Mechanical isolation of stromal vascular fraction from adipose tissue: methods and cellular outcomes: a systematic review and meta-analysis.

Abstract

<h4>Background</h4>Stromal vascular fraction (SVF) from adipose tissue is a rich and accessible source of regenerative cells, including adipose-derived stem cells (ADSCs). SVF is most commonly isolated from lipoaspirate via enzymatic digestion, a process that is costly and considered 'more than minimal manipulation' by the United States Food and Drug Administration. In contrast, mechanically based isolation techniques have gained attention as a simpler, faster, and regulatory-compliant alternative, making them increasingly appealing for clinical applications.<h4>Main text</h4>This systematic review and meta-analysis aimed to evaluate the outcomes of mechanical methods for harvesting SVF from human adipose tissue. Key parameters assessed included cell yield, viability, surface marker expression, and differentiation capacity. Additionally, split-sample studies were analysed descriptively to compare mechanical and enzymatic isolation approaches, thereby reducing variability in tissue source and preparation. A narrative synthesis was performed for all eligible studies (k = 22), and a single-arm meta-analysis of pooled outcomes of mechanical protocols was conducted for total cell yield and expression of CD34, CD73, and CD105 markers, depending on data availability. Mechanical isolation approaches varied considerably, but most high-performing protocols involved dedicated devices or systems. Meta-analysis revealed a pooled mean SVF cell yield of 11.96 × 10⁴ cells/ml. The pooled expression levels of CD105 (4.08%) and CD73 (11.63%) indicated the presence of ADSC-associated markers, while CD34 (8.70%) reflected vascular and hematopoietic progenitor subpopulations commonly found in SVF. Mechanically isolated SVF cells demonstrated retained viability (up to 98%) and multilineage differentiation capacity, supporting their potential in regenerative applications. Furthermore, the retention of immunomodulatory and migratory functions may facilitate the integration of transplanted cells into host tissue environments.<h4>Conclusion</h4>Mechanical SVF isolation methods can demonstrate comparable cell viability and differentiation potential and may outperform enzymatic protocols in terms of ADSC content and some functional properties (migration, immunomodulation). The main drawback of mechanical approaches is relatively lower total cell yield. The emergence of specialised devices for mechanical SVF isolation represents a key trend in the field. Continued efforts towards methodology and reporting standardisation are required to improve reproducibility and clinical reliability.