Positive effects of alpha-asarone on transplanted neural progenitor cells in a murine model of ischemic stroke

Background: Some traditional Oriental herbal medicines, such as Acorus tatarinowii and Acorus gramineus, produce beneficial effects for cognition enhancement. An active compound in rhizomes and the bark of these plants is alpha-asarone. Purpose: This study investigated the effects of alpha-asarone on the proliferation and differentiation of neural progenitor cells (NPCs) in a primary culture and a murine model of ischemic stroke. Methods: NPCs were isolated from mouse fetal cerebral cortices on embryonic day 15, and all experiments were performed using passage 3 NPCs. We utilized a cell counting kit-8 assay, flow cytometry, western blot, and immunohistochemical analysis to assess proliferation and differentiation of NPCs and employed alpha-asarone in NPC transplanted ischemic stroke mice to evaluate stroke-related functional recovery using behavioral and immunohistochemical analysis. Result: Treatment with 1 mu M, 3 mu M, or 10 mu M alpha-asarone induced significant NPC proliferation compared to vehicle treatment. Induced NPCs expressed the neuronal marker neuronal nuclei (NeuN) or the astrocyte marker S100 calcium-binding protein B (S100 beta). Both immunohistochemistry and flow cytometry revealed that treatment with a-asarone increased the number of NeuN-immunoreactive cells and decreased the number of S100 beta-immunoreactive cells. Treatment with alpha-asarone also increased the expression of beta-catenin, cyclin D1, and phosphorylated extracellular signal-regulated kinase (ERK) compared to vehicle treatment. In a murine model of ischemic stroke, treatment with alpha-asarone and transplanted NPCs alleviated stroke-related functional impairments. The corner and rotarod test results revealed that treatment with alpha-asarone in the NPC transplanted group had greater-than-additive effects on sensorimotor function and motor balance. Moreover, alpha-asarone treatment promoted the differentiation of transplanted NPCs into NeuN-, glial fibrillary acidic protein (GFAP)-, platelet-derived growth factor-alpha (PDGFR-alpha)-, and 2', 3'-cyclic nucleotide 3'-phosphodiesterase (CNPase)-immunoreactive cells. Conclusion: Phi-asarone may promote NPC proliferation and differentiation into neuron-lineage cells by activating beta-catenin, cyclin D1, and ERK. Moreover, alpha-asarone treatment facilitated neurofunctional recovery after NPC transplantation in a murine model of ischemic stroke. Therefore, alpha-asarone is a potential adjunct treatment to NPC therapy for functional restoration after brain injuries such as ischemic stroke.