The stem cells chosen for the transplant are from umbilical cord blood. Umbilical cord blood is collected from healthy newborn babies and frozen. One cord blood collection is called a "cord blood unit." On transplant day, the cord blood will be given through the catheter just like a blood transfusion. Transplants done this way have been successful. However, this type of transplant is fairly new. Therefore, it is important to study it so the doctors can better understand how it works.