X-irradiation-induced loss of O-2A progenitor cells in rat spinal cord is inhibited by implants of cells engineered to secrete glial growth factor 2.

The loss of O-2A progenitor cells has been implicated as a critical event in radiation-induced spinal cord demyelination. To investigate whether glial growth factor 2 (GGF2) affects the number of O-2A cells in the irradiated rat cervical spinal cord, an ex vivo gene therapy approach was applied in which CHO cells engineered to express recombinant human GGF2 were injected into the cisterna magna of adult rats. Spinal cord irradiation reduced the number of O-2A cells in a dose-dependent manner. However, this radiation-induced decrease in O-2A progenitor cells was significantly attenuated by the delivery of GGF2 after irradiation. These data indicate that the cell-mediated delivery of GGF2 can reduce the loss of O-2A progenitors after irradiation.

Neuregulin in neuron/glial interactions in the central nervous system. GGF2 diminishes autoimmune demyelination, promotes oligodendrocyte progenitor expansion, and enhances remyelination.

Glial growth factor 2 (GGF2) is a neuronal signal that promotes the proliferation and survival of the oligodendrocyte, the myelinating cell of the central nervous system (CNS). This study has focused on recombinant human GGF2 (rhGGF2) and it's potential to affect clinical recovery and repair to damaged myelin in chronic relapsing experimental autoimmune encephalomyelitis (EAE) in the mouse, a major animal model for the human demyelinating disease, multiple sclerosis (MS). Mice with EAE were treated with rhGGF2 during both the acute and relapsing phases, and GGF2 treatment led to delayed signs, decreased severity and resulted in statistically significant reductions in relapse rate. Further, rhGGF2-treated groups displayed CNS lesions with more remyelination than in controls. This correlated with increased expression of myelin basic protein exon 2, a marker for remyelination, and with an increase of the regulatory cytokine, IL-10. Thus, a beneficial effect of a neurotrophic growth factor has been demonstrated upon the clinical, pathologic and molecular manifestations of autoimmune demyelination, an effect that was associated with increased expression of a Th2 cytokine. rhGGF2 treatment may represent a novel approach to the treatment of MS (Cannella et al., 1998).