Tibial cortex transverse transport regulates Orai1/STIM1-mediated NO release and improve the migration and proliferation of vessels via increasing osteopontin expression

Background

Diabetic foot is a major complication of diabetes. The bone transverse transport method could be applied in clinics for treatment, which could improve the metabolism of the tissues via lasting distraction forces. However, the process’ specific regulating mechanism is still unknown.

Methods

Based on the notion that the healing of bones involves the recruitment of calcium ions, in this study, we established the model of tibial cortex transverse transport (TTT) on rats and then used tissue immunologic detection, such as the double fluorescent staining to explore the expression of the calcium channels’ calcium release-activated calcium modulator 1 (Orai1)/stromal interaction molecule 1 (STIM1), which belong to the store-operated calcium entry (SOCE) signaling pathways on the tissues around the bone transport area. By using the laser capture microdissection (LCM) tool, we acquired samples of tissues around the bone and endeavored to identify pivotal protein molecules. Subsequently, we validated the functions of key protein molecules through in vitro and in vivo experiments.

Results

After protein profile analysis, we found the differentially expressed key protein osteopontin (OPN). The in vitro experiments verified that, being stimulated by OPN, the migration, proliferation, and angiogenesis of human umbilical vein endothelial cells (HUVEC) were observed to be enhanced. The activation of Orai1/STIM1 might increase the activity of endothelial nitric oxide synthase (eNOS) and its effect on releasing nitric oxide (NO). Subsequently, the migration and proliferation of the HUVECs are improved, which ultimately accelerates wound healing. These signaling pathway was also observed in the OPN-stimulated healing process of the skin wound surface of diabetic mice.

Conclusion

This study identifies the molecular biological mechanism of OPN-benefited the migration and proliferation of the HUVECs and provides ideas for searching for new therapeutic targets for drugs that repair diabetes-induced wounds to replace invasive treatment methods.

The translational potential of this article

The OPN is highly expressed in the tissues surrounding the TTT bone transfer area, which may possibly stimulate the activation of eNOS to increase NO release through the SOCE pathway mediated by Orai1/STIM1. This mechanism may play a significant role in the angiogenesis of diabetic foot's wounds promoted by TTT, providing new therapeutic strategies for the non-surgical treatment for this disease.