In Situ Volumetric Imaging and Analysis of FRESH 3D Bioprinted Constructs Using Optical Coherence Tomography

• Published in: bioRxiv
• Main Authors: Tashman, Joshua W, Shiwarski, Daniel J, Ruesch, Alexander, Lanni, Frederick, Kainerstorfer, Jana, Feinberg, Adam W
• Format: Paper
• Language: English
• Published: Cold Spring Harbor Cold Spring Harbor Laboratory Press 05.12.2021; Cold Spring Harbor Laboratory
• Edition: 1.2
• Subjects: 3-D printers; Bioengineering; Collagen; Embedding; Equity stake; Hydrogels; Printing; Quality control; Regulatory approval; Soft tissues; Structure-function relationships; Tomography
• ISSN: 2692-8205; 2692-8205
• DOI: 10.1101/2021.06.30.450389

As 3D bioprinting has grown as a fabrication technology, so too has the need for improved analytical methods to characterize these engineered constructs. This is especially challenging for soft tissues composed of hydrogels and cells as these materials readily deform, posing a barrier when trying to assess print fidelity and other properties non-destructively. Indeed, given the importance of structure-function relationships in most tissue types, establishing that the 3D architecture of the bioprinted construct matches its intended anatomic design is critical. Here we report development of a multimaterial bioprinting platform with integrated optical coherence tomography (OCT) for in situ volumetric imaging, error detection, and 3D reconstruction. While generally applicable to extrusion-based 3D bioprinting, we also report improvements to the Freeform Reversible Embedding of Suspended Hydrogels (FRESH) bioprinting process through new collagen bioink compositions, support bath optical clearing, and machine pathing. This enables high-fidelity 3D volumetric imaging with micron scale resolution over centimeter length scales, the ability to detect a range of print defect types within a 3D volume, and real-time imaging of the printing process at each print layer. These advances provide FRESH and other extrusion-based 3D bioprinting approaches with a comprehensive methodology for quality assessment that has been absent in the field to date, paving the way for translation of these engineered tissues to the clinic and ultimately to achieving regulatory approval. Competing Interest Statement A.W.F. has an equity stake in FluidForm Inc., which is a startup company commercializing FRESH 3D printing. FRESH 3D printing is the subject of patent protection including U.S. Patent 10,150,258 and provisional patent No. 63/082621 held by Carnegie Mellon University. Footnotes * The main text has been edited for clarity and the references expanded.