A £45 million research project could see future generations of drugs tested on "organ chips" that mimic different parts of the human body.
As well as improving and speeding up drug development, the move could prevent the suffering and death of many thousands of laboratory animals.
One goal of the US programme is to simulate a whole human body by linking together 10 different organ chips. Each "organ" will be about the size of a computer memory stick. The clear plastic chips contain tiny hollow channels lined with living human cells.
A separate arm of the five-year project will develop a "microbrain bioreactor", seeded with human neurons, to mimic the biology of the human brain. The devices will be used to identify, develop and test novel drugs to treat a host of different diseases. Currently, much of this work is done by experimenting on animals, usually mice or rats.
But although there are many biological and genetic similarities between a rodent and a human, there are crucial differences too. In some cases, adverse reactions or side effects only become apparent during patient trials - or even when a drug is marketed.
The "Tissue Chip for Drug Testing" programme, worth 70 million dollars (£45 million), is being funded by three giant US agencies, the National Institutes of Health, the Food and Drugs Administration and the Defence Advanced Research Projects Agency.
Scientists at the Wyss Institute for Biologically Inspired Engineering at Harvard University will focus on the multi-organ chip device. Colleagues at Vanderbilt University in Nashville are working on the microbrain bioreactor, which like the organ chip will contain human cells.
The brain is an especially difficult target for drug development because it puts up multiple natural barriers to potentially toxic molecules.
Professor John Wilkswo, director of the Vanderbilt Institute for Integrative Biosystems Research and Education, said: "Given the differences in cellular biology in the brains of rodents and humans, development of a brain model that contains neurons and all three barriers between blood, brain and cerebral spinal fluid, using entirely human cells will represent a fundamental advance in and of itself."
The US initiative was welcomed by animal welfare campaigners in the UK. Dr Katy Taylor, scientific adviser for the British Union for the Abolition of Vivisection, said: "This is an exciting example of how modern-day innovation can produce a humane and more reliable approach to understanding the inner workings of human disease without the need for animal suffering. The USA appears to be leading the way in funding alternatives, it is now time for the UK to catch up."