Fig. 4. The mechanism by which mesenchymal stem cells-derived exosomes (MSCs-Exos) promotes angiogenesis and regulates blood-spinal cord barrier (BSCB) integrity. MSCs-Exos can promote angiogenesis by promoting the expression of vascular endothelial growth factor (VEGF) via the PKA signaling pathway. BMSC-Exos can suppress pericyte pyroptosis and inhibit pericyte migration by activating the NF-κB signaling pathway to maintain BSCB integrity. MSCs-Exos could increase the expression of cell junction proteins via the TIMP2/MMP pathway to attenuate the destruction of the BSCB. MSCs-Exos could reduce BSCB permeability by targeting M2 macrophages to upregulate TGFβ and TGFβ receptor expression.