| Background and objectives Alzheimer’s disease(AD)is a kind of progressive and neurodegenerative disease,which pathogen is unknown.It causes irreversible brain damaged,and widely be recognized as a refractory disease.Its main early symptoms is recent memory disorder.Its morbidity related to the growth of age.With the increase of aging population and human average life span,the number of AD patients is on the rise year by year.According to the World Alzheimer Report 2015,there were 46 million AD patients in global.It cost $ 8180 trillion to treating and looking after those patients.However,AD patients will reach 74.7 million people by 2030,they will give the community and the family a heavy economic burden,but also seriously affect the quality of life of patients with family.In clinical,the treatment of AD include drug therapy and non-drug therapy are just for symptoms,they can’t effectively cure and prevent the further development of disease.So it is important to develop a new drug or find a new method to cure AD or prevent it from progressing too fast,or improve the quality of AD patients’ life.In the current study of AD,stem cells are increasingly receiving more and more attention,a number of basic research and clinical studies have shown that stem cells transplantation is expected to have a good therapeutic effect of AD and other nervous system related diseases.Because of the characteristics and advantages of stem cells,include the high proliferative capacity,pluripotent differentiation potential,paracrine multiple activity factors which are involved in cell survival,developmental differentiation,microenvironment improvement,anti-apoptosis,promote angiogenesis and so on,and its good efficacy of AD model and feasibility of clinical application,it is expected to play an important role in the clinical treatment of AD.Mesenchymal stem cells(MSCs)have shown their advantages among many stem cells,in terms of tissue sources,security,clinical applications,therapeutic effects,ethics and immunization.At present,number of basic research and clinical research reported that MSCs could be obtained from teeth,umbilical cord,placenta,bone marrow,fat and other tissues.They can be differentiated into a variety of tissue cells,even neurons.Moreover,its strong secretion can regulate the immune response,and provide the nutritional support.However,in these studies,MSCs from different tissues were not studied in the same disease,the same in vitro culture and evaluation system,and it was difficult to obtain an accurate evaluation of the therapeutic effect and failed to elucidate its possible mechanism.The purpose of this study is to evaluate the effect of six different tissues derived MSCs on the repairing of injured nerve cells in AD cell model,and to explore the possible mechanism of MSCs.Methods In this study,we obtained six different tissues derived MSCs through classical primary separation method from periodontal ligament,pulp,umbilical cord,amniotic membrane,smooth chorionic membrane and adult bone marrow,and identified them.Meanwhile,we used okadaic acid(OA)to injury neurofibrillary cell line(SH-SY5Y)and primary neurons by to simulate the pathological features of neurofibrillary tangles,to establish AD cells model.On the basis of this,the conditioned medium of MSCs cells from different origins was co-cultured with the in vitro AD model cells,and then,we evaluated therapeutic effects of MSCs from the aspects of cell morphology,cell viability and proliferation ability,mitochondrial function,number of dendritic spines,ultrastructure.Furthermore,we used the Western Blot method to detect the expression of serine phosphorylation at Tau protein 396,which is closely related to the development of AD.In the same time,we used the real-time quantitative PCR to screen a variety of related genes.Results After treated with OA,SH-SY5Y cells and primary neurons’ cell bodies shrinkage and became rounded,dendrites retracted and shortened.The average length of neuronal dendrites was shortened by 66.6%.The viability of SH-SY5Y cells decreased by 35%,the mitochondrial membrane potential decreased by 13.9%.The number of neurons dendritic spines decreased by 64.4%.Cytoskeleton disordered,the expression level of Ser 396 phosphorylation site of Tau protein decreased.These results proved that we successfully established the AD cell model.Then,MSCs were treated with the neural cells damaged by OA,and all the neural cells recovered their shape,their dendrites were prolonged,the average length of neuronal dendrites increased by more than 93.8%,the cell viability increased by 10%,mitochondrial membrane potential increased by more than 6.4%,neuronal dendritic spine increased more than doubled,the cytoskeleton arranged neatly.The expression level of Ser396 phosphorylation site of Tau protein of SH-SY5Y by western blot were decreased,and the expression level of BRCA1 gene was higher than the expression of OA group.Therefore,we speculated that MSCs might decrease the hyper phosphorylation site of Tau protein,and increased the expression of BRCA1 gene to play its role in the treatment of damaged neural cells.Conclusion These six different tissues derived MSCs are able to exert therapeutic effect on neural cells by OA damage through their secreted factors.And its possible mechanism may be through the reduction of the hyper phosphorylation of Tau protein and of activation of the expression of BRCA1 in neural cells. |
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