title: The effect of lipoaspirates cryopreservation on adipose-derived stem cells.
abstract: BACKGROUND
  Autologous fat grafting has gained popularity, particularly with the discovery of adipose-derived stem cells (ADSC). The possibility of freezing lipoaspirates (LA) for later use has intriguing clinical potential. However, the effect of LA cryopreservation on ADSC is unclear.
  
  
  OBJECTIVE
  The authors explore the effect of LA cryopreservation on ADSC viability.
  
  
  METHODS
  Human LA (n = 8) were harvested using a standard technique. Lipoaspirate samples were either processed immediately as fresh LA (A) or stored at -20°C and then at -80°C for 30 days with (B) or without (C) freezing medium. Stromal vascular fraction (SVF) was separated from adipocytes and either cultured to obtain purified ADSC or processed for the isolation of 3 distinct ADSC subpopulations (CD90(+)/CD45(-), CD105(+)/CD45(-), and CD34(+)/CD31(-)). Apoptosis and necrosis were determined by an annexin V/propidium iodide assay and quantified by flow cytometry. The capability of ADSC for long-term proliferation and differentiation was also examined.
  
  
  RESULTS
  There were no significant differences in the apoptosis and necrosis of adipocytes, SVF, or ADSC between groups A and B. However, cell viability in SVF and ADSC was significantly compromised in group C as compared with group B (P < .01) due to higher ADSC apoptosis but not necrosis. The viable ADSC isolated from fresh or frozen LA were cultured for more than 20 passages and demonstrated similar patterns and speed of proliferation with strong capability to differentiate, evidenced by cell doubling time and positive staining with Oil Red O (Sigma-Aldrich, St Louis, Missouri) and alkaline phosphatase.
  
  
  CONCLUSIONS
  Lipoaspirates cryopreservation had a significant impact on ADSC apoptosis but not on ADSC necrosis, proliferation, or differentiations. Freezing medium provides significant protection against ADSC apoptosis.
authors: Department of Surgery, Division of Plastic Surgery at the University of Nevada School of Medicine, Las Vegas, Nevada.
authors: Wei Z
authors: WZ
authors: Wang
authors: Xin-Hua
authors: XH
authors: Fang
authors: Shelley J
authors: SJ
authors: Williams
authors: Linda L
authors: LL
authors: Stephenson
authors: Richard C
authors: RC
authors: Baynosa
authors: Nancy
authors: N
authors: Wong
authors: Kayvan T
authors: KT
authors: Khiabani
authors: William A
authors: WA
authors: Zamboni
mesh_terms: D017667:Adipocytes / Q000166:cytology*; D000328:Adult; D017209:Apoptosis; D002454:Cell Differentiation; D049109:Cell Proliferation; D002470:Cell Survival; D002478:Cells, Cultured; D015925:Cryopreservation; D005434:Flow Cytometry; D006801:Humans; D009336:Necrosis; D013234:Stem Cells / Q000166:cytology*; D013696:Temperature; D013997:Time Factors
keywords: SVF; adipocytes; adipose-derived stem cells; apoptosis; cryopreservation; fat grafting; lipoaspirates; necrosis