Joris van Dongen

48 Chapter 2 Stromal cell population (CD31min/CD34pos) consists of supra-adventitial cells, ASCs and pericytes, only pericytes defined as CD31min/CD146pos, CD31min/CD34min/ pos or CD34min/CD146pos/CD90pos are placed separately in the table. a No exact data described in text, data extracted from figures by authors JAD and AJT. AIS Automated Isolation System; (CHA-Biotech); CYT Celution System Enzymatic (Cytori); FAST Fastem Corios (Corios); GID SVF2 (GID Europe); LIPOG Lipogems (Lipogems); LIPOK Lipokit System (Medi-khan); PNC Multi station (PNC); REF Residual tissue of emulsified fat; SEPAX Sepax (Biosafe); SF Squeezed fat;TGCIS Tissue Genesis Cell Isolation System (Tissue Genesis) The enzymatic procedures: Automated isolation system, Tissue genesis cell isolation system and Sepax isolated more endothelial progenitor cells in comparison to other intraoperative isolation procedures 69,75,76 . Nonetheless, more endothelial progenitor cells were not corresponding to less stromal cells or pericytes. In all differently obtained SVF, the origin of large numbers of cells remains unidentified. This is partly because not every study identified both adipose tissue-derived and blood-derived cell types, but probably not every subpopulation of all cell types is already known as well. When donor variability is neutralized by the use of the same lipoaspirate, intraoperative isolation procedures resulted in different SVF compositions. Lipogems isolated significantly more pericytes and stromal cells than the non-intraoperative isolation protocol control (p<0.05, fig. 2) 22 . The enzymatic Celution system resulted in significantly more endothelial progenitor cells in comparison with the CHA-system, Lipokit system and Multi station, which is not necessarily preferred (p=0.003) 72 . All other intraoperative isolation procedures compared with non-intraoperative isolation protocols showed no significant differences. Modified IFATS/ISCT Index Score for the measurement of adipose tissue- derived stromal vascular fraction Modified IFATS/ISCT index scores ranged from 1 to 4.6 out of 5. Güven et al. scored 4.6 and presented the most complete characterization of the SVF and ASCs 75 (Table 8). Tonnard et al. scored 2 points, but had only used CD34 as a marker to identify a subpopulation in the SVF 68 . Two studies used other methods than flow cytometry to determine the composition of SVF 67,71 . No studies were excluded based on a low number of outcomes of interest measured by the modified IFATS/ISCT Index Score, because five out of thirteen studies scored less than half of the possible points given. This high number of lowscores given to studies underlines the need for standardization.