TY - JOUR

T1 - Engineering in vitro vascularization

T2 - Enhanced network formation in bioprinted, vat photopolymerized dECM constructs

AU - Schüler, Kristin

AU - Almalla, Ahed

AU - Seitel, Sebastian

AU - Ebner, Friederike

AU - Seiffert, Sebastian

AU - Weinhart, Marie

AU - Elomaa, Laura

N1 - Publisher Copyright: © 2025 The Authors.

PY - 2025/12

Y1 - 2025/12

N2 - 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.

AB - 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.

KW - Covalent hydrogels

KW - Decellularized small intestinal submucosa (dSIS)

KW - Engineered tissue

KW - Vascularization

KW - Vat photopolymerization

UR - http://www.scopus.com/inward/record.url?scp=105021971663&partnerID=8YFLogxK

U2 - 10.1016/j.bprint.2025.e00452

DO - 10.1016/j.bprint.2025.e00452

M3 - Article

AN - SCOPUS:105021971663

VL - 52

JO - Bioprinting

JF - Bioprinting

SN - 2405-8866

M1 - e00452

ER -