100-150 microns), using antisera to the endothelial marker von Willebrand factor (vWf) and the pan-neuronal marker protein gene product 9.5 (PGP9.5). The results suggest that the neovascularization and reinnervation in the cultured keratodermal graft is almost complete at 6 weeks. Neovascularization precedes innervation, reaching the surface covered by the keratinocytes at 2 weeks, initially with a linear vascular pattern. From 3 weeks, there is a gradual arborization of the vessels to form a typical vascular plexus. The process of reinnervation is similar in pattern to that of neovascularization, although slower in developing a full network of fibres. In conclusion, the use of confocal microscopy allows the precise definition of complex patterns of neovascularization and nerve growth, which are not fully apparent when using conventional microscopy. Because angiogenesis occurs first, it probably plays a leading role in the survival of keratodermal grafts during wound healing. Indeed, new blood vessels form a pathway for the subsequent innervation process, and quickly reach the epidermal layer which, in turn, may play a key role in the tropism of both blood vessels and nerves.