Background: Stem cells (SCs) considerably vary in morphological, immunophenotypic, proliferative, and differentiation characteristics depending on their tissue source. The comparative analysis of their biological properties is essential for the optimal choice of SCs for regenerative therapies.
Methods: Using immunocytochemistry, flow cytometry, histochemistry and real-time RT-PCR, we have investigated SCs obtained from human subepicardial (SEC-AT) and subcutaneous (SC-AT) adipose tissue and cultured under similar culture conditions without any differentiation-promoting factors.
Results: The cultures were similar in the high proportion of proliferating cell nuclear antigen (PCNA)-positive cells. In both cultures, immunophenotyping has revealed high expression of mesenchymal stem cell surface markers CD29, CD44, CD73, and CD105, low expression of CD31, CD34 and CD45, and wide variability in CD117, CD146 and CD309 expression. The only distinction in CD marker profile was significantly lower expression of CD90 in SCs from SEC-AT. Histochemical analysis has shown the lack of Oil Red O-positive cells in both cultures and about ten-fold higher number of alkaline phosphatase-positive cells among SCs from SC-AT. In the both cultures, immunocytochemistry has detected similar low expression of slow myosin heavy chain marker MAB1628 and smooth muscle actin marker α-hSMA. Gap junctional protein Connexin-43 expression was markedly higher in SCs from SC-AT, and epithelial cell marker Cytokeratin-19 expression was detected only in these cells. By RT-PCR, GATA4 mRNA was found to be highly expressed only in SCs from SEC-AT.
Conclusions: Our results suggest that SC-AT, as compared with SEC-AT, is richer in epithelial cell and osteogenic progenitors. In turn, SEC-AT possesses cardiomyogenic SCs, and can be considered as an alternative to SC-AT as a source of SCs for cell cardiotherapy.