Effects of fluid flow on the in vitro degradation kinetics of biodegradable scaffolds for tissue engineering

Scaffolds fabricated from biodegradable polymers are used extensively in th e field of tissue engineering. Many of these scaffolds are subjected to flu id flow, either in vivo or in bioreactors ex vivo. The goal of this study w as to examine the effects of fluid flow on the degradation characteristics and kinetics of scaffolds in vitro. Scaffolds with different porosity and p ermeability values were fabricated using a copolymer of polylactic acid and polyglycolic acid. These scaffolds were subjected to degradation in phosph ate buffered saline at 37 degrees C for up to 6 weeks under two test condit ions: static and flow (250 mu l/min). The porosity of the scaffolds decreas ed up to 2 weeks and then increased, while the elastic modulus first increa sed and then decreased over the course of the study. The mass and molecular weight of the scaffolds exhibited a steady decrease up to 6 weeks. The res ults further indicated that lower the porosity and permeability of the scaf folds, the faster their rate of degradation. Additionally, fluid flow decre ased the degradation rate significantly. It is possible that the high rates of degradation observed here were due to autocatalysis of the degradation reaction by the acidic degradation products. (C) 2000 Elsevier Science Ltd. All rights reserved.