Gradient composite film with calcium phosphate silicate for improved tendon -to-Bone intergration

The tendon enthesis is a very complex tissue interface that connects a flexible tissue (tendon) to a stiff tissue (bone). Few available forms of gradient scaffolds with multiple components have been fabricated for applications in vivo because of the complexities of enthesis. In the present work, gradient-poly(e-caprolactone)/calcium phosphate silicate (G-P/C) composite films were fabricated with tape casting technique. Films with different P/C ratio were used to evaluate the material's properties and effects of composition on cellular behaviors. The results showed that the G-P/C composite film offered a gradually changing composition transition. The higher levels of calcium phosphate silicate of each film stimulated stronger osteogenic differentiation and mineralized matrix deposition. When the films were interposed between the supraspinatus tendon and humerus bone, the G-P/C composite film group exhibited more tissue cellularity, better collagen alignment, better gradient mineralized cartilage formation and gradient Ca distribution than other groups. All these histological improvements were well consistent with the biomechanical results of the G-P/C composite film group. Thus, the G-P/C composite film may be a promising scaffold for tendon-to-bone interface engineering.

Automated summary

This study fabricated gradient poly(e-caprolactone)/calcium phosphate silicate (G-P/C) composite films with varying P/C ratio, showing that higher levels of calcium phosphate silicate stimulated stronger osteogenic differentiation and mineralized matrix deposition. When interposed between the supraspinatus tendon and humerus bone, the G-P/C composite film group exhibited more tissue cellularity, better collagen alignment, better gradient mineralized cartilage formation, and gradient Ca distribution compared to other groups, suggesting its promising potential as a scaffold for tendon-to-bone interface engineering.