Yield and characterization of subcutaneous human adipose-derived stem cells by flow cytometric and adipogenic mRNA analyses

Background aims. Adipose-derived stromal/ stem cells (ASC) capable of multipotential differentiation can be isolated with high yields from human subcutaneous lipoaspirates. This study reports our recent experience of isolating and immunophenotypically characterizing ASC from >60 human patients with a mean age of 43.6 and body mass index (BMI) of 27. Methods. We examined the ASC yield per unit volume of lipoaspirate tissue, the surface antigen profile based on flow cytometry, histochemical differentiation potential along the adipogenic and osteogenic pathways, and expression of adipogenic mRNA by transcriptomic microarray and reverse transcription (RT)-polymerase chain reaction (PCR). Results. The population (n = 64) of predominantly Caucasian (84.3%) female (90.6%) donors had a mean age of 43.6 +/- 11.1 years and a mean BMI of 27.0 +/- 3.8. A yield of 375 +/- 142 x 10(3) ASC was obtained per milliliter of lipoaspirate within a 4.1 +/- 0.7-day culture period (n = 62). The ASC population was uniformly CD29(+) CD34(+) CD44(lo) CD45(lo) CD73(+) CD90(+) CD105(+) and capable of undergoing both adipogenesis and osteogenesis in vitro based on Oil Red O and Alizarin Red staining, respectively. Adipogenic differentiation was associated with a significant induction of multiple mRNA associated with lipid storage and synthesis based on microarray analysis of n = 3 donors. During an adipogenic differentiation time course, representative mRNA (adiponectin, C/EBP alpha, leptin and LPL) displayed increases of several orders of magnitude. Conclusions. These findings demonstrate the reproducibility of subcutaneous lipoaspirates as a consistent and abundant source of functional ASC from donors across a spectrum of ages and BMI. These results have relevance for regenerative medical applications exploiting autologous and allogeneic ASC for soft and hard tissue engineering.