An alternative method for harvest and processing fat grafts: an in vitro study of cell viability and survival.

Background: Adipocyte viability has been emphasized as essential for fat graft survival. There is no universal agreement on the methodology for handling fat grafts.

Objective: Two different methods of fat harvesting and techniques of tissue processing were compared by assessing cell viability, damage, and growth in vitro.

Method: Fat was harvested from Zucker rats (n = 5) using (1) a 3-mm liposuction cannula with a 60-cc syringe (right side) or (2) a 2-mm blunt needle with a 10-cc syringe adapted to a fine-needle aspiration apparatus (left side). Tissues were then processed by decantation or cotton towel drying. Five samples for each of the four techniques were studied. Fat samples were processed for culture, and adipocytes and preadipocytes were plated in culture medium and expanded in vitro. Cell viability was assessed using cell counts, the MTT proliferation assay, G3PDH activity, and Oil Red O stain.

Results: Method 1 exerted significantly higher pressure (p = 0.009) than method 2 (643 +/- 2.5 versus 537 +/- 13.6 mm Hg). A larger oil layer was apparent with method 1 (1.11 +/- 0.29 g) than with method 2 (0.56 +/- 0.28 g). In addition, the highest number of viable preadipocytes was obtained using method 2B (p = 0.017). In culture, preadipocytes plated in 4F differentiation medium started to differentiate after 1 week, while those in Dulbecco's modified Eagle's medium/F12 with serum proliferated but did not differentiate. Mature adipocytes in adipogenic medium dedifferentiated and later redifferentiated into fat cells.

Conclusions: Fat viability was better when fat was harvested by fine-needle aspiration. The plasticity of mature adipocytes and preadipocytes in vitro suggested that both might be involved in fat graft integration.