Abstract

Multipotent mesenchymal stromal cells [also referred to as mesenchymal stem cells (MSCs)] as was previously described, are a heterogeneous subset of stromal cells with regenerative potential. Their present tropism for inflamed sites included tumors lesion may thus be adverse or therapeutic effects arising from MSC administration, in this context their potential for producing trophic and immunomodulatory factors raises the question as to whether MSCs promote or interact with a tumor microenvironment. Previous studies show a paradoxical effect regarding MSCs, which seems to depend on isolation and expansion, cell source, dose and both route and timing of administration. It has been reported the occurrence of neoplastic transformation in ex-­vivo expanded MSCs after long-­term culture. However, this event has been subsequently described as uncommon, with an estimated frequency of <10-­9. Furthermore, neither ectopic tissue formation nor MSC originating tumors have ever been reported so far in hundreds of patients treated with MSC therapy. The biosafety of these cells both cancerous and precancerous environment has been poor investigated to date. We found in an animal model of oral cancer that systemically administered allogeneic MSCs do not aggravate the progression of precancerous lesions. Moreover, they preclude cancer progression and tumor growth, particularly at papilloma stage.