Cancer cells do live significantly longer than the average cell so would it be plausible to take some aspects of cancer cells and give them to the rest of cells. Don't cancer cells also regenerate and mutliply faster than regular cells which could be used to heal wounds much faster. If our cells live longer wouldn't we live longer? Another idea; to make extremely strong WBCs couldn't we take the cell put it up against disease after disease and when it is killed clone its remains and put it up against more diseases and just keep doing that untill the cell knows how to destroy anything and is super resistant. Sort of like Doomsday from the superman comics. Of course that would probably make organ transplants next to impossible but I would think this is practical and possible if we wanted to put more resources into genetic engineering. I don't know I might just be insane as most say when I suggest such things.