Type I Collagen (COL1) Used for the Preparation of Gradient COL1/HAp Scaffolds for Tendon–Bone Interface Regeneration

[mindyhausler]

Type I collagen (COL1), the primary structural protein in the extracellular matrix of tendons and bone, plays a pivotal role in the development of biomimetic materials for regenerative medicine. This study demonstrates the application of COL1 in the fabrication of a dual-phase, gradient composite scaffold designed to repair tendon–bone interface injuries—a clinical challenge due to the poor healing capacity of this transitional tissue.

A bilayer scaffold was engineered using COL1 and hydroxyapatite (HAp) powders, each blended with 10% gelatin and stirred separately to form uniform mixtures. The HAp layer was first cast and set at 4 °C, followed by the addition of the COL1 layer. After sequential cooling, the scaffold underwent chemical cross-linking using either Genipin, EDC/NHS, or a dual cross-linking strategy to enhance structural integrity and biological performance.

The optimal scaffold—dual cross-linked COL1/HAp—was loaded with human amniotic mesenchymal stem cells (hAMSCs) and implanted in a rat rotator cuff injury model. Micro-CT, histological, and biomechanical analyses confirmed superior healing, including aligned collagen fibers, fibrocartilage formation, and improved mechanical strength at 12 weeks post-implantation.

This work highlights the critical role of COL1 in scaffold design and provides a viable strategy for enhancing tendon–bone interface healing through biomimetic materials combined with stem cell therapy.