Mathematical modeling of uniaxial mechanical properties of collagen gel scaffolds for vascular tissue engineering

R. M. IRASTORZA; B. DROUIN; E. BLANGINO; D. MANTOVANI

SCIENTIFIC WORLD JOURNAL, THE

THESCIENTIFICWORLD LTD

Lugar: New York; Año: 2015

1537-744X

Vascular tissue engineering aims to develop regenerated vascular tissue by culturing and maturing cells in 3D in a scaffold in bioreactors. The major bottleneck today is still constituted by the limited mechanical properties that the regenerated tissue exhibit after culture. A second bottleneck is represented by the invasive nature of most of the tests required to assess the mechanical properties of the regenerated tissue after and during maturation process. Small diameter tissue-engineered arteries improve their mechanical and functional properties when they are mechanically stimulated. Applying a suitable stress and/or strain with or without a cycle to the scaffolds and cells during the culturing process resides in our ability to generate a suitable mechanical model. Collagen gel is one of the most used scaffold in vascular tissue engineering, mainly because it is the principal constituent of the extracellular matrix for vascular cells in human. The mechanical modelling of such a material is not a trivial task, mainly for its viscoelastic nature. In this context, computational and experimental methods for developing a suitable model for collagen gels is of primary importance for the field. In this research, we focused on mechanical properties of collagen gels under unconfined compression. First, mechanical viscoelastic models are discussed and framed in the control system theory. Second, models are fitted using system identification methods which are generally used to build a model for a process to be controlled. Then, several models are evaluated and two non linear models are proposed: Mooney-Rivlin inspired and Hammerstein model. The results presented here suggest that Mooney-Rivlin and Hammerstein models succeed in describing the mechanical behaviour of collagen gels for cyclic tests on scaffolds (with best fitting parameters 58.3% and 75.8%, respectively). When Akaike criterion is used the best model is the Mooney-Rivlin inspired model.