The search for a useful method for the optimal cryopreservation of adipose aspirates: part II. In vivo study.

PURPOSE The previous in vitro study showed that trehalose, when used as a cryoprotective agent (CPA) in an optimal concentration, can provide adequate protection of adipose aspirates during cryopreservation. OBJECTIVE The authors evaluated the efficacy of trehalose in its optimal concentration for cryopreservation of human fat grafts in a well-established animal model. METHODS In this study (n = 20 in each group), adipose aspirates were harvested and processed from a female patient; the protocol for freezing and thawing of fat grafts was the same as the in vitro study. In the control group, 0.5 mL of fresh fat grafts was injected into the posterior scalp of a nude mouse. In the cryopreservation group 1, a combination of dimethyl sulfoxide (in 0.5M) and trehalose (in 0.2M) was injected as a CPA. In the cryopreservation group 2, only the optimal concentration of trehalose (in 0.35M) was administered as a CPA. In both cryopreservation groups, 0.5 mL of cryopreserved fat grafts was thawed and injected into the animal in the same manner as the control group. All animals in each group were observed for gross appearance of maintained fat grafts over their posterior scalps for up to eight weeks. The final volume and weight of maintained fat grafts and their histology were evaluated at the end of the study. RESULTS Group 2, compared with group 1, respectively, had equivalently maintained volume (38.2 +/- 10.1% versus 46.1 +/- 14.4%, ns) and weight (34.1 +/- 12.1% versus 38.9 +/- 14.7%, ns). However, the results from both cryopreservation groups were still inferior to those from the control group (both P < .05). Histologically, the basic structure of adipose tissue was maintained in all three groups. CONCLUSION Trehalose, serving as a CPA in its optimal concentration, appears to provide adequate protection of human fat grafts during cryopreservation in vivo. Such protection is similar to that provided by the combination of dimethyl sulfoxide and trehalose as a CPA. Because of its safety and effectiveness, trehalose can possibly be administered to patients for long-term preservation of their fat grafts.