Clonogenic Neoblasts Are Pluripotent Adult Stem Cells That Underlie Planarian Regeneration

TLDR

Planarian regeneration relies on proliferating neoblasts, but it is unclear whether this process is driven by pluripotent cells or by multiple lineage‑restricted types. The authors used ionizing radiation and single‑cell transplantation to isolate neoblasts capable of forming large descendant‑cell colonies in vivo. Clonogenic neoblasts (cNeoblasts) are broadly distributed adult pluripotent stem cells that generate neuronal, intestinal, and other postmitotic cell types and can restore regeneration in irradiated hosts, demonstrating that they underlie planarian regenerative capacity.

Abstract

Pluripotent cells in the embryo can generate all cell types, but lineage-restricted cells are generally thought to replenish adult tissues. Planarians are flatworms and regenerate from tiny body fragments, a process requiring a population of proliferating cells (neoblasts). Whether regeneration is accomplished by pluripotent cells or by the collective activity of multiple lineage-restricted cell types is unknown. We used ionizing radiation and single-cell transplantation to identify neoblasts that can form large descendant-cell colonies in vivo. These clonogenic neoblasts (cNeoblasts) produce cells that differentiate into neuronal, intestinal, and other known postmitotic cell types and are distributed throughout the body. Single transplanted cNeoblasts restored regeneration in lethally irradiated hosts. We conclude that broadly distributed, adult pluripotent stem cells underlie the remarkable regenerative abilities of planarians.