Dataset Information

Postnatal Development of the Murine Notochord Remnants Quantified by High-resolution Contrast-enhanced MicroCT.

ABSTRACT: The notochord gives rise to spinal segments during development, and it becomes embedded within the nucleus pulposus of the intervertebral disc (IVD) during maturation. The disruption of the notochord band has been observed with IVD degeneration. Since the mechanical competence of the IVD relies on its structural constituents, defining the structure of the notochord during aging is critical for investigations relating to IVD function and homeostasis. The assessment and imaging of the notochord has classically relied on histological techniques, which introduces sectioning artifacts during preparation and spatial biases. Magnetic resonance imaging (MRI) does not offer sufficient resolution to discriminate the notochord from the surrounding the nucleus pulposus, especially in murine models. Current X-ray based computed tomography systems provide imaging resolutions down to the single- and sub- micron scales, and when coupled with contrast-enhancing agents, enable the high-resolution three-dimensional imaging of relatively small features. Utilizing phosphomolybdic acid to preferentially bind to collagen cationic domains, we describe the structure of the notochord remnants with aging in the lumbar IVDs of BALB/c mice. These results provide a highly quantitative and sensitive approach to monitoring the IVD during postnatal development.

SUBMITTER: Bhalla S

PROVIDER: S-EPMC5645339 | biostudies-literature | 2017 Oct

REPOSITORIES: biostudies-literature

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Postnatal Development of the Murine Notochord Remnants Quantified by High-resolution Contrast-enhanced MicroCT.

Bhalla Sameer S Lin Kevin H KH Lin Kevin H KH Tang Simon Y SY

Scientific reports 20171017 1

The notochord gives rise to spinal segments during development, and it becomes embedded within the nucleus pulposus of the intervertebral disc (IVD) during maturation. The disruption of the notochord band has been observed with IVD degeneration. Since the mechanical competence of the IVD relies on its structural constituents, defining the structure of the notochord during aging is critical for investigations relating to IVD function and homeostasis. The assessment and imaging of the notochord ha ...[more]

PMID: 29042621

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Project description:Articular cartilage lines the load-bearing surfaces of long bones and undergoes compositional and structural degeneration during osteoarthritis progression. Contrast enhanced microcomputed tomography (?CT) is being applied to a variety of preclinical models, including the mouse, to map structural and compositional properties in 3-D. The thinness (?30-50??m) and high cellularity of mouse articular cartilage presents a significant imaging challenge. Our group previously showed that mouse articular cartilage and proteoglycan (PG) content can be assessed by ?CT with the ioxagalate-based contrast agent Hexabrix, but the voxel size used (6??m) was deemed to be barely adequate. The objective of the present study is to assess the utility of a novel contrast agent, CA4+, to quantify mouse articular cartilage morphology and composition with high resolution ?CT imaging (3??m voxels) and to compare the sensitivity of CA4+ and Hexabrix to detect between-group differences. While both contrast agents are iodine-based, Hexabrix is anionic and CA4+ is cationic so they interact differently with negatively charged PGs. With CA4+, a strong correlation was found between non-calcified articular cartilage thickness measurements made with histology and ?CT (R2 ?=?0.72, p?<?0.001). Cartilage degeneration-as assessed by loss in volume, thickness, and PG content-was observed in 34-week-old mice when compared to both 7- and 12-week-old mice. High measurement precision was observed with CA4+, with the coefficient of variation after repositioning and re-imaging samples equaling 2.8%, 4.5%, 7.4% and 5.9% for attenuation, thickness, volume, and PG content, respectively. Use of CA4+ allowed increased sensitivity for assessing PG content compared to Hexabrix, but had no advantage for measurement of cartilage thickness or volume. This improvement in imaging should prove useful in preclinical studies of cartilage degeneration and regeneration. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 35:2740-2748, 2017.

Project description:A targeted injury to the mouse intervertebral disc (IVD) is often used to recapitulate the degenerative cascade of the human pathology. Since injuries can vary in magnitude and localization, it is critical to examine the effects of different injuries on IVD degeneration. We thus evaluated the degenerative progression resulting from either a partial- or full-width injury to the mouse lumbar IVD using contrast-enhanced micro-computed tomography and histological analyses. A lateral-retroperitoneal surgical approach was used to access the lumbar IVD, and the injuries to the IVD were produced by either incising one side of the annulus fibrosus or puncturing both sides of the annulus fibrosus. Female C57BL/6J mice of 3-4 months age were used in this study. They were divided into three groups to undergo partial-width, full-width, or sham injuries. The L5/6 and L6/S1 lumbar IVDs were surgically exposed, and then the L6/S1 IVDs were injured using either a surgical scalpel (partial-width) or a 33G needle (full-width), with the L5/6 serving as an internal control. These animals recovered and then euthanized at either 2-, 4-, or 8-weeks after surgery for evaluation. The IVDs were assessed for degeneration using contrast-enhanced microCT (CEµCT) and histological analysis. The high-resolution 3D CEµCT evaluation of the IVD confirmed that the respective injuries were localized within one side of the annulus fibrosus or spanned the full width of the IVD. The full-width injury caused significant deteriorations in the nucleus pulposus, annulus fibrous and at the interfaces after 2 weeks, which was sustained through the 8 weeks, while the partial width injury caused localized disruptions that remained limited to the annulus fibrosus. The use of CEµCT revealed distinct IVD degeneration profiles resulting from partial- and full-width injuries. The partial width injury may serve as an alternative model for IVD degeneration resulting from localized annulus fibrosus injuries.

Dataset Information

Postnatal Development of the Murine Notochord Remnants Quantified by High-resolution Contrast-enhanced MicroCT.

Publications

Postnatal Development of the Murine Notochord Remnants Quantified by High-resolution Contrast-enhanced MicroCT.

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