Objective

Growing three-dimensional tissue-engineered constructs is one of the few alternatives to the use of heart-lung transplants for critically ill patients. Creating a large, complex viable construct that is capable of supporting human life is a formidable challenge. Ten years ago such an enterprise would have been technically impossible. However, recent results from two fields of materials science indicate that in vitro formation of three-dimensional functional organs may be feasible within the next decade. The developments are: (1) bioactive materials that activate the regenerative potential of tissues and release proteins needed for organogenesis, and (2) sol-gel processing of hierarchical porous materials that can direct growth of three-dimensional (3-D) interconnected structures that mimic the natural architecture of tissues.

The objective of this chapter is to review the concepts of these two fields and indicate how they can be directed towards the goal of engineering biomolecularly tailored 3-D constructs for growth of tissues and organs. The function of the bioactive composition will be to stimulate and control the rate and sequence of differentiation and proliferation of the tissues, whereas the role of the hierarchical bioactive matrix will be to direct formation of the 3-D architecture of the engineered tissue.

Introduction

Tissue engineering combines biology, materials science and biomedical engineering to achieve long-term repair and replacement of failing human tissues and organs [1–3]. Three strategies can be employed: (1) in vitro construction of bioartificial tissues from cells harvested from the patient or from cell lines, (2) in vivo alteration of cell growth and function, and (3) a combination of (1) and (2) [1].