Microstructure design of biodegradable scaffold and its effect on tissue regeneration.

Biodegradable scaffolds play a critical role in therapeutic tissue engineering, in which the matrix degradation and tissue ingrowth are of particular importance for determining the ongoing performance of tissue-scaffold system during regenerative process. This paper aims to explore the mechanobiological process within biodegradable scaffolds, where the representative volume element (RVE) is extracted from periodic scaffold micro-architectures as a base-cell design model. The degradation of scaffold matrix is modeled in terms of a stochastic hydrolysis process enhanced by diffusion-controlled autocatalysis; and the tissue ingrowth is modeled through the mechano-regulatory theory. By using the finite element based homogenization technique and topology optimization approach, the effective properties of various periodic scaffold structures are obtained. To explore the effect of scaffold design on the mechanobiological evolutions of tissue-scaffold systems, different scaffold architectures are considered for polymer degradation and tissue regeneration. It is found that the different tissues can grow into the degraded voids inside the polymer matrix. It is demonstrated that the design of scaffold architecture has a considerable impact on the tissue regeneration outcome, which exhibits the importance of implementing different criteria in scaffold micro-structural design, before being fabricated via rapid prototyping technique, e.g. solid free-form fabrication (SFF). This study models such an interactive process of scaffold degradation and tissue growth, thereby providing some new insights into design of biodegradable scaffold micro-architecture for tissue engineering.