Does Supplementing Adipose Tissue with Regenerative Cells Really Make a Difference in Comparison to Conventional Fat Grafting?

Goals/Purpose: Given the wide application of autologous fat grafting and the growing interest in regenerative medicine, approaches to supplement fat grafts with adipose-derived stem cells (ASCs) are evolving in hopes of promoting vascularization and neoadipogenesis. This new emphasis on fat processing techniques has emerged in an effort to decrease the degree of resorption often seen and to obtain better results when performing fat grafting in challenging cases such as delayed wound healing and radiation fibrosis. Therefore we aimed to compare cell-supplemented lipotransfer with conventional fat grafting and evaluate the outcomes of these grafts to determine which method leads to higher percentage of graft retention and better quality graft.

Methods/Technique: Adipose tissue was prepared using four techniques: decantation, washing, high-speed centrifugation and cell-enrichment (after obtaining adipose-derived cells by enzymatic digestion). The morphology and quantity of adipocytes with each method were determined by histological analysis. The viability and number of ASCs were obtained by flow cytometry. Subsequently, a total of 32 subcutaneous injections of processed human lipoaspirate were carried out in eight athymic rats, each animal receiving four different conditions, in a random fashion, and followed for 12 weeks. Evaluation of graft survival included serial measurements of volume retention and histological analysis.

Results/Complications: Cell count per high-powered field of intact nucleated adipocytes was significantly greater in decanted lipoaspirates, whereas centrifuged samples showed a greater majority of altered adipocytes. ASCs concentration was significantly higher in washed lipoaspirates compared to decanted and centrifuged samples taken from the middle layer. However, the pellet collected at the bottom of the centrifuged samples showed the highest concentration of ASCs. At 12 weeks, cell-supplemented and centrifuged grafts showed consistent volume maintenance. Based on histological analysis, cell-supplemented and washed grafts had higher scores of viability and vascularity, with the former presenting fewer cystic necrosis, minimal inflammation and least calcification.

Conclusion: Graft retention is a strong indicator of long term survival of fat grafts. Viability and vascularity are also critical indicators of the long term survival of fat grafts. Cell-supplemented lipotransfer had optimal outcomes when evaluated based on these criteria, while washing resulted in high viability with a less intensive process, and high-speed centrifugation resulted in consistent volume retention but lower viability. These approaches offer distinct advantages making them ideal under different circumstances and contribute to the versatility and reliability of fat grafting. When using fat grafting in challenging cases such as radiation fibrosis and delayed wound healing or severe scarring tissue, viability and vascularity play an even bigger role in the long term survival of these grafts. Therefore, cell-supplemented lipotransfer might be a better choice to further improve the quality of the graft in these challenging cases.