1.   It is done in one operation, where transplants involve two.

2.   The transplant involved no pain or risk for Adam, because it used only the blood from his umbilical cord and placenta, blood that is normally discarded.

3.   But previous domino transplants had involved only three patients.

4.   But previous domino transplants involved only three patients.

5.   Previous domino transplants have involved only three donors and recipients.

6.   Cord blood transplants involve taking blood cells from umbilical cords to enable patients to grow normal blood cells.