Cool Fat, Hot Topic: A Systematic Review on Cryopreservation of Adipose Tissue.

Autologous fat grafting is increasingly used in plastic, reconstructive, and esthetic surgery. Cryopreservation offers a promising solution for the long-term storage of adipose tissue, enabling multiple grafting sessions while minimizing patient discomfort associated with repeated liposuction for fat harvesting. This systematic review aims to analyze the current literature focusing on factors that influence the outcome of cryopreservation, including the use of cryoprotectants, the cooling and warming rate, the storage temperature, and the enrichment of cryopreserved fat grafts. A systematic search of the PubMed/MEDLINE database up to November 2024 was performed, including original preclinical and clinical studies written in English describing the cryopreservation of unprocessed or mechanically processed adipose tissue (macrofat, microfat, or nanofat). Eligible articles needed to describe the applied cryopreservation protocol, at least the storage temperature. Studies on cryopreservation of adipose-derived stem cells (ASCs), stromal vascular fraction, microvascular fragments, and other isolated components of adipose tissue were excluded. Data on cryoprotectants, cooling and warming rates, storage temperature, and eventual supplementation or enrichment of frozen fat were collected. Of the 679 records identified, 59 met the inclusion criteria. Adipose tissue cryopreservation at -80°C with a cryoprotectant, controlled slow cooling, and fast warming represented the most often applied protocol with encouraging outcomes in maintaining tissue survival and histological structure. Several studies indicated that the supplementation of frozen adipose tissue with ASCs improves tissue survival. Taken together, existing studies present diverse, and to some extent, conflicting results regarding cryopreservation protocols and their effects on adipose tissue viability. Hence, the ideal cryopreservation protocol for autologous fat remains to be established. Moreover, tailored protocols may be necessary for the cryopreservation of fat derivatives, such as nanofat.