This is the first demonstration of a regulated chondroitinase gene therapy system in vivo. One previous attempt to generate Tet-On chondroitinase, using an adenoviral vector encoding chondroitinase AC has been reported and used in a human astrocytoma cell line (Curinga et al., 2007) but this was not tested in vivo. Here, we use a tetracycline derivative to induce expression of an optimized ChABC transgene in order to exert temporal control over enzyme delivery in vivo, in the mammalian spinal cord, following a clinically-relevant cervical level spinal contusion injury to adult rats. Here, GALNS is linked to astrocytoma (excluding glioblastoma).