Osmotic Pressure Alters Time-dependent Recovery Behavior of the Intervertebral Disc

Abstract Background Establishing an optimal animal model for intervertebral disc (IVD) degeneration is essential for developing new IVD therapies. The intra-articular injection of monosodium iodoacetate (MIA), which is commonly used in animal models of osteoarthritis, induces cartilage degeneration and progressive arthritis in a dose- and time-dependent manner. The purpose of this study was to determine the effect of MIA injections into rabbit IVDs on the progression of IVD degeneration evaluated by radiographic, micro-computerized tomography (micro-CT), magnetic resonance imaging (MRI), and histological analyses. Methods In total, 24 New Zealand White (NZW) rabbits were used in this study. Under general anesthesia, lumbar discs from L1–L2 to L4–L5 had a posterolateral percutaneous injection of MIA in contrast agent (CA) (L1–L2: CA only; L2–L3: MIA 0.01 mg; L3–L4: 0.1 mg; L4–L5: 1.0 mg; L5–L6: non-injection (NI) control). Disc height was radiographically monitored biweekly until 12 weeks after injection. Six rabbits were sacrificed at 2, 4, 8, and 12 weeks post-injection and processed for micro-CT, MRI (T2-mapping), and histological analyses. Three-dimensional (3D) disc height in five anatomical zones was evaluated by 3D reconstruction of micro-CT data. Results Disc height of MIA-injected discs (L2–L3 to L4–L5) gradually decreased time-dependently (P < 0.0001). The disc height of MIA 0.01 mg-injected discs was significantly higher than those of MIA 0.1 and 1.0 mg-injected discs (P < 0.01, respectively). 3D micro-CT analysis showed the dose- and time-dependent decrease of 3D disc height of MIA-injected discs predominantly in the posterior annulus fibrosus (AF) zone. MRI T2 values of MIA 0.1 and 1.0 mg-injected discs were significantly decreased compared to those of CA and/or NI controls (P < 0.05). Histological analyses showed progressive time- and dose-degenerative changes in the discs injected with MIA (P < 0.01). MIA induced cell death in the rabbit nucleus pulposus with a high percentage, while the percentage of cell clones was low. Conclusions The results of this study showed, for the first time, that the intradiscal injection of MIA induced degenerative changes of rabbit IVDs in a time- and dose-dependent manner. This study suggests that MIA injection into rabbit IVDs could be used as an animal model of IVD degeneration for developing future treatments.

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Compression and recovery behavior of three-dimensional woven spacer composites

Journal of Industrial Textiles ◽

10.1177/1528083719874477 ◽

2019 ◽

pp. 152808371987447

Author(s):

Muhammad Umair ◽

Syed Talha Ali Hamdani ◽

Yasir Nawab ◽

Muhammad Ayub Asghar ◽

Tanveer Hussain

Keyword(s):

Mechanical Performance ◽

Permanent Deformation ◽

Three Dimensional ◽

Time Dependent ◽

Cyclic Compression ◽

Recovery Behavior ◽

Dynamic Time ◽

Thick Composites ◽

Work Done ◽

Different Parts

Three-dimensional woven spacer composites have great potential for use in different parts of automobiles and construction application due to their better mechanical performance. In literature, time-dependent compression and recovery behavior of three-dimensional woven spacer composites was not studied. In this study, three-dimensional woven spacer composites (three thickness levels) were evaluated under static and dynamic (time-dependent) compression and recovery. The static compressive strength of composites was reduced with the increase in sample thickness. Also, the highest amount of energy was absorbed during the fracture of 4 mm (Comp4) thick composite, followed by 10 mm (Comp10) and 20 mm (Comp20) thick composites. Compressibility (%) and resiliency (%) was highest in Comp4 but recovery (%) was a bit lower as compared to the Comp10 and Comp20, while recovery (%) was highest in 10 mm thick composite as compared to the 4 mm and 20 mm thick samples. Moreover, higher value of permanent deformation in thickness with time was observed in Comp20 showing higher creep followed by Comp4 and Comp10. Furthermore, Comp4 showed the highest values of work done during cyclic compression loading–unloading testing, presenting highest toughness.

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