I know people that grow spliced apple trees and they survive the minus 60 winter temps but the moose are hard on them.
I just prune the old trees, I haven't planted any, but as I understand it all apple trees in common use are grafted. You take a hardy rootstock and graft the kind of apple tree you want onto it. That's why new shoots coming up from the roots need to be cut back, because they won't produce any useful fruit.
We get down to around 30 below here from time to time, so we need hardy stock, but that's still quite a ways above 50 below.