Poster Presentation 50th International Society for the Study of the Lumbar Spine Annual Meeting 2024

LOW-MAGNITUDE HIGH-FREQUENCY VIBRATION INCREASES CELLULARITY AND PRODUCTION OF CATABOLIC FACTORS IN A SIMULATED DEGENERATIVE BOVINE INTERVERTEBRAL DISC MODEL (#208)

Graciosa Q Teixeira 1 , Felizitas Figel 1 , Jan Ulrich Jansen 1 , Franziska Widmayer 1 , Morten Vogt 1 , Hans-Joachim Wilke 1 , Anita Ignatius 1 , Melanie Haffner-Luntzer 1 , Cornelia Neidlinger-Wilke 1
  1. Institute of Orthopaedic Research and Biomechanics, Ulm University, Ulm, BADEN-WüRTTEMBERG, Germany

Introduction. Postmenopausal women are a group particularly at risk of intervertebral disc (IVD) degeneration due to estrogen (E2) decrease.1 Low-magnitude high-frequency vibration (LMHFV) is used as a therapeutic approach for postmenopausal osteoporosis; however, there is controversy regarding its effect on the IVD.2 Moreover, it is not known whether the effects of LMHFV are estrogen-dependent, as shown for bone.3 The aim of the present work was to identify the effects of E2 and/or LMHFV on a degenerative IVD culture model.

Methods. Bovine IVDs (n=6-12 IVDs/group) were injected with papain (PP, 13U in 200 mL/IVD) to simulate degeneration4 and treated with either i) E2 (10-7 M), ii) LMHFV on a custom-made vibration platform at 0.3 g peak-to-peak acceleration/45 Hz for 20 min/day, 5 days/week, or iii) the combination of E2+LMHFV. Unstimulated IVDs were kept as controls. Two days later, the expression of extracellular matrix components (COL1A1, COL2A1), matrix metalloproteinases (MMP1, MMP3) and their inhibitors (TIMP1, TIMP2) by annulus fibrosus (AF) and nucleus pulposus (NP) cells was investigated by qPCR. After 14 days, DNA, glycosaminoglycans (GAG) and collagen were quantified by biochemical assays. Production and distribution of interleukin (IL)-6 and matrix metalloproteinase (MMP)-3 were analyzed by immunohistochemistry. AF interlamellar adhesion stiffness and strength were determined by peeling test.5 Statistics: Brown-Forsythe and Welch one-way ANOVA or Kruskal-Wallis test.

Results. After two days, PP digestion downregulated the expression of MMP1 and MMP3 (p<0.05) in the AF and NP without affection COL1A1, COL2A1, TIMP1 or TIMP2, compared to unstimulated controls. E2 supplementation did not alter the gene expression of AF and NP cells at day 2, when compare to PP digestion. After LMHFV of PP-digested IVDs, TIMP2 was significantly upregulated in the AF and NP (p<0.05); E2+LMHFV reverted this effect and downregulated COL1A1 (p<0.05). After 14 days, PP decreased the GAG content (p<0.05) in the AF and NP, which was not reversed by any of the treatments. Collagen and IL-6 content were increased (p<0.05, Fig.1A) after PP digestion, but without affecting MMP-3 (Fig.1B). The AF stiffness and strength (p<0.05, Fig.1C) were also increased. At day 14, E2 supplementation of PP-digested samples led to less collagen content in the NP, as well as lower AF peel stiffness (p<0.05) versus PP digestion alone, but higher MMP-3 production in comparison to control samples (p<0.05). Interestingly, PP+LMHFV and PP+E2+LMHFV presented higher DNA content/cellularity compared to the control and PP groups, and higher IL-6 and MMP-3 production compared to the control in the AF and NP (p<0.05).

Conclusions. Overall, PP simulated a harsh degenerative microenvironment of the IVD. In addition, the combination PP and LMHFV contributed to an increase in cellularity, but also to the production of catabolic factors. These effects are in line with previous observations.2,6 E2 did not have a protective effect against IVD degeneration, in contrast to in vivo reports.3 This is possibly due to the already harsh environment simulated by PP alone, indicating that E2 may play a more relevant role in early stages of IVD degeneration with minor matrix degradation. This will be further investigated.

 

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  1. Lou et al., Menopause, 2017.
  2. McCann et al., Osteoarthritis Cartilage, 2017.
  3. Liu et al., Artif Cells Nanomed Biotechnol, 2018.
  4. Vernengo et al., Front Bioeng Biotechnol, 2023.
  5. Gregory et al., Eur Spine J, 2012.
  6. Widmayer et al., Int J Mol Sci, 2023.