Qualitative and quantitative differences of adipose-derived stromal cells from superficial and deep subcutaneous lipoaspirates: a matter of fat

BACKGROUND Subcutaneous fat represents a valuable reservoir of adipose-derived stem cells(ASCs) in the stromal vascular fraction (SVF), widely exploited in regenerative medicine applications, being easily harvested through lipoaspiration. The lack for standardized procedures for autologous fat grafting, guided research efforts aimed at identifying possible differences related to the harvesting site, affecting cell isolation yield, cell growth properties and clinical outcomes. Subcutaneous fat features a complex architecture: the superficial fascia separates superficial adipose tissue (SAT) from deep layer (DAT). We aimed to unravel the differences between SAT and DAT, considering morphological structure, SVF composition and ASCs’ properties. METHODS SAT and DAT were collected from female donors and comparatively analyzed to evaluate cellular yield and viability, morphology, immunophenotype and molecular profile. ASCs were isolated in primary culture and used for in vitro differentiation assays. SAT and DAT from cadaver donors, were also analyzed through histology and immunohistochemistry, to assess morphology and cell localization within the hypoderm. RESULTS liposucted SAT contained a higher stromal tissue compound, along with a higher proportion of CD105-positive cells, compared to DAT from the same harvesting site. Also, cells isolated from SAT displayed increased multipotency and stemness features. All differences were mainly evidenced in specimens harvested from the abdominal region. According to our results, SAT features overall increased stem properties. DISCUSSION Given that subcutaneous adipose tissue is currently exploited as the gold standard source for high yield isolation of somatic adult stem cells, these results may provide precious hints toward the definition of standardized protocols for microharvesting.