A Gargantuan Effort

Human-on-a-Chip is an intricate experimental system designed to study an aspect of the human body under controlled conditions. The design of such a system requires the knowledge of the human body, biological systems and engineering to set-up and install regulated control systems to support living cells. Microfluidic devices provide dynamic conditions and keep cells alive with continuous monitoring to conduct specific experiments. However, the human body is a complex system of many cells. Scientists Sender, Fuchs and Milo from Weizmann Institute reported that the number of human cells in a 70 kg “reference man” is estimated to be about 30 trillion and the number of bacterial cells found throughout the body is about 39 trillion. These trillions of human and bacterial cells live together in the body in a coordinated fashion influenced by countless external and internal signals, hormones, cytokines, local responses and mediators. How easy will it be to design a system that includes these trillions of different cells and signals? Even though the microfluidic channels do provide layers of cells attached to a plastic substratum, the materials used are far-removed from the living world of the architecture of the microcirculation and capillary beds. The synthetic material commonly used is PDMS (polydimethylsiloxane) which has been explicitly shown to adsorb biomolecules. Thus, surface chemists can provide expertise to modify such surfaces or develop alternative materials for better compatibility with cells and less adsorption of molecules.