An Update on Cryopreservation of Adipose Tissue.

Abstract

Sir: We read with great interest the study published by Gal and Pu entitled, “An Update on Cryopreservation of Adipose Tissue” (Plast Reconstr Surg. 2020;145:1089–1097).1 The authors want to provide the best cryopreservation protocol based on their research and a literature review based on recent works on the subject. We would like to discuss some points on which our opinion diverges with this considerable special topic. First, the authors claim that cryopreservation is a technique that will avoid multiple fat grafting procedures to complete reconstruction. This technique should reduce health-related costs. This is questionable, because decreasing costs of operations will be counterbalanced by the expenses of structures allowing cryopreservation, identical to those of cell therapy units. This will represent a major obstacle in coming decades. Furthermore, regarding the cryopreservation protocol, our results were different from those of the authors.2 We had highlighted the superiority of a long-term cryopreservation with a temperature storage of −80°C, with the use of a cryoprotective solution of 5% dimethylsulfoxide as intracellular cryoprotectant, and the 95% of hydroxyl ethyl starch as extracellular cryoprotectant. This is in contradiction with the authors’ protocol. Moreover, our in vivo analysis showed that adipose tissue grafted after cryopreservation was resorbed at a higher rate as compared with fresh adipose tissue, which is not surprising because it is the principle of the treatment of excess fat by cryolipolysis. This represents another problem to overcome to spread the technique in clinical practice. In addition, in our opinion, the best cryopreservation strategy is perhaps not to keep the adipose tissue but rather its useful components for cell therapies, which is already being realized in some academic centers and pharmaceutical companies. Since the isolation of adipose-derived stromal cells by Zuk et al. in 2001,3 adipose tissue has gained widespread popularity among researchers and surgeons, leading to a multitude of preclinical and clinical trials based on adipose-derived cell therapies. Two cell therapy strategies can be derived from adipose tissue based on adipose-derived stromal cells and stromal vascular fraction cells, respectively.4 Contrary to the authors’ statement, these cells do not differentiate in vivo into adipocytes, and it is unlikely that we will use them “de novo” to create adipose tissue, even if in vitro these cells present differentiation capacities in multiple lineages. Currently, clinical use of adipose-derived stromal cells and stromal vascular fraction cells is based on their immunomodulatory properties, enabling them to produce trophic and immunosuppressant factors during short periods after administration.5 For these reasons, adipose-derived stromal cells are used in autoimmune abnormalities with encouraging results, such as in the treatment of anal fistulas of Crohn disease. Stromal vascular fraction cells are used for the enrichment of adipose tissue during fat grafting. This concept, known as “cell-assisted lipotransfer,” was developed to improve adipose graft survival through the production of proangiogenic factors, accelerating neovascularization. The results were contrasting. In conclusion, we would like to thank the authors for this well-conducted review with their contributive perspectives on fundamental and clinical research. DISCLOSURE The authors declare no potential conflicts of interest with respect to the research, authorship, and/or publication of this communication. The authors received no financial support for the research, authorship, and/or publication of this communication. Silvia Gandolfi, M.D.Department of Plastic and Reconstructive SurgeryCharles Nicolle University HospitalRouen, France Raphael Carloni, M.D.Department of Plastic and Aesthetic SurgeryPrivate Hospital de l’EstuaireLe Havre, France Benoit Chaput, M.D., Ph.D.Department of Plastic, Reconstructive, and Aesthetic SurgeryRangueil University HospitalToulouse, France Nicolas Bertheuil, M.D., Ph.D.Department of Plastic and Reconstructive SurgeryPontchaillou University HospitalRennes, France