The evaluation of the effect of neurotrophic factors-secreting cells on synaptogenesis and Tau protein phosphorylation in an in vitro model of Alzheimer's desease

Abstract

This study investigated physical proximity and paracrine activity of neurotrophic factor-secreting cells (NTF-SCs) differentiated from adipose-derived mesenchymal cells on beta-amyloid treated cells an in-vitro Alzheimer's model. Methods: Mesenchymal stem cells (MSCs) - to-NTF-SCs (Astrocyte –like cells) trans-differentiation was confirmed using GFAP immunofluorescence staining. BDNF and NGF levels were measured by ELISA assay. To mimic Alzheimer’s disease (AD)-like condition, SH-SY5Y cells were exposed to 10 µM amyloid- β (Aβ)1-42. SH-SY5Y cells were allocated into Control; and Aβ1–42-treated cells. Treated cells were further classified into three subgroups including Aβ1–42 cells, Aβ1–42 cells + NTF-SCs condition media(CM) and Aβ1–42 cells + NTF-SCs co-culture. Cell viability and toxicity rate were measured by the MTT assay. Anti-inflammatory and anti-tauopathy effects of NTF-SCs were assessed via monitoring of tumor necrosis factor- α (TNF-α) and phosphorylated tau protein expression levels, respectively. To explore the impact of NTF-SCs on synaptogenesis and synaptic functionality, the real-time PCR assay was performed to measure the expression of synapsin 1, homer 1 and ZIF268. The level of synaptophysin as a transmission synaptic marker was monitored via immunofluorescence staining. Results: MSCs potential in trans-differentiating toward NTF-SCs was proved by enhanced GFAP expression (p<0.05). ELISA assay confirmed the superiority of NTF-SCs in releasing NGF and BDNF compared to the MSCs (p<0.05). Aβ significantly induced SH-SY5Y cells death while juxtacrine and paracrine activity of NTF-SCs significantly blunted these conditions (p<0.05). Trans-differentiated cells could reduce TNF-α and tau hyperphosphorylation level after treatment with Aβ through juxtacrine and paracrine mechanisms (p<0.05). Moreover, NTF-SCs significantly increased the expression of synapsin 1, homer 1 and zif 268 genes in Aβ-treated cells compared to matched-control group coincided with induction of synaptophysin at the protein level(p<0.05).