An Optimized Method for Adipose Stromal Vascular Fraction Isolation and its Application in Fat Grafting

Background: The stromal vascular fraction (SVF) derived from adipose tissue contains heterogeneous cell populations and has enormous potential for clinical therapy. There are two main methods for SVF isolation: enzymatic isolation and mechanical isolation, both of which have shortcomings. In this study, optimized conditions for the isolation of high-quality SVF were established, and applications in fat grafting were evaluated.

Methods: Adipose tissue was chopped into small pieces and then ground into an erosive shape using a syringe. The pieces were digested with 0.15% type II collagenase for 35 min at 37 °C. After centrifugation, the pellets were resuspended in DMEM and passed through a 100-μm strainer. The filtered cells were analyzed by flow cytometry. The fat graft was enriched with isolated SVF and subcutaneously transplanted into nude mice. Three weeks after transplantation, grafts were isolated, and H&E staining, immunocytochemistry, and western blotting were conducted.

Results: The harvested SVF cells reached > 2 × 10⁶/ml of adipose tissue within 90 min of operation. The number of CD34⁺ ADSCs in our SVF pellets was > 6 × 10⁵/ml of adipose tissue, which has the potential for differentiating into osteoblasts, adipocytes, and chondrocytes. Freshly collected adipose tissue is better for SVF isolation, and isolated SVF should also be kept at 4 °C and used as soon as possible. SVF may promote revascularization after fat grafting. The adipose tissue of an SVF co-transplanted group had an integral structure, clear capillaries, and higher VEGF expression. SVF co-transplantation inhibited adipose cell apoptosis.

Conclusion: Our study provides an efficient procedure for SVF isolation, its application in fat grafting, and possible underlying mechanisms.

Level of evidence iv: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .