Factors Influencing SVF Yields from Human Adipose Tissue: Isolation Technique, Age, and Sex

<b>Background/Objectives:</b> Stromal vascular fraction (SVF) from adipose tissue contains regenerative cell populations, including adipose-derived stem cells (ADSCs), and is increasingly used in clinical therapies. However, the effects of isolation technique and donor characteristics on SVF yield and viability remain unclear. This study aims to assess the impact of mechanical versus enzymatic isolation, as well as donor age and sex, on SVF total nucleated cell count (TNC) and viability. <b>Methods:</b> A retrospective analysis was conducted on 114 patients undergoing ADSC harvesting via a mini-liposuction. SVF was isolated using enzymatic digestion (<i>n</i> = 100) or mechanical digestion (<i>n</i> = 14). Percent viability and TNC were assessed using the Chemometec NC-200 NucleoCounter^®. The influence of isolation technique, donor age, and donor sex on SVF yield and viability was evaluated using Pearson's correlation and independent <i>t</i>-tests. <b>Results:</b> Enzymatic digestion yielded significantly higher cell viability compared to mechanical isolation (<i>p</i> < 0.001), although no significant difference in TNC was observed between the two methods. Increasing donor age was modestly associated with reduced viability in enzymatically processed samples but not in mechanically processed samples. Donor age showed no significant association with TNC for either isolation method. Donor sex was not correlated with viability in either group; however, female donors exhibited significantly higher TNC following enzymatic digestion, a trend not observed with mechanical isolation. <b>Conclusions:</b> Enzymatic digestion preserves cell viability more effectively than mechanical methods, while donor age and sex have variable effects depending on the isolation protocol. These findings underscore the importance of considering both biological and methodological factors in SVF preparation for clinical use. Further studies with larger, balanced cohorts are needed to validate these results.