Despite advances in clinical
therapies and technologies, the prognosis for patients with
malignant glioma is poor. Neural stem cells (NSCs) have a chemotactic tropism toward
glioma cells. The use of NSCs as carriers of therapeutic agents for
gliomas is currently being explored. Here, we demonstrate that cells isolated from the umbilical cord blood show mesenchymal characteristics and can differentiate to adipocytes, osteocytes, and neural cells and show tropism toward
cancer cells. We also show that these stem cells derived from the human umbilical cord blood (hUCB) induce apoptosis-like cell death in the
glioma cell line SNB19 via Fas-mediated
caspase-8 activation. From our
glioma tropism studies, we have observed that hUCB cells show tropism toward
glioma cells in vitro, in vivo, and ex vivo. We determined that this migration is partially dependent on the expression levels of
platelet-derived growth factor (PDGF)-D from
glioma cells and have observed that local concentration gradient of PDGF-D is sufficient to cause migration of hUCB cells toward the gradient as seen from our brain slice cultures. In our animal experiment studies, we observed that intracranially implanted SNB19
green fluorescent protein cells induced tropism of the hUCB cells toward themselves. In addition, the ability of these hUCBs to inhibit established intracranial
tumors was also observed. We also determined that the migration of stem cells toward
glioma cells was partially dependent on PDGF secreted by
glioma cells and that the presence of
PDGF-receptor (PDGFR) on hUCB is required for migration. Our results demonstrate that hUCB are capable of inducing apoptosis in human
glioma cells and also show that
glioma tropism and hUCB tropism toward
glioma cells are partially dependent on the PDGF/PGGFR system.