Development of mechanically stable alginate/chondrocyte constructs: effects of guluronic acid content and matrix synthesis

The purpose of this study was to investigate factors which enhanced the com pressive properties of alginate/chondrocyte constructs. firstly, we studied the effect of biochemical composition thigh, mid and low guluronic acid co ntent) and sterilization method on alginate properties. Secondly, we studie d the biosynthetic characteristics of chondrocytes in three different algin ate compositions and performed mechanical tests to determine whether the sy nthesis of cartilage matrix components could significantly enhance the comp ressive properties. 2% alginate solutions containing an initial cell densit y of 4 x 10(6) cells/ml were cast into cylinders and cultured for seven wee ks. Compression tests, biochemistry, immunohistochemistry and electron micr oscopy were performed at fixed intervals during the seven-week culture peri od. The dynamic modulus. peak strain, and peak stress were maximum for algi nate with the highest guluronic acid content. The presence of cells and the ir respective matrix components enhanced the equilibrium modulus of the con structs for all types of alginate. though this effect M as small. Alginate containing the middle amount of guluronic acid resulted in constructs which were both mechanically stable and which promoted synthesis of cartilage ma trix proteins. In experiments and applications in which the mechanical inte grity of the alginate is important, the composition and purity of the algin ate and its method of sterilization should be selected with care. (C) 2001 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.