Soft Tissue augmentation is a commonly performed procedure in most plastic surgery practices. While no material is ideal for soft tissue augmentation, autogenous fat has many advantages over other materials: it is biocompatible, abundant, inexpensive, and potentially permanent. Unfortunately, its volume maintenance has proven unpredictable and temporary in most surgeon's experience. In an attempt to improve our knowledge of the grafting process, previous studies have evaluated the effects of cell culture media (Ullman 1998, Har-Shal 1999), harvest site (Rohrich 2004), growth factors (Yuksel 2000), postoperative hyperbaric oxygen (Chao 2000), recipient site vascularity (Baran 2002), and centrifugation force (Rohrick 2004). While these studies offer critical insights into the mechanisms of fat graft survival, the measured endpoints are often limited to graft volume, weight, and histologic stains.
Clinically, advocates of fat grafting have strong opinions regarding their personal methods for harvesting, processing, and injecting the fat, but frequently no scientific adapt exist to support the claims. Though good clinical results can be achieved, the underlying mechanisms that may enhance these results have not been methodically evaluated, and variability exists in the results that different surgeons achieve. Multiple variables exist in the fat grafting process; effects of refrigeration, regional variation of harvested fat, effects of cannula diameter, effects of various storage processes on fat (time, +/- exposure to air, oxygen rich storage media), effects of various negative pressures used to harvest fat, different processing techniques (centrifuge, straining, gentle spread over Telfa, washing), and effects of graft maintenance when combined with various FDA-approved growth factor containing media (platelet rich plasma, fibrin glue). To date no study has systematically evaluated each step of the fat grafting process.
The purpose of this study is to evaluate the safety and efficacy of several of the major variables in autogenous fat grafting using state-of-the-art immunohistochemistry and molecular biologic techniques, and to comprehensively evaluate the mechanisms that could contribute to the unpredicationle fate of the grafted fat. The aims of this study are to 1) evaluate the impact of tissue harvest and processing methods on cell viability , graft biology and long term survival; 2) evaluate the intrinsic differences in fat characteristics from different sites and correlate these differences with effect on graft maintenance; 3) evaluate the effects of refrigeration and air exposure on fat grafting as well as 3-D imaging. Immunohistochemistry and pathology includes techniques that can assess adipose cell morphology and survival, local hypoxia apoptosis, vascularization, and cell replication. The techniques proposed in this project have all been extensively utilized in our laboratory in our ongoing studies of adipose cell biology and autogenous fat graft physiology.
Page 2 Cont'
Autogenous fat grafting is a versatile, important tool in the armamentarium of the plastic surgeon; and experimentation to improve clinical efficacy and safety is the primary objective of this project. To date the majority of experience in autologous fat grafting is anecdotal. The mechanism of fat grafting has not been comprehensively and methodically evaluated using current Immunohistochemistry and molecular biology techniques. This study intends to evaluate the safety and efficacy of the commonly described variables in autogenous fat grafting. Through the use of these established experimental techniques, our understanding of fat grafting will be significantly advanced and will result in increased safety and efficacy of this procedure.