What makes a cell pluripotent?

Pluripotent stem cells (PSC) can generate any cell type in the organism. Therefore, PSCs could potentially form the basis of therapies that replace damaged or missing cells -- for example in neurodegenerative disorders. Most organisms that are used in research do not have pluripotent stem cells in the adult making it challenging to study how pluripotency persists in normal, physiological, conditions. We use planarians, freshwater flatworms, animals that have an abundant population of PSCs. Planarians use PSCs for tissue maintenance and for regeneration. We are particularly interested in the regulation of differentiation vs. proliferation of planarian stem cells, and how the balance of these processes allow the animals to regenerate.

Shown is a planrian labeled in magenta for an abudnant neoblast marker (smedwi-1). Neoblasts are found through the animal except for the pharynx and the head tip.

Wound response across the animal kingdom

All animals developed mechanisms to survive injuries, including transcriptional programs that are activated in response to wounding. Despite the critical contribution of these transcriptional responses to recovery and healing, it is unknown whether they are conserved across the phylogeny, and how they evolved in organisms with different survival and regenerative capacities. Finding the conserved components of the injury response is essential for understanding the differences in survival and regenerative capacities of different organisms. We use comparative genomics for unraveling the conserved regulatory circuitry of injury-response and harness the planarian system to study its conserved functions.

Wurtzel lab @ Tel Aviv University

Major cell types

Single-cell RNA sequencing of planarian cells reveals the ajor planarian cell types. Gene expression is represented using a tSNE plot, where each dot represents the gene expression of a single cell. Density-based clustering was used to assign cells to clusters, and the identity of each cluster was determined using published and novel gene expression markers.