Migration of mouse-induced pluripotent stem cells to glioma-conditioned medium is mediated by tumor-associated specific growth factors.

Neural and mesenchymal stem cells have extensive tropism for malignant glioma. The tumor tropism of induced pluripotent stem (iPS) cells was tested using the Matrigel invasion assay. Mouse iPS cells showed a significant tropism to the conditioned media prepared from six rodent and human glioma cell lines and this tropism to the glioma conditioned media was partially blocked by the neutralizing antibodies for four major tumor-associated growth factors [stem cell factor (SCF), platelet-derived growth factor BB (PDGF-BB), stromal-derived factor-1α (SDF-1α) and vascular endothelial growth factor (VEGF)], which are secreted from the malignant gliomas. The tropism of the iPS cells was enhanced by the growth factors in a concentration-dependent manner from 0.1 to 100 ng/ml. The receptors for those growth factors (c-Kit, ICAM-1, CXCR4 and VEGFR2), measured by reverse transcriptase-polymerase chain reaction, were highly up-regulated in the mouse iPS cells compared to the mouse fibroblasts. The results showed that the specific growth factors secreted from the gliomas strongly attracted the iPS cells. Therefore, gene therapies using iPS cells as vectors to deliver anti-tumor agents are novel strategies for the treatment of malignant gliomas that deeply infiltrate the brain.