Semi-automated layer-by-layer biofabrication using rotational internal flow layer engineering technology

The automation of biofabrication processes has the potential to increase both the scale and reproducibility of human tissue production for replacing animal usage in research and ultimately clinical use. The biofabrication technology, Rotational Internal Flow Layer Engineering (RIFLE), produces layered tubular constructs with a resolution commensurate with the microscale strata observed in many human tissue types. The previously published RIFLE process required liquid phase cell-laden hydrogels to be manually applied onto the inner surface of a high-speed rotating mould. Here we describe improvement of the RIFLE system by automating elements of the process, in particular the liquid dispensing element, and present the use of this system for two commonly used biofabrication hydrogels; alginate and collagen. Semi-automatically assembled cell layers matched the viabilities of those produced manually, with automated collagen demonstrating the highest viabilities (>91 %) over the 10 days measured, highlighting its advantages as a material for tissue engineering applications. The encapsulation of labelled cells in predefined collagen layer patterns confirmed that the semi-automated RIFLE system was able to assemble separate cell populations in cell-width layers (≈14 µ m). Semi-automated dosing reduced the manual operations in the RIFLE process, reducing the workload on researchers and minimising the opportunity for human error. Further opportunity exists for higher levels of automation in the overall process, particularly needed in the preparation of cell-hydrogel suspensions, a common manual labour-intensive process in many biofabrication technologies.