Retroviral vector-producer cell-mediated in vivo gene transfer of TIMP-3 restricts angiogenesis and neuroblastoma growth in mice

Destruction and remodeling of the extracellular matrix occurs during the formation of new blood vessels that are required for tumor growth. We sought to determine whether gene-therapy mediated in vivo delivery of tissue inhibitor of matrix metalloproteinase-3 (TIMP-3), using retroviral vector-producer cells, could suppress angiogenesis and subsequent tumor growth in a murine neuroblastoma model. Tumor volume 28 days after coinjection of tumor cells with producer cells generating TIMP-3-encoding retroviral vectors was 21% that of controls, as was the mean tumor vascular index, a measure of blood vessel maturity. When tumors were allowed to reach a mean volume of 0.05 cm(3) before treatment, their size 2 weeks later was 47% relative to controls; larger tumors were not significantly affected. When producer cells were injected at surgical sites following excision of subcutaneous tumors, local recurrence 14 days later was only 22% in TIMP-3 producer cell treated mice as compared to 71% in controls. Unsuccessful transduction of melanoma cells in situ, another tumor of neural crest origin, resulted in unimpaired tumor growth, despite the fact that these tumors are susceptible to TIMP-3 overexpression, demonstrating the importance of tumor cell transduction in this approach. Thus, retroviral vector-producer cell-mediated in vivo gene transfer of TIMP-3 to tumor cells can significantly restrict tumor-induced angiogenesis and tumor growth. This approach may be an effective adjuvant in the treatment of neuroblastoma and other solid tumors refractory to traditional therapy, although it appears to be most effective in smaller tumors or in the setting of minimal residual disease, and the tumor cells must be susceptible to retroviral vector-mediated transduction.