A. A. Gassman1, M. Lewis2, J. C. Lee1 1University Of California – Los Angeles,Surgery/ Plastic Surgery,Los Angeles, CA, USA 2West Los Angeles VA,Pathology,Los Angeles, CA, USA
Introduction:
Fat grafting has become a useful adjunct in the reconstructive surgeon’s treatment armamentarium. Inconsistencies in transfer and local ischemia prior to the development of recipient circulation all contribute to highly variable long-term results associated with fat grafting. Remote Ischemic Preconditioning (RIPC) is a cheap non-invasive technique that has been used in several animal models and multicenter clinical trials to protect several organ systems. The specific aim of this project was to analyze the volume retention of lipoaspirate transferred in the setting of either donor or recipient RIPC.
Methods:
We obtained subcutaneous adipose tissue from FVB mice transgenically engineered to express eGFP and Luciferase. These samples were obtained either with or without the use of temporary hindlimb tourniquet time prior to harvest. The samples were excised and passed to through serially smaller lipoaspiration cannulas (16 to 19 gauge), centrifuged (500g for 2 min), and decanted. The treatment and control fat was injected into the dorsal skin folds of genetically identical FVB mice that did not express GFP or Luciferase. The viability and volume of the transferred tissue was examined over a 28-day time period by bioluminescence after intraperitoneal injection of Luciferin using a Maestro IVIS optical small animal scanner. Additionally, after experimental completion the tissue transferred was explanted and examined histologically. The specimens were stained with H&E, CD31, CD34, and GFP.
Results:
Bioluminescence was able to non-invasively track the presence of transferred lipoaspirate tissue over a 28 day time period. There was a significant difference in bioluminescence and calculated graft volume at Day 0 and 28. The RIPC group demonstrated approximately 700% and 400% increase over control at each time point, respectively. Histological analysis at 28 days confirmed the presence of donor adipocytes, and that they were gradually replaced by recipient inflammation and scar tissue. However the amount of interstitial fibrosis was substantially less in the RIPC group. Additionally, the RIPC group retained a substantially greater amount of GFP suggesting retention of donor cells. The control tissue demonstrated increased CD31 and CD34 suggesting increased vascularity.
Conclusion:
This work has achieved two goals. Firstly, It demonstrates that the bioluminescence of adipocytes transferred from a luciferase expressing donor may be used to non-invasively monitor tissue viability and volume over a prolonged period of time. Secondly, RIPC has the ability to increase the viability of donor adipocytes when transferred via liposuction cannula, and the transferred tissue is less likely to undergo interstitial fibrosis.