Overcoming Challenges in Engineering Large, Scaffold-Free Neocartilage with Functional Properties

Area of Science:

• Tissue Engineering
• Biomaterials Science
• Regenerative Medicine

Background:

• Current cartilage engineering methods struggle to produce constructs larger than 4 cm², limiting cell-based therapies for significant cartilage defects.
• Existing treatments primarily address focal lesions, leaving a critical need for effective therapies for large, non-isolated cartilage damage.

Purpose of the Study:

• To scale up the fabrication of self-assembled neocartilage from standard 0.2 cm² to over 8 cm².
• To develop a novel strategy for generating large, mechanically stable, and morphologically uniform neocartilage constructs suitable for implantation.

Main Methods:

• Articular chondrocytes from sheep were self-assembled into scaffoldless neocartilage constructs of 5 mm and 25 mm diameters.
• A novel fabrication strategy involving mechanical confinement, a deadweight, and chemical stimulation (cytochalasin D, TGF-β1, chondroitinase-ABC, lysyl oxidase-like 2) was employed for large constructs.

Main Results:

• The 25 mm constructs scaled up to 9.3 cm² but initially deformed and were unusable.
• The novel fabrication strategy successfully produced large (25 mm diameter) constructs with flat, homogeneous morphology.
• Chemical stimulation significantly increased collagen content and tensile Young's modulus in both 5 mm and 25 mm constructs, with greater enhancements in the larger ones.

Conclusions:

• Exceedingly large self-assembled neocartilage constructs can be fabricated using a combination of mechanical and chemical stimuli.
• The developed method maintains or enhances the biomechanical properties of neocartilage, making it suitable for treating extensive cartilage defects.