Mechanically Isolated Stromal Vascular Fraction Provides a Valid and Useful Collagenase-Free Alternative Technique: A Comparative Study

Background: The use of stromal vascular fraction and adipose-derived stromal cells in tissue regeneration is now being increasingly investigated, and studies have demonstrated that adipose-derived stromal cells present differentiation and immunomodulatory capacities. The development of a rapid, inexpensive, and enzyme-free technique to isolate adipose-derived stromal cell-enriched stromal vascular fraction is a major goal for stem cell therapy. Therefore, the authors compared innovative mechanical procedures to the gold standard technique, collagenase digestion. Methods: Stromal vascular fraction was prepared from 21 liposuctions using either enzymatic digestion or two different mechanical methods: high vortexing/centrifugation and dissociation by intersyringe processing. The effects of tissue processing on cell count, viability, proliferation, clonogenic enrichment, and the phenotypes of the different native cell were determined. Adipose-derived stromal cell phenotypes from the different protocols, and their differentiation and immunosuppressive potential, were compared. Results: Enzymatic digestion isolated more viable cells than dissociation by intersyringe processing and vortexing/centrifugation. The expansion rate and clonogenic enrichment were higher for stromal vascular fraction isolated with collagenase. The proportion of adipose-derived stromal cells was higher in stromal vascular fraction extracted with dissociation than with enzymatic digestion and vortexing/centrifugation (p < 0.01). Interestingly, all cultured adipose-derived stromal cells displayed similar differentiation and immunosuppressive capacities. Conclusions: Enzymatic digestion extracts more adipose-derived stromal cells, but intersyringe dissociation enables the rapid extraction of adipose-derived stromal cell-enriched stromal vascular fraction. Moreover, mechanical methods enable adipose-derived stromal cell isolation with stemness and immunosuppressive properties, similar to enzymatic digestion. Such mechanical procedures could allow easier and more rapid isolation of adipose-derived stromal cell-enriched stromal vascular fraction for practitioners.