title: Hypoxia preconditioning enhances the viability of ADSCs to increase the survival rate of ischemic skin flaps in rats.
abstract: Use of a skin flap has been a common technique in reconstructive surgery for more than five decades. However, partial necrosis of its distal end is still a serious postoperative complication. Many theories about this problem have been proposed, including deficient blood supply, which is the most accepted theory. In this study we demonstrated that hypoxic preconditioning enhanced the viability of adipose-derived stem cells (ADSCs) in vivo and improved their ability to increase the survival rate of ischemic skin flaps in rats. Seven days after flap elevation, the flap survival rate in the hypoxic preconditioned ADSC group was higher than that in the control group. Moreover, histological examination showed that more ADSCs survived in flaps treated by hypoxic preconditioning. Vascular density in the hypoxic preconditioned ADSC group was 30-90 % greater than that in the control group. In addition, the expressions of vascular endothelial growth factor and hypoxia inducible factor-1α (HIF-1α) were higher in the hypoxic preconditioned ADSC group than in the control group (p < 0.05). This enhancive phenomenon reached its highest level at the precondition times of 3 and 7 days in the hypoxic preconditioned ADSC group. We conclude that hypoxia preconditioning effectively enhances the viability of ADSCs to increase the survival rate of ischemic skin flaps. Furthermore, 3 days is the optimal preconditioning time point.
  
  
  METHODS
  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                                        .
authors.affiliation: Department of Plastic Surgery, The Second Hospital of Harbin Medical University, Harbin, 150086, China.
authors.forename: Yeli
authors.initials: Y
authors.lastname: Yue
authors.forename: Peipei
authors.initials: P
authors.lastname: Zhang
authors.forename: Dan
authors.initials: D
authors.lastname: Liu
authors.forename: Jenny F
authors.initials: JF
authors.lastname: Yang
authors.forename: Chunlei
authors.initials: C
authors.lastname: Nie
authors.forename: Daping
authors.initials: D
authors.lastname: Yang
mesh_terms: D000273:Adipose Tissue / Q000166:cytology*; D000818:Animals; D015687:Cell Hypoxia; D002470:Cell Survival; D007511:Ischemia; D019194:Ischemic Preconditioning; D008297:Male; D051381:Rats; D011917:Rats, Inbred Lew; D013234:Stem Cells; D013524:Surgical Flaps / Q000098:blood supply*