title: What is the current optimal fat grafting processing technique? A systematic review.
abstract: BACKGROUND
  With the advents of new processing techniques and new graft survival theories in fat grafting, the question is: Which processing technique is of preference? This study systematically reviewed literature regarding current techniques for processing fat grafts.
  
  
  METHODS
  PubMed, Embase, Cinahl, and Cochrane databases were searched until August 2015. Studies comparing different fat grafting processing techniques were included. Outcomes were viability of adipocytes, number of adipose-derived stromal/stem cells (ASC) and growth factors in vitro, volume and quality of the graft in animal studies, and satisfaction and volume retention in human studies.
  
  
  RESULTS
  Thirty-five studies were included. Adipocyte viability and ASC numbers were the best using the gauze/towel technique (permeability principle) compared to centrifugation. With regard to centrifugation, the pellet contained more ASCs compared to the middle layer. The animal studies' and patients' satisfaction results were not distinctive. The only study assessing volume retention in humans showed that a wash filter device performed significantly better than centrifugation.
  
  
  CONCLUSIONS
  In this study, processing techniques using permeability principles proved superior to centrifugation (reinforced gravity principle) regarding viability and ASC number. Due to the variety in study characteristics and reported outcome variables, however, none of the processing techniques in this study demonstrated clinical evidence of superiority.
authors.affiliation: Department of Oral & Maxillofacial Surgery, University Medical Center Groningen, University of Groningen, The Netherlands. Electronic address: a.j.tuin@umcg.nl.
authors.forename: A Jorien
authors.initials: AJ
authors.lastname: Tuin
authors.affiliation: Department of Surgery, Scheper Hospital Emmen, University of Groningen, The Netherlands.
authors.forename: Patrick N
authors.initials: PN
authors.lastname: Domerchie
authors.affiliation: Department of Oral & Maxillofacial Surgery, University Medical Center Groningen, University of Groningen, The Netherlands.
authors.forename: Rutger H
authors.initials: RH
authors.lastname: Schepers
authors.affiliation: Department of Plastic Surgery, University Medical Center Groningen, University of Groningen, The Netherlands.
authors.forename: Joep C N
authors.initials: JC
authors.lastname: Willemsen
authors.affiliation: Department of Rehabilitation, University Medical Center Groningen, University of Groningen, The Netherlands.
authors.forename: Pieter U
authors.initials: PU
authors.lastname: Dijkstra
authors.affiliation: Department of Oral & Maxillofacial Surgery, University Medical Center Groningen, University of Groningen, The Netherlands.
authors.forename: Fred K L
authors.initials: FK
authors.lastname: Spijkervet
authors.affiliation: Department of Oral & Maxillofacial Surgery, University Medical Center Groningen, University of Groningen, The Netherlands.
authors.forename: Arjan
authors.initials: A
authors.lastname: Vissink
authors.affiliation: Department of Oral & Maxillofacial Surgery, University Medical Center Groningen, University of Groningen, The Netherlands.
authors.forename: Johan
authors.initials: J
authors.lastname: Jansma
mesh_terms: D017667:Adipocytes; D000273:Adipose Tissue / Q000637:transplantation*; D000818:Animals; D002498:Centrifugation; D006085:Graft Survival; D006801:Humans; D017154:Stromal Cells
keywords: Adipose derived stromal/stem cells; Fat graft; Processing; Systematic review; Viability; Volume