Discussion: Mechanical Micronization of Lipoaspirates: Squeeze and Emulsification Techniques.

www.PRSJournal.com 91 T authors conducted a study in which two mechanical lipoaspirate micronization techniques were compared. The squeezing technique consisted of fragmenting centrifuged fat with an automated slicer, and the emulsification technique consisted of repeatedly transferring centrifuged fat between two syringes through a small-hole connecter and filtering it through a gravitational mesh. Partial removal of largediameter adipocytes and hematopoietic cells was obtained with both techniques, and viable adipose stromal vascular cells were retained. The authors underlined the clinical relevance of these processing techniques where, depending on the extent of adipocyte removal, the obtained product could be used for tissue volumization or therapeutic revitalization/fertilization of pathologic conditions. This study is certainly interesting; however, we must make some clarifications. The authors referenced our article on nanofat grafting1 when describing their emulsification technique, whereas our nanofat emulsification protocol was completely different. First, in this study, the lipoaspirate was centrifuged before undergoing the micronization process. In our protocol, the lipoaspirate was not centrifuged before being transferred into the syringes. Second, the centrifuged fat was transferred between two Luer-lock syringes joined by a connector with three small holes (Transfer Emulsifier; Tulip Medical, San Diego, Calif.). We do not use this connector, as it is often difficult for the lipoaspirate to pass through very small holes because of the fibrous nature of the fat encountered in many patients. As shown in Supplemental Digital Content 2 in the authors’ article, there was quite some force applied at the first passages of the fat through the connector when performing the emulsification technique. In our protocol, the lipoaspirate was shifted between two syringes joined by a female-to-female Luer-lock connector. Third, the emulsified fat was centrifuged (representing a second centrifugation of the lipoaspirate), which was not included in our protocol. Fourth, after centrifugation, the remainder of the product was separated by decanting filtration through a stainless steel mesh with a 500-μm pore size (Tokyo Screen, Tokyo, Japan) to generate filtrated fluid of emulsified fat and residual tissue of emulsified fat. In contrast, we filtered the emulsified fat over a nylon fabric with an approximately 500-μm pore size to get rid of any fibrous tissue that could eventually clog a 27-gauge needle. From the two products obtained with the emulsification process, the residual tissue of emulsified fat closely resembled our product, termed nanofat, used clinically, with the exception that the residual tissue of emulsified fat contained fibrous fatty tissue remnants that would clog small needles and prevent us from injecting it intradermally. Although the analysis of the cellular content of the different processed lipoaspirates in this study is convincing, the link to clinical applications is a topic open for discussion. Our final product, as described previously in our nanofat grafting technique, is a liquid fat emulsion with a reduced number of adipocytes and a limited filling capacity. However, the clinical results observed (notably, the improvement in skin quality and elasticity when injected intradermally) may be attributable to the large number of good-quality stromal vascular cells isolated from the nanofat sample. Recent studies on fat emulsification techniques, with slight differences in the protocols, confirmed and supplemented our previous findings.1 The mechanical procedure of shuffling the lipoaspirate up to 30 times facilitated controlled fat injection without compromising graft viability.2 There was no impact on the stromal vascular