Computer aided design of architecture of degradable tissue engineering scaffolds.

One important factor affecting the process of tissue regeneration is scaffold stiffness loss, which should be properly balanced with the rate of tissue regeneration. The aim of the research reported here was to develop a computer tool for designing the architecture of biodegradable scaffolds fabricated by melt-dissolution deposition systems (e.g. Fused Deposition Modeling) to provide the required scaffold stiffness at each stage of degradation/regeneration. The original idea presented in the paper is that the stiffness of a tissue engineering scaffold can be controlled during degradation by means of a proper selection of the diameter of the constituent fibers and the distances between them. This idea is based on the size-effect on degradation of aliphatic polyesters. The presented computer tool combines a genetic algorithm and a diffusion-reaction model of polymer hydrolytic degradation. In particular, we show how to design the architecture of scaffolds made of poly(DL-lactide-co-glycolide) with the required Young's modulus change during hydrolytic degradation.

Evolutionary design of bone scaffolds with reference to material selection.

The favourable scaffold for bone tissue engineering should have desired characteristic features, such as adequate mechanical strength and three-dimensional open porosity, which guarantee a suitable environment for tissue regeneration. In fact, the design of such complex structures like bone scaffolds is a challenge for investigators. One of the aims is to achieve the best possible mechanical strength-degradation rate ratio. In this paper we attempt to use numerical modelling to evaluate material properties for designing bone tissue engineering scaffold fabricated via the fused deposition modelling technique. For our studies the standard genetic algorithm was used, which is an efficient method of discrete optimization. For the fused deposition modelling scaffold, each individual strut is scrutinized for its role in the architecture and structural support it provides for the scaffold, and its contribution to the overall scaffold was studied. The goal of the study was to create a numerical tool that could help to acquire the desired behaviour of tissue engineered scaffolds and our results showed that this could be achieved efficiently by using different materials for individual struts. To represent a great number of ways in which scaffold mechanical function loss could proceed, the exemplary set of different desirable scaffold stiffness loss function was chosen.