Mesenchymal progenitors able to differentiate into osteogenic, chondrogenic, and/or adipogenic cells in vitro are present in most primary fibroblast-like cell populations.

MSCs and mesenchymal progenitor cells (MPCs) are studied for their potential in regenerative medicine. MSCs in particular have great potential, because various reports have shown that they can differentiate into many different cell types. However, the difference between mesenchymal stem/progenitor cells and so-called fibroblasts is unclear. In this study, we found that most of the distinct populations of primary fibroblast-like cells derived from various human tissues, including lung, skin, umbilical cord, and amniotic membrane, contained cells that were able to differentiate into at least one mesenchymal lineage, including osteoblasts, chondrocytes, and adipocytes. We therefore propose that primary fibroblast-like cell populations obtained from various human tissues do not comprise solely fibroblasts, but rather that they also include at least MPCs and possibly MSCs, to some extent. Disclosure of potential conflicts of interest is found at the end of this article.