Meflin defines mesenchymal stem cells and/or their early progenitors with multilineage differentiation capacity

Mesenchymal stem cells (MSCs) are the likely precursors of multiple lines of mesenchymal cells. The existence of bona fide MSCs with self-renewal capacity and differentiation potential into all mesenchymal lineages, however, has been unclear because of the lack of MSC-specific marker(s) that are not expressed by the terminally differentiated progeny. Meflin, a glycosylphosphatidylinositol-anchored protein, is an MSC marker candidate that is specifically expressed in rare stromal cells in all tissues. Our previous report showed that Meflin expression becomes down-regulated in bone marrow-derived MSCs cultured on plastic, making it difficult to examine the self-renewal and differentiation of Meflin-positive cells at the single-cell level. Here, we traced the lineage of Meflin-positive cells in postnatal and adult mice, showing that those cells differentiated into white and brown adipocytes, osteocytes, chondrocytes and skeletal myocytes. Interestingly, cells derived from Meflin-positive cells formed clusters of differentiated cells, implying the in situ proliferation of Meflin-positive cells or their lineage-committed progenitors. These results, taken together with previous findings that Meflin expression in cultured MSCs was lost upon their multilineage differentiation, suggest that Meflin is a useful potential marker to localize MSCs and/or their immature progenitors in multiple tissues.