A shortage of blood in the blood banks could be putting lives at risk. The banks have enough blood for only 1.7 days, whereas ideally there should be enough for at least five days.Vanessa Raju, of SA National Blood Services, said, "Low blood stocks or no blood means that people could die."Winter is a difficult time for maintaining blood stocks. The cold weather and flu badly affect our collections."Andrew McDonald, a clinical haematologist at the Pretoria East Hospital, said: "There is always a shortage of blood, especially platelets and red cells. It's worse during the school holidays and long weekends, when people who usually donate blood are away."Scientists in the UK announced last month that the first clinical trial of the use of synthetic blood on humans will begin in 2017.The UK's National Health Service said: "Scientists have been investigating for a number of years how to manufacture red blood cells to offer an alternative to donated blood to treat patients."We are confident that, by 2017, our team will be ready to carry out the first early phase clinical trials in human volunteers.""Human blood is still the best option for patients in need of transfusions," Raju said.Marlize van der Merwe, of the Western Province Blood Transfusions Services, said: "In an ideal world, [synthetic blood] would alleviate the pressure on collecting sufficient natural blood and we will be keeping an eye on developments, but there is still a long way to go."McDonald said that although the development of synthetic blood was a major breakthrough it will take time to accrue the benefits."When something goes on trial, it takes another five years before it can be put into practice."There are the trials, then the regulatory processes to go through. It's never quick," he said.How the blood was createdPregnant mothers donated umbilical cord blood.Stem cells were isolated from this blood.Scientists then manipulated the cells to develop functioning red blood cells, which transport oxygen from the lungs to the rest of the body...