Mesenchymal stromal/stem cells: historical perspective and ongoing challenges

The potential of stem cell-based therapy was accompanied by high expectations and led, consequently, to an increase in clinical translational investments. Mesenchymal stem/stromal cells (MSCs) became the cell-based product most experimentally studied worldwide. However, uncertainties about the mechanisms and the in vivo identity of MSCs impose concerns about their large-scale use in regenerative medicine. This review comprises a historical summary on MSC, a critical discussion about their identity and function, and the ongoing challenges for their use in therapy and tissue bioengineering.