Bone Marrow Mesenchymal Stem Cell-Derived Exosomes Improves Spinal Cord Function After Injury in Rats by Activating Autophagy.

BACKGROUND: Spinal cord injury (SCI) is a global medical problem. The smallest membrane-bound nanovesicles, known as exosomes, have a role in complex intercellular communication systems and can be used directly as therapeutic agents by acting as important paracrine factors. Nevertheless, the use of exosomes derived from BMSCs (BMSC-Exos) to treat SCI has been less, and the specific mechanism has not yet been reported. METHODS: BMSC-Exos were characterized by TEM, NTA and Western blot. The effects of BMSC-Exos treatment were compared by SCI in vivo model and a series of in vitro experiments. RESULTS: BMSC-Exos were found to enhance the expression of autophagy-related proteins LC3IIB and Beclin-1 and enabled autophagosomes formation. After BMSC-Exos treatment, there was marked decline in the level of expression of proapoptotic protein cleaved caspase-3, while that of the antiapoptotic protein Bcl-2 was upregulated. CONCLUSION: BMSC-Exos can attenuate neuronal apoptosis by promoting autophagy and promote the potential efficacy of functional behavior recovery in SCI rats. In summary, these findings expand the theoretical knowledge and forms a realistic route for the future treatment of SCI by BMSC-Exos.

[Seed flows of restoration succession series communities in alkaline meadow of Northeast China Songnen Plain].

After compared the source seed bank, soil seed bank, and seedling bank of the dominant species in four communities of restoration succession series in alkaline meadow of Songnen Plain, the model of seed flows was established. At early succession stage, the density of dominant source seed bank in Choris virgata community arrived its maximal value 446,182 +/- 180,455 seeds x m(-2) being 7.2 times of that in Puccinellia tenuiflora community at intermediate succession stage, 11.4 times of that in P. tenuiflora + Leymus chinensis community at later succession stage, and 164.8 times of that in L. chinensis community at climax succession stage. The densities of soil seed bank and seedling bank were all the maximal in C. virgata community, which were 63,650 +/- 14,541 seeds x m(-2) and 39,160 +/- 15,192 seedlings x m(-2), while the minimal in L. chinensis community, being 14,310 +/- 7,686 seeds x m(-2) and 790 +/- 745 seedlings x m(-2), respectively, representing a decreasing trend with the restoration. In the seedling banks of all communities in the restoration succession series, C. virgata was dominant, with its percentage ranged from 79.8% to 100%. In the seed flows, the input from dominant source seed banks to soil seed banks was only 10%-35%, while the output differed significantly at different succession stages, being the highest (62.3%) in C. virgata community and none in P. tenuiflora and L. chinensis communities.