"Stemness" does not explain the repair of many tissues by mesenchymal stem/multipotent stromal cells (MSCs)

Abstract

There has recently been an explosion of interest in adult stem/progenitor cells that have the potential to repair tissues, with over 3,000 citations to publications (PubMed) and numerous announcements of clinical trials in which the cells are used to treat individuals with a broad range of diseases. At the same time, the data present a paradox-the cells originally attracted attention because of their stem-cell-like properties, but the cells frequently repair injured tissues without much evidence of either engraftment or differentiation.