Adult somatic stem cells in the human parasite Schistosoma mansoni

This study reports the identification of adult stem cells in the human parasite Schistosoma mansoni (blood fluke); the cells proliferate and differentiate into derivatives of multiple germ layers, and their maintenance requires a fibroblast growth factor receptor orthologue. Blood fluke stem cells key to robustness Adult stem cells (or neoblasts) are found in free-living planarians and parasitic tapeworms and can support impressive feats of tissue regeneration. Phillip Newmark and colleagues now report the identification of adult stem cells in the human parasite Schistosoma mansoni . This trematode flatworm, also known as the blood fluke, infects millions of people worldwide. The schistosomal stem cells proliferate and differentiate into derivatives of multiple germ layers, and express a fibroblast growth factor receptor orthologue. Using RNA interference, the authors showed that this gene is required for the maintenance of the neoblast-like cells. These findings might help to elucidate the mechanisms that promote the parasite's longevity and so could be relevant for medical treatment. Schistosomiasis is among the most prevalent human parasitic diseases, affecting more than 200 million people worldwide 1 . The aetiological agents of this disease are trematode flatworms ( Schistosoma ) that live and lay eggs within the vasculature of the host. These eggs lodge in host tissues, causing inflammatory responses that are the primary cause of morbidity. Because these parasites can live and reproduce within human hosts for decades 2 , elucidating the mechanisms that promote their longevity is of fundamental importance. Although adult pluripotent stem cells, called neoblasts, drive long-term homeostatic tissue maintenance in long-lived free-living flatworms 3 , 4 (for example, planarians), and neoblast-like cells have been described in some parasitic tapeworms 5 , little is known about whether similar cell types exist in any trematode species. Here we describe a population of neoblast-like cells in the trematode Schistosoma mansoni . These cells resemble planarian neoblasts morphologically and share their ability to proliferate and differentiate into derivatives of multiple germ layers. Capitalizing on available genomic resources 6 , 7 and RNA-seq-based gene expression profiling, we find that these schistosome neoblast-like cells express a fibroblast growth factor receptor orthologue. Using RNA interference we demonstrate that this gene is required for the maintena