Purpose of review: Our understanding of the biology and properties of mesenchymal stem cells or multipotent mesenchymal stromal cells has expanded dramatically over the last 3 years and is likely to have an impact on clinical practice in the near future, making a review of this topic both timely and relevant
Recent findings: Recommendations regarding nomenclature and the definition of mesenchymal stromal cells have been proposed, a rapidly dividing population within the mesenchymal stromal cell compartment has been better defined and the ability of these cells to exhibit characteristics of cells from a variety of lineages has been extended. The notion that tissue repair with mesenchymal stromal cells is related to transdifferentiation has been re-evaluated and, for the myocardium at least, may be due rather to a paracrine mechanism. The most dramatic developments have been in identifying some of the complex mechanisms underlying the immunosuppressive and nonimmunogenic properties of mesenchymal stromal cells which have important implications for the management of conditions like acute graft-versus-host disease.
Summary: Mesenchymal stromal cells are a biologically important cell population that are able to support hematopoiesis, can differentiate along mesenchymal and nonmesenchymal lineages in vitro, are capable of suppressing alloresponses and appear to be nonimmunogenic. These properties suggest emerging roles for mesenchymal stromal cells in cell therapy.