Sodium tanshinone IIA sulfonate promotes proliferation and differentiation of endogenous neural stem cells to repair rat spinal cord injury via the Notch pathway

Interventions that promote the proliferation of endogenous neural stem cells (ENSCs) and induce their differentiation into neurons after spinal cord injury (SCI) hold significant potential for SCI repair. Tanshinone IIA (TIIA) exhibits extensive neuroprotective effects, and its derivative, sodium tanshinone IIA sulfonate (STS), has enhanced water solubility, making it easier to prepare injectable formulations and increasing bioavailability. STS injections have been extensively utilized in the treatment of cardiovascular and cerebrovascular diseases, and their clinical application in SCI shows promising potential. However, it remains unclear whether STS can promote spinal cord injury repair in rats by modulating the proliferation and differentiation of ENSCs, and the underlying regulatory mechanisms are yet to be elucidated. In this study, an incomplete spinal cord injury model was established in rats using the NYU spinal cord impactor. The regulatory effects of STS on ENSCs in rats post-SCI were observed by detecting the NSC marker Nestin, the neuronal marker NeuN, and the astrocyte marker GFAP. Additionally, rat behavioral assessments, histopathology, serum inflammation indices, and Notch signaling pathway activation were evaluated. In vitro experiments utilized an lipopolysaccharide (LPS)-induced rats spinal cord NSCs inflammation model. The effects of STS on the proliferation and viability of rats spinal cord NSCs were assessed using the CCK-8 assay and immunofluorescence cell counting. The mechanisms by which STS regulates NSC proliferation and differentiation via the Notch pathway were verified using immunofluorescence, Western blot, and RT-PCR techniques. In vitro, STS significantly reduced the levels of inflammatory indices in the LPS-induced rats NSCs inflammation model and improved the viability of rats NSCs following inflammatory injury. STS also significantly increased the proliferation of NSCs and their differentiation into neurons while reducing their differentiation into astrocytes. Moreover, LPS significantly activated the Notch pathway, similar to the effects of the Notch pathway agonist valproic acid (VPA), whereas STS intervention could inhibit the LPS- or VPA-induced activation of the Notch pathway. In vivo, STS markedly improved the hindlimb motor function of rats with SCI, decreased the levels of pro-inflammatory factors IL-6 and TNF-α, and increased the level of the anti-inflammatory factor IL-10, thereby improving the pathological morphology of the injured spinal cord in rats post-SCI. STS effectively promoted the proliferation of ENSCs post-SCI, facilitated their differentiation into neurons, and inhibited their differentiation into astrocytes. Additionally, STS suppressed the excessive activation of the Notch signaling pathway following SCI. STS promotes the proliferation of ENSCs post-SCI in rats, induces their differentiation into neurons, and inhibits their differentiation into astrocytes, thereby improving the pathological morphology of the injured spinal cord and promoting the recovery of hindlimb motor function in rats post-SCI. Furthermore, the regulatory effects of STS on the proliferation and differentiation of ENSCs post-SCI in rats may be related to its inhibition of the excessive activation of the Notch signaling pathway.