Long-term stability, high strength, and 3D printable alginate hydrogel for cartilage tissue engineering application

Area of Science:

• Biomaterials Science
• Tissue Engineering
• Regenerative Medicine

Background:

• Cartilage damage is a major cause of disability.
• 3D bioprinting offers potential for creating customized cartilage tissue engineering scaffolds.
• Alginate hydrogels are suitable for bioinks but lack mechanical strength and long-term stability.

Purpose of the Study:

• To develop a double crosslinked alginate (DC-Alg) hydrogel for 3D bioprinting.
• To improve the mechanical properties and stability of alginate hydrogels for cartilage repair.
• To evaluate the potential of DC-Alg scaffolds for chondrogenic differentiation of human umbilical cord mesenchymal stem cells (huMSCs).

Main Methods:

• Sequential modification of alginate with L-cysteine and 5-norbornene-2-methylamine.
• Formation of DC-Alg hydrogels using CaCl2 and UV light.
• 3D bioprinting of DC-Alg scaffolds and culture with huMSCs.
• Assessment of mechanical properties, stability, cell viability, printing accuracy, and chondrogenic gene expression.

Main Results:

• DC-Alg hydrogels exhibited enhanced mechanical properties and stability compared to single crosslinked alginate.
• The 3D printed DC-Alg scaffolds demonstrated high printing accuracy (∼200 µm).
• huMSCs cultured on DC-Alg scaffolds showed successful chondrogenic differentiation, confirmed by gene expression (agg, col II, sox-9) and immunohistochemistry.

Conclusions:

• The developed DC-Alg hydrogel is a promising biomaterial for 3D bioprinting of cartilage scaffolds.
• DC-Alg hydrogels support huMSC differentiation into chondrocytes, indicating potential for cartilage defect repair.
• This study presents the first use of DC-Alg in 3D bioprinting for cartilage regeneration.