Quantitative and Qualitative Analysis of Human Stromal Vascular Fraction from Different Methods of Liposuction Short Title: Stromal Fraction from Liposuction Types

Background: Although the widespread use for harvesting fat, liposuction is not represented by a single procedure and, in the absence of evidence based guidelines regarding cell based therapies, different protocols may be employed to extract the Stromal Vascular Fraction (SVF) and its cellular subpopulations. Usually the tissue-harvesting procedures has been underestimated as a factor to impact the outcomes.Methods: 4 methods of liposuction were employed in triplicate in 16 patient candidates for liposuction: Manual liposuction with 10.0 mL Luer-Lok syringe and 2.0 mm blunt tip cannula Manual liposuction with 60.0 mL syringe and 2.5 mm cannula Power-Assisted Liposuction (PAL) (Vibrofit®- Faga Medical) set at 3.000 cycles and 3.0 mm cannula and Suction-Assisted Liposuction (SAL) ( Nevoni® 3003 model) and 4.0 mm cannula They were divided in 3 groups, according to the aspirated volume:- group I: 20.0 mL, group II: 60.0 mL and group III: 120.0 mL, obtaining 48 samples for analysis. Cellular quantification, viability and mesenchymal characterization was performed in the extracted SVF in all samples and the results were compared by Pearson statistical test and logistic probability, adopting α significant level above 0.05 (α>0.05).Results: The worst cell yielding was obtained with SAL and 4 mm blunt tip cannulas in all volumes. The manual method with 10.0 mL seringe/2.0 mm cannula and PAL/3.0 mm cannula showed better cellular SVF extraction in all groups, with no differences statistically significant between them. The cell frequencies of these best scores showed an exponential increase with increasing volumes from 2.900.000 cells/20 mL group to 18.500.000/60 mL group (6.4xx) and to 380.000.000/120 mL group (20.5xx).Conclusion: The mechanical stress applied over the subcutaneous tissue may impact the cell yielding of the extracted SVF. Syringes with small cannulas (2.0 mm), and/or in-vivo emulsification of the adipose tissue through PAL seem to have a positive effect, optimizing future liposuction protocols.