There's more than just fabrication to consider. The reason they think generated limbs might be useful is that in current hand transplants, pre-existing limb nerves grow into the new hand, giving it sensation. This does not happen with the spinal cord (and anything that made it happen would be a huge therapeutic breakthrough all on its own). The cranial nerves (those going directly from the brain to the heart, gut, ears, nose, etc) are another potential stumbling block.

That said, it does make the (numerous!) science fiction novels that have had something like this as a premise seem somewhat more plausible...