HUC-MSCs Activate the TRPV1-[Ca2+]i-AMPK Signaling Pathway to Improve Mitochondrial Dynamics in Schwann Cells under Hyperglycemic Conditions

Objective To investigate the relationship between the therapeutic effects of human umbilical cord mesenchymal stem cells (HUC-MSCs) on diabetic peripheral neuropathy (DPN) in mice and the involvement of the transient receptor potential vanilloid 1 (TRPV1) signaling pathway. Methods A mouse model of diabetic neuropathy was established. Neuropathic pain was assessed using the Von Frey test and KW-LB hot plate assay. Primary Schwann cells were isolated from the sciatic nerves of mice, and intracellular calcium ([Ca²⁺]i) levels were measured by flow cytometry. Protein expression was analyzed by Western blotting, while apoptosis and proliferation were evaluated using TUNEL staining and the CCK-8 assay, respectively. Results Treatment with HUC-MSCs reduced mechanical withdrawal thresholds and increased thermal withdrawal latency in diabetic mice. Co-culture with HUC-MSCs significantly increased the p-TRPV1/TRPV1 ratio and [Ca²⁺]i levels in high-glucose-treated Schwann cells. The expression of Cleaved-Caspase-3 and Bax decreased, while Bcl-2 expression increased. These effects were attenuated by AMG9810, a TRPV1 antagonist. Furthermore, co-culture with HUC-MSCs enhanced the p-AMPK/AMPK ratio in high-glucose-treated Schwann cells, but this effect was diminished by Compound C (an AMPK inhibitor) or AMG9810. Additionally, HUC-MSC co-culture reduced Drp1 expression and increased PGC-1α, TFAM, and Mfn2 expression in high-glucose-exposed Schwann cells. However, these changes were reversed by Compound C, which increased Drp1 expression and decreased PGC-1α, TFAM, and Mfn2 expression. Conclusion HUC-MSCs improve neuropathic pain in diabetic mice through activation of the TRPV1-[Ca²⁺]i-AMPK signaling pathway. This activation promotes mitochondrial biogenesis via PGC-1α and TFAM, and regulates mitochondrial fission and fusion via DRP1 and MFN2, thereby mitigating hyperglycemia-induced apoptosis in Schwann cells. The beneficial effects of HUC-MSCs are attenuated by TRPV1 or AMPK inhibitors, highlighting the critical role of this signaling axis in diabetic neuropathy treatment.