Entire organism regenerated from single cell

This image shows the head region from an adult planarian (Schmidtea mediterranea). The creature was fixed 7 days after ionizing radiation treatment and contains a growing stem cell colony marked in red. Courtesy Peter Reddien.

This isn't just replacing a lost limb - this is the entire organism...

One cell is all it takes to rebuild a complete, functioning flatworm, researchers have learned. The animals possess a special type of cell throughout their bodies, which shares some qualities with human embryonic stem cells. If scientists can find out how this special cell works, they could someday study ways to use the cells for human tissue regeneration.

The findings are the first time pluripotent stem cells have been found in an adult animal, according to researchers at MIT and the Howard Hughes Medical Institute. Pluripotent stem cells have a unique ability to turn into any kind of cell, which is what makes them so valuable for disease research, tissue regeneration and other fields. But these cells are only found in embryos, or are induced in complex lab processes. Adults have stem cells, but they have greater specificity — blood stem cells can turn into any constituent part of the blood, and skin stem cells can turn into skin or hair, but they can’t turn into other cells like neurons, for instance...

They watched as the transplanted cNeoblast multiplied, differentiated and “ultimately replaced all the host’s tissues,” according to a news release from the Whitehead Institute for Biomedical Research. Descendants of the single neoblast cell differentiated into neuronal, intestinal and other adult cell types, taking over the jobs of the host’s dying cells. The newly restored worm was an exact genetic copy of the cNeoblast donor. All this from one single cell.

The results were published in today's issue of the journal Science.