(Newser) – It’s the kind of organ donation that California hospital officials say they’ve never seen before: The mother of a man who had a lifesaving pancreas transplant almost 10 years ago is now donating her own kidney to the father of the deceased pancreas donor. When Bill Millard’s 20-year-old son, Kalem, was killed in an ATV accident in 2004, he and his wife donated their son's pancreas, which ended up saving the life of then 19-year-old Jake MacKinnon, reports the San Francisco Chronicle. Now 49-year-old Bill needs a kidney transplant because of advanced diabetes—and the woman who was donating the kidney to him this week was Janice MacKinnon, Jake's mom.

The Millard and MacKinnon families became close friends after Kalem’s pancreas saved Jake’s life. (Today, Jake is a healthy 28-year-old, engaged to be married.) So when the MacKinnons heard that Millard, who has been on dialysis for more than two years, needed a kidney, MacKinnon arranged to take the blood and tissue tests to see if she was a match—she was. "We've had interesting stories, but nothing like this," an official at California Pacific Medical Center tells KTVU. “You say 'thank you' when someone opens the door for you—there are no words to say this,” Janice MacKinnon tells the Chronicle of the transplant that saved her son. Tish Millard, Kalem’s mom, adds, “Because of their son, part of my son is still alive—most people don't get back what we've gotten back." (Click to read about another case in which a total stranger stepped up to donate a kidney to a child.)

