Chinese Journal of Tissue Engineering Research ›› 2024, Vol. 28 ›› Issue (8): 1180-1185.doi: 10.12307/2023.995

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Effects of static traction on the nucleus pulposus and annulus fibrosus of the rat intervertebral disc

Mo Jun1, Luo Zongping2   

  1. 1Jiangsu Institute of Parasitic Diseases, Wuxi 214064, Jiangsu Province, China; 2Orthopedic Institute, the First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu Province, China
  • Received:2022-11-28 Accepted:2023-02-04 Online:2024-03-18 Published:2023-07-18
  • Contact: Luo Zongping, MD, Professor, Orthopedic Institute, the First Affiliated Hospital of Soochow University, Suzhou 215006, Jiangsu Province, China
  • About author:Mo Jun, Master, Physician, Jiangsu Institute of Parasitic Diseases, Wuxi 214064, Jiangsu Province, China

Abstract: BACKGROUND: Traction is clinically used for the early treatment of intervertebral disc degeneration, but its effect on the normal intervertebral disc remains unknown. Whether it directly causes intervertebral disc degeneration or has a positive effect is the key point of this study. 
OBJECTIVE: To design a static traction model and observe the effect of static traction on the nucleus pulposus and annulus fibrosus of the intervertebral disc
METHODS: Twenty Sprague-Dawley rats, 3 months of age, were included in the study. The intervertebral disc spaces between 7/8, 8/9 and 9/10 were stretched by 1 mm, and the intervertebral disc spaces between 6/7 and 10/11 were used as control. Five rats were randomly selected at 2, 4, 6, and 8 weeks of traction to perform MRI T2-weighted scans of the caudal vertebra, tissue section staining, and RT-PCR gene assays for anabolic metabolism to observe the effects of static traction on the nucleus pulposus and annulus fibrosus of the intervertebral disc.
RESULTS AND CONCLUSION: After short-term static traction of the rat caudal vertebra, the T2-weighted image signal in the nucleus pulposus region was enhanced. During the traction period, nucleus pulposus cells grew well, the intercellular matrix was abundant, and the annulus fibrosus arranged regularly. The RT-PCR results showed that after traction, the mRNA expression of proteoglycan increased, the expression of matrix metalloproteinase-3 decreased, the expression of type I and II collagen decreased, and the expression of matrix metalloproteinase-13 increased and tissue inhibitor of matrix metalloproteinase 1 increased. These gene results also indicated that traction made proteoglycan more inclined to an anabolic state, and type I and II collagen more inclined to a catabolic state. To conclude, static traction promotes proteoglycan anabolism making the nucleus pulposus moist.

Key words: static traction, nucleus pulposus, annulus fibrosus, T2 high signal, proteoglycan

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