Bioprinted Collagen Cell Constructs with Gradient BMP-2-Loaded Microbeads for Rotator Cuff Tear Regeneration

Area of Science:

• Biomaterials Science
• Regenerative Medicine
• Tissue Engineering

Background:

• Rotator cuff tears (RCT) have limited self-healing capacity, often requiring surgical repair.
• Current surgical treatments struggle to fully restore the bone-to-tendon interface (BTI).
• Effective tissue-engineering strategies are needed to promote BTI formation.

Purpose of the Study:

• To develop a bioprinted cell construct for repairing complex rotator cuff tears.
• To utilize stem cells and bone morphogenic protein 2 (BMP-2) carriers for enhanced tissue regeneration.
• To create a multi-layered construct mimicking native tissue gradients for improved BTI healing.

Main Methods:

• A collagen-based bioink was loaded with stem cells and collagen methacrylate microbeads (CMA-beads) as BMP-2 carriers via a water-in-oil emulsion.
• A core-shell nozzle bioprinter fabricated a multi-layered construct with graded pore sizes and decreasing BMP-2 concentration from bone to tendon regions.
• The constructs were implanted into a rabbit full-thickness partial-width RCT (FTPWRCT) model.

Main Results:

• CMA-beads sustained BMP-2 release, promoting stem cell activity and osteogenesis in vitro.
• The bioprinted constructs exhibited a graded structure mimicking native tissue interfaces.
• In vivo implantation significantly accelerated the remodeling of bone-to-tendon tissue in the rabbit RCT model.

Conclusions:

• The proposed bioprinted cell construct effectively supports the restoration of the bone-to-tendon interface in rotator cuff tears.
• BMP-2 loaded CMA-beads are a viable strategy for enhancing cell activity and osteogenesis in engineered tissues.
• This tissue-engineering approach shows promise for improving surgical outcomes in rotator cuff repair.