Dataset Information

Quantifying Baseline Fixed Charge Density in Healthy Human Cartilage Endplate: A Two-point Electrical Conductivity Method.

ABSTRACT: Regional measurements of fixed charge densities (FCDs) of healthy human cartilage endplate (CEP) using a two-point electrical conductivity approach.The aim of this study was to determine the FCDs at four different regions (central, lateral, anterior, and posterior) of human CEP, and correlate the FCDs with tissue biochemical composition.The CEP, a thin layer of hyaline cartilage on the cranial and caudal surfaces of the intervertebral disc, plays an irreplaceable role in maintaining the unique physiological mechano-electrochemical environment inside the disc. FCD, arising from the carboxyl and sulfate groups of the glycosaminoglycans (GAG) in the extracellular matrix of the disc, is a key regulator of the disc ionic and osmotic environment through physicochemical and electrokinetic effects. Although FCDs in the annulus fibrosus (AF) and nucleus pulposus (NP) have been reported, quantitative baseline FCD in healthy human CEP has not been reported.CEP specimens were regionally isolated from human lumbar spines. FCD and ion diffusivity were concurrently investigated using a two-point electrical conductivity method. Biochemical assays were used to quantify regional GAG and water content.FCD in healthy human CEP was region-dependent, with FCD lowest in the lateral region (P?=?0.044). Cross-region FCD was 30% to 60% smaller than FCD in NP, but similar to the AF and articular cartilage (AC). CEP FCD (average: 0.12?±?0.03?mEq/g wet tissue) was correlated with GAG content (average: 31.24?±?5.06??g/mg wet tissue) (P?=?0.005). In addition, the cross-region ion diffusivity in healthy CEP (2.97?±?1.00?×?10?cm/s) was much smaller than the AF and NP.Healthy human CEP acts as a biomechanical interface, distributing loads between the bony vertebral body and soft disc tissues and as a gateway impeding rapid solute diffusion through the disc.N/A.

SUBMITTER: Wu Y

PROVIDER: S-EPMC5509527 | biostudies-other | 2017 Sep

REPOSITORIES: biostudies-other

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Quantifying Baseline Fixed Charge Density in Healthy Human Cartilage Endplate: A Two-point Electrical Conductivity Method.

Wu Yongren Y Cisewski Sarah E SE Sun Yi Y Damon Brooke J BJ Sachs Barton L BL Pellegrini Vincent D VD Slate Elizabeth H EH Yao Hai H

Spine 20170901 17

<h4>Study design</h4>Regional measurements of fixed charge densities (FCDs) of healthy human cartilage endplate (CEP) using a two-point electrical conductivity approach.<h4>Objective</h4>The aim of this study was to determine the FCDs at four different regions (central, lateral, anterior, and posterior) of human CEP, and correlate the FCDs with tissue biochemical composition.<h4>Summary of background data</h4>The CEP, a thin layer of hyaline cartilage on the cranial and caudal surfaces of the in ...[more]

PMID: 28699925

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Project description:Injurious mechanical loading of articular cartilage and associated lesions compromise the mechanical and structural integrity of joints and contribute to the onset and progression of cartilage degeneration leading to osteoarthritis (OA). Despite extensive in vitro and in vivo research, it remains unclear how the changes in cartilage composition and structure that occur during cartilage degeneration after injury, interact. Recently, in silico techniques provide a unique integrated platform to investigate the causal mechanisms by which the local mechanical environment of injured cartilage drives cartilage degeneration. Here, we introduce a novel integrated Cartilage Adaptive REorientation Degeneration (CARED) algorithm to predict the interaction between degenerative variations in main cartilage constituents, namely collagen fibril disorganization and degradation, proteoglycan (PG) loss, and change in water content. The algorithm iteratively interacts with a finite element (FE) model of a cartilage explant, with and without variable depth to full-thickness defects. In these FE models, intact and injured explants were subjected to normal (2 MPa unconfined compression in 0.1 s) and injurious mechanical loading (4 MPa unconfined compression in 0.1 s). Depending on the mechanical response of the FE model, the collagen fibril orientation and density, PG and water content were iteratively updated. In the CARED model, fixed charge density (FCD) loss and increased water content were related to decrease in PG content. Our model predictions were consistent with earlier experimental studies. In the intact explant model, minimal degenerative changes were observed under normal loading, while the injurious loading caused a reorientation of collagen fibrils toward the direction perpendicular to the surface, intense collagen degradation at the surface, and intense PG loss in the superficial and middle zones. In the injured explant models, normal loading induced intense collagen degradation, collagen reorientation, and PG depletion both on the surface and around the lesion. Our results confirm that the cartilage lesion depth is a crucial parameter affecting tissue degeneration, even under physiological loading conditions. The results suggest that potential fibril reorientation might prevent or slow down fibril degradation under conditions in which the tissue mechanical homeostasis is perturbed like the presence of defects or injurious loading.

Dataset Information

Quantifying Baseline Fixed Charge Density in Healthy Human Cartilage Endplate: A Two-point Electrical Conductivity Method.

Publications

Quantifying Baseline Fixed Charge Density in Healthy Human Cartilage Endplate: A Two-point Electrical Conductivity Method.

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