Seeding of Dermal Substitutes with Glucose-Pretreated Nanofat Accelerates In Vivo Vascularization and Tissue Integration

The exposure of endothelial cells to high glucose concentrations promotes angiogenesis. The present study investigated whether this pro-angiogenic effect of glucose is suitable to improve the capability of nanofat to vascularize implanted dermal substitutes. Nanofat was processed from white adipose tissue originating from green fluorescent protein (GFP) C57BL/6J donor mice and incubated for 1 h in Hank's Balanced Salt Solution with or without (control) a high level of glucose (30 mM). The pretreated nanofat was seeded onto dermal substitutes, which were analyzed by intravital fluorescence microscopy, histology and immunohistochemistry in dorsal skinfold chambers of GFP C57BL/6J mice to assess their vivo performance over a period of 14 days. A high level of glucose-pretreated nanofat did not induce a stronger immune response when compared to the control. However, it improved the vascularization of the implants, as shown by a significantly higher density of blood-perfused microvessels in the border zones (~3.6-fold increase) and more CD31/GFP microvessels (~3-fold increase) inside the implants. Accordingly, high glucose-pretreated nanofat levels also enhanced the tissue integration of the dermal substitutes, as indicated by the deposition of more type I collagen (~2.9-fold increase). These findings suggest that the short-term exposure of nanofat to a high level of glucose represents a promising and clinically feasible strategy to enhance its regenerative properties when seeded onto dermal substitutes.