In recent years, scientists have introduced organ-like chips, which mimic the physiological activities of a whole human organ. It is said they will soon revolutionise the process of drug discovery and end the era of animal testing. This technology has such potential that London’s Design Museum named it Design of the Year 2015, for the first time ever in the field of medicine. But how can all functions of a lung or a heart be represented in a chip no bigger that a standard memory stick?
Organs-on-a-chip are small, polymeric devices with tiny tubes inside them, which enable the flow of air, blood or any other compound needed for a given organ to function. These tubes are lined with actual human cells making it possible for scientists to analyse how a given chemical effects the organ. Microfluidic models of organs such as lungs, a heart or a kidney have already been developed.
Let us look at the example of a lung-on-a-chip. It has two channels, one for the flow of blood, the other for the air, separated by a porous membrane, which enables molecules such as white blood cells to move through it. The tubes are lined with capillary blood vessels on one side and lung cells on the other, which is the arrangement present in a real human lung. The adjacent vacuum channels mimic the stretching and shrinking of the organ when we breathe. To check if the chip works, scientists from the Wyss Institute introduced bacteria into the air flow of the device. They then observed how white blood cells from the blood flow go through the membrane and lung cells to attack the bacteria present in the air flow tube. Organs-on-a-chip provide the possibility of easy observations and direct measurements, in a real-time course of a given process.
How could those small, artificial cell cultures be so useful? Firstly, they provide great models for drug trials. In the near future scientists may no longer need animals to test a drug. They will simply introduce a given substance into an organ-on-a-chip and directly observe how the cells react. This approach is not only more cost-effective compared to animal testing, but also much faster. Animal testing is also not as accurate as the use of chips, because of the significant differences between animal and human cells. Additionally, it is a great step forward towards personalized medicine. Those micro-devices can be lined with cells from a particular group of people from the same ethnic group and similar genetic background. This may lead to the production of variants of drugs targeting a particular group of patients. We can go even further. Cells from individual patients can line a chip, so that a fully personal response to a medicine is observed.
Critics of the technology say that the experiments conducted on isolated organs are not accurate, as they do not take into the account the physiology of the whole human body. Some have already addressed that problem by developing a network of organs-on-a-chip, all connected to each other and this way have analysed how different parts of an organism respond to a given chemical. Japanese scientists created a chip that mimics the functions of three parts of the human body: a liver, intestines and breast cells and measured their response to cancer drugs. The designers of a lung-on-a-chip are planning to build a human-like system of 10 organs, which will allow to observe how changes in one organ affect the rest of the organism.
Monitoring of the physiological changes occurring within the organs can be a dull process, taking several weeks. Therefore, a good measurement system is needed. With the use of Google Glass and additional hardware and software integrated within it, scientists have been able to remotely observe and control organs-on-a-chip. The device contains valves, which control the flow of the fluid going in and out of the chip and many sensors that monitor different aspects of the organ’s physiology such as its pH and temperature. The collected data is instantaneously sent to the Google Glass to be easily obtained and analysed by a scientist. This approach can be particularly useful when exposing the chips to life-threatening conditions such as dangerous viruses or radioactive substances as no human action is required when working on a chip.
Organs-on-a-chip provide an amazingly simple and efficient drug testing technique. Inexpensive, easy to produce and handle, with additional hardware and software available to collect the experimental data these devices are bound to entirely change the processes of drug development in the future.