Improved fat graft viability by delayed fat flap with ischaemic pretreatment.

The aim of this study was to investigate the efficacy of the delayed fat flap on viability and longevity of grafted fat in an animal model. Sixty New Zealand rabbits were used for the long-term study. In each animal, a U-shaped fat flap was raised randomly in the inguinal region on one leg and then resutured in place to delay the flap for ischaemic pretreatment. The contralateral inguinal region was left untreated as a matched control. At 12h after the delaying operation, vascular endothelial growth factor (VEGF) expression in the fat from both groups of 10 rabbits was assessed. At 3 weeks, fat grafts from both the pretreated and control inguinal regions were transferred into a pocket that had been created on each side of the dorsal midline of the rabbit. Ten rabbits were sacrificed at intervals of 1, 3, 6, 9 and 12 months after transplantation for gross and histomorphometric analysis. Results showed that VEGF protein level in the pretreated fat flaps was significantly higher than that in the controls at 12h after the delaying operation. The number of vessels was increased in pretreated groups at 1 month, but no significant difference observed between two groups at 3 months. Histomorphometric analysis showed that the capillary density of the fat grafts was significantly higher in the pretreated group than that in controls at 1 and 3 months, respectively (P<0.01). There was no statistical difference in fat graft size and weight between the pretreated and control groups at 1 and 3 months after transplantation (P>0.05). However, the fat grafts in control groups disappeared after 6 months, and those in the pretreated groups were still maintained up to 12 months. This study demonstrated that the pretreatment of fat tissues with ischaemia insult could be advantageous for their viability and longevity. These results encourage further studies on potential clinical application of this new and simple technique to enable long lasting results.