Cryopreservation of mature human adipocytes - In vitro measurement of viability

Cryopreservation of fat grafts for autologous fat transplantation renders repeated harvesting procedures unnecessary. Anecdotic reports have been published, yet data about adipocyte survival are sparse. The beneficial effect of added cryoprotective agents (CPA) is known from other tissues but has not been investigated in adipocytes. Fat cells were harvested using the Coleman method (n = 24). Tests were done after 0, 2, 7, 14, and 30 days of cooling to -20 degrees C and -80 degrees C and after addition of various CPA. Analysis included cell stains, measurement of metabolic activity by MTT and XTT tests, and measurement of cell stability by assessment of extracellular glycerol-3-phosphate-dphydrogenase enzyme. After freezing, up to 92.7% of metabolic activity was lost, but the addition of CPA led to preservation of up to 54% of baseline activity. Also, lower storage temperature showed more cell destruction but yielded higher viability of the surviving cells. Our results implicate that the widely used practice of simple storage in a freezer leads to reinjection of nonviable tissue. Cell survival can be improved by addition of CPA.