High-throughput laser printing of cells and biomaterials for tissue engineering

In parallel with ink-jet printing and bioplotting, biological laser printing (BioLP) using laser-induced forward transfer has emerged as an alternative method in the assembly and micropatterning of biomaterials and cells. This paper presents results of high-throughput laser printing of a biopolymer (sodium alginate), biomaterials (nano-sized hydroxyapatite (HA) synthesized by wet precipitation) and human endothelial cells (EA.hy926), thus demonstrating the interest in this technique for three-dimensional tissue construction. A rapid prototyping workstation equipped with an IR pulsed laser (tau=30 ns, lambda=1064 nm, f=1-100 kHz), galvanometric mirrors (scanning speed up to 2000 mm s(-1)) and micrometric translation stages (x, y, z) was set up. The droplet generation process was controlled by monitoring laser fluence, focalization conditions and writing speed, to take into account its mechanism, which is driven mainly by bubble dynamics. Droplets 70 microm in diameter and containing around five to seven living cells per droplet were obtained, thereby minimizing the dead volume of the hydrogel that surrounds the cells. In addition to cell transfer, the potential of using high-throughput BioLP for creating well-defined nano-sized HA patterns is demonstrated. Finally, bioprinting efficiency criteria (speed, volume, resolution, integrability) for the purpose of tissue engineering are discussed.