Enhancement of Progenitor Cells by Two-Step Centrifugation of Emulsified Lipoaspirates.

BACKGROUND: Adipose-derived stem cells, endothelial progenitor cells, and soluble factors jointly contribute to the regenerative effect of fat grafts. Nanofat grafting emulsifies the lipoaspirate and increases the progenitor cell yield. In the present study, the authors evaluated their extended nanofat grafting method that includes two additional centrifugation steps and results in a lipoaspirate of low volume that they termed "lipoconcentrate." Furthermore, the authors investigated the oily fractions after centrifugation for their regenerative potential. METHODS: Lipoaspirates of 20 healthy patients were processed by emulsification and/or centrifugation. Six groups were created: native (not emulsified) fat, 1× centrifuged native fat, 2× centrifuged native fat, nanofat (emulsified), 1× centrifuged nanofat, and lipoconcentrate (i.e., 2× centrifuged nanofat). The oily phases after the centrifugation steps were collected. Progenitor cells and basic fibroblast growth factor, insulin-like growth factor 1, matrix metalloproteinase-9, platelet-derived growth factor-BB, and vascular endothelial growth factor-A levels were measured by flow cytometry and immunoassays. RESULTS: Lipoconcentrate contained significantly higher numbers of adipose-derived stem cells and endothelial progenitor cells per gram compared with all other fractions. No difference of all five soluble factors between groups was found. The oily phases after centrifugation showed no or very few adipose-derived stem cells and endothelial progenitor cells, and no or very low levels of soluble factors. CONCLUSIONS: Centrifugation of emulsified lipoaspirates increases the progenitor cell count in the lipoaspirate. The oily phase after centrifugation of lipoaspirates may be disposable because of the minuscule content of progenitor cells and soluble factors.