Technology and Health Care 10 (2002) 187–201 187 IOS Press Fundamentals of tissue engineering: Carrier materials and an application G.T. K¨ ose, A. Tezcaner and V. Hasırcı Middle East Technical University, Department of Biological Sciences, Biotechnology Research Unit, Ankara, Turkey Abstract. 1. Introduction Tissue engineering is the concept that the repair and regeneration of biological tissues can be guided through application and control of cells, materials, and chemoactive proteins. It began with the use of active biomaterials; materials designed to interact with the body to encourage tissue repair. It is still an emerging technology [1] and encompasses the interrelated fields such as chemical engineering, material science and cell biology. The approach is to harvest a relatively small piece of tissue, remove the cells and increase the cell population, seed the cells on a carrier material and generate a substantial amount of tissue by reimplanting the cell-polymer composite. This form of therapy differs from standard therapies in that the engineered tissue becomes integrated within the patient, affording a potentially permanent and specific cure of the disease state. Tissue engineering requires the reformation of an extracellular matrix. The main components of the extracellular matrix are collagen and proteoglycan. In contrast to proteoglycans, which can be thought as the ground substance, collagens primarily provide stress resistance to tissues. Current tissue engineering approaches commonly use cell attachment scaffolds that are complex composites of naturally occurring extracellular matrix (ECM) molecules (e.g. collagen, glycosaminoglycan), or decellularized biological matrices produced by means of enzymatic or detergent treatments [2] which would closely mimic the native cellular environment or synthetic biomaterials (polyurethanes, α-hydroxyacids, ceramics, etc) which will be discussed in detail. The control of material properties (e.g. strength, degradation profile, porosity, surface properties and microstructure), ease and reproducibility of fabrication make them good candidates for tissue engineered constructs [3]. 2. Importance of carrier materials in tissue engineering It has been known for a long time that cells differ in their ability to grow and differentiate depending on both the chemistry and mechanics of their ECM substratum. Epithelial cells commonly express more differentiated functions when grown on immobilized ECM molecules (e.g. collagen, fibronectin, and laminin) compared to tissue culture plastic alone. These cells function even better when maintained on 0928-7329/02/$8.00  2002 – IOS Press. All rights reserved