Transformation of murine bone marrow-derived stem cells Free

A101

Mesenchymal stem cells (MSCs) are multi-potent cells with many potential clinical applications due to their capacity to be expanded in vitro and differentiate into several lineages. Although stem cells for therapeutic purposes can be managed safely, MSCs can undergo spontaneous transformation following long-term in vitro culture and genetic manipulations.
 We evaluated spontaneous transformation in culture of bone marrow derived murine mesenchymal stem cells that were used for magnetic resonance imaging and tracking in tumor models. We report that loading of MSCs with the Bangs particles containing iron oxide and long-term culture of genetically modified stem cells (transfected with the reporter gene) lead to their spontaneous transformation.
 We used established mouse mesenchymal stem cell line developed by the group of Dr.Prockop, Tulane University. These cells were originally derived from femurs and tibiae of C57BL mice. Differentiation assay performed with Passage 5 cells demonstrated that they maintain pluripotency. For transformation assay, we used MSCs transiently labeled in vitro with iron-oxide Bang’s particles (diameter 0.9 μm) or engineered MSCs expressing a unique cell surface receptor with GFP reporter.
 Our results indicate that transformation frequency (number of transformed foci per cell number) in iron oxide labeled MSCs was 5 times higher than in unlabeled MSCs. Incidence of transformation was also significantly higher in cells transfected with plasmid DNA (pEF1a-GFP-IRES-CD4), probably, due to increased genome instability in transfected cells.
 Normal stem cells and cancer stem cells share certain features, such as self- renewal and differentiation potential. These clear similarities suggest that some cancer stem cells could derive from adult stem cells. Our findings support the hypothesis of cancer stem cell origin and indicate the importance of bio-safety studies for efficient clinical applications of stem cells.