In vitro evaluation of mesenchymal stromal cell senescence

Abstract

Mesenchymal stromal cells (MSCs) are adult multipotent stem cells that, for their immunomodulatory and reparative/anti-inflammatory properties, are a promising tool in cell therapy. For the treatment of patients, MSCs are in vitro stimulated to proliferate in a non-physiological condition and this situation could lead MSCs to malignant transformation. The clinical application of MSCs requires that the biosafety of these cells must be investigated. The cellular senescence is a crucial mechanism that prevents the growth of cells at risk for neoplastic transformation. The aim of this study was to investigate the capacity of healthy donor bone marrow derived MSCs to enter the senescence phase by evaluating the β-galactosidase activity. We tested 131 MSC batches after long-term in vitro culture, resulting positive for β-gal staining and showing a branched shape morphology typical of senescent cells. They displayed a progressive decline in proliferative capacity and none of them bypassed the senescence. In conclusions, our data indicate that MSCs are not inclined towards spontaneous neoplastic transformation. We believe that the control of MSC capacity to enter senescence is fundamental for quality and safety, considering the relevant interest in the MSC clinical applications.