A high-throughput model for fat graft assessment

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.

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.

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.

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.