Abstract
Background aims. It is unclear whether the plastic-adherent multipotent mesenchymal stromal cells (MSC) isolated from human bone marrow (BM) represent a uniform cell population or are heterogeneous in terms of cell-surface constituents and hence functionality. Methods. We investigated the expression profile of certain biofunctional lipids by plastic-adherent MSC, focusing particularly on two membrane microdomain (lipid raft)-associated monosialogangliosides, GM1 and GM3, using indirect confocal laser scanning fluorescence microscopy and flow cytometry. Results. Phenotypically, we observed a differential expression where certain MSC subsets exhibited GM1, GM3 or both at the plasma membrane. Furthermore, disialoganglioside GD2 detection increased the complexity of the expression patterns, giving rise to seven identifiable cell phenotypes. Variation of standard culture conditions, such as the number of cell passage and period in culture, as well as donors, did not influence the heterologous ganglioside expression profile. In contrast, the binding of various lectins appeared homogeneous throughout the MSC population, indicating that the general glycosylation pattern remained common. Morphologically, the expression of a given ganglioside-based phenotype was not related to a cell with particular size or shape. Interestingly, a segregation of GM1 and GM3 clusters was observed, GM3 being mostly excluded from the highly curved plasma membrane protrusions. Conclusions. These data highlight the phenotypic heterogeneity of plastic-adherent MSC in terms of certain lipid constituents of the plasma membrane, and the presence and/or absence of distinct ganglioside-based membrane microdomains suggest their potential functional diversity.
Acknowledgments
We would like to thank Fernando Fierro and Katrin Müller for providing primary mesenchymal stromal cells. DF was supported by the Medical Faculty (MeDDrive 2009). MB was supported by Deutsche Forschungsgemeinschaft (DFG; SFB655 A12) and DC by the DFG (SFB655 A13/B3) and Sächsisches Ministerium für Wissenschaft und Kunst-Europäischer Fond für Regionale Entwicklung (4212/05-16).
Declaration of interest: All authors declare no competing financial interest. The authors alone are responsible for the content and writing of the paper.