Organ-on-a-chip: Are we near the end of animal testing?

Humans have studied animals for thousands of years to learn more about their own anatomy. And they have put animals through countless tests to develop life-saving medicines.

These tests have also often led to friction between science and morality, and over ethical concerns raised by many.

However, a new technology is emerging that could revolutionise the field and put an end to animal testing once and for all: organ-on-a-chip technology.

Organ-on-a-chip technology involves growing tiny replicas of human organs on microchips, allowing researchers to test the safety and efficacy of drugs and treatments for animal testing.

In December of 2022, the US passed a new legislation, the FDA Modernization Act 2.0, to override the Federal Food, Drug, and Cosmetics Act of 1938, which mandated animal testing for every new drug development protocol.

It has opened up the possibility of using new technologies to model how the human body might react to cutting-edge treatments instead of relying on animal testing.

But does this mean an end to the animal testing era?

Evolution of animal studies

Animal studies enclose a long and controversial history, with the earliest recorded instances dating back to Aristotle's dissection of live animals in the 4th century BCE.

While social and religious beliefs prevented human cadaver dissection, animal dissection continued for centuries. In the early 1900s, animal testing became a popular method for testing new medicines, with researchers giving experimental treatments for diseases such as diphtheria and diabetes to animals before testing them on humans.

These experiments proved successful, earning scientists global accolades, including the coveted Nobel Prize. Despite ongoing ethical concerns, animal testing continues to be used in medical research even today.

For 84 years, US law required preclinical animal testing for new drugs before they were tested on humans. The requirement came into effect after a bad batch of diphtheria antitoxin and a deadly antibiotic medicine caused multiple fatalities in the early 20th century.

However, recent technological advancements could bring about significant changes in drug development and animal welfare by allowing companies to use novel testing methods as alternatives to animal testing.

Pitfalls of animal testing

Although animal testing has advanced science and paved the way for medicines and vaccines that have saved countless lives, it is not without flaws.

Scientists use thousands of dogs, mice, rats, and monkeys every year in animal testing. Some experts argue that this suffering is largely in vain because animal models don’t even work incredibly well.

Don Ingber, the founding director of Harvard University's Wyss Institute for Biologically Inspired Engineering and co-founder of organ-on-a-chip company Emulate, has expressed his belief that animal models used in drug development are “terrible”.

Ingber says that everyone involved in drug development knows this, including drug companies and the Food and Drug Administration (FDA).

According to Ingber, animals such as mice, rats, dogs, and monkeys are fundamentally different from humans and react differently when sick. This means that animal testing is not an accurate way to predict human reactions to drugs.

In recent years, however, scientists have developed a wide range of biomedical technologies, including the use of real human cells, to show precisely how human bodies may react to novel medications.

Replacing animal testing

The organ-on-a-chip is designed to mimic the structure and function of human organs, providing a more accurate representation of how drugs and treatments will work in the human body.

A major advantage of organ-on-a-chip technology is its potential to reduce the number of animals used in medical research.

According to the National Institutes of Health (NIH), over 20 million animals are used in experiments in the United States each year. This number could be significantly reduced with the use of organ-on-chip technology, as researchers would be able to conduct experiments in a more ethical and accurate manner.

In 2006, Shinya Yamanaka, a professor at Kyoto University, disclosed his discovery of a method to transform adult mouse cells into pluripotent cells that can differentiate into various cell types. This breakthrough ultimately resulted in the development of human induced pluripotent stem cells (iPSCs).

These cells can be used to create organoids, which are 3D, hollow clusters of cells that mimic full-grown organs.

In addition, human cells and tissues can be used to create organs-on-chips, which contain narrow channels lined with living human cells that can re-create the interfaces between tissues and simulate the interactions between different kinds of tissues.

The benefits of organ-on-a-chip technology go beyond ethics. The technology also allows researchers to conduct experiments more quickly and efficiently than traditional animal testing methods.

By simulating the human body on a microchip, researchers can do experiments in a controlled environment without the need to wait for animal models to reproduce or deal with issues related to genetic variability.

Despite these benefits, there are still some challenges to overcome before organ-on-a-chip technology can entirely replace animal testing.

For instance, there is currently a lack of standardisation in the field, with different labs using different chips and methods of testing. Additionally, some researchers have expressed concern that organ-on-a-chip technology may not be able to replicate the complexity of the human body in its entirety.

Despite these challenges, many experts believe that organ-on-a-chip technology is the future of medical research. The technology has already been used to successfully model a variety of organs, including the lungs, liver, and heart, and is being used by major pharmaceutical companies and academic research institutions around the world.

If the technology continues to advance and become more widely adopted, it could mark the end of animal experimentation and usher in a new era of more ethical and accurate medical research.