Characterization of subcutaneous and visceral fat derived mesenchymal stromal cells

The stromal progenitors of mesodermal cells, mesenchymal stromal cells (MSC), are an heterogenenous population of plastic adherent fibroblast-like cells with extensive proliferative capacity and differentiation potential. Human MSC have now been isolated from various tissues including bone marrow, muscle, skin and adipose tissue, the latter being one of the most suitable cell sources for cell therapy, because of its easy accessibility, minimal morbidity and abundance of cells. Bone marrow (BM), subcutaneous (lipoaspirate, L) or visceral (omental, O) adipose tissue (AT) samples were collected, digested with collagenase if needed, and seeded in Iscove’s medium containing 5% human platelet lysate. Non-adherent cells were removed after 2-3 days and the medium replaced twice a week. Confluent adherent cells were detached and replated at low density in the same culture conditions. Initially, expanded cells were analyzed for biological MSC properties such as morphology, immunophenotype and differentiation capacity. In all the experiments BM-MSC was used as positive control. AT-derived MSC strongly express CD105, CD90, and CD73 markers, although at different rates, and lack the expression of the hematopoietic marker CD45. L-MSC and O-MSC, as well as BMMSC, showed their multipotency in their ability to differentiate in osteocytes, adipocytes, and chondrocytes, although the extent of differentiation was higher for L-MSC. Cell lines were then challenged in cellular limiting diluition, expression of senescent marker β-galactosidase, immunosuppression, and angiogenic potential of conditioned medium. The results show significant differences between lines derived from subcutaneous fat compared to those derived from visceral fat. We are convinced that the identification of the peculiarities of MSC isolated from different tissues will lead to their more accurate use in cell therapy.