Last update:
06-Dec-2017

Mesenchymal stem cells are primitive, undifferentiated cells which consist of distinct, heterogeneous subpopulations. They have common characteristics such as self-renewal and pluripotency and, depending on their origin, they also present some unique features. Their migration ability towards injured tissues, in combination with their low immunogenicity, highlights these cells as promising mediators for cell therapy against many diseases. In particular, the discovery that mesenchymal stem cells have an inherent tendency for tropism towards tumor sites, and that they interact with the tumor microenvironment, has prompted the search for efficient protocols for their use in cancer cell therapy. Current preclinical therapeutic approaches are based on both the direct interaction between stem and cancer cells, and the results of the paracrine effects of stem cells on tumor cells. Studies include the use of both naïve and genetically modified stem cells as carriers of anticancer agents or genes to target cancer cells. Despite the encouraging results in several preclinical models of cancer, the use of genetically modified stem cells raises important safety issues, due to the involvement of viral vectors. Furthermore, experiments on the interaction between tumor cells and naïve stem cells, both in vitro and in vivo, have led to contradictory results, in some cases suppressing, and in other cases promoting tumor growth. These completely opposite actions that these cells show have been related to various factors, among which are the source of the stem cells, the cancer type and the experimental conditions. This is a review of the various different characteristics of heterogeneous stem cell populations and how they interact with the microenvironment of tumors, and of the experimental results to date regarding the use of naïve and genetically modified stem cells in various types of cancer.

Key words: Cancer, Cytotherapy, Stem cells, Targeted therapy, Tropism.