Modeling material-degradation-induced elastic property of tissue engineering scaffolds.

The mechanical properties of tissue engineering scaffolds play a critical role in the success of repairing damaged tissues/organs. Determining the mechanical properties has proven to be a challenging task as these properties are not constant but depend upon time as the scaffold degrades. In this study, the modeling of the time-dependent mechanical properties of a scaffold is performed based on the concept of finite element model updating. This modeling approach contains three steps: (1) development of a finite element model for the effective mechanical properties of the scaffold, (2) parametrizing the finite element model by selecting parameters associated with the scaffold microstructure and/or material properties, which vary with scaffold degradation, and (3) identifying selected parameters as functions of time based on measurements from the tests on the scaffold mechanical properties as they degrade. To validate the developed model, scaffolds were made from the biocompatible polymer polycaprolactone (PCL) mixed with hydroxylapatite (HA) nanoparticles and their mechanical properties were examined in terms of the Young modulus. Based on the bulk degradation exhibited by the PCL/HA scaffold, the molecular weight was selected for model updating. With the identified molecular weight, the finite element model developed was effective for predicting the time-dependent mechanical properties of PCL/HA scaffolds during degradation.

[1]  Ralph Müller,et al.  Smooth surface meshing for automated finite element model generation from 3D image data. , 2006, Journal of biomechanics.

[2]  Josep A Planell,et al.  Computational modelling of the mechanical environment of osteogenesis within a polylactic acid-calcium phosphate glass scaffold. , 2009, Biomaterials.

[3]  B. Sabel,et al.  Small drug sample fabrication of controlled release polymers using the microextrusion method , 1998, Journal of Neuroscience Methods.

[4]  D. Castner,et al.  Modulus-dependent macrophage adhesion and behavior , 2008, Journal of biomaterials science. Polymer edition.

[5]  E. Kotomin,et al.  Modified Maxwell-Garnett equation for the effective transport coefficients in inhomogeneous media , 1998 .

[6]  T. D. Fornes,et al.  Modeling properties of nylon 6/clay nanocomposites using composite theories , 2003 .

[7]  Julián Bravo-Castillero,et al.  A comprehensive numerical homogenisation technique for calculating effective coefficients of uniaxial piezoelectric fibre composites , 2005 .

[8]  G. Perale,et al.  A new model of resorbable device degradation and drug release: transient 1-dimension diffusional model. , 2009, Journal of controlled release : official journal of the Controlled Release Society.

[9]  N. Kikuchi,et al.  Homogenization theory and digital imaging: A basis for studying the mechanics and design principles of bone tissue , 1994, Biotechnology and bioengineering.

[10]  M. Swain,et al.  Mechanical behaviour of porous hydroxyapatite. , 2008, Acta biomaterialia.

[11]  R. Langer,et al.  Biodegradable polymers as drug delivery systems , 1990 .

[12]  Xiaoxiao Han,et al.  An entropy spring model for the Young's modulus change of biodegradable polymers during biodegradation. , 2010, Journal of the mechanical behavior of biomedical materials.

[13]  N. Kikuchi,et al.  A comparison of homogenization and standard mechanics analyses for periodic porous composites , 1992 .

[14]  S. Hollister,et al.  Optimal design and fabrication of scaffolds to mimic tissue properties and satisfy biological constraints. , 2002, Biomaterials.

[15]  R. Landel,et al.  Mechanical Properties of Polymers and Composites , 1993 .

[16]  Hideki Aoki,et al.  Mechanical properties of sintered hydroxyapatite for prosthetic applications , 1981 .

[17]  Jingzhe Pan,et al.  A phenomenological model for the degradation of biodegradable polymers. , 2008, Biomaterials.

[18]  W. J. Zhang,et al.  Off-line control of time-pressure dispensing processes for electronics packaging , 2003 .

[19]  P. Prendergast,et al.  Effect of a degraded core on the mechanical behaviour of tissueengineered cartilage constructs: A poro-elastic finite element analysis , 2006, Medical and Biological Engineering and Computing.

[20]  C. V. van Blitterswijk,et al.  Porous Ti6Al4V scaffold directly fabricating by rapid prototyping: preparation and in vitro experiment. , 2006, Biomaterials.

[21]  K. Beningo,et al.  Flexible substrata for the detection of cellular traction forces. , 2002, Trends in cell biology.

[22]  A. Schindler,et al.  Aliphatic polyesters. I. The degradation of poly(ϵ‐caprolactone) in vivo , 1981 .

[23]  J M García-Aznar,et al.  On scaffold designing for bone regeneration: A computational multiscale approach. , 2009, Acta biomaterialia.

[24]  Mathieu Charlebois,et al.  Validation of a voxel-based FE method for prediction of the uniaxial apparent modulus of human trabecular bone using macroscopic mechanical tests and nanoindentation. , 2007, Journal of biomechanics.

[25]  Jingzhe Pan,et al.  A model for simultaneous crystallisation and biodegradation of biodegradable polymers. , 2009, Biomaterials.

[26]  Jyoti K. Sinha,et al.  The use of model updating for reliable finite element modelling and fault diagnosis of structural components used in nuclear plants , 2003 .