LiveScience reports on progress in understanding how salamander biochemistry regenerates entire lost body parts: scientists "ran experiments in which they chopped off red-spotted newts' limbs and the attached nerves. The nerves are needed to stimulate the production of the nAG protein, so the nerve-severing essentially removed the newts' source of nAG. Then they zapped the cells of the now-exposed body region with electrical pulses so they could deliver little bundles of DNA carrying genes for the protein nAG. Within 30 to 40 days, the newts had regenerated their lost limbs, digits and all. However, the new limbs had less muscle mass than the original ones. Further lab experiments revealed the nAG protein - a molecule - works directly on the blastema cells, causing them to grow and divide. ... It essentially tells us that one single molecule is able to support the proliferation of blastema cells right from the start of regeneration all the way through to the formation of the digits." As the researcher notes, it is a solid step but many more steps are required before we humans will be regrowing damaged organs.