Designing porous scaffolds for tissue engineering.

Biomaterials are either modified natural or synthetic materials, with an appropriate response in the host tissue, which find application in a wide spectrum of implants and prostheses used in reconstructive medicine. The subsequent integration and longevity of the implanted device depends on the effectiveness of the associated biological repair. Hence, there has been considerable interest in the development of novel, second generation, biomaterials, which are favourably bioactive in terms of promoting the desired cellular response in vivo. Such biomaterials in a porous form can also act as cellular scaffolds and allow in vitro, as well as in vivo incorporation of the appropriate tissue cells, with potential control of the sequence of cell attachment, proliferation and the production of extra-cellular matrix. Such generic tissue engineering depends critically on the porous architecture of the biomaterial scaffold so as to allow both the cellular ingress and vascularization required to create a living tissue. The particular requirements of tissue-engineering scaffolds with respect to macro- and micro-porosity, as well as chemistry, are reviewed.