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Nano and micro biomechanical analyses of the nucleus pulposus after in situ immobilization in rats
- Source :
- Micron. 130:102824
- Publication Year :
- 2020
- Publisher :
- Elsevier BV, 2020.
-
Abstract
- Immobilization can lead to intervertebral disc degeneration. The biomechanical characteristics of such discs have not so far been investigated at the micro- or nanoscale, the level at which cells sense and respond to the surrounding environment. This study aimed to characterize changes in the elastic modulus of the collagen fibrils in the nucleus pulposus at the nanoscale and correlate this with micro-biomechanical properties of the nucleus pulposus after immobilization, in addition to observation of tissue histology and its gene expressions. An immobilization system was used on the rat tail with an external fixation device. The elastic modulus was measured using both nano and micro probes for atomic force microscopy after 4 and 8 weeks of immobilization. Histology of the tissue was observed following hematoxylin and eosin staining. Gene expression in the annulus fibrosus tissue was quantified using real-time reverse transcription-polymerase chain reaction. The elastic modulus of the collagen fibrils in the nucleus pulposus at the nanoscale increased from 74.07 ± 17.06 MPa in the control to 90.06 ± 25.51 MPa after 8 weeks (P = 0.007), and from 33.51 ± 9.33 kPa to 43.18 ± 12.08 kPa at the microscale (P = 0.002). After immobilization for 8 weeks, a greater number of cells were observed by histology to be aggregated within the nucleus pulposus. Collagen II (P = 0.007) and aggrecan (P = 0.003) gene expression were downregulated whereas collagen I (P = 0.002), MMP-3 (P < 0.001), MMP-13 (P < 0.001) and ADAMTs-4 (P < 0.001) were upregulated. Immobilization not only influenced individual collagen fibrils at the nanoscale, but also altered the micro-biomechanics and cell response in the nucleus pulposus. These results suggest that significant changes occur in intervertebral discs at both scales after immobilization, a situation about which clinicians should be aware when immobilization has to be used clinically.
- Subjects :
- Male
Tail
In situ
Nucleus Pulposus
H&E stain
Gene Expression
General Physics and Astronomy
02 engineering and technology
Microscopy, Atomic Force
01 natural sciences
Rats, Sprague-Dawley
Immobilization
Structural Biology
Elastic Modulus
0103 physical sciences
Gene expression
medicine
Animals
General Materials Science
Elastic modulus
Aggrecan
010302 applied physics
Chemistry
Annulus Fibrosus
Intervertebral disc
Histology
Cell Biology
musculoskeletal system
021001 nanoscience & nanotechnology
Extracellular Matrix
Rats
Disease Models, Animal
medicine.anatomical_structure
Biophysics
Collagen
0210 nano-technology
Nucleus
Subjects
Details
- ISSN :
- 09684328
- Volume :
- 130
- Database :
- OpenAIRE
- Journal :
- Micron
- Accession number :
- edsair.doi.dedup.....d5055d914aa230de746a6b7bcd06b612