Improving Low-Density Fat by Condensing Cellular and Collagen Content through a Mechanical Process: Basic Research and Clinical Applications

Abstract

Background: Large-volume fat grafting results in high absorption and complication rates. Low-density fat includes small numbers of viable cells and considerable oil, resulting in nodules and oil cysts. This study evaluated a strategy for large-volume fat grafting using a mechanical process to condense low-density fat and transplanting it with high-density fat. Methods: Low-density fat, defined as the upper half of centrifuged lipoaspirates, was emulsified by intersyringe shifting and centrifuged to obtain condensed low-density fat. Fresh condensed low-density fat was analyzed by counting cells in the stromal vascular fraction, and by electron scanning and Western blotting. The retention rate and histologic changes of the product were analyzed using a fat grafting model in nude mice. Transplantation with a combination of condensed low-density fat and high-density fat was tested in patients undergoing breast reconstruction and breast augmentation. Results: The condensed low-density fat derived from low-density fat contained a large number of stromal vascular fraction cells and collagens, comparable to that of high-density fat and much higher than in low-density fat and Coleman fat. Retention rates 12 weeks after transplantation were higher for condensed low-density fat (55.0 ± 7.5 percent) than for low-density fat (31.1 ± 5.7 percent) and Coleman fat (41.1 ± 6.8 percent), with condensed low-density fat having fewer oil cysts and lower macrophage infiltration. Patients grafted with combined condensed low-density fat and high-density fat showed good long-term volume retention. Conclusions: Using mechanical methods to condense low-density fat to a level comparable to that of high-density fat is a practical method of improving fat graft retention and avoiding severe complications. This new strategy may improve the quality of lipoaspirates for patients requiring large-volume augmentation.