Enhancement of Progenitor Cells by Two Step Centrifugation of Emulsified Lipoaspirates

Background: Adipose-derived stem cells (ASCs), endothelial progenitor cells (EPCs) and soluble factors jointly contribute to the regenerative effect of fat grafts. The nanofat grafting technique is a simple method to mechanically emulsify the lipoaspirate and increase the ASC yield in the lipoaspirate. In the present study, we evaluated our extended nanofat grafting method that includes two additional centrifugation steps and results in a lipoaspirate of low volume that we termed "lipoconcentrate". Furthermore, we investigated the oily fractions after centrifugation for its regenerative potential. Methods: Lipoaspirates of 20 healthy patients were collected and processed by emulsification and/or centrifugation. Six groups were created: native (not emulsified) fat, 1x centrifuged native fat, 2x centrifuged native fat, nanofat (emulsified), 1 x centrifuged nanofat and lipoconcentrate (=2x centrifuged nanofat). The oily phases after the centrifugation steps also were collected. Progenitor cells and protein levels of bFGF, IGF-1, MMP-9, PDGF-BB and VEGF-A were measured by flow cytometry and immunoassays, respectively. Results: Lipoconcentrate contained significantly higher numbers of ASCs and EPCs per gram when compared to all other fractions. No difference in the content of all five soluble factors between the groups was found. The oily phases after centrifugation showed none or very little numbers of ASCs, EPCs and none or very low levels of soluble factors. Conclusion: Centrifugation of emulsified lipoaspirates increases the progenitor cell count in the lipoaspirate. The oily phase after centrifugation of lipoaspirates may be disposable due to the little content of progenitor cells and soluble factors. Financial Disclosure Statement: None of the authors has a financial interest in any of the products, devices, or drugs mentioned in this manuscript Corresponding author: Norbert Pallua, M.D., Ph.D., Department of Plastic Surgery and Hand Surgery – Burn Center, University Hospital of the RWTH Aachen , Pauwelsstrasse 30 52074 Aachen, Germany. Phone: +49 241 8089701, Fax +49 241 8082448, email: npallua@ukaachen.de ©2018American Society of Plastic Surgeons

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