SVF-GEL Cryopreserved for Different Times Exhibits Varied Preservation and Regeneration Potential After Transplantation in a Mouse Model

Abstract

Background Matrix vascular component (SVF) gels derived from fat preserve tissue integrity and cell viability under cryopreserved conditions, making them easy to inject again for later use. Here, we compared the preservation power and regeneration potential of SVF-gel under different cryopreservation times. Methods The SVF-gel stored under − 20 °C, without cryoprotectant cryopreservation for 5, 15, and 45 days, with fresh SVF-gel as control. We evaluated the rate of volume retention after thawing the SVF-gel and the apoptosis rate of adipose-derived stem cells. Next, we analyzed retention rated, adipogenesis, angiogenesis, and connective tissue hyperplasia of the grafts, one month after subcutaneously transplanting the specimen into immunodeficient mice. Results SVF-gel cryopreserved for 5 and 15 days exhibited no significant different in apoptosis rates relative to the control group. Extending the cryopreservation time to 45 days resulted in significantly increased and decreased apoptosis and volume retention rates of SVF-gel, respectively. SVF-gel grafts cryopreserved for 5 and 15 days exhibited no significant differences from those in the control group, although their weights and volumes still fluctuated. Extending the cryopreservation time to 45 days resulted in significantly decreased retention rates of the grafts. Histologically, extending freezing time resulted in a gradual decline in the graft’s health adipose tissue, as well as decreased angiogenesis, and connective tissue hyperplasia. Conclusion Simple freezing of SVF-gel at − 20 °C conferred them with sufficient cell viability. Notably, short-term cryopreservation did not significantly increase the apoptosis rate, and it still had a certain regeneration after transplantation. However, prolonging freezing time to 45 days resulted in increased apoptosis rate and worsened transplantation effect. No Level Assigned This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. 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.

One-step stromal vascular fraction therapy in osteoarthritis with tropoelastin-enhanced autologous stromal vascular fraction gel

“…Of particular note, preparing SVF-gel involves sourcing adipose tissue from subcutaneous fat of the patient, a process that is minimally invasive and carries low risk. An added advantage is the ability of SVF-gel to be stored at low temperatures for an extended period, allowing for a single extraction that requires only a small Frontiers in Bioengineering and Biotechnology frontiersin.org incision (Tao et al, 2023). Another significant aspect to consider is the adaptability of SVF-gel for use in clinical surgeries.…”

Short-term cryoprotectant-free cryopreservation at −20°C does not affect the viability and regenerative capacity of nanofat

“…Another major challenge is the cryopreservation of nanofat, because it cannot be simply mixed with cryoprotectants, whose residue-free removal by centrifugation and washing steps after the thawing process would markedly change its composition. Therefore, we herein chose a cryoprotectant-free protocol, as it has previously been applied for fat grafts and other fat derivatives ( MacRae et al, 2004 ; Tao et al, 2023 ).…”

“…In fact, we tested our cryopreservation protocols in combination with a relatively short storage period of only 7 days. Because it is known that the storage time can affect cell viability and regenerative properties of different cell types ( Kim et al, 2014 ; Tao et al, 2023 ), we therefore cannot exclude that longer storage periods would have resulted in other outcomes related to cell viability. Moreover, we herein used PRP to stably fix the nanofat inside the wound bed.…”

“…Cryopreservation of cells and tissues including fat derivatives has shown promising results ( Laschke et al, 2003 ; Xu et al, 2012 ; Laschke et al, 2018 ; Tao et al, 2023 ). Over the years, various cryopreservation protocols have been established that involve different freezing procedures and storage temperatures ( MacRae et al, 2004 ; Villaverde-Doménech et al, 2021 ; Tao et al, 2023 ).…”

“…Cryopreservation of cells and tissues including fat derivatives has shown promising results ( Laschke et al, 2003 ; Xu et al, 2012 ; Laschke et al, 2018 ; Tao et al, 2023 ). Over the years, various cryopreservation protocols have been established that involve different freezing procedures and storage temperatures ( MacRae et al, 2004 ; Villaverde-Doménech et al, 2021 ; Tao et al, 2023 ). Many of them use cryoprotective agents, such as ethylene glycol, glycerol, methanol or dimethyl sulfoxide (DMSO), to prevent ice crystal formation by interfering with hydrogen bonding between water molecules ( Karlsson et al, 1994 ; Pegg, 2007 ; Best, 2015 ; Whaley et al, 2021 ).…”