Document Detail


3D finite element analysis of nutrient distributions and cell viability in the intervertebral disc: effects of deformation and degeneration.
MedLine Citation:
PMID:  22010741     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The intervertebral disc (IVD) receives important nutrients, such as glucose, from surrounding blood vessels. Poor nutritional supply is believed to play a key role in disc degeneration. Several investigators have presented finite element models of the IVD to investigate disc nutrition; however, none has predicted nutrient levels and cell viability in the disc with a realistic 3D geometry and tissue properties coupled to mechanical deformation. Understanding how degeneration and loading affect nutrition and cell viability is necessary for elucidating the mechanisms of disc degeneration and low back pain. The objective of this study was to analyze the effects of disc degeneration and static deformation on glucose distributions and cell viability in the IVD using finite element analysis. A realistic 3D finite element model of the IVD was developed based on mechano-electrochemical mixture theory. In the model, the cellular metabolic activities and viability were related to nutrient concentrations, and transport properties of nutrients were dependent on tissue deformation. The effects of disc degeneration and mechanical compression on glucose concentrations and cell density distributions in the IVD were investigated. To examine effects of disc degeneration, tissue properties were altered to reflect those of degenerated tissue, including reduced water content, fixed charge density, height, and endplate permeability. Two mechanical loading conditions were also investigated: a reference (undeformed) case and a 10% static deformation case. In general, nutrient levels decreased moving away from the nutritional supply at the disc periphery. Minimum glucose levels were at the interface between the nucleus and annulus regions of the disc. Deformation caused a 6.2% decrease in the minimum glucose concentration in the normal IVD, while degeneration resulted in an 80% decrease. Although cell density was not affected in the undeformed normal disc, there was a decrease in cell viability in the degenerated case, in which averaged cell density fell 11% compared with the normal case. This effect was further exacerbated by deformation of the degenerated IVD. Both deformation and disc degeneration altered the glucose distribution in the IVD. For the degenerated case, glucose levels fell below levels necessary for maintaining cell viability, and cell density decreased. This study provides important insight into nutrition-related mechanisms of disc degeneration. Moreover, our model may serve as a powerful tool in the development of new treatments for low back pain.
Authors:
Alicia R Jackson; Chun-Yuh C Huang; Mark D Brown; Wei Yong Gu
Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural    
Journal Detail:
Title:  Journal of biomechanical engineering     Volume:  133     ISSN:  1528-8951     ISO Abbreviation:  J Biomech Eng     Publication Date:  2011 Sep 
Date Detail:
Created Date:  2011-10-20     Completed Date:  2012-02-15     Revised Date:  2013-06-27    
Medline Journal Info:
Nlm Unique ID:  7909584     Medline TA:  J Biomech Eng     Country:  United States    
Other Details:
Languages:  eng     Pagination:  091006     Citation Subset:  IM    
Affiliation:
Tissue Biomechanics Lab, Department of Biomedical Engineering, University of Miami, Coral Gables, FL 33146, USA.
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MeSH Terms
Descriptor/Qualifier:
Adult
Calcinosis / complications
Cell Count
Cell Survival
Finite Element Analysis*
Glucose / metabolism*
Humans
Intervertebral Disc / metabolism*,  pathology*
Intervertebral Disc Degeneration / complications,  metabolism*,  pathology*
Male
Mechanical Processes*
Permeability
Grant Support
ID/Acronym/Agency:
AG030921/AG/NIA NIH HHS; AR050609/AR/NIAMS NIH HHS; AR056101/AR/NIAMS NIH HHS; EB008653/EB/NIBIB NIH HHS; F31 AG030921-01A2/AG/NIA NIH HHS; R01 AR050609-01A2/AR/NIAMS NIH HHS; R01 EB008653-01A1/EB/NIBIB NIH HHS; R03 AR056101/AR/NIAMS NIH HHS; R03 AR056101-01A1/AR/NIAMS NIH HHS
Chemical
Reg. No./Substance:
50-99-7/Glucose
Comments/Corrections

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