Abstract

Introduction: Burn injuries have been seen in increasing frequency and severity in our military personnel, and comprise 5-10% of all military casualties. Recent advances using adipose derived stem cells to produce “skin equivalent” autografts have allowed patients with large burn injuries to receive autografts engineered from normally discarded adipose tissue following debridement, yet techniques to enhance revascularization of the graft are still limited. Purpose: Evaluate the growth and stability of vascular elements within a bilayer gel composed of adipose derived stem cells when exposed to the locally released extracellular growth factor VEGF. Methods: Bilayer gels composed of adipose derived stem cells embedded within a PEGylated fibrin gel and layered with either de-cellularized human amniotic membrane or collagen gel and seeded with keratinocytes. Revascularization success was evaluated at the end of a two-week incubation period by histological analysis and immunocytochemical staining. Results: Cells were verified as stem cells prior to incubation based on immunocytochemical staining for stem cell positive markers (Figure 1). Light photomicrographs of cell cultures on different days show growth of three dimensional microvascular networks in bilayer gels comparable to that of controls (Figure 2, 4). Vascular growth is confirmed by immunocytochemical staining of endothelial specific von Willebrand factor, CD31 and vascular specific alpha smooth muscle actin. Conclusion: Mature vascular networks were shown to grow in the presence of epidermal equivalents and growth factors released locally by keratinocytes with results comparable to that of controls. Further research into the stability and longevity of these vascular networks is necessary to determine the best epidermal equivalent to employ for autografts in patients.