Can Organ-on-a-Chip Technology Really Replace Animal Testing of Drug and Chemical Safety
There is currently great interest in applying microfluidics technology to the construction of complex in vitro models with the eventual goal of simulating the behaviour of an organ or even a whole organism. The enthusiasm for microtechnology has been generated by past success in scaling cell culture from a petri dish down to the current multiple well plates. However our gold standard for clinical response is the human body, which incorporates functional units that require larger scale. It is widely recognised that 3D cell cultures are more representative of human physiology than 2D monolayers of cells growing on a flat surface. Correct organ function also requires gradients of oxygen and metabolites and removal of waste material, as well as co-culture of multiple cell types- hence advanced and accurate models also require flow of media. Any technology which aims to replace animal based methods for safety and toxicity testing will have to meet the following requirements: •Systemic models •Long term and repeat dose exposure •Maintain homeostasis (before insult) •Good disease models The goal for organ-on-a- chip is to accurately mimic clinical behaviour. Once this milestone is achieved then models must demonstrate robustness, repeatability and ease of use, and be economic compared with alternative methods. It is suggested here that the currently available meso-scale Quasi Vivo® technology is a useful stepping stone on the route to the ultimate micro-scale miniaturisation, by acting as a physiologically relevant ‘breadboarding’ tool to aid development of co-culture and long term models with full metabolic capability.