3D printing facilitated scaffold-free tissue unit fabrication

Area of Science:

• Biomaterials Engineering
• Tissue Engineering
• Regenerative Medicine

Background:

• Tissue spheroids are crucial building blocks for functional tissue engineering.
• Current methods using agarose molds for spheroid fusion have limitations, including specific temperature requirements.
• Developing advanced molding techniques is essential for efficient scaffold-free tissue fabrication.

Purpose of the Study:

• To develop and present an alginate-based, direct 3D mold-printing technology for fabricating scaffold-free tissue engineering constructs.
• To create biocompatible, bio-inert hydrogel molds for efficient tissue spheroid fusion.
• To investigate the role of cell-secreted collagen type I in tissue formation and maturation.

Main Methods:

• Developed a direct 3D printing technology to create microdroplets of alginate solution.
• Fabricated ring-shaped 3D hydrogel molds using a layer-by-layer deposition technique on calcium-containing substrates.
• Utilized a 3D printer to robotically place tissue spheroids (50% endothelial cells, 50% smooth muscle cells) into the alginate molds.

Main Results:

• Successfully fabricated scaffold-free tissue engineering constructs using 3D printed alginate molds.
• Tissue spheroids rapidly fused within the molds to form toroid-shaped tissue units.
• Histological and immunofluorescence analyses confirmed cell-secreted collagen type I promotes cell-cell adhesion, tissue formation, and maturation.

Conclusions:

• Alginate-based 3D mold-printing offers a promising alternative to agarose for tissue spheroid fabrication.
• The developed technology enables rapid fusion and maturation of engineered tissues.
• Collagen type I secretion plays a vital role in the development of these engineered tissue constructs.