Swiss researchers have developed a machine that, they say,can keep human livers alive outside of the body for one week.Current technology and methods are only able to keep human livers alive for up to 24 hours.The new machine is able to keep the liver activeby performing several functions normally carried out by the human body.Researchers say they expect the technologyto greatly increase the number of livers available for transplant.This could save the lives of many patients sufferingfrom severe liver disease who need to have their liver replaced.Scientists from the University of Zurich in Switzerland developed the machine.They recently reported their results in the publication Nature Biotechnology.The researchers say the purpose of their "Liver4Life" machineis to perform what they call liver perfusion operations outside of the human body.Perfusion is the process by which blood or other fluids are pumped through organs and tissue.The machine keeps the liver at the right temperatureand moves it in a way that would be natural in the body.It uses a pump to fill the liver with blood acting like a replacement for a human heart.The machine also provides oxygen to the organ,controls red blood cell levels and removes waste.A healthy liver is necessary to support life.The liver receives about 25 percent of blood from the heartand carries out about 5,000 different tasks in the body.Livers are among the most commonly transplanted human organs.Most transplants involve patients suffering from severe liver disease or cancer.The Mayo Clinic in the state of Minnesota reported that, in 2017,about 8,000 liver transplants were performed in the U.S. among adults and children.Of those, 360 involved livers from living donors.In addition, about 11,500 people were registered on a waiting listto receive a liver transplant, the organization said.Keeping livers alive and functioning for longer periodscould greatly improve the chances of survival for patients.The research team began their experiments using livers from pigs.After repeated testing and engineering development,the team said it was able to get the pig livers to survive for seven dayswith support only provided from the Liver4Life machine.The scientists said they also discovered that the system can work to repair damaged livers.In one test, the team connected the machine to 10 injured human liversthat had been rejected for transplantation by all European medical centers.After seven days of perfusion treatment from the machine, six of the human liversfully regained important liver functions, the researchers reported.Pierre-Alain Clavien is chairman of the Department of Surgery and Transplantation at University Hospital Zurich.He helped lead the research."The success of this unique perfusion system - developed over a four-year periodby a group of surgeons, biologists and engineers - paves the way for many new applicationsin transplantation and cancer medicine,helping patients with no liver grafts available," Clavien said in a statement.He added that the successful treatment of poor-quality liverscould lead to a wide range of new treatment possibilities.Such treatments could be used to repair preexisting liver damage,remove fat from the organ or even recreate partial livers.The team is now planning its next step in the development process.It is making preparations to transplant machine-treated organs into patients.