Application of the disc angiogenesis system to tumor-induced neovascularization.

Solid tumors elaborate soluble substances that (directly or indirectly) induce angiogenesis by a step-wise process which ultimately results in a microvascular network that nourishes the growing tumor. To study angiogenesis induced by brain tumors we have used a rat glioma model. Modifying the disc angiogenesis system (DAS) we evaluated quantitatively the angiogenic response to cultured, live RT-2 rat glioma cells placed in the center of the discs. DAS were implanted in the subcutaneous tissue of rats and evaluated for vessel proliferation 2 weeks later. Recognition of vessels was greatly facilitated by the staining of their basement membrane using a polyclonal anti-collagen IV antibody. Experimental discs containing 10(3) or 10(5) glioma cells as well as positive control discs containing the agonist prostaglandin E1 consistently demonstrated greater vessel growth than negative controls (discs containing a balanced salt solution). The disc angiogenesis system is a useful tool for the measurement of angiogenic response to living tumor cell suspensions.