Adult somatic stem cells in the human parasite Schistosoma mansoni

摘要

成年干细胞(或未分化细胞)见于自由生活的真涡虫和寄生的绦虫中，能支持组织再生这样的“绝活”。现在，Plqiilip Newmark及其同事报告了对人体寄生虫“曼氏血吸虫”中成年干细胞的识别。这种吸虫类扁形虫(亦称为血吸虫)在全世界感染数百万人。血吸虫干细胞增殖和分化成多个胚层的衍生物，表达“成纤维细胞生长因子受体”的一个直系同源基因。本文作者利用RNA干涉发现，这个基因是维持“未分化细胞样细胞”(rleoblast-like cells)所必需的。这些发现也许可帮助阐明促进该寄生虫长寿的机制，所以对医学处理也可能会有帮助。%Schistosomiasis is among the most prevalent human parasitic diseases, affecting more than 200 million people worldwide1. 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 decades2, 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(for example, planarians), and neoblast-like cells have been described in some parasitic tapeworms5, 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 and RNA-seq-based gene expression profiling, we find that these schis-tosome neoblast-like cells express a fibroblast growth factor receptor orthologue. Using RNA interference we demonstrate that this gene is required for the maintenance of these neoblast-like cells. Our observations indicate that adaptation of developmental strategies shared by free-living ancestors to modern-day schisto-somes probably contributed to the success of these animals as long-lived obligate parasites. We expect that future studies deciphering the function of these neoblast-like cells will have important implications for understanding the biology of these devastating parasites.