Cells from human embryos could be used to help some people with spinal injuries to walk again, successful work involving rats has indicated. Scientists from the University of California at Irvine college of medicine said that paralysed rats walked again after being injected with stem cells from "early-stage" human embryos. They hope that the breakthrough will prove to American policy makers that the use of human embryonic stem cells and therapeutic cloning - presently banned in the US - are justified. The team, led by Hans Keirstead, took stem cells from early-stage human embryos, and altered them in the laboratory...