Inhibition of Sema-3A Promotes Cell Migration, Axonal Growth, and Retinal Ganglion Cell Survival.

ABSTRACT

Purpose: Semaphorin 3A (Sema-3A) is a secreted protein that deflects axons from inappropriate regions and induces neuronal cell death. Intravitreal application of polyclonal antibodies against Sema-3A prevents loss of retinal ganglion cells ensuing from axotomy of optic nerves. This suggested a therapeutic approach for neuroprotection via inhibition of the Sema-3A pathway. Methods: To develop potent and specific Sema-3A antagonists, we isolated monoclonal anti-Sema-3A antibodies from a human antibody phage display library and optimized low-molecular weight Sema-3A signaling inhibitors. The best inhibitors were identified using in vitro scratch assays and semiquantitative repulsion assays. Results: A therapeutic approach for neuroprotection must have a long duration of action. Therefore, antibodies and low-molecular weight inhibitors were formulated in extruded implants to allow controlled and prolonged release. Following release from the implants, Sema-3A inhibitors antagonized Sema-3A effects in scratch and repulsion assays and protected retinal ganglion cells in animal models of optic nerve injury, retinal ischemia, and glaucoma. Conclusions and Translational Relevance Collectively, our findings indicate that the identified Sema-3A inhibitors should be further evaluated as therapeutic candidates for the treatment of Sema-3A-driven central nervous system degenerative processes.