Work

Engineering in vitro vascularization: Enhanced network formation in bioprinted, vat photopolymerized dECM constructs

Year: 2025

Type: article

Abstract: Formation of blood vessels sustaining the metabolic demands of the tissue-forming cells remains the greatest challenge in engineered tissues for regenerative medicine and in vitro organ modelling. We investigated vascularization of covalently crosslinked hydrogels derived from porcine decellularized small intestinal submucosa (dSIS), focusing on optimizing conditions for bioprinting and subsequent vascular network formation. dSIS was solubilized via enzymatic digestion with papain and formulated into a photocrosslinkable bioresin by combining it with a photoinitiator system of ruthenium/sodium persulfate (Ru/SPS) and human umbilical vein endothelial cells (HUVECs). This bioresin allowed bioprinting of cell-laden dSIS hydrogels via vat photopolymerization. Cytotoxicity testing of the bioresins revealed high viability of HUVECs encapsulated in the dSIS hydrogels, and coculturing the bioprinted HUVEC-laden hydrogels in presence of human dermal fibroblasts resulted in the formation of an interconnected vascular network within the gels. A lower Ru/SPS concentration (0.25/5 mM) in the bioresin led to the formation of a denser vascular network compared to the higher one (0.5/5 mM), indicating the significance of the Ru/SPS concentration in the covalent hydrogel crosslinking and the subsequent vascularization. The lowest dSIS concentration (0.375 wt-%) yielded soft hydrogels with incomplete printing fidelity, while the stiffest (0.75 wt-%) hydrogels failed to support the HUVEC network formation. The dSIS concentration of 0.5 wt-% was found optimal for both the bioprinting fidelity and the vascular network formation. Our findings highlighted the need for optimizing hydrogel composition and thus its covalent crosslinking for efficient vascularization of bioprinted tissue constructs, with potential implications for further development of vascularized 3D tissue models. • Our study tackles the longstanding challenge of vascularization in bioprinted hydrogels, especially in those fabricated via photopolymerization techniques • We developed a novel visible-light photocrosslinkable bioresin derived from decellularized porcine small intestine submucosa (dSIS), enabled by a ruthenium/sodium persulfate photoinitiator system • Fine-tuning the covalent crosslinking of the bioresins via dSIS and photoinitiator concentrations allowed for the controlled formation of vascular-like networks within the bioprinted constructs, supporting endothelial cell integration and organization • This represents a critical step forward in engineering functional in vitro vasculature, expanding the complexity, viability, and translational potential of tissue-engineered constructs for regenerative medicine and in vitro tissue modelling

Source: Bioprinting

DOI: 10.1016/j.bprint.2025.e00452