Mesenchymal stem cell-derived exosomes rescue stress-dependent morphological deficits in primary hippocampal neurons via Wnt5a/β-catenin/WAVE2 pathway

Objectives: Increasing evidence indicates that chronic stress impairs dendritic branching and synaptic plasticity in hippocampal neurons. Mesenchymal stem cell-derived exosomes (MSC-Exos) are crucial for tissue injury repair, facilitating cell communication and transporting bioactive cargo like lipids, proteins, and nucleic acids. Herein, we investigate the therapeutic effects and molecular mechanism of MSC-Exos against stress-dependent morphological deficits in primary hippocampal neurons.

Methods: MSC-Exos were obtained and identified. Primary hippocampal neurons were exposed to corticosterone (CORT) to simulate stress in vitro. Adeno-associated virus (AAV) that targets MSC was used to knock down Wnt5a in MSC-Exos. MSC-Exos, Wnt5a-sh RNA MSC-Exos and small molecule compound inhibitor interventions were conducted respectively to study the therapeutic impact and molecular mechanisms in primary hippocampal neurons under CORT stimulation. Western blotting and immunofluorescence labeling were applied for evaluating protein levels. GEO database analysis was used to screen potential targeting gene of MSC-Exos in neurons. Sholl analysis was employed to evaluate morphology of primary hippocampal neurons.

Results: This study found that MSC-Exos improved the morphological deficits of primary hippocampal neurons under CORT stimulation. This improvement was associated with enhanced nuclear translocation of β-catenin and increased expression of downstream genes N-Cadherin and Cyclin D3. These effects were reversible with the β-catenin Inhibitor ICG-001.We also discovered that Wnt5a was contained in MSC-Exos, knockdown of Wnt5a in MSC-Exos significantly abrogated activation of β-catenin signaling and promotion of dendrite morphogenesis. Gene expression array data from the GEO database linked to a chronic stress animal model indicated a significant down-regulation of WAVE2 in the hippocampus. In addition, MSC-Exos induced Wnt5a/β-catenin signaling exhibited the capacity to increase the expression of WAVE2, thereby rescued the morphological deficit in primary hippocampal neurons.

Conclusions: Our study indicates that MSC-Exos ameliorate stress-dependent morphological deficits in primary hippocampal neurons via the exosomal Wnt5a/β-catenin/WAVE2 pathway.

Chronic stress; Exosome; Mesenchymal stem cell; Primary hippocampal neurons; Sholl analysis.