Scientists grow pieces of miniature human lab rats

A bioterror attack 14 years ago killed five people and sickened another 17 when someone spread anthrax through the United States Postal Service. That attack spurred research to develop countermeasures for potential biological, chemical, or radiological warfare.

Each year the U.S. government spends hundreds of millions of dollars to develop agents to fight bioterrorism, but for obvious ethical reasons, many of the agents have never been tested in humans. Now U.S. military and civilian science agencies have developed a method to grow miniature 3-D human organs on plastic chips, which the researchers hope can provide a testing solution.

The organs are made by seeding human cells into channels on small, clear plastic chips, about the size of a computer memory stick, and then feeding them with nutrient-rich fluids that flow through the system, much like blood flowing through veins. The chips can be used individually or connected to other organs on chips to approximate a biological system, perhaps one day, even an entire human body.

The researchers also envision using the organs on chips to replace traditional animal testing of new drugs before they are tested on humans.

Testing for a single new drug can cost more than $2 million and often fails to accurately predict human responses because animal physiology does not perfectly mimic human physiology.

Donald Ingber, bioengineer at Harvard University’s Wyss Institute, has designed bone marrow on a chip to study the effects of radiation on humans and to investigate possible remedies. “It’s unethical to expose humans to the kind of radiation that you’d see in a disaster like Fukushima, but you need to be prepared,” Ingber toldScientific American.

The U.S. Environmental Protection Agency plans an $18 million program to link livers on chips with chips simulating fetal membranes, developing limbs and mammary glands to study how environmental contaminants alter metabolism in these organs after they have been processed by the liver.

The U.S. department of Homeland Security is interested in using the chips to test the ability of anthrax spores to infect a 3-D lung, Joshua Powell, microbiologist at the Pacific Northwest National Laboratory in Richland, Wash., told Scientific American.

Simulating a human body will not be easy, Vanderbilt University physiologist John Wikswo said. The blood substitute must reach the organ chips, which Wikswo jokingly refers to as “Homo chippiens,” in the right order, in the right quantity, and with the right nutrients for each organ.

Many researchers are investigating various possibilities. The Wyss Institute plans to link 10 organ chips together to simulate a “human-on-a-chip” to rapidly assess responses to new drug candidates, and to provide critical information on their safety and efficacy.

The researchers predict some of the systems could be available to academics and industry within five years.