mesenchymal stem cells genetically modified CD34 negative for tumor treatment

CD34- mesenchymal stem cells genetically modified for use in treating tumors in subjects, wherein the treatment comprises introducing into the bloodstream of a subject a therapeutically effective number of said cells, wherein each cell CD34 - genetically modified contains an exogenous nucleic acid comprising (i) a region encoding a cytotoxic protein operably linked to (ii) a promoter or combination of promoter / specific enhancer endothelium, whereby the cytotoxic protein is selectively expressed when genetically modified stem cells CD34- mesenchymal are located in the vicinity of, and differentiate into endothelial-like cells in the vicinity of tumor tissue angiogenesis who is suffering, and where the introduction of a therapeutically effective number of CD34- stem cells genetically modified in the bloodstream of their jeto is not preceded, accompanied or followed by myeloablation