Development of biodegradable scaffolds for tissue engineering: a perspective on emerging technology

The scaffold, a three-dimensional (3D) substrate that serves as a template for tissue regeneration, plays an essential role in tissue engineering. The ideal scaffold should have surface chemistry and microstructure tailored to facilitate cellular attachment, proliferation and differentiation; adequate mechanical strength for handling; and an appropriate biodegradation rate without undesirable byproducts. Research on biopolymer formulation and scaffold fabrication has been intense over the past 10 years. A perspective is provided of important issues related to scaffold development from biodegradable polymers. The mechanical properties and biocompatibility (including biodegradability and bioresorptability) of commonly used biopolymers are reviewed. Scaffold design and fabrication techniques are assessed and compared. Scaffold architecture, including pore size and size distribution, and its effects on cell growth are discussed. The importance of structural hierarchy over a range of length scales is highlighted. Unfortunately, conventional processing techniques cannot yet control both scaffold architecture and surface chemistry. An emerging scaffold fabricating technique using solid free form fabrication (SFF), although currently restricted to relatively symmetrical structures, has been shown to be highly effective in integrating structural architecture with changes in surface chemistry of the scaffolds, and integration of growth factors. Several examples of the application of SFF are presented.