Theranostics 2019; 9(7):2017-2035. doi:10.7150/thno.29400

Research Paper

Mitochondrial Transfer from Bone Marrow Mesenchymal Stem Cells to Motor Neurons in Spinal Cord Injury Rats via Gap Junction

Heyangzi Li1*, Chao Wang1*, Teng He1*, Tengfei Zhao2, Ying-ying Chen1, Yue-liang Shen1, Xiaoming Zhang1✉, Lin-lin Wang1✉

1. Department of Basic Medicine Sciences, Zhejiang University School of Medicine, Hangzhou 310058, China
2. Department of Orthopedic Surgery, Second Affiliated Hospital of Zhejiang University School of Medicine, Hangzhou 310009, China
*These authors contributed equally to this work.

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Citation:
Li H, Wang C, He T, Zhao T, Chen Yy, Shen Yl, Zhang X, Wang Ll. Mitochondrial Transfer from Bone Marrow Mesenchymal Stem Cells to Motor Neurons in Spinal Cord Injury Rats via Gap Junction. Theranostics 2019; 9(7):2017-2035. doi:10.7150/thno.29400. Available from https://www.thno.org/v09p2017.htm

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Abstract

Recent studies have demonstrated that bone marrow mesenchymal stem cells (BMSCs) protect the injured neurons of spinal cord injury (SCI) from apoptosis while the underlying mechanism of the protective effect of BMSCs remains unclear. In this study, we found the transfer of mitochondria from BMSCs to injured motor neurons and detected the functional improvement after transplanting.

Methods: Primary rat BMSCs were co-cultured with oxygen-glucose deprivation (OGD) injured VSC4.1 motor neurons or primary cortical neurons. FACS analysis was used to detect the transfer of mitochondria from BMSCs to neurons. The bioenergetics profiling of neurons was detected by Extracellular Flux Analysis. Cell viability and apoptosis were also measured. BMSCs and isolated mitochondria were transplanted into SCI rats. TdT-mediated dUTP nick end labelling staining was used to detect apoptotic neurons in the ventral horn. Immunohistochemistry and Western blotting were used to measure protein expression. Re-myelination was examined by transmission electron microscope. BBB scores were used to assess locomotor function.

Results: MitoTracker-Red labelled mitochondria of BMSCs could be transferred to the OGD injured neurons. The gap junction intercellular communication (GJIC) potentiator retinoid acid increased the quantity of mitochondria transfer from BMSCs to neurons, while GJIC inhibitor 18β glycyrrhetinic acid decreased mitochondria transfer. Internalization of mitochondria improved the bioenergetics profile, decreased apoptosis and promoted cell survival in post-OGD motor neurons. Furthermore, both transplantation of mitochondria and BMSCs to the injured spinal cord improved locomotor functional recovery in SCI rats.

Conclusions: To our knowledge, this is the first evidence that BMSCs protect against SCI through GJIC to transfer mitochondrial to the injured neurons. Our findings suggested a new therapy strategy of mitochondria transfer for the patients with SCI.

Keywords: spinal cord injury, bone marrow stromal cells, mitochondria, transfer, gap junction