69. Tumor-Targeting Innumogene Therapy by Mesenchymal Stem Cells Expressing CX3CL1

Abstract

Top of pageAbstract Bone-marrow derived mesenchymal stem cells (MSC) have high proliferative capacity and can differentiate into adipocytes, chondrocytes, osteoblasts, and probably other cells types. Recent studies reported that MSC migrates to the tumor and contributes to the formation of stromal tissue in the solid tumor, suggesting that MSC can be useful for tumor targeting of gene therapy. Since MSC lacks coxsackievirus-adenovirus receptor (CAR), we first investigated the efficiency of infection by either regular Ad vector or Ad-RGD vector, and then investigated anti-tumor effects by MSC expressing CX3CL1 (fractalkine) using Ad-RGD vector expressing CX3CL1 (AdRGDFKN). Murine MSC was infected either AdLacZ or AdRGDLacZ at different doses in vitro, and b-Gal staining positive cells were counted after 48 h infection. MSC infected with AdLacZ demonstrated only 2% positive cells, whereas MSC with AdRGDLacZ demonstrated 18% positive cells at 100 MOI. These results indicated that Ad-RGD could efficiently infect to the MSC. MSC infected with AdRGDFKN in vitro at 100 MOI revealed over 68% MSC expressed CX3CL1 on the cell membrane by FACS analysis. These MSC infected with AdRGDFKN (5|[times]|105/mouse) were injected into subcutaneously transplanted C26 tumor (5|[times]|105/mouse) on day 5. The C26 tumor regressed tumor growth by 59% compared to control tumor on day 22. Intravenous injection of MSC (5|[times]|105/mouse) of GFP mice into mice with established C26 pulmonary metastases led to incorporation of MSC in the tumor architecture. Intravenous injection of MSC-transduced with AdRGDFKN (5|[times]|105/mouse) into mice with established C26 pulmonary metastases suppressed the growth of pulmonary metastases and significantly reduced the number (PBS, 147.2; MSC-RGDLacZ, 136.2; MSC-RGDFKN, 16.3; BALB 3T3-RGDFKN, 157.2) of the metastasis in the C26 model on day 12, and prolonged mouse survival. These results indicate that MSC can be used for tumor-targeting immunogene therapy for multiple metastatic tumors.