CD146 expression in mesenchymal stem cells is associated with vascular smooth muscle commitment

Bone-marrow mesenchymal stem cells (MSCs) are plastic adherent cells that can differentiate into various tissue lineages, including osteoblasts, adipocytes and chondrocytes. However, this progenitor property is not shared by all cells within the MSC population. In addition, MSCs vary in their proliferation capacities and expression of markers. Because of heterogeneity of CD146 expression in the MSC population, we compared CD146-/Low and CD146High cells under clonal and non-clonal (sorted MSCs) conditions to determine whether this expression is associated with specific functions. CD146-/Low and CD146High MSCs did not differ in colony-forming unit-fibroblast number, osteogenic and adipogenic differentiation or in vitro hematopoietic supportive activity. However, CD146-/Low clones proliferated slightly but significantly faster than did CD146High clones. In addition, a strong expression of CD146 molecule was associated with a commitment towards a vascular smooth muscle cell lineage with upregulation of calponin-1 expression. Thus, within a bone-marrow MSC population, certain subpopulations characterized by high expression of CD146, are committed toward a vascular smooth muscle cell lineage. Clonal MSC were selected on the basis of CD146 level at their surface (CD146Low and CD146 High) and non-clonal MSC were compared from 4 different donors.