Does a body part taken from a dead person, and transplanted onto a live person lose its Tumah?
[May a kohen enter a room where there is someone who received a body part transplant from a dead person?]
Rav Shlomo Zalman Aurbach printed in שבט מיהודה חלק ג' דף ת"ו writes that once the limb is attached to the person, it is like it is back alive.
However, it is possible that Rav Elyashiv would disagree with this. Because he writes [printed in Kovetz Teshuvos 4/pg.124]that if it was a limb that had an obligation of burial while detached, that obligation still exists when it is latter attached. "The limb does not become back alive."