Abstract
For three-dimensional bio-printed cell-laden hydrogel tissue constructs, the well-designed internal porous geometry is tailored to obtain the desired structural and cellular properties. However, significant differences often exist between the designed and as-printed scaffolds because of the inherent characteristics of hydrogels and cells. In this study, an iterative feedback bio-printing (IFBP) approach based on optical coherence tomography (OCT) for the fabrication of cell-laden hydrogel scaffolds with optimal geometrical fidelity and cellular controllability was proposed. A custom-made swept-source OCT (SS-OCT) system was applied to characterize the printed scaffolds quantitatively. Based on the obtained empirical linear formula from the first experimental feedback loop, we defined the most appropriate design constraints and optimized the printing process to improve the geometrical fidelity. The effectiveness of IFBP was verified from the second run using gelatin/alginate hydrogel scaffolds laden with C3A cells. The mismatch of the morphological parameters greatly decreased from 40% to within 7%, which significantly optimized the cell viability, proliferation, and morphology, as well as the representative expression of hepatocyte markers, including CYP3A4 and albumin, of the printed cell-laden hydrogel scaffolds. The demonstrated protocol paves the way for the mass fabrication of cell-laden hydrogel scaffolds, engineered tissues, and scaled-up applications of the 3D bio-printing technique.
Highlights
Three-dimensional (3D) bio-printing represents a promising method for fabricating complex 3D tissue or organ constructs through the layer-wise and controllable positioning of cell-containing media[1,2,3]
This study presented an optical coherence tomography (OCT)-iterative feedback bio-printing (IFBP) protocol for the 3D bio-printing of cell-laden hydrogel scaffolds with high geometric fidelity and cellular controllability. 3D OCT image analysis illustrated that the directly printed cell-laden hydrogel scaffolds had low geometrical fidelity
Inter-batch quantitative characterization and intra-batch linear correlation analysis confirmed good the repeatability and controllability of our 3D bio-printing system and technique, which corroborated the feasibility of OCT-IFBP
Summary
Three-dimensional (3D) bio-printing represents a promising method for fabricating complex 3D tissue or organ constructs through the layer-wise and controllable positioning of cell-containing media[1,2,3]. High geometrical fidelity between the designed and as-printed scaffolds enables the efficient utilization of the unique structurally tailored advantages of 3D bio-printing technique to facilitate cellular controllability. 3D bio-printing cell-laden hydrogel scaffolds with optimal geometrical fidelity and cellular controllability are of great significance for research on the biofunctional reconstruction of printed cell-laden scaffolds, mass fabrication of engineered tissues and organs, and scaled-up applications of the 3D bio-printing technique. The IFBP method is based on accurately and nondestructively detecting the mismatch between the design and as-printed scaffolds, thereby providing quantitative linear feedback control to improve the 3D bio-printing process. Two types of tailored cell-laden hydrogel scaffolds were printed with high geometric fidelity and cellular controllability using the OCT-IFBP approach. An evaluation of the cell-laden hydrogel scaffolds was performed, and comparison between the OCT-IFBP and direct printing methods were based on the cell viability, proliferation, and morphology, as well as the functional expression of hepatocyte markers, such as CYP3A4 and albumin
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