Studies On Mechanical Strength And Degradation In Vitro Of Silk Matrix For Tissue Engineered Ligaments

Objective: A significant need exists for biomaterials which low rates of degradation and the low level of inflammatory potential to developing biological artificial ligament.Method: In this study Bombyx mori silk fibroin yarns were incubated in 1mg/ml collagenase IA at 37oC to create an in vitro model system of proteolytic degradation. Samples were harvested at designated time points up to 12 weeks and (1)lyophilized and weighed,(2)mechanical properties determined. Control samples were incubated in phosphate-buffered saline. The direct inflammatory potential of silk fibers was studied by culturing with RAW 264.7 murine macrophage cells in an in vitro system.Results: After 9 weeks, the weight of silk fibroin immersed in collagenase IA was 50% of its starting weight and that in phosphate buffer was 3% of the pretreatment measure. UTS decreased by greater than 50% of initial strength after 8 weeks of in collagenase IA incubation; no significant change in UTS was observed for PBS incubated controls. In two separate experimental protocols designed to examine the effects of short- and long-term cultures, silk fibers failed to stimulate significant TNF release from RAW 264.7 murine macrophage cells.Conclusions: Silk is a mechanically robust biomaterial with predictable long-term degradation characteristics. The low level of inflammatory potential of silk fibers makes them promising candidates in future tissue engineering scaffold biomedical applications.