In Vivo, In Vitro, In Silico: Computational Tools for Product and Process Design in Tissue Engineering - Computational Modeling in Tissue Engineering - page 5

Fig. 1 Overview of the different models developed in the research group of the author of this
chapter. Models can be classified according to the origin of their development (phenomenological
vs. mechanistic) or according to the length and time scales of the processes they describe (gene/
protein, cell, tissue/organ). a Roberts et al. [ 23 ]; b Kerkhofs et al. [ 24 ]; c Geris et al. [ 25 ];
d Peiffer et al. [ 26 ]; e Carlier et al. [ 27 ]; f Geris et al. [ 28 ]; g Geris et al. [ 29 , 30 ]
characterisation of hydrogels, frequently used as carrier structure in tissue engi-
neering, but each focusing on a different aspect. Israelowitz et al. [ 31 ] argue that in
order to define the correct position of e.g. collagen in the fibre network arrange-
ment of extracellular matrix, which is important to determine its tensile strength,
an optimized tertiary structure of the protein needs to be characterized. They
provide an introduction into the different methods that are currently used to
determine protein conformation in silico. On a higher length scale, Nekouzadeh
et al. [ 32 ] describe the development of a mechanical model to design and evaluate
engineered tissues and/or carrier structures (such as hydrogels) that serve a
mechanical role. An important component of such models is often viscoelasticity,
or the dependence of mechanical response on loading rate and loading history. In a
great number of biological and bio-artificial tissues the passive tissue force (or
stress) relates to changes in tissue length (or strain) in a nonlinear viscoelastic
manner. Choosing and fitting nonlinear viscoelastic models to data for a specific
tissue can be a computational challenge. Nekouzadeh et al. [ 32 ] describe the range
of such models (focusing in particular on adaptive quasi-linear viscoelastic
models), criteria for selecting amongst them, and computational and experimental
techniques needed to fit these to uniaxial data. Additional to structural mechanics,
mass transport is an important property of hydrogels which can influence the
behaviour of cells encompassed in these hydrogels in various ways. Lambrechts
et al. [ 33 ] provide a thorough overview of how consumption and production of
soluble medium components gives rise to gradients inside hydrogels and how mass
transport related phenomena can shape these gradients. The authors focus on the