Advances in modern medicine are coming so quickly that it can be easy to forget how mind-blowing they truly are – and it doesn’t seem as if scientists have any limit to what they can accomplish.

Every year, around 40,000 people in the United States will need access to a new liver through transplantation. Recently, researchers at the University of Pittsburgh have figured out how to grow tiny human livers, which could help cut down on waiting times for transplants and save thousands of lives.

They used 10 years of existing research to reverse engineer stem cells to form a liver.

Then, they grafted those liver cells onto an existing scaffolding of rat cells before transplanting the tiny livers into a small group of rats.

During a four-day observation window, all five livers performed optimally, secreting bile and urea as expected from a functioning organ – and the livers took less than a month to grow.

More research is required before any potential human trials, but the findings are promising as far as an expedited process for growing and transplanting human livers in the future.