Identification Of High-Quality Fat Based On Precision Centrifuging In Lipoaspirates Using Marker Floats

Background and Objectives:Soft tissue volume defects caused by surgery,trauma,disease,and aging can affect people's appearance and self-confidence,and often require plastic surgery to repair them.In recent years,autologous fat transplantation has been favored by more and more people.Its biocompatibility and effectiveness make it widely used in soft tissue volume filling.Although obtaining and transplanting of autologous fat is safe and simple relatively,its unpredictable absorption is still a problem that puzzles clinicians.Although the factors leading to different absorption have not been fully clarified,it is generally believed that the lack of standardized procedures is an important reason for the difference,especially in terms of adipose tissue processing.Recent studies have shown that adipose tissue will form a density gradient after centrifugation,and adipose tissue in the lower layer(with higher density)has a higher graft retention than adipose tissue in the upper layer(with lower density),which provides clinicians with a certain degree of judgement on the graft retention rate.However,research has found that adipose tissue is constantly reshaped in order to adapt to changes in metabolism and hormone levels in different individuals.Therefore,adipose tissue often possesses different characteristics in different individuals or at different stages of the same person,such as adipocyte size,SVF composition and ECM content.Therefore,we need a standard method to identify adipose tissue that is more suitable for transplantation in different individuals.In this study,we use glass marker floats combined with centrifugation technique to grade the adipose layer precisely.We hypothesized that glass marker floats can accurately distinguish adipose tissues of different densities,and thus determine the fat portion that is more suitable for transplantation.Based on the hypothesis,we established experiments in vitro and in vivo for verification.In the in vitro experiment,we compared the characteristics of adipose tissue in different density ranges and determined the dividing line with the most statistical difference.This grading line was used to distinguish the high-quality fat,which is more suitable for transplantation and the low-quality fat,which is less effective.In the in vivo experiment,we will further examine the transplantation effect of high quality fat(HQF)and low quality fat(LQF)Methods and materials1?Comparison of the characteristics of different adipose fractions.Five glass marker floats(0.925,0.930,0.935,0.940,and 0.945 g/ml)were added to the human lipoaspirates,and centrifuged at 1200 g for 3 minutes according to Coleman technical standards.After centrifugation,four parts of adipose tissue(0.925?0.930 g/ml,0.930?0.935 g/ml,0.935?0.940 g/ml and 0.940?0.945 g/ml)were divided according to the position of the marker float.Analysis were conducted on each adipose fraction.The best grading line between HQF and LQF was determined based on statistical results of the composition of SVF,the adipocyte size,and the ECM content.2?Comparison of long-term survival between HQF and LQF.HQF and LQF were transplanted into Nude mice respectively,and Coleman fat was considered as a control group.The volume retention of each group was evaluated and grafted fat adipogenesis and angiogenesis were investigated.Results:1.The centrifuged adipose tissue showed significant differences in SVF cells,ADSCs,ECM content and fat cell size with a boundary of 0.935 g/ml.Therefore,we define adipose tissue>0.935 g/ml as HQF and<0.935 g/ml as LQF.Compared with LQF,HQF contains more SVF cells,ADSCs and ECM.In addition,HQF has significantly smaller adipocyte sizes than LQF.2.At 12 weeks after transplantation,HQF grafts retain larger volumes than LQF grafts.The adipogenic genes PPAR-? and angiogenic genes VEGF of HQF grafts were significantly higher than those of LQF grafts from 1 to 4 weeks after transplantation.ConclusionGlass marker float combined with centrifugation can be used to grade lipoaspirates accurately.HQF contains more stromal vascular fraction cells,extracellular matrix content and small adipocytes,leading to a highest implant volume retention,while LQF contains more fragile large adipocytes,leading to the least volume retention.Marker floats can be used to grade the density of lipoaspirates,with a fat>0.935 g/ml recommended as a suitable alternative for implantation.