Transfer Of Three Transcription Factors Via A Lentiviral Vector Ameliorates Cognitive Function Impairment In A Mouse Model Of Alzheimer’s Disease

Background and Objects:Alzheimer’s disease (AD) is known as a neurodegenerative disease of the central nervous system in old age or early old, with the main feature including cognitive impairment of the learning-memorialand personality changes. It is characterized by the presence of four pathologic lesions:senile plaques (SP), neurofibrillary tangles (NFTs), hippocampal pyramidal cellgranulovacuolar degeneration and neurons loss. Considering the still fast growing number of the elderly, it has become a serious social phenomenon nowadays. However, its etiopathogenisis and mechanism is still unknown, a considerable evidence suggests that the progressive loss of neurons and the neuroinflammatory response are central to AD pathogenesis. Consequently, to find out the effective treatment of AD is a tremendous challenge for the neuroscientists. With the development of the molecular biology and medical biotechnology, the gene therapy and cell-replacement therapy have raised hope for the possibility of prevention and treatment of AD.In this study, the C57BL/6mice were used as research model; the AD animal model was established by injecting Aβ1-42bilaterally into the mice hippocampus. Lentiviral ABP (Ascll, Brn2and Pax6) at two different titers (1.0×109TU/ml and1.5×109TU/ml) were given as intervention treatment. And then, the aim of this study is also to evaluate the influence of lentiviral ABP on learning and memory loss and the damage of hippocampus neuron in a mouse model of AD induced by Aβ1-42and the potential mechanisms, which provides a more favorable theoretical basis for clinical administration.Methods: A total of40adult male C57BL/6mice were used in this study and were randomly divided into four experimental groups:the sham operation group, AD model group, high titer treated group (1.5x109TU/ml) and low titer treated group (1.0x109TU/ml). Each group was8mice. A mouse model of AD was established by injecting Aβ1-42bilaterally into the mouse hippocampus. Lentiviral ABP at two different titers was delivered bilaterally into the hippocampus of mice previously injected (3d prior) with Aβ1-42or PBS control, and a Morris water maze test was conducted to examine the learning and memory abilities in these mice. The brain tissue of mice were removed to be made paraffin sections, the HE stain was performed to detect the cell morphology of the hippocampus. Additionally, an antibody microarray screen comparing protein expression among these experimental groups was used to profile the protein alterations in the hippocampus most associated with learning and memory.Results:The results of Morris water maze test showed that the mice in the AD model group exhibited longer escape latencies, less mean number of crossings over the platform position and had a significant decrease in the time in the targeted quadrant when compared with the control group (P<0.05). However, the mice treated with Lentiviral ABP transcription factors (both at high and low titers) displayed significantly lower escape latencies, more mean number of crossings over the platform position and longer time in the targeted quadrant than the Aβ1-42-induced AD model (P<0.05), which indicated that Lentiviral ABP can ameliorate spatial learning and memory impairment in an AD mouse model.The result of HE stain showed that the neural cells in dentate gyrus and CA3sections of hippocampal in the sham-operated groupwere over-shaped, tightly packed neatly, evenly stained, round nucleus and clear nucleolus. Hippocampal neural cells in AD model group exhibited sparse arrangement, reduced cellular, deeply stained nuclei condensation. Meanwhile the glial cell proliferation was significant increased. When compared with the AD model group, hippocampal neural cells in both high and low titers Lentiviral ABP treated group arranged in neat rows, oval or round, rare cell depigmentation, reduced glial cell proliferation and clearly visible nucleolus.The result of antibody microarray showed that the expression levels of eight proteins were changed significantly in Aβ1-42-induced AD mice compared with sham-operated group. The LV-ABP treated groups (both low and high titers) had altered expression levels of a large number of proteins compared to the AD model group. Among the proteins identified, most were considered to be neurotrophic or growth factors and inflammatory factors. Expression levels were significantly increased, by twofold or more, for ten proteins, VEGF, FGF2, IL-3, HGF, IL-4, IL-5, SDF-la, TIMP-1, TIMP-2and Chordin. Expression levels of four proteins, CD40, TNFa, IL-17and CD27Ligand, decreased significantly.Conclusions:(1) The results of the study suggested that the mice which are established by injecting Aβ1-42bilaterally into the mouse hippocampusexhibit the changes of praxeology and pathology of AD, indicating that the mice model is establishedsuccessfully.(2) The result of Morris water maze test showed that the learning and memory of the model mice were decreased obviously,which indicated that Lentiviral ABPcould ameliorate spatial learning and memory impairment in an AD mouse model.(3) Lentiviral ABP can decrease neuronal loss and improve pyramidal cells pathomorphological changesin hippocampal CA3and dentate gyrus of AD mice, hence it can prevent neurons in hippocampus CA3and dentate gyrus sectors of AD mice from impairment.(4) Lentiviral ABP can improve the learning and spatial memory ability of AD mice, those partly may be linked to protect hippocampal neurons, stimulate neurogenesis, prevent neural cell apoptosis and inhibit the neuroinflammatory response.