In 3D bioprinting, bioinks with high concentrations of polymeric materials are frequently used to enable fabrication of 3D cell‐hydrogel constructs with sufficient stability. However, this is often associated with restricted cell bioactivity and an inhomogeneous distribution of newly produced extracellular matrix (ECM). Therefore, this study investigates bioink compositions based on hyaluronic acid (HA), an attractive material for cartilage regeneration, which allow for reduction of polymer content. Thiolated HA and allyl‐modified poly(glycidol) in varying concentrations are UV‐crosslinked. To adapt bioinks to poly(ε‐caprolactone) (PCL)‐supported 3D bioprinting, the gels are further supplemented with 1 wt% unmodified high molecular weight HA (hmHA) and chondrogenic differentiation of incorporated human mesenchymal stromal cells is assessed. Strikingly, addition of hmHA to gels with a low polymer content (3 wt%) results in distinct increase of construct quality with a homogeneous ECM distribution throughout the constructs, independent of the printing process. Improved ECM distribution in those constructs is associated with increased construct stiffness after chondrogenic differentiation, as compared to higher concentrated constructs (10 wt%), which only show pericellular matrix deposition. The study contributes to effective bioink development, demonstrating dual function of a supplement enabling PCL‐supported bioprinting and at the same time improving biological properties of the resulting constructs.

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Melt electrowriting (MEW) is an additive manufacturing process that produces highly defined constructs with elements in the micrometer range. A specific configuration of MEW enables printing tubular constructs to create small‐diameter tubular structures. The small pool of processable materials poses a bottleneck for wider application in biomedicine. To alleviate this obstacle, an acrylate‐endcapped urethane‐based polymer (AUP), using a poly(ε‐caprolactone) (PCL) (molar mass: 20 000 g mol−1) (AUP PCL20k) as backbone material, is synthesized and utilized for MEW. Spectroscopic analysis confirms the successful modification of the PCL backbone with photo‐crosslinkable acrylate endgroups. Printing experiments of AUP PCL20k reveal limited printability but the photo‐crosslinking ability is preserved post‐printing. To improve printability and to tune the mechanical properties of printed constructs, the AUP‐material is blended with commercially available PCL (AUP PCL20k:PCL in ratios 80:20, 60:40, 50:50). Print fidelity improves for 60:40 and 50:50 blends. Blending enables modification of the constructs' mechanical properties to approximate the range of blood vessels for transplantation surgeries. The crosslinking‐ability of the material allows pure AUP to be manipulated post‐printing and illustrates significant differences in mechanical properties of 80:20 blends after crosslinking. An in vitro cell compatibility assay using human umbilical vein endothelial cells also demonstrates the material's non‐cytotoxicity.