Endothelial progenitor cells’ ‘homing’ specificity to brain tumors

Current treatment of malignant glioma brain tumors is unsatisfactory. Gene therapy has much promise, but target-specific vectors are needed. Endothelial progenitor cells (EPCs) have in vivo homing specificity to angiogenic sites and are thus potential vehicles for site-specific gene therapy. However, reports of EPCs ‘homing’ to intracranial solid tumors are lacking. We investigated EPCs’ ‘homing’ specificity using a murine intracranial glioma model. EPCs, derived from human cord blood, were labeled with a fluorogenic agent CFSE and intravenously injected into SCID mice bearing orthotopic gliomas. At 7–14 days after EPC injection, mouse brains and other vital organs were examined for distribution of transplanted EPCs. As controls, CFSE-labeled human umbilical vein endothelial cells (HUVECs) and EPCs were intravenously injected into matched glioma SCID mice (HUVEC control groups) and nontumor SCID mice (nontumor-bearing control groups), respectively. Fluorescence image analysis revealed that systemically transplanted EPCs ‘homed’ to brain tumors with significantly higher specificity as compared to other organs within the experimental group (P