The Zayas Lab

Planarian Regeneration

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Planarian stem cells labeled with BrdU (black).My laboratory studies the molecular and cellular mechanisms underlying tissue regeneration.  To examine this long-standing biological problem we investigate regeneration in freshwater planarians, free-living members of the phylum Platyhelminthes (the flatworms).  Planarians can completely regenerate entire worms from small body fragments.  Their amazing capacity for regeneration is supported by a population of adult pluripotent stem cells (called neoblasts), which serve to replace cells lost during normal cell turnover and after wounding.

When a planarian is cut, the wounded area is sealed by muscle contraction and rapidly covered by a thin layer of epithelial cells.  Regeneration proceeds as the neoblasts migrate to the area below the wound epithelium and proliferate to give rise to a structure known as the regeneration blastema.  The blastema grows by further accumulation of neoblasts and, within a week, the missing structures differentiate.  Little is known about the molecular events leading to the differentiation of the missing tissues during regeneration.

Illustration of planarian CNS.Research in our laboratory is directed at understanding how regeneration of the central nervous system (CNS) is achieved in planarians.  In contrast to most model organisms currently studied, planarians have a remarkable ability to replace lost neurons after injury or amputation, and quickly regain normal function.  Thus, planarians provide an exceptional opportunity to investigate fundamental mechanisms underlying stem cell-based regeneration and re-modeling of the CNS.

We are currently examining neural regeneration in the planarian Schmidtea mediterranea; our goal is to identify and analyze the function of conserved genes that stimulate proliferation and differentiation of stem cells in the CNS.

Our research is supported by a grant from 
the California Institute for Regenerative Medicine.