Effects of Frozen Stromal Vascular Fraction on the Survival of Cryopreserved Fat Tissue

BACKGROUND: Nowadays, the use of cryopreserved fat tissue for soft tissue augmentation is common, except for its unpredictable fat graft absorption, and the toxicity of the cryoprotective agent remains a limitation. In this study, the effects of freezing stored fat tissue without a cryoprotector, and the addition of the stromal vascular fraction (SVF) on the survival of cryopreserved transplants was studied. METHODS: Lipoaspirates from six donors were processed and cryopreserved at − 20 °C, − 80 °C and − 196 °C, respectively. The authors evaluated the lipoaspirates in vitro, on the basis of fat tissue and SVF viability after cryopreservation. In vivo fat grafting was performed in nude mice. Six trenches were injected on the backs of mice. Cryopreserved tissues (− 20 °C, − 80 °C and − 196 °C) were injected on the right side, and the other side received the SVF combination. At 4 and 8 weeks after transplantation, the authors examined the weight, volume and morphology of the tissue and analyzed histochemical staining and immunohistochemistry (i.e., DIL, CD31 and VWF) to evaluate the survival of the fat grafts. RESULTS: After cryopreservation without the cryoprotective agent, adipose tissue maintained its morphology better in − 80 °C than − 20 °C and − 196 °C. SVF cells can retain their adhesive and proliferative properties after cryopreservation. Although cryopreservation caused damage to fat tissue, all explants showed intact adipocytes and vascular ingrowth. Most of all, the − 80 °C group had less graft resorption and fibrosis than the other temperature groups. There was increased survival of fat grafts in the SVF group compared with the control group. CONCLUSION: In this study, the authors demonstrated that the storage temperature of − 80 °C was promising for 3 months of adipose tissue cryopreservation without a cryoprotective agent, and SVF could increase the survival rate of cryopreserved fat tissue. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266.