Drop-on-demand bioprinting allows the controlled placement of living cells, and will benefit research in the fields of tissue engineering, drug screening and toxicology. We show that a bio-ink based on a novel microgel suspension in a surfactant-containing tissue culture medium can be used to reproducibly print several different cell types, from two different commercially available drop-on-demand printing systems, over long printing periods. The bio-ink maintains a stable cell suspension, preventing the settling and aggregation of cells that usually impedes cell printing, whilst meeting the stringent fluid property requirements needed to enable printing even from many-nozzle commercial inkjet print heads. This innovation in printing technology may pave the way for the biofabrication of multi-cellular structures and functional tissue.

The development of cell printing is vital for establishing biofabrication approaches as clinically relevant tools. Achieving this requires bio-inks which must not only be easily printable, but also allow controllable and reproducible printing of cells. This review outlines the general principles and current progress and compares the advantages and challenges for the most widely used biofabrication techniques for printing cells: extrusion, laser, microvalve, inkjet and tissue fragment printing. It is expected that significant advances in cell printing will result from synergistic combinations of these techniques and lead to optimised resolution, throughput and the overall complexity of printed constructs. AbstractThe development of cell printing is vital for establishing biofabrication approaches as clinically relevant tools. Achieving this requires bio-inks which must not only be easily printable, but also allow controllable, reproducible printing of cells. This review outlines the general principles, current progress, and compares the advantages and challenges for the most widely used biofabrication techniques for printing cells: extrusion, laser, microvalve, inkjet and tissue fragment printing. It is expected that significant advances in cell printing will result from synergistic combinations of these techniques and lead to optimised resolution, throughput and the overall complexity of printed constructs.

Gellan gum is an anionic linear polysaccharide well known for its use as a multi-functional gelling, stabilising and suspending agent in a variety of foods and personal care products. In this Highlight, we explore the recently established directions for gellan gum hydrogels as materials for applications in tissue engineering. We highlight that modified gellan gum will be well suited for this purpose, providing that a number of remaining challenges are addressed. Gellan gum is an anionic linear polysaccharide well known for its use as a multi-functional gelling, 5 stabilising and suspending agent in a variety of foods and personal care products. In this Highlight, we explore the recently established directions for gellan gum hydrogels as materials for applications in tissue engineering. We highlight that modified gellan gum will be well suited for this purpose, providing that a number of remaining challenges are addressed.