Effect of porosity on long-term degradation of poly (ε-caprolactone) scaffolds and their cellular response

Porous poly(ε-caprolactone) (PCL) scaffolds are widely used as in vivo implants in tissue engineering, and their long-term degradation behaviors are of great importance for their in vivo performances. However, the influence of porosity on long-term degradation of PCL scaffold in phosphate buffer solution (PBS) has been rarely reported so far. Herein, a 72-week degradation study of PCL scaffolds with various porosities was conducted to elucidate the changes of physico-chemical properties such as weight, molecular weight, morphology and compressive modulus. Within 72 weeks, PCL scaffolds experienced three stages: stable stage, mechanical loss stage and structural collapse stage. The higher porosity induced the severer loss of weight, molecular weight and compressive modulus. It was found that a minimal acid autocatalysis also happened in the scaffold samples with low porosities (less than 85%). Cellular response on the scaffolds with various porosities was further evaluated. The cell ingrowth improved on the scaffold with high porosity (e.g. S-10) in contrast to those with low porosity (e.g. S-6 and S-4). The combined results demonstrated that an optimal porosity of PCL scaffolds should be designed greater than 90% due to the appropriate degradation rate and good cell performance.