Sometimes doctors take healthy pancreas cells from a healthy person and transplant it to a diabetic person.  Diabetic people don't have pancreas cells that make insulin for themselves.  The pancreas cells from another person are usually rejected because they are different from the diabetic person.  A doctor will give the diabetic person a special "anti-rejection" medicine so that the transplanted cells will be accepted by the body and continue to grow.  The new transplant pancreas cells make insulin for the body.  Now the diabetic person does not need to get insulin injections.  The first time that this pancreas cell transplant worked was in Edmonton, Alberta, and it was called the "Edmonton Project".   

"This colour enhanced scanning electron micrograph shows a stem cell collected from human marrow.  Researchers are studying how such cells may someday be used to stimulate regeneration of islets when transplanted into the pancreas of a diabetic patient." Courtesy of Patient Care Archive, September 2003
Bibliography Patient Care Archive, September 2003 at: www.patientcareonline.com/content/journals/p/data/2003/0915/0903technology.html