Repair of spinal cord injury in rats via exosomes from bone mesenchymal stem cells requires sonic hedgehog

Abstract

Objective The loss of neural ability leading to subsequent diminishing of motor function and the impairment below the location of the injury is a result of the SCI (Spinal Cord Injury). Among the many therapeutic agents for SCI, the exosomes considered as extracellular vesicles seem to be the most promising. Sonic Hedgehog (Shh) is an exosome-carrying protein. This Study's purpose was to identify whether Shh is required for exosomes from BMSCs (mesenchymal stem cells of the bone) and plays a protective effect on SCI. Methods Spinal cord injection with shRNA Shh-adeno associated virus (sh-Shh-AAV) were used to silence Shh. Exosomes were extracted from BMSCs. Rats that had suffered SCI were given intravenous injections of exosomes through the veins of the tail. Immunohistochemistry was used to identify the expression of Shh glycoprotein molecule as well as the expression of Gli-1 (glioma-associated oncogene homolog 1) in the rat spinal cord tissues. Western blot was performed to measure the levels of growth associated protein-43 (GAP-43). The BBB (Basso Beattie Bresnahan) score was used to assess the motor functions of the hind legs. In the same manner, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling or TUNEL and Nissl Staining was deployed to assess the level of regeneration of neurons and assess the level of histopathological damage in the tissues of the Spinal Cord. Results In the case of the rats with SCI, the levels of display of Gli-1 and Shh showed dramatic improvement after the BMSCs exosome injections. In comparison to rats with SCI, the subjects of BMSCs exosomes group showed an improvement in their SCI, including a higher BBB score and Nissl body count, increasing GAP-43 expression, along with a much-decreased number of cells that suffered apoptosis. While the exosome effect on Spinal Cord Injury was completely ineffective in rats that had Shh silencing. Conclusions Exosomes secreted from BMSCs showed great effectiveness in the SCI healing with a vital involvement of Shh in this repair.

Therapeutic Effect of Exosomes Derived From Stem Cells in Spinal Cord Injury: A Systematic Review Based on Animal Studies

“…Among the included 32 studies, only two studies were controlled studies ( 29 , 33 ), and the remaining 30 studies were randomized controlled studies. The species of animals included SD rats ( 19 – 21 , 28 – 37 , 39 , 40 , 42 – 44 , 46 , 47 , 49 – 53 , 55 , 56 ), Wistar rats ( 41 , 54 ), and C57BL/6 mice ( 38 , 45 , 48 ); gender included male ( 28 , 30 – 32 , 38 – 45 , 49 , 53 , 54 ) and female ( 19 , 20 , 29 , 33 , 34 , 36 , 37 , 46 – 48 , 50 – 52 , 55 , 56 ), two studies did not report the sex of the animals ( 21 , 35 ); the weights of animals were between 150 ( 41 ) and 300 g ( 20 , 44 ), the weight of the mouse was between 17 and 22 g ( 48 ), and seven of the studies did not report the weight of the animals ( 21 , 29 , 30 , 38 , 42 , 45 , 50 ); age was between 6 ( 38 , 44 , 45 , 50 , 51 ) and 12 weeks ( 47 , 56 ), and nine of the studies did not report the age of the animals ( …”

“…Six studies reported types of exosomes but did not report specific sources ( 31 , 32 , 38 , 40 , 45 , 46 ). The transplantation route of exosomes included tail vein ( 19 – 21 , 29 – 32 , 34 – 50 , 52 – 56 ), intranasally ( 33 ) and subcutaneous ( 51 ), and one study did not report the route of exosome transplantation ( 28 ); the time transplantation of exosome ranged from 0 ( 19 , 20 , 31 , 38 , 41 , 44 – 47 , 49 ) to 24 h ( 42 , 43 ) after modeling, one study did not report the time of exosome transplantation ( 40 ); dose of exosomes ranged from 20 ( 29 ) to 200 μg ( 28 , 30 – 33 , 36 – 38 , 41 , 43 , 45 – 49 , 53 , 56 ); the control group includes PBS ( 19 – 21 , 28 – 32 , 34 , 35 , 38 , 39 , 41 , 43 – 51 , 53 – 56 ), saline ( 33 , 36 , 37 , 40 , 42 ), and blank ( 52 ). Basic information of the study subjects was summarized in Supplementary Table 2 .…”

“…Twenty-nine studies reported the results of BBB scores of animals after exosome transplantation ( 19 – 21 , 28 – 37 , 39 – 44 , 46 , 47 , 49 – 56 ). The meta-analysis results of the random effects model showed that the BBB score of the exosome group was significantly better than that of the negative control group, and the difference was statistically significant [1st week after transplantation: WMD = 1.82 (1.18, 2.46).…”

The Sonic Hedgehog Pathway Modulates Survival, Proliferation, and Differentiation of Neural Progenitor Cells under Inflammatory Stress In Vitro

“…As such, recent findings are ascribing Shh a crucial role in the neuroregeneration after CNS injuries [ 32 , 33 , 34 , 35 ]. New evidence even suggests that the activation of the Shh-pathway may be necessary to enable MSC-derived exosome mediated SCI repair [ 36 ].…”

The Role of Exosomes and Exosomal Noncoding RNAs From Different Cell Sources in Spinal Cord Injury

“…MSCs-Exos were separated and concentrated by ultracentrifugation and differential centrifugation in many studies (Huang et al, 2017 , 2020a ; Lankford et al, 2018 ; Wang et al, 2018 ; Guo et al, 2019 ; Ji et al, 2019 ; Kang et al, 2019 ; Li et al, 2019 ; Li C. et al, 2020 ; Li et al, 2021 ; Chen et al, 2021 ; Cheng et al, 2021 ; Han et al, 2021 ; Jia et al, 2021 ; Jiang and Zhang, 2021 ; Liu W. Z. et al, 2021 ; Liu et al, 2022 ; Nakazaki et al, 2021 ; Nie and Jiang, 2021 ; Noori et al, 2021 ; Sheng et al, 2021 ; Xiao et al, 2021 ; Xin et al, 2021 ; Zhang A. et al, 2021 ; Liang et al, 2022 ; Zhou et al, 2022 ) and by precipitation kits/polymer (PEG or others) in some studies (Li et al, 2018 ; Ren et al, 2019 ; Xu et al, 2019 ; Yu et al, 2019 ; Zhao et al, 2019 ; Fan et al, 2021 ; Jia et al, 2021a , b ; Kang and Guo, 2022 ). To achieve better specificity of MSCs-Exos separation, many researchers isolated MSCs-Exos using ultrafiltration-centrifugation combined with density-gradient ultracentrifugation (Liu et al, 2020 ; Shao et al, 2020 ; Chang et al, 2021 ; Luo et al, 2021 ; Huang et al, 2022 ).…”