3D printing microporous scaffolds from modular bioinks containing sacrificial, cell-encapsulating microgels.

Area of Science:

• Biomaterials Science
• Tissue Engineering
• 3D Bioprinting

Background:

• Microgel-based biomaterials offer inherent porosity and extrudability, suitable for 3D bioprinting.
• Current cell infiltration methods struggle with depth-independent cell distribution in thick 3D bioprinted constructs due to slow cell migration.

Purpose of the Study:

• To develop a microgel ink strategy for achieving tunable porosity and uniform cell distribution in 3D bioprinted constructs.
• To overcome the limitations of post-printing cell infiltration in thick geometries.

Main Methods:

• Developed a modular granular ink by combining structural gelatin methacryloyl (GelMA) microgels and sacrificial, cell-laden oxidized alginate (AlgOx) microgels.
• Created a series of GelMA:AlgOx microgel inks with varying ratios to achieve tunable void fractions (0.03–0.35).
• Investigated the effect of void fraction on cell morphology and distribution within 3D printed constructs using human umbilical vein endothelial cells (HUVEC).

Main Results:

• The blended GelMA:AlgOx microgel inks demonstrated high printability and tunable porosity.
• Void fraction influenced the morphology of encapsulated HUVEC cells.
• Crucially, void fraction did not negatively impact the uniform HUVEC distribution throughout the depth of the 3D printed samples.

Conclusions:

• This microgel ink strategy enables the fabrication of 3D bioprinted constructs with controlled porosity and depth-independent cell distribution.
• The combination of structural and sacrificial microgels offers a promising approach for advanced 3D bioprinting applications.
• This method addresses key challenges in achieving uniform cell seeding in complex, thick tissue constructs.