2023 Fiscal Year Research-status Report
Energy metabolism in neuronal degeneration at the caudal site of spinal cord injury
| Project/Area Number |
22K09248
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| Research Institution | National Cardiovascular Center Research Institute |
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Principal Investigator |
大西 諭一郎 国立研究開発法人国立循環器病研究センター, 研究所, 非常勤研究員 (00533811)
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| Co-Investigator(Kenkyū-buntansha) |
山本 正道 国立研究開発法人国立循環器病研究センター, 研究所, 特任部長 (70423150)
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| Project Period (FY) |
2022-04-01 – 2025-03-31
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| Keywords | spinal cord injury / metabolic stress / ATP / mitochondria |
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| Outline of Annual Research Achievements |
Spinal cord injury (SCI) presents the axonal degeneration in the caudal site of lesion. The caudal axonal degeneration prevents the functional recovery due to the axonal regenerative sprouting and sprouting at the injury site. The axonal mitochondrial transport to the distal site of lesion is impaired in SCI, leading to the metabolic stress. Previously, we revealed that axons activated the glycolysis system to maintain ATP levels, and inactivated tricarboxylic acid cycle because of mitochondrial degeneration. A gradual decrease in ATP levels was observed before the progression of axonal degeneration. Furthermore, glycolysis activation increased ATP levels and delayed axonal degeneration. In this study, we investigated the mitochondria transfer to SCI to prevent the caudal axonal degeneration.
T8 partial and complete transection were performed in GO-ATeam1 and GO-ATeam2 mice, which expressed a fluorescence resonance energy transfer-based ATP biosensor with orange fluorescent protein and green fluorescent protein in the mitochondria and cytosol, respectively. Mitochondrial isolation was proceeded by differential centrifugation from littermate liver and new born liver. Isolated mitochondria transferred to T9 spinal cord with stereotactic apparatus after cord transection. The mitochondrial and intracellular ATP level was assessed in GO-ATeam1 and GO-ATeam2 mice, respectively. Ultrathin distal spinal cord cross-sections were analyzed for axon diameter, G-ratio and number of mitochondria in axon by electron microscopy.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
JC-1 dye indicated the preservation of membrane potential in isolated mitochondria. FRET analysis also presented the ATP production in isolated mitochondria. In vivo imaging presented that the transfer of adult liver derived mitochondria elevated ATP level in the distal cord, and improved locomotor function. However, control buffer, ATP solution, and new born liver derived non-function mitochondria had no ATP elevation, and no locomotor improvement. Immunohistochemical analysis revealed that adult liver derived mitochondria were distally spread, and incorporated into neuron. The transfer of adult liver derived mitochondria increased the number of mitochondria in axon and thickness of myelin sheath.
These results indicated that the transfer of mitochondria into the distal site of spinal cord injury prevented the axonal degeneration, and improved locomotor function.
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| Strategy for Future Research Activity |
We investigate how transfferd mitochondria contribute the improvement of locomotor function.
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| Causes of Carryover |
研究は順調に進んでいる。今年度購入予定であった物品を次年度に持ち越した。
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