A freezer failure at a kids’ hospital in Los Angeles has destroyed blood stem cells from dozens of young patients who are fighting cancer. In a statement Wednesday, the Children’s Hospital Los Angeles apologized and said it has informed the families of all 56 affected patients. It’s believed the freezer’s temperature sensors failed and the hospital said it has now upgraded the system to prevent another accident in the future. Elizabeth Anderson, whose son was affected, told KABC that he burst out crying when he read the letter. She said: “Once you’re through that whole process of doing all the treatment, you’ve damaged your body... That’s how damaging chemo is or the radiation alone. And so it’s the same with the stem cells. He doesn’t have that as an option to just collect more.” However, James Stein, the hospital’s chief medical officer, said patients can go through the process again. “Were there to be a recurrence of disease that required stem cells, the patients can have their stem cells collected again,” he said.