Blood Impairs Viability of Fat Grafts and Adipose Stem Cells: Importance of Washing in Fat Processing.

BACKGROUND Fat processing plays a pivotal role in graft survival. Each component of the blood in lipoaspirate affects fat survival in different manners, but the mechanisms are not clear. OBJECTIVES The authors performed multiple experiments to investigate the effect of blood on the viability of fat grafts and adipose stem cells. METHODS Blood and fat samples were obtained from 6 female patients undergoing aesthetic liposuction. For the in vivo experiment, we compared fat mixed with normal saline or various ratios of blood in nude mice. The samples were explanted at 2 and 8 weeks to evaluate the gross volume retention and histologic and immunohistochemical characteristics. For in vitro experiments, adipose stem cells were pretreated with hemoglobin at different concentrations and for different times. Then we assessed the proliferation, migration, adipogenesis, and reactive oxygen species production of adipose stem cells. RESULTS Blood in the graft led to a decrease in graft viability, as evaluated by general observation and histologic and immunohistochemical morphology in vivo. In vitro experiments showed an inhibited proliferation, migration, and adipogenesis and an increased reactive oxygen species production in adipose stem cells after hemoglobin treatment, suggesting impaired adipose stem cell viability. CONCLUSIONS This study suggests that blood impairs the viability of fat grafts and adipose stem cells and provides evidence that washing to remove blood is important in fat processing.