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Centrifugation Compared To A Combined Mesh/telfa Technique For Fat Grafting: Mechanism, Outcomes And Effect On ADSCs
Harry M. Salinas, MD, Felix Broelsch, MD, Justin Fernandes, MD, Saiqa Khan, MD, Michael C. McCormack, MBA, Amanda Meppelink, BSc, Mark Randolph, MSc, William G. Austen, Jr., MD.
Massachusetts General Hospital, Boston, MA, USA.
Purpose: Fat grafting involves lipoaspirate harvest, isolation of adipocyte fraction, and subsequent injection of processed fat. Centrifugation is cumbersome and the mechanism by which it improves outcomes remains unclear. Hypotheses include fat concentration, reduction of inflammatory response by removal of nonviable components and concentration of adipose-derived stem cells (ADSCs). We performed a series of experiments to compare the process of centrifugation to a faster, simpler, processing method that combines mesh and telfa techniques.
Methods: The mesh/telfa technique involves placing lipoaspirate on a 0.149mm nylon mesh, which sits on top of a thick layer of gauze. A 1:1 wash is performed with normal saline. Tumescence and debris are absorbed by the gauze through capillary action.
Lipoaspirate was collected from nine females. In-vitro experiments included: 1.Quantification of lipoaspirate components by centrifugation at increasing speeds, 2.Quantification of components after processing with mesh/telfa, 3.Quantification of ADSCs in fat after centrifugation at 1,200g and mesh/telfa technique. ADSCs were identified as CD90/73+ and CD105/45- by FACS analysis of the stromal vascular fraction.
In-vivo experiments were performed by grafting 1g aliquots into the flank of nude mice and harvesting after 4-6 weeks. Experiments included: 1.Graft survival at increasing centrifugation speed, 2. Survival of fat graft only and fat grafts mixed with various spin-off products, 3.Graft survival after centrifugation at 1,200g and mesh/telfa. End-points included weight and histology.
Results: In-vitro: The infranatant remains constant above 1,200g. Oil separate out at 1,200g and increased linearly with higher speeds. The volume of fat remained constant above 5,000g. High-speed centrifugation of fat previously processed with mesh/telfa results in 90% fat and 10% infranatant. The total number of ADSCs in one gram of centrifuged fat was 1,603±2020 and 1,857±1832 cells in the mesh/telfa grafts. (p = 0.86).
In-vivo: Weight at explantation after centrifugation at 50g, 1,200g, 5,000g, 10,000g, 23,000g were 0.58±0.11, 0.68±0.09, 0.72±0.13, 0.81±0.19, and 0.76±0.09 grams respectively. Histologically, 5,000g samples appeared healthiest with reduced injury. Five “add-back” groups were tested: 1.Fat plus oil, 2.Fat plus surgical tumescence, 3.Fat plus fresh tumescence, 4.Fat plus cell pellet and fresh tumescence, 5.Fat plus cell pellet. There were statistically significant differences between the fat only group (0.66 g ± 0.08) and groups mixed with tumescence (Groups 2-4: 0.56±0.12, 0.58±0.09, and 0.50±0.11 grams). Mixing with oil did not affect graft take (0.62±0.08 grams). In fact, fat plus oil superior histology scores, similar to control. Graft weight and histology after centrifugation at 1,200g and mesh/telfa was equivalent (0.73±0.12 and 0.72±0.13 grams).
Conclusion: The fat volume remains constant after 5,000g. Fat isolated by increasing centrifugation results in a linear increase in graft take up to 10,000g. The mesh/telfa technique results in similar fat graft volume, while the washing step removes blood and cellular components. ADSC content is equivalent after both processing techniques. The add-back data suggests that the mechanism by which centrifugation improves graft take is concentration of fat. Fat processed by the mesh/telfa technique results in equivalent results without a costly and time-consuming centrifuge.
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