12:00 – 12:30 Ana González Manteiga

Novel models of cortical regeneration: the role of Nrg1 signaling upon brain damage.

Brain damage is the major cause of adult disabilities, specifically on the elderly population. In this paradigm, there is a variety of biological events to consider in brain injury: neuronal death, neuroinflammation, loss of synapses and alteration in neuronal circuitry. The rewiring process upon brain damage is poorly understood and there is no pharmacological treatment available. Neuregulin 1 (Nrg1) regulates the formation of cortical circuitry. Recently, others and we showed that Nrg1 signaling is neuroprotective upon stroke. Hence, the aim of my PhD project is to investigate the role of Nrg1 signaling in axonal regeneration and cortical rewiring upon injury. To address this objective, we developed both in vitro and in vivo approaches, developing different injury models to understand the role of Nrg1 in neuroregeneration. For our in vitro studies, we performed gain- and loss-of function studies in a model for axonal injury and regeneration in vitro based on the mechanical severing of the axons. Our results showed that Nrg1 and the activation of its intracellular signaling potentiated axonal regeneration. To study the role of Nrg1 in vivo, we established a new model of cortical injury (Controlled Cortical Damage, CCD). Briefly, we trace callosal projection with viral vectors to study cortical rewiring upon a mechanical injury on the hindlimb motor cortex. To study functional motor outcome, we perform a battery of different motor behavioral test. Finally, we designed a multiplexed and tridimensional analysis from coronal brain sections, which allows investigating different immunolabelings: since a 3D reconstruction of the contralateral innervation around the injured area to cellular population. In this model, we started as well to perform both gain- and loss of function studies to test whether Nrg1 promotes cortical regeneration upon brain damage. Altogether, our research provide a novel experimental model for brain injury, both in vitro and in vivo approaches and suggest a role for Nrg1, specifically its intracellular signaling, in cortical regeneration upon brain damage.

12:30 – 13:00 Sonia Hingonari Jai

Peripheral neuron transplantation overexpressing NaChBac as a therapeutic intervention for spinal cord injury.

Spinal cord injury (SCI) is a devastating, debilitating and life altering injury that hampers the life of a patient and is characterized by partial or complete loss of muscle function. A lot has been studied about the regeneration, increase in functional recovery and mechanisms behind this loss to improve the current therapies and/or strategies used to treat SCI without significant success. Current consensus defends two major impediments limiting the neuronal regeneration; 1) the inhibitory extrinsic signal generated by the hostile microenvironment after injury and the 2) limited intrinsic capacity of adult central neurons to regenerate. Therefore, the combination of strategies targeting extrinsic and intrinsic limitations have been accepted to show better results. Peripheral nerve grafts transplantation creates permissive substrate and has been reported to allow central axons to regenerate in a complete lesion. However, the ephemeral life cell engraftment and the axonal growth inhibitory signals results in insufficient functional regeneration. To overcome this limitation, we have introduced in the isolated peripheral neurons the expression of NaChBac (NC), a bacterial sodium channel, known to increase neuronal survival as well as their integration in brain circuits. Our findings show that transplantation of peripheral neurons are able to survive and grow axons near around the lesion site in mice after SCI. The NC expressing neurons grafts survived and integrated significantly better in the injured tissue, inducing a significant improvement in the locomotor outcomes 2 months after severe SCI. The peripheral neurons expressing NC are able to modulate the lesion environment, improving and maintaining the integrity of the spinal cord after injury. In a step further, we also propose the combination of peripheral neurons transplantation and the local pharmacological treatment for axon microtubules and actin-myosin remodelling, tested in a preclinical model of SCI to overcome the intrinsic axon regeneration limitation. We studied the effect of cytoskeleton modulating drug Blebbistatin, a non-muscle myosin II inhibitor on neurons isolated from neonatal dorsal root ganglia plated over non-permissive environments, showing increased axonal elongation capacity. Further in vivo evaluation is needed, but we hypothesize that the combinatory therapy of transplanted peripheral neurons and Blebbistatin would serve as a possible improved therapy for SCI tested in rodent models.