3D bioprinting of a hyaluronan bioink through enzymatic-and visiblelight-crosslinking

摘要

Extrusion-based three-dimensional bioprinting relies on bioinks engineered to combine viscoelasticproperties for extrusion and shape retention, and biological properties for cytocompatibility andtissue regeneration. To satisfy these conflicting requirements, bioinks often utilize either complexmixtures or complex modifications of biopolymers. In this paper we introduce and characterize abioink exploiting a dual crosslinking mechanism, where an enzymatic reaction forms a soft gel suitablefor cell encapsulation and extrusion, while a visible light photo-crosslinking allows shape retention ofthe printed construct. The influence of cell density and cell type on the rheological and printabilityproperties was assessed correlating the printing outcomes with the damping factor, a rheologicalcharacteristic independent of the printing system. Stem cells, chondrocytes and fibroblasts wereencapsulated, and their viability was assessed up to 14 days with live/dead, alamar blue and trypanblue assays. Additionally, the impact of the printing parameters on cell viability was investigated.Owing to its straightforward preparation, low modification, presence of two independent crosslinkingmechanisms for tuning shear-thinning independently of the final shape fixation, the use of visiblegreen instead of UV light, the possibility of encapsulating and sustaining the viability of different celltypes, the hyaluronan bioink here presented is a valid biofabrication tool for producing 3D printedtissue-engineered constructs.