| Summary: | 碩士 === 國立中山大學 === 生物科學系研究所 === 104 === Cervical spinal cord injury usually leads to respiratory impairment and locomotor paralysis due to the lesion of the bulbospinal pathway and damage of spinal motorneurons. Cellular replacement therapy has a potential to replace damaged spinal cells and restore neural connectivity; therefore, transplantation of neural progenitors may be a promising therapeutic strategy for spinal cord repair. This study was designed to examine whether a delayed transplantation of fetal spinal cord(FSC)tissue can reconstruct cervical spinal neural circuit and modulate respiratory and locomotor function. Embryonic day 14 spinal cord tissue expressing green fluorescence protein(GFP)or hank’s balanced salt solution(HBSS)were transplanted in the C4 spinal cord hemi-section(C4Hx)cavity of adult Sprague Dawley rat at 1 week post-injury. Respiratory patterns and locomotor behaviors were evaluated before and at 1, 2, 4 and 8 weeks post-transplantation by whole body plethysmography and open-field tracking system, respectively. Histological data showed that a robust GFP expression was observed in the lesion side in most transplanted animals. Immunofluorescence staining revealed that neural cell markers [e.g., neuronal nuclei(NeuN)for neuron; glial fibrillary acidic protein(GFAP)for astrocyte; ionized calcium binding adapter molecule 1(Iba1)for microglia; receptor interacting protein(RIP)for oligodendrocyte] were detected in GFP-positive tissue. The graft-derived neuron can differentiate into specific neuron [e.g., serotonergic, 5-hydroxytryptamine(5-HT); noradrenergic, dopamine beta hydroxylase(DBH); cholinergic, choline acetyltransferase(ChAT)]. FSC-derived graft received a robust innervation of GABAergic(GAD65/67 positive)and glutamatergic(vGluT2 positive)fibers. Physiological data demonstrated that respiratory patterns and locomotor behaviors were similar between C4Hx animals received FSC or HBSS transplantation. Retrograde monosynaptic tracer (Cholera toxin B)or transsynaptic tracer(wheat germ agglutinin; WGA)were painted on the diaphragm at 8 week post-transplantation to examine whether transplanted FSC-derived graft can innervate the phrenic motor system. The result showed that there were some WGA-positive cells detected within the graft region. These data suggest that fetal spinal cord tissue can survive and differentiate into neural cells in the injured host spinal cord and reconstruct the spinal cord respiratory circuit; however, this approach is not sufficient to significantly improve the respiratory motor function.
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