Cytochalasin B modulates biological properties of human Wharton’s Jelly Mesenchymal Stem Cells (hWJ-MSCs)

Wharton’s Jelly Mesenchymal Stem cells (hWJ-MSCs) are of particular concern for research purposes on cell therapy and regenerative medicine. They can be placed between embryonic and adult mesenchymal stem cells, with the advantage of not being tumorigenic. Particularly advantageous is the ease of their harvesting, since it is painless and free of ethical issues. Moreover, hWJ-MSCs, being perinatal stem cells, are not as influenced by age and can be easily cultured in vitro, maintaining both stem properties and a high proliferative rate for several passages. Furthermore, hWJ-MSCs are multipotent stem cells: they differentiate toward all the three cytotypes of the germ layers. Cytoskeleton provides architectural and signaling cues within the cells. Cytoskeletal proteins are able to reorganize themselves in response to mechanical forces or chemical molecules, converting the stimulus received into a specific cellular response. In fact, cytoskeleton is able to influence cell morphology, proliferation, senescence, and in mesenchymal stem cells it has been demonstrated to influence their commitment. Several molecules can interact with the cytoskeletal proteins modulating their dynamics. Among them, Cytochalasin B (CB), a cyto-permeable mycotoxin, inhibits polymerization of the actin microfilaments, leading to several changes in cell properties. We previously studied the role of CB in adult-derived human adipose mesenchymal stem cells (hASCs). Here we present an investigation into the role of CB in hWJ-MSCs, a model of perinatal stem cells. We investigated on the one hand the same characteristics observed in hASCs to compare them, and on the other hand we explored other new stem cells features. We first observed that CB altered hWJ-MSC morphology in a reversible and dose-dependent manner; at the same time, the cytoskeletal organization was destabilized, as evinced by immunofluorescence analysis of actin microfilaments, vimentin, an intermediate filament, and vinculin, a protein of the focal adhesion complexes. Moreover, CB treatment affected hWJ-MSC number, proliferation, and metabolism, but not cell viability, in a dose-dependent manner, as evaluated by cell count, BrdU incorporation and Alamar Blue assays, respectively. Finally, CB treatment has been seen to modulate specifically the osteogenic commitment. All changes in hWJ-MSC properties have been also confirmed with a gene expression analysis of specific markers, as those of cell cycle, proliferation and osteogenesis. We have shown that CB is able to modulate the properties of hWJ-MSCs in a dose- and time-dependent manner, prompting us to continue our research to better understand the molecular mechanisms underlying the relationship between cytoskeleton and stem cell properties.