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.