title: Phenotypic Analysis of Stromal Vascular Fraction after Mechanical Shear Reveals Stress-Induced Progenitor Populations.
abstract: BACKGROUND
  Optimization of fat grafting continues to gain increasing attention in the field of regenerative medicine. "Nanofat grafting" implements mechanical emulsification and injection of standard lipoaspirate for the correction of superficial rhytides and skin discoloration; however, little is known about the cellular constituents of the graft. Based on recent evidence that various stressors can induce progenitor activity, the authors hypothesized that the shear forces used in common fat grafting techniques may impact their regenerative capacities.
  
  
  METHODS
  Lipoaspirates were obtained from 10 patients undergoing elective procedures. Half of each sample was subjected to nanofat processing; the other half was left unchallenged. The viscosity of each sample was measured for computational analysis. The stromal vascular fraction of each sample was isolated, quantified, and analyzed by means of flow cytometry with two multicolor fluorescence antibody panels.
  
  
  RESULTS
  Standard lipoaspirate is ideally suited for mechanical stress induction. The mechanical emulsification involved in nanofat processing did not affect cell number; however, viability was greatly reduced when compared with the stromal vascular fraction of standard lipoaspirate. Interestingly, nanofat processing resulted in stress-induced stromal vascular fraction with a higher proportion of endothelial progenitor cells, mesenchymal stem cells, and multilineage differentiating stress-enduring cells. Single-parameter analysis also revealed significant increases in CD34, CD13, CD73, and CD146 of the stress-induced stromal vascular fraction, markers associated with mesenchymal stem cell activity.
  
  
  CONCLUSIONS
  Mechanical processing used in techniques such as nanofat grafting induces the up-regulation of progenitor phenotypes consistent with multipotency and pluripotency. These data provide a first step in characterizing the potential regenerative benefits realized through stress induction in fat grafting.
  
  
  METHODS
  Therapeutic, V.
authors.affiliation: Orange, Calif.|From the Center for Tissue Engineering, Department of Plastic Surgery; the Departments of Biomedical Engineering and Chemical Engineering and Materials Science; and the Chao Family Comprehensive Cancer Center, University of California, Irvine.
authors.forename: Derek A
authors.initials: DA
authors.lastname: Banyard
authors.affiliation: Orange, Calif.|From the Center for Tissue Engineering, Department of Plastic Surgery; the Departments of Biomedical Engineering and Chemical Engineering and Materials Science; and the Chao Family Comprehensive Cancer Center, University of California, Irvine.
authors.forename: Christos N
authors.initials: CN
authors.lastname: Sarantopoulos
authors.affiliation: Orange, Calif.|From the Center for Tissue Engineering, Department of Plastic Surgery; the Departments of Biomedical Engineering and Chemical Engineering and Materials Science; and the Chao Family Comprehensive Cancer Center, University of California, Irvine.
authors.forename: Anna A
authors.initials: AA
authors.lastname: Borovikova
authors.affiliation: Orange, Calif.|From the Center for Tissue Engineering, Department of Plastic Surgery; the Departments of Biomedical Engineering and Chemical Engineering and Materials Science; and the Chao Family Comprehensive Cancer Center, University of California, Irvine.
authors.forename: Xiaolong
authors.initials: X
authors.lastname: Qiu
authors.affiliation: Orange, Calif.|From the Center for Tissue Engineering, Department of Plastic Surgery; the Departments of Biomedical Engineering and Chemical Engineering and Materials Science; and the Chao Family Comprehensive Cancer Center, University of California, Irvine.
authors.forename: Garrett A
authors.initials: GA
authors.lastname: Wirth
authors.affiliation: Orange, Calif.|From the Center for Tissue Engineering, Department of Plastic Surgery; the Departments of Biomedical Engineering and Chemical Engineering and Materials Science; and the Chao Family Comprehensive Cancer Center, University of California, Irvine.
authors.forename: Keyianoosh Z
authors.initials: KZ
authors.lastname: Paydar
authors.affiliation: Orange, Calif.|From the Center for Tissue Engineering, Department of Plastic Surgery; the Departments of Biomedical Engineering and Chemical Engineering and Materials Science; and the Chao Family Comprehensive Cancer Center, University of California, Irvine.
authors.forename: Jered B
authors.initials: JB
authors.lastname: Haun
authors.affiliation: Orange, Calif.|From the Center for Tissue Engineering, Department of Plastic Surgery; the Departments of Biomedical Engineering and Chemical Engineering and Materials Science; and the Chao Family Comprehensive Cancer Center, University of California, Irvine.
authors.forename: Gregory R D
authors.initials: GRD
authors.lastname: Evans
authors.affiliation: Orange, Calif.|From the Center for Tissue Engineering, Department of Plastic Surgery; the Departments of Biomedical Engineering and Chemical Engineering and Materials Science; and the Chao Family Comprehensive Cancer Center, University of California, Irvine.
authors.forename: Alan D
authors.initials: AD
authors.lastname: Widgerow
mesh_terms: D017667:Adipocytes / Q000637:transplantation*; D002478:Cells, Cultured; D005434:Flow Cytometry; D006801:Humans; D015187:Lipectomy; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D010641:Phenotype; D019651:Plastic Surgery Procedures / Q000379:methods*; D044968:Regenerative Medicine / Q000379:methods*; D015595:Skin Aging; D013314:Stress, Mechanical; D017154:Stromal Cells / Q000637:transplantation*