Alpha-modified minimum essential medium (αMEM) has been found to cross-link a 1% gellan gum solution, resulting in the formation of a self-supporting hydrogel in 1:1 and 5:1 ratios of polysaccharide: αMEM. Rheological data from temperature sweeps confirm that in addition to orders of magnitude differences in G^' between 1% gellan and 1% gellan with αMEM, there is also a 20^°C increase in the temperature at which the onset of gelation takes place when αMEM is present. Frequency sweeps confirm the formation of a true gel; mechanical spectra for mixtures of gellan and αMEM clearly demonstrate G^' to be independent of frequency. It is possible to immobilize cells within a three-dimensional (3D) gellan matrix that remain viable for up to 21 days in culture by adding a suspension of rat bone marrow cells (rBMC) in αMEM to 1% gellan solution. This extremely simple approach to cell immobilization within 3D constructs, made possible by the fact that gellan solutions cross-link in the presence of millimolar concentrations of cations, poses a very low risk to a cell population immobilized within a gellan matrix and thus indicates the potential of gellan for use as a tissue engineering scaffold.

There have been a number of recently reported approaches for the manufacture of complex 3D printed cell‐containing hydrogels. Given the fragility of the parts during manufacturing, the most successful approaches use a supportive particulate gel bed and have enabled the production of complex gel structures previously unattainable using other 3D printing methods. The supporting gel bed provides protection to the fragile printed part during the printing process, preventing the structure from collapsing under its own weight prior to crosslinking. Despite the apparent similarity of the particulate beds, the way the particles are manufactured strongly influences how they interact with one another and the part during fabrication, with implications to the quality of the final product. Recently, the process of suspended layer additive manufacture (SLAM) is demonstrated to create a structure that recapitulated the osteochondral region by printing into an agarose particulate gel. The manufacturing process for this gel (the application of shear during gelation) produced a self‐healing gel with rapid recovery of its elastic properties following disruption. Here, the physical characteristics of the supporting fluid‐gel matrix used in SLAM are explored, and compared to other particulate gel supporting beds, highlighting its potential for producing complex hydrogel‐based parts.

A method for the production of complex cell-laden structures is reported, which allows high-levels of spatial control over mechanical and chemical properties. The potential of this method for producing complicated tissues is demonstrated by manufacturing a complex hard/soft tissue interface and demonstrating that cell phenotype can be maintained over four weeks of culture.