Human Bone Marrow Mesenchymal Stem Cell-Derived Exosomes Attenuate Blood-Spinal Cord Barrier Disruption via the TIMP2/MMP Pathway after Acute Spinal Cord Injury

After spinal cord injury (SCI), destruction of the blood spinal cord barrier (BSCB) results in infiltration of blood cells, such as neutrophils and macrophages, leading to permanent neurological dysfunction. Previous studies have shown that human bone marrow mesenchymal stem cell (BMSC)-derived exosomes have a beneficial neuroprotective effect in SCI models. However, whether BMSC-Exos contribute to the integrity of the BSCB has not been clarified. The purpose of this study was to investigate the mechanism of BMSC-Exo-induced changes in the permeability of the BSCB after SCI. Here, we showed that BMSC-Exos can inhibit BSCB permeability damage and improve spontaneous repair in a SCI model. Importantly, tissue inhibitors of matrix metalloproteinases 2 (TIMP2) were shown to play an important role in the functions of BMSCS-Exos by inhibiting the matrix metalloproteinase (MMP) pathway, thereby mitigating the reduction in cell junction proteins. Moreover, the ability of BMSC-Exos was significantly attenuated when TIMP2 was inhibited by siRNA. This proof-of-principle study demonstrates that BMSC-Exos can preserve the integrity of the BSCB and improve functional recovery after SCI through the TIMP2/MMP signaling pathway.