Originally Posted by Teelie
So his body regenerated its own healing factor... that is what it seems like although the way it was presented was more like draining a battery of its power. Once it's gone, it's gone only in this case he regenerated his regeneration.
He had enough (bone marrow?) left in him to stay alive. Enough to start the regeneration process. I expect he replenished the rest more gradually.
But we don't know yet what his healing powers are like now, because we didn't really see them in action after the final battle. Maybe they aren't as powerful as before...