The Effects of Fat Harvesting and Preparation, Air Exposure, Obesity, and Stem Cell Enrichment on Adipocyte Viability Prior to Graft Transplantation

Abstract

Background: Adipocyte viability is affected by fat preparation and processing methods, but rigorous and objective studies of these relationships are lacking. Objectives: The authors conducted a comprehensive evaluation of variables affecting adipocyte viability prior to injection of fat at the recipient site. Methods: Lipoaspirates from 48 patients were processed by high or low vacuum pressure, decantation, electric or manual centrifugation, concentration with cotton gauze, washing, repeated syringe transfer, exposure to lidocaine, and exposure to air. The effects of these variables on adipocyte viability in vitro were ascertained with the MTT assay. The influences of patient obesity (ie, a body mass index [BMI] >30 kg/m 2 ) and enrichment with stem cells on adipocyte viability also were determined. Results: High vacuum pressure decreased adipocyte viability. Decantation yielded the highest cell viability, followed by washing, concentration with cotton gauze, and centrifugation. Exposure to concentrated lidocaine ambient air exposure, and transfer between syringes significantly decreased viability. Patient obesity was predictive of lower adipocyte viability regardless of processing method, whereas stem cell enrichment significantly improved viability (P < .0001). Conclusions: To maximize adipocyte viability, fat should be obtained with dilute local anesthetics and low vacuum pressure, and the lipoaspirate should be maintained in a closed system. To clear cellular debris and blood, the lipoaspirate should be prepared by washing, and the fat should be enriched with adipose stem cells. Decreased adipocyte viability should be expected when fat is harvested from patients with high BMIs.