A high-throughput model for fat graft assessment.

BACKGROUND AND OBJECTIVES

Current fat-graft animal models require weeks, to months, for results. The purpose of this study was to develop a model for the rapid identification of adipocyte protectants, using apoptosis-specific fluorescence. The goal of our model was to predict long-term fat graft survival within a 10-day period.

STUDY DESIGN/MATERIALS AND METHODS: Human fat was obtained from liposuction aspirates, washed with saline, and centrifuged at 200g. The fat was then treated with one of four agents: P188, polyethylene glycol (PEG 8000), lipoic acid (LA), or saline control. Fat lobules were explanted over a 10-day period, and then at six weeks. The explanted fat was measured for apoptosis. Samples were weighed, sent for histology, measured for DNA content, and examined using confocal microscopy.

RESULTS

Fat-grafts demonstrated variable apoptosis over the 10-day period. P188 and LA treated samples demonstrated 11-28% less apoptosis during early engraftment than saline treated controls. This early reduction in apoptosis correlated to a approximately 20% reduction in reabsorption by weight six weeks later. P188 and LA samples demonstrated three-times higher DNA content by PICO green analysis when compared to saline controls. PEG 8000 treated samples demonstrated 11% more apoptosis than saline. PEG 8000 treated samples demonstrated an approximately 10% higher level of reabsorption by weight, and two-times higher levels of DNA. Histology of treated samples at six weeks showed architecturally normal fat in P188 and LA treated fat; whereas PEG 8000 had high levels of inflammatory infiltrates, and saline had large amounts of fibrosis.

CONCLUSIONS

This model of fat-grafting and early apoptosis can be used to screen agents and grafting methods and predict long-term graft survival. We show that levels of apoptosis within ten days correlate with weight, DNA, and histology, at six weeks. Using this model, long-term adipocyte survival and graft take can be predicted during the first 10 days post-implantation.