Pluripotent, germ cell competent adult stem cells underlie cnidarian regenerative ability and clonal growth

In most animals, pluripotency is irreversibly lost post gastrulation. By this stage, all embryonic cells have already committed either to one of the somatic lineages (ectoderm, endoderm, or mesoderm) or to the germ -line. The lack of pluripotent cells in adult life may be linked to organismal aging. Cnidarians (corals and jellyfish) are an early branch of animals that do not succumb to age, but the developmental potential of their adult stem cells remains unclear. Here, we show that adult stem cells in the cnidarian Hydractinia symbiolon-gicarpus (known as i-cells) are pluripotent. We transplanted single i-cells from transgenic fluorescent donors to wild-type recipients and followed them in vivo in the translucent animals. Single engrafted i-cells self -re-newed and contributed to all somatic lineages and gamete production, co-existing with and eventually displacing the allogeneic recipient's cells. Hence, a fully functional, sexually competent individual can derive from a single adult i-cell. Pluripotent i-cells enable regenerative, plant-like clonal growth in these animals.

Automated summary

In most animals, pluripotent cells are lost after gastrulation, but the developmental potential of adult stem cells in cnidarians remains unclear. This study shows that adult stem cells in the cnidarian Hydractinia symbiolon-gicarpus are pluripotent and can contribute to different cell lineages and gamete production. This discovery has implications for understanding regeneration and clonal growth in these animals.