Neuroprotective effect of tanshinone IIA-incubated mesenchymal stem cells on Aβ25-35-induced neuroinflammation.

Mesenchymal stem cell transplantation can regulate neuroinflammation and treat Alzheimer's disease (AD), but its effect is attenuated by in vitro expansion. To solve this problem, we used tanshinone IIA (TIIA)-incubated mesenchymal stem cells (MSCs) to treat neuroinflammation caused by amyloid β-protein (Aβ). Here, we demonstrated that behavioral performance was rescued in rats receiving an intracerebroventricular injection of TIIA-incubated MSCs (TIIA-MSCs), and the TIIA-MSCs protected against neurotoxicity in the rat hippocampus by suppressing Aβ25-35-induced neuroinflammation. The levels of interleukin-1 (IL-1), IL-4, IL-6, IL-10 and tumor necrosis factor α (TNF-α) in Aβ25-35-induced rats were attenuated by TIIA-MSCs treatment, and IL-6 was the key difference between the TIIA-MSCs and MSCs groups. Furthermore, TIIA-MSCs reduced Aβ production-related mRNA (BACE1 and PS1) expression but had no significant effect on clearance (AMDM10). TIIA-MSCs also had the same effects on the protein levels. For the first time, we found that TIIA-MSCs have greater neuroprotective effects and prevent toxic protein production better than MSCs. These effects are related to Aβ modulation via downregulated BACE1 expression that promotes the survival of hippocampal neurons, as well as regulates neuroinflammatory-associated cytokines. These results provide support for the clinical application of MSCs, which will bring new hope for the treatment of AD.