Planarian stem cells: a simple paradigm for regeneration.

Planarians are capable of profound regenerative feats dependent upon a population of self-renewing adult stem cells called neoblasts. The key features of neoblasts are their capacity for indefinite self-renewal, their totipotency and the ability of their progeny to interpret differentiation and polarity signals and correctly replace lost structures after tissue damage. Regeneration in planarians offers a paradigm for understanding the molecular and cellular control of the repair and regeneration of animal tissues, and could provide valuable insights for the safe use of stem cells to repair damaged, diseased and ageing human tissues with little or no regenerative capacities. Here, I review recent progress in understanding neoblasts in regeneration and the growing potential this research has to be broadly informative for human biology.