Joris van Dongen

31 Comparison of SVF isolation procedures: a systematic review Synthesis of results In some studies, derivate numbers of graphs are used when the actual number of outcomes was not given. Cell types within the SVF can be distinguished based on CD marker expression or immuno-staining. To compare SVF compositions between different studies and to compare intraoperative procedures with their control ( i.e. non- intraoperative protocols or other intraoperative procedures) in the same study, only CD marker expression was used. Studies evaluating a single CD marker expression to analyze different cell types were seen as insufficient distinctive andwere excluded. Cells were divided into two major groups: CD45min (adipose tissue-derived) and CD45pos (blood derived) cells to analyze the expression of stromal cells, pericytes, vascular endothelial cells/endothelial progenitor cells, endothelial cells, lymphocytes, leukocytes and hematopoietic stem cells. All other cells are placed in the category: other cell types. The CD34pos/CD146pos population is excluded from analysis because of the inability to discriminate between progenitor pericytes and progenitor endothelial cells 22 . Risk of bias across studies Included studies could present different outcome variables related to SVF analysis. There is a risk that studies did not present a full SVF characterization and thereby bias their results. In order to provide an overview of the used outcome variables per study, a Modified IFATS/ISCT Index Score was used. The risk of publication bias of positive results might be expected in those articles were the authors have benefits in the investigated products. Disclosure agreements were reviewed for each study. Modified IFATS/ISCT Index Score for the measurement of adipose tissue- derived stromal vascular fraction Studies were assessed based on the reported outcome variables. The assessment of quality was evaluated based on the position statement of the International Federation of Adipose Therapeutics and Science (IFATS) and the International Society of Cellular Therapy (ISCT) 5 . The IFATS and ISCTS proposed guidelines to develop reproducible standardized endpoints and methods to characterize ASCs and SVF cells. For each of the following characterization methods a grade was given by the authors (JAD, AJT) to an article if the characterization was carried out: viability of nucleated cells, flow cytometry of SVF cells, flow cytometry of ASCs (CD13, CD29, CD31, CD34, CD44, CD45, CD73, CD90, CD105, CD235a), proliferation and frequency (CFU-F) and functional assays (adipogenic, osteogenic and chondrogenic differentiation assays) of ASCs. The maximum score in case of a full characterization was 5.