A mother said she was able to "say goodbye" to her son, who was stabbed to death, because of blood donors.
Azaan Kaleem, 18, was found hurt on Hartsfield Road, Luton, on 22 March and died of his injuries in hospital two days later.
He received 16 units of blood and 16 platelets, enabling him to be stabilised and undergo vital surgery, NHS Blood and Transplant said.
Azaan's mother, Roseann Taylor, is calling for more people to give blood.
Ms Taylor said: "It is thanks to blood donors that Azaan could be operated on and as a family we were given the time to gather around and say goodbye.
"It brought me immense comfort knowing that thanks to the selfless act of blood donors, donating just an hour of their time, I got to spend another 48 hours with my son."
She is now urging anyone, "especially those from black and Asian backgrounds such as myself and Azaan", to donate.
Ms Taylor is also raising money for the trauma unit at the Luton and Dunstable Hospital where he was treated.
Five people charged with Azaan Kaleem's murder are due to stand trial at Luton Crown Court on 2 October.