• Increasing the proportion of poly(ethylene oxide) in the bioink increases the pore size of 3D bioprinted methacrylated gelatin hydrogels.
• Larger pores enhance the spreading of human dental pulp stem cells and promote the formation of vascular-like structures in vitro.
• In vivo, hydrogels with larger pores and encapsulated cells showed significant vascularization, while no vascularization was observed in cell-free or small-pore groups.
• The study demonstrates that internal porosity is a critical factor for pre-vascularization of bioprinted hydrogels for tissue engineering.