Cell-driven elastomeric particle packing in composite bioinks for engineering and implantation of stable 3D printed structures

This paper introduces a granular-composite bioink that integrates elastomeric poly(octamethylene maleate anhydride citrate) (POMaC) microparticles into natural hydrogels (fibrin, GelMA, alginate) to overcome hydrogel compaction, swelling, and poor shape fidelity in 3D-printed cell-laden constructs. The hybrid bioink displayed fast UV-crosslinking, high ultimate compressive strength, and excellent printability by stereolithography and extrusion. Micromechanical and finite-element analyses showed that POMaC particle packing distributed stress and preserved geometry under cellular traction. Cardiac and vascular tissues printed with GelMA/POMaC retained architecture, exhibited greater cardiomyocyte contractility (lower excitation threshold, higher capture rate), and developed wider, more stable vessels in vitro and after implantation in mice. In vivo, POMaC constructs promoted angiogenesis and pro-regenerative macrophage recruitment over 4 weeks. This hybrid approach unites mechanical robustness and biocompatibility for next-generation bioinks for tissue repair and implantation.