Optimizing fat grafting in an in vivo tissue engineering chamber model.

PURPOSE : Autologous fat grafts are used in various body contour procedures, such as breast reconstruction.  The mechanisms involved are however unclear and clinical outcome can be variable.  One of the main concerns is tissue resorption over time, raising questions of sustainability.  The aim of this study is to gain insights in fat grafting and to improve long term outcome.

METHODOLOGY : An arteriovenous loop, microsurgically created from the femoral vessels, is positioned inside a 2ml hemispheric perforated chamber in rats.  1mL minced autologous fat, a novel adipose derived matrix (ADM) or a combination of both is inserted within a groin chamber made of either polycarbonate or a biodegradable material.  The constructs were morphologically and histologically examined at 6 and 12weeks. (n=6, for all groups)

RESULTS : In groups where fat alone was used, the volume of grafted tissue remained stable at 6 weeks, but most of the inserted fat cells appeared non-viable.  In all groups, neo-adipogenesis took place between 6 and 12weeks.  In terms of fat percentage, the ADM group showed similar results to fat whereas combining both resulted in significantly better results at 12weeks (double to triple as much fat).  The results were even more remarkable where the biodegradable chamber was used; it was completely filled with vascularised viable fat (images).

CONCLUSION : The mechanisms behind fat grafting seem to be based on regeneration of fat, likely from adipose stem cells.  At 12 weeks, excellent adipogenesis  was seen when ADM was added to fat, in contrast to fat or ADM alone.  Furthermore, adipogenesis was enhanced in the biodegradable chamber.  We believe that the use of ADM has a great potential in fat grafting, particularly in ensuring long term graft viability.