I had a double chord blood transplant 1 year ago maybe i can help with some info. My Dr. at Dana Farber was the chief of transplants he explained to me that umbilicol chord stem cells are immature cells as such they have found they are a little more adaptable to a recipients body and they have found less Graft vs Host disease problems. That being said i have done remarkably well with some GVH on my skin it flares up and i have to put ointment on it and it goes away it looks like a red rash on your skin when it flares up. They have to use 2 chords in an adult transplant because the chords have a small supply in them sometimes only 1 takes over as did for me other times the 2 combine and one will get stronger and kill off the other and become your new immune system. They have only been using chords at Dana Farber for just over 3 years so it's new and it's a great option i was happy when they told me i was getting chord stem cells. I kept a Blog http://scorp37.wordpress.com/page/2/
of my journey please read it it tells you what to expect and can give you some perspective into transplant. It's a tough thing to go thru but they are having great success with chords. I wish you the best and the best for your brother karl please keep us informed.