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 first used BMSC-Exos to treat an SCI rat model, showing that BMSC-Exos can inhibit BSCB permeability damage and improve spontaneous repair. Next, we found that tissue inhibitors of matrix metalloproteinase 2 (TIMP2) have been shown to play an important role in the function of BMSC-Exos by inhibiting the matrix metalloproteinase (MMP) pathway, thereby reducing the reduction of cell junction proteins. Therefore, we constructed siTIMP2 to knock out TIMP2 in BMSC-Exos, which caused the activity of BMSC-Exos to be significantly weakened. Finally, we constructed an in vitro model of BSCB with HBMECs and verified that TIMP2 in BMSC-Exos in vitro can also alleviate BSCB damage. 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.

Isolation and characterization of bacteriophage against extended-spectrumβ-lactamase-producing Escherichia coli strains / 上海交通大学学报（医学版）

Objective · To isolate phages which can fight against extended-spectrum β-lactamase (ESBLs)-producing Escherichia coli (E. coli), and provide basic research for establishment of E. coli phage library and treatment of bacterial infection. Methods · Samples collected from sewage were co-cultured with 93 ESBLs-producing E. coli strains. A phage named JDEC001 was isolated by double agar overlay plaque assay. The biological characteristics, complete genome sequence and comparative genome analyses of JDEC001 were studied respectively. Results · JDEC001 belongs to the lytic phage as a member of the Caudovirales order, Podoviridae family. It has high activity at pH from 5 to 11 and with temperature from 0 to 39 ℃ .Whole-genome sequencing of JDEC001 demonstrated double-stranded DNA genome of 38745 bp with GC content of 49.93%, which encoded 46 open reading frames. The comparative genomics also showed that there was no virulent genes or antibiotic resistant genes in its genome. Conclusion · The phage JDEC001 against ESBLs-producing E. coli was isolated and purified, with good stability in a broad range of pH and temperature.