Biomaterials 26 (2005) 63–72 The effect of PEGT/PBT scaffold architecture on the composition of tissue engineered cartilage J. Malda a,b,c, *, T.B.F. Woodfield a,b , F. van der Vloodt a,c , C. Wilson d , D.E. Martens c , J. Tramper c , C.A. van Blitterswijk a,b , J. Riesle a a IsoTis S.A., Bilthoven, The Netherlands b Institute for Biomedical Technology (BMTI), University of Twente, Enschede, The Netherlands c Food and Bioprocess Engineering Group, Wageningen University, Wageningen, The Netherlands d Department of Orthopaedics, University Medical Center, Utrecht, The Netherlands Received 1 September 2003; accepted 2 February 2004 Abstract A highly interconnecting and accessible pore network has been suggested as one of a number of prerequisites in the design of scaffolds for tissue engineering. In the present study, two processing techniques, compression-molding/particulate-leaching (CM), and 3D fiber deposition (3DF), were used to develop porous scaffolds from biodegradable poly(ethylene glycol)-terephthalate/ poly(butylene terephthalate) (PEGT/PBT) co-polymers with varying pore architectures. Three-dimensional micro-computed tomography (mCT) was used to characterize scaffold architectures and scaffolds were seeded with articular chondrocytes to evaluate tissue formation. Scaffold porosity ranged between 75% and 80%. Average pore size of tortuous CM scaffolds (182 mm) was lower than those of organized 3DF scaffolds (525 mm). The weight ratio of glycosaminoglycans (GAG)/DNA, as a measure of cartilage- like tissue formation, did not change after 14 days of culture whereas, following subcutaneous implantation, GAG/DNA increased significantly and was significantly higher in 3DF constructs than in CM constructs, whilst collagen type II was present within both constructs. In conclusion, 3DF PEGT/PBT scaffolds create an environment in vivo that enhances cartilaginous matrix deposition and hold particular promise for treatment of articular cartilage defects. r 2004 Elsevier Ltd. All rights reserved. Keywords: Chondrocytes; Cartilage tissue engineering; Scaffold; Cell culture; In vitro; In vivo 1. Introduction Tissue engineering holds promise for revolutionary advances in health care and considerable efforts have been directed towards the development of autologous substitutes to regenerate, maintain, or improve tissue and organ function. None more so than articular cartilage (AC), a connective tissue which, when damaged, exhibits limited intrinsic regenerative capacity [1]. In general, tissue-engineered constructs require a highly porous artificial extra-cellular matrix (ECM) or scaffold material to accommodate mammalian cells and to organize tissue regeneration in a three-dimensional (3D) environment. Nevertheless, limitation in the diffusion of nutrients has been suggested as a cause for the inhomogeneous neo- cartilage distribution observed in larger tissue-engineered cartilaginous constructs, whereby, the onset of chondro- genesis occurs solely within the peripheral boundaries [2– 5]. Indeed, it has been demonstrated that nutrient gradients, such as oxygen in particular [5,6], can be measured and do occur within these tissue-engineered constructs. Therefore, in an effort to improve nutrient transport to cells, there has been considerable interest in the development of bioreactors in which medium flow is applied [7–9], or which mimic the periodic compressive stresses within articulating joints [10,11]. Although these dynamic culture conditions typically result in an im- proved quality of the neo-cartilage tissue formed, the 3D pore architecture present within scaffolds used for cartilage tissue engineering also likely has a large influence on tissue formation. While several investigators [12–14] have evaluated the effect of scaffold pore size on cartilage tissue formation, ARTICLE IN PRESS *Corresponding author. Department of Polymer Chemistry and Biomaterials, University of Twente/IsoTis S.A., P.O. Box 98, 3720 AB Bilthoven, Netherlands. E-mail address: jos@malda.nl (J. Malda). 0142-9612/$-see front matter r 2004 Elsevier Ltd. All rights reserved. doi:10.1016/j.biomaterials.2004.02.046