On the relative relevance of subject-specific geometries and degeneration-specific mechanical properties for the study of cell death in human intervertebral disc models

Frontiers in Bioengineering and Biotechnology

Marc M van Rijsbergen¹  Keita eIto¹  Jerome eNoailly²  Andrea eMalandrino²  Jose Maria ePozo³  Isaac eCastro-Mateos³  Alejandro F Frangi³  Hans-Joachim eWilke⁴  Marie-Christine eHo Ba Tho⁵  Tien Tuan eDao⁵ 

[1] Eindhoven University of Technology;Institute for Bioengineering of Catalonia (IBEC);The University of Sheffield;University of Ulm;Université de Technologie de Compiègne (UTC);

关键词: Intervertebral Disc Degeneration;    Finite element modelling;    lumbar spine;    poroelasticity;    Damage model;    Subject-specific modelling;   

DOI  :  10.3389/fbioe.2015.00005

来源: DOAJ

【 摘 要 】

Capturing patient- or condition-specific intervertebral disc (IVD) properties in finite element models is outmost important in order to explore how biomechanical and biophysical processes may interact in spine diseases. However, disc degenerative changes are often modelled through equations similar to those employed for healthy organs, which might not be valid. As for the simulated effects of degenerative changes, they likely depend on specific disc geometries. Accordingly, we explored the ability of continuum tissue models to simulate disc degenerative changes. We further used the results in order to assess the interplay between these simulated changes and particular IVD morphologies, in relation to disc cell nutrition, a potentially important actor in disc tissue regulation. A protocol to derive patient-specific computational models from clinical images was applied to different spine specimens. In vitro IVD creep tests were used to optimize poro-hyperelastic input material parameters in these models, in function of the IVD degeneration grade. The use of condition-specific tissue model parameters in the specimen-specific geometrical models was validated against independent kinematic measurements in vitro. Then, models were coupled to a transport-cell viability model in order to assess the respective effects of tissue degeneration and disc geometry on cell viability. While classic disc poromechanical models failed in representing known degenerative changes, additional simulation of tissue damage allowed model validation and gave degeneration-dependent material properties related to osmotic pressure and water loss, and to increased fibrosis. Surprisingly, nutrition-induced cell death was independent of the grade-dependent material properties, but was favoured by increased diffusion distances in large IVDs. Our results suggest that in situ geometrical screening of IVD morphology might help to anticipate particular mechanisms of disc degeneration.

【 授权许可】

Unknown