Lymphoid cell development from fetal hematopoietic progenitors and human pluripotent stem cells

Lymphoid cells encompass the adaptive immune system, including T and B cells and Natural killer T cells (NKT), and innate immune cells (ILCs), including Natural Killer (NK) cells. During adult life, these lineages are thought to derive from the differentiation of long-term hematopoietic stem cells (HSCs) residing in the bone marrow. However, during embryogenesis and fetal development, the ontogeny of lymphoid cells is both complex and multifaceted, with a large body of evidence suggesting that lymphoid lineages arise from progenitor cell populations antedating the emergence of HSCs. Recently, the application of single cell RNA-sequencing technologies and pluripotent stem cell-based developmental models has provided new insights into lymphoid ontogeny during embryogenesis. Indeed, PSC differentiation platforms have enabled de novo generation of lymphoid immune cells independently of HSCs, supporting conclusions drawn from the study of hematopoiesis in vivo. Here, we examine lymphoid development from non-HSC progenitor cells and technological advances in the differentiation of human lymphoid cells from pluripotent stem cells for clinical translation.

A CX3CR1 Reporter hESC Line Facilitates Integrative Analysis of In-Vitro-Derived Microglia and Improved Microglia Identity upon Neuron-Glia Co-culture

Multiple protocols have been published for generation of iMGLs from hESCs/iPSCs. To date, there are no guides to assist researchers to determine the most appropriate methodology for microglial studies. To establish a framework to facilitate future microglial studies, we first performed a comparative transcriptional analysis between iMGLs derived using three published datasets, which allowed us to establish the baseline protocol that is most representative of bona fide human microglia. Secondly, using CRISPR to tag the classic microglial marker CX3CR1 with nanoluciferase and tdTomato, we generated and functionally validated a reporter ESC line. Finally, using this cell line, we demonstrated that co-culture of iMGL precursors with human glia and neurons enhanced transcriptional resemblance of iMGLs to ex vivo microglia. Together, our comprehensive molecular analysis and reporter cell line are a useful resource for neurobiologists seeking to use iMGLs for disease modeling and drug screening studies.

Long Non-Coding RNA H19 Promotes Porcine Satellite Cell Differentiation by Interacting with TDP43

Long non-coding RNAs (lncRNAs) have been implicated in fundamental and diverse biological processes, including myogenesis. However, the molecular mechanisms involved in this process remain largely unexplored. This study found that H19 affected the differentiation of porcine satellite cells (PSCs) by directly binding to the DNA/RNA-binding protein TDP43. Functional analyses showed that TDP43 knockdown decreased PSC differentiation, whereas TDP43 overexpression exerted opposite effects in vitro. Furthermore, rescue experiments demonstrated that TDP43 can rescue the decrease in PSC differentiation caused by H19 knockdown. Mechanistically, H19 may act as a scaffold to recruit TDP43 to the promoters of MYOD and thereby activate the transcription of MYOD, leading to PSC differentiation. In summary, we elucidate the molecular mechanism by which H19 and TDP43 regulate myogenesis.