Effect of cyclic loading on in vitro degradation of poly(L-lactide-co-glycolide) scaffolds.

The in vitro degradation performance of porous scaffolds is very important in tissue engineering, especially the scaffold implanted in the environment imitating the repaired tissue. In this paper, the effect of cyclic loading on in vitro degradation of porous poly(L-lactide-co-glycolide) (PLGA) scaffolds was studied by incubating the samples in phosphate-buffered saline at 37 degrees C and pH 7.4 under dynamic conditions (cyclic loading) and static conditions (shaking water bath) for 12 weeks. The results showed earlier morphological variations and faster reduction in mass, dimensions and relative molecular mass of the scaffolds under dynamic conditions. Mechanical properties (the compressive modulus and the compressive strength) of the PLGA scaffolds under both conditions tended to increase in the first 3 weeks, but showed a decrease tendency afterward. The scaffolds under dynamic conditions were too brittle to be further characterized after degradation for 6 weeks, while those under static conditions endured degradation until week 8. The degradation mechanism of the PLGA scaffolds under cyclic loading was clearly explained and a three-stage degradation model based on the degradation behaviors of the scaffolds under two conditions was presented.