In vivo culture of encapsulated endostatin-secreting Chinese hamster ovary cells for systemic tumor inhibition.

Microencapsulation of recombinant cells is a novel alternative approach to tumor gene therapy. Therapeutic protein delivery can be sustained for systemic treatment of tumors because the recombinant cells are enclosed in microcapsules and the semipermeable membrane of the microcapsules protects the cells from host immune rejection and reduces the need for frequent injection. In this study, we describe a method to systemically inhibit tumor growth by in vivo culture of antiangiogenic endostatin-secreting Chinese hamster ovary (CHO) cells in microcapsules as small as 200 microm in diameter. Peritoneal administration of encapsulated endostatin-CHO cells inhibited melanoma growth to 66.4% and enhanced the survival of treated mice to 80% by 27 days posttreatment. Continuous systemic release of endostatin from microcapsules offers an effective therapeutic strategy to eradicate solid tumors.