Tailoring agarose fluid gels for use in suspension bath bioprinting and culture of spheroid-based bioinks.
Journal Article
Overview
abstract
Suspension bath bioprinting, whereby bioinks are extruded into a yield stress bath with rapid recovery from shearing, has enabled the printing of low viscosity bioinks into constructs with high geometric complexity. This is particularly useful for soft materials, such as bioinks of cells and hydrogel precursors or even those comprised of cells alone (e.g., cell suspensions, cell spheroids). Previous studies have often relied upon external stabilization of the suspension bath (e.g., thermally crosslinking collagen or basement membrane extract) in order to culture soft materials without loss of printed structure. Here, we report a systematic investigation of suspension bath properties that support the printing, fusion, and culture of spheroid-only bioinks without any external stabilization. Specifically, agarose fluid gel suspension baths of varied polymer concentrations and dilutions were produced and characterized morphologically and rheologically. Juvenile bovine chondrocytes were formed into spheroids of ~150 µm in diameter and their fusion was investigated across the suspension baths in hanging drop cultures. Suspension baths of lower polymer concentrations and increased dilution enabled faster spheroid fusion. Further, spheroids were jammed by centrifugation into a paste-like bioink and printed into the agarose fluid gel suspension baths and cultured. The most heavily diluted suspension bath was unable to maintain print fidelity, whereas other formulations supported the printing, fusion, and culture of spheroid inks. These findings help to inform the design of suspension baths for bioprinting and culture without the use of external stabilization.
