Great work by Helen, her supervisor Uri Frank and other colleagues which shows that a single Hydractinia i-cell is pluripotent and germ cell competent
Helen and colleagues demonstrate that a single Hydractinia stem cell (i-cell) is truly pluripotent. They developed a novel method which takes advantage of Hydractinias ability to fuse with allogeneic relatives and share migratory cells. They fused a double transgenic animal which has GFP+ stem cells and mScarlet+ somatic cells, to a wild type sibling. They allowed a single GFP+ stem cell to migrate into the wild type tissue then isolated this piece of tissue and cultured it. Overtime they pruned away wild type tissue, giving the progeny of the stem cell the best chance to show their full developmental potential. Ultimately they ended up with animals which had been completely taken over by transgenic cells, where all of their somatic cells were red and their stem cells green. They proved that a single transplanted stem cell could give rise to all cell types by analysing the animals using flow cytometry and identifying known cell types using antibody stainings and observed morphology. Finally, the single transplanted cell also gave rise to germ cells which they crossed and the resultant offspring were also fluorescent. As such they have demonstrated that a single Hydractinia i-cell is pluripotent and germ cell competent.