We know from the end of Deathly Hallows that Harry becomes the master of the Elder Wand, and uses it to repair his own broken wand. Until this point, it has been impossible to repair broken wands, and that the wand could be repaired shows that it is not limited by the traditional boundaries and limitations of magic.
Could Harry have used the Elder Wand to heal Mr and Mrs Longbottom? I do not think this is referred to specifically in canon but I would like to know if any likely conclusions can be drawn based on any precedents already set by the Elder Wand or healers.