Comparison of Stromal/Stem Cells Isolated from Human Omental and Subcutaneous Adipose Depots: Differentiation and Immunophenotypic Characterization

The emerging field of regenerative medicine has identified adipose tissue as an abundant source of stromal/stem cells for tissue engineering applications. Therefore, we have compared the differentiation and immunophenotypic features of adipose-derived stromal/stem cells (ASC) isolated from either omental or subcutaneous adipose depots. Human tissue samples were obtained from bariatric and plastic surgical practices at a university-affiliated teaching hospital and a private practice, respectively, with informed patient consent. Primary cultures of human ASC were isolated from adipose specimens within 24 h of surgery and culture expanded in vitro. The passaged ASC were induced to undergo adipogenic or osteogenic differentiation as assessed by histochemical methods or evaluated for surface antigen expression profiles by flow cytometry. ASC yields per unit weight of tissue were comparable between omental and subcutaneous depots. At passage 0, the immunophenotype of omental and subcutaneous ASC were not significantly different with the exception of CD105 and endoglin, a component of the transforming growth factor β receptor. The adipogenic differentiation of omental ASC was less robust than that of subcutaneous ASC based on in vitro histochemical and PCR assays. Although the yield and immunophenotype of ASC from omental adipose depots resembled that of subcutaneous ASC, omental ASC displayed significantly reduced adipogenic differentiation capacity following chemical induction. Further studies are necessary to evaluate and optimize the differentiation function of omental ASC in vitro and in vivo. Pending such analyses, omental ASC should not be used interchangeably with subcutaneous ASC for regenerative medical applications.