Neural stem cell transplantation : neuroprotection and LTP-induced facilitation of neurogenesis

• Main Author: Cho, Taesup
• Language: English
• Published: University of British Columbia 2011
• Online Access: http://hdl.handle.net/2429/36960

Transplantation of neural progenitor cells (NPC) constitutes a putative therapeutic maneuver for use in treatment of neurodegenerative diseases. At present, effects of NPC transplantation in the Alzheimer’s disease (AD) brain are largely unknown and a primary objective of this work is to demonstrate possible efficacy of NPC administration in an AD animal model. The benefits of transplantation could involve a spectrum of effects including replacement of endogenous neurons, conferring neuroprotection with enhancement of neurotrophic factors, and diminishing levels of neurotoxic agents. Additionally, since chronic inflammation is a characteristic property of the AD brain, I considered NPC transplantation could have a particular utility in inhibiting ongoing inflammatory reactivity. Accordingly, intra-hippocampal transplantation of NPC has been examined for efficacy in attenuating inflammatory responses and conferring neuroprotection in the hippocampus. These findings indicate efficacy for NPC transplantation with effects consistent with cellular actions to attenuate inflammatory reactivity. Synaptic plasticity, such as long-term potentiation (LTP), is thought to play a critical role in modification of neuronal circuitry in learning and memory, but the role in neurogenesis is not well known. A critical aspect of my study was to examine potential roles of N-methyl-D-aspartate receptor (NMDAR)-dependent LTP in promoting neurogenesis by facilitating proliferation/survival and neuronal differentiation of endogenous NPCs in the dentate gyrus (DG) and exogenously transplanted neural stem cells (NSCs) in the CA1. I found that LTP induction significantly facilitates proliferation/survival and neuronal differentiation of endogenous NPCs and exogenously transplanted NSCs in the hippocampus. These effects were eliminated by a NMDAR competitive antagonist, CPP. Accordingly, chemical LTP stimulation reproduced enhanced proliferation/survival and neuronal differentiation of NSCs when co-cultured with hippocampal neurons. These effects were eliminated by a NMDAR competitive antagonist, D-APV and inhibited by the tyrosine kinase inhibitor, K252a. ELISA and biotinylation results revealed that NMDAR-mediated LTP facilitates the release of a neurotrophic factor, BDNF. The conditioned media from cLTP-induced hippocampal neurons were sufficient to activate the BDNF receptor, TrkB. Overall, my results suggest that NMDAR-dependent LTP plays a critical role in neurogenesis and may contribute to the utility of NSC transplantation as an effective cell therapy for a variety of neurodegenerative diseases.