Identification of the Centrifuged Lipoaspirate Fractions Suitable for Postgrafting Survival

Background: The Coleman centrifugation procedure generates fractions with different adipocyte and progenitor cell densities. This study aimed to identify all fractions that are feasible for implantation. Methods: Human lipoaspirates were processed by Coleman centrifugation. The centrifugates were divided arbitrarily into upper, middle, and lower layers. Adipocyte viability, morphology, numbers of stromal vascular fraction cells, and adipose-derived mesenchymal stem cells of each layer were determined. The 12-week volume retention of subcutaneously implanted 0.3-ml lipoasperate of each layer was investigated in an athymic mice model. Results: Most damaged adipocytes were located in the upper layers, whereas the intact adipocytes were distributed in the middle and lower layers. A gradient of stromal vascular fraction cell density was formed in the centrifugates. The implant volume retentions of samples from the upper, middle, and lower layers were 33.44 5.9, 55.11 +/- 4.4, and 71.2 +/- 5.8 percent, respectively. Furthermore, the middle and lower layers contained significantly more adipose-derived stem cells than did the upper layer. Conclusions: The lower layer contains more viable adipocytes and stromal vascular fraction cells leading to the highest implant volume retention, whereas the most impaired cells are distributed in the upper layer, leading to the least volume retention. Although with a lower stromal vascular fraction content, the middle layer has a substantial number of intact adipocytes that are capable of retaining partial adipose tissue volume after implantation, suggesting that the middle layer may be an alternative fat source when large volumes of fat grafts are needed for transplantation.