Generation of mature T cells from human hematopoietic stem and progenitor cells in artificial thymic organoids

Studies of human T cell development require robust model systems that recapitulate the full span of thymopoiesis, from hematopoietic stem and progenitor cells (HSPCs) through to mature T cells. Existing in vitro models induce T cell commitment from human HSPCs; however, differentiation into mature CD3^+TCR-αβ^+ single-positive CD8^+ or CD4^+ cells is limited. We describe here a serum-free, artificial thymic organoid (ATO) system that supports efficient and reproducible in vitro differentiation and positive selection of conventional human T cells from all sources of HSPCs. ATO-derived T cells exhibited mature naive phenotypes, a diverse T cell receptor (TCR) repertoire and TCR-dependent function. ATOs initiated with TCR-engineered HSPCs produced T cells with antigen-specific cytotoxicity and near-complete lack of endogenous TCR Vβ expression, consistent with allelic exclusion of Vβ-encoding loci. ATOs provide a robust tool for studying human T cell differentiation and for the future development of stem-cell-based engineered T cell therapies

Transcriptional analysis for the difference in carotenoids accumulation in flesh and peel of white-fleshed loquat fruit.

Loquat (Eriobotrya japonica Lindl.) is divided into yellow- and white-fleshed based on the difference in fruit color, and the variations in carotenoids accumulation are considered as the main reasons for this difference. Using RNA-seq technology, a transcriptome analysis was carried out on the flesh and peel of 'Baiyu' fruit during four different fruit development stages. A total of 172.53 Gb clean reads with an average of 6.33 Gb reads were detected for each library, and the percentage of Q30 was higher than 90.84%. We identified 16 carotenogenic and 13 plastid-lipid-associated protein (PAP) genes through RNA-seq. Of these, five carotenogenic and four PAP related genes exhibited remarkable differences in the expression patterns. Carotenoids biosynthetic genes, including DXS, PSY1 and VDE displayed higher expression levels in peel than that in the flesh. However, carotenoids decomposition gene, such as NCDE1, exhibited higher expression in flesh than that in the peel. Notably, all differentially expressed PAP genes showed higher expression levels in peel than flesh. We inferred that the differential accumulation of carotenoids in flesh and peel of 'Baiyu' is caused by the up- or down-regulation of the carotenogenic and PAP related genes. The functional analysis of these important genes will provide valuable information about underlying molecular mechanism of carotenoids accumulation in loquat

Butterfly-like enantiomerically homochiral {CoII6CoIII4} clusters exhibiting both slow magnetic relaxation and ferroelectric property

A pair of enantiomerically homochiral {CoII6CoIII4} clusters featuring a butterfly-like structure, [CoII6CoIII4(μ3-OH)(μ3-X)(S-pa)4(pdm)6(pdmH)2](ClO4)4·3.5H2O (S-1) and [CoII6CoIII4(μ3-OH)(μ3-X)(R-pa)4(pdm)6(pdmH)2](ClO4)4·3.5H2O (R-1) (X = OH or OMe, S- or R-paH = S- or R-phenylalaninol and pdmH2 = pyridine-2,6-diyldimethanol), have been synthesized and structurally characterized. They are the second largest homochiral Co clusters constructed by chiral ligands. They are also the first example of high-nuclearity homochiral Co clusters having both slow magnetic relaxation behaviour and ferroelectric property

Pleiotropic Roles of VEGF in the Microenvironment of the Developing Thymus

Neonatal life marks the apogee of murine thymic growth. Over the first few days after birth, growth slows and the murine thymus switches from fetal to adult morphology and function; little is known about the cues driving this dramatic transition. In this study, we show for the first time (to our knowledge) the critical role of vascular endothelial growth factor (VEGF) on thymic morphogenesis beyond its well-known role in angiogenesis. During a brief window a few days after birth, VEGF inhibition induced rapid and profound remodeling of the endothelial, mesenchymal and epithelial thymic stromal compartments, mimicking changes seen during early adult maturation. Rapid transcriptional changes were seen in each compartment after VEGF inhibition, including genes involved in migration, chemotaxis, and cell adhesion as well as induction of a proinflammatory and proadipogenic signature in endothelium, pericytes, and mesenchyme. Thymocyte numbers fell subsequent to the stromal changes. Expression patterns and functional blockade of the receptors VEGFR2 and NRP1 demonstrated that VEGF mediates its pleiotropic effects through distinct receptors on each microenvironmental compartment of the developing mouse thymus

Generation of mature T cells from human hematopoietic stem and progenitor cells in artificial thymic organoids.

Studies of human T cell development require robust model systems that recapitulate the full span of thymopoiesis, from hematopoietic stem and progenitor cells (HSPCs) through to mature T cells. Existing in vitro models induce T cell commitment from human HSPCs; however, differentiation into mature CD3+TCR-αβ+ single-positive CD8+ or CD4+ cells is limited. We describe here a serum-free, artificial thymic organoid (ATO) system that supports efficient and reproducible in vitro differentiation and positive selection of conventional human T cells from all sources of HSPCs. ATO-derived T cells exhibited mature naive phenotypes, a diverse T cell receptor (TCR) repertoire and TCR-dependent function. ATOs initiated with TCR-engineered HSPCs produced T cells with antigen-specific cytotoxicity and near-complete lack of endogenous TCR Vβ expression, consistent with allelic exclusion of Vβ-encoding loci. ATOs provide a robust tool for studying human T cell differentiation and for the future development of stem-cell-based engineered T cell therapies

In Vitro Recapitulation of Murine Thymopoiesis from Single Hematopoietic Stem Cells.

We report a serum-free, 3D murine artificial thymic organoid (M-ATO) system that mimics normal murine thymopoiesis with the production of all T cell stages, from early thymic progenitors to functional single-positive (CD8SP and CD4SP) TCRαβ and TCRγδ cells. RNA sequencing aligns M-ATO-derived populations with phenotypically identical primary thymocytes. M-ATOs initiated with Rag1-/- marrow produce the same differentiation block as seen in the endogenous thymus, and Notch signaling patterns in M-ATOs mirror primary thymopoiesis. M-ATOs initiated with defined hematopoietic stem cells (HSCs) and lymphoid progenitors from marrow and thymus generate each of the downstream differentiation stages, allowing the kinetics of T cell differentiation to be tracked. Remarkably, single HSCs deposited into each M-ATO generate the complete trajectory of T cell differentiation, producing diverse TCR repertoires across clones that largely match endogenous thymus. M-ATOs represent a highly reproducible and efficient experimental platform for the interrogation of clonal thymopoiesis from HSCs

Organoid-Induced Differentiation of Conventional T Cells from Human Pluripotent Stem Cells.

The ability to generate T cells from pluripotent stem cells (PSCs) has the potential to transform autologous T cell immunotherapy by facilitating universal, off-the-shelf cell products. However, differentiation of human PSCs into mature, conventional T cells has been challenging with existing methods. We report that a continuous 3D organoid system induced an orderly sequence of commitment and differentiation from PSC-derived embryonic mesoderm through hematopoietic specification and efficient terminal differentiation to naive CD3+CD8αβ+ and CD3+CD4+ conventional T cells with a diverse T cell receptor (TCR) repertoire. Introduction of an MHC class I-restricted TCR in PSCs produced naive, antigen-specific CD8αβ+ T cells that lacked endogenous TCR expression and showed anti-tumor efficacy in vitro and in vivo. Functional assays and RNA sequencing aligned PSC-derived T cells with primary naive CD8+ T cells. The PSC-artificial thymic organoid (ATO) system presented here is an efficient platform for generating functional, mature T cells from human PSCs

A functional genomics screen identifying blood cell development genes in Drosophila by undergraduates participating in a course-based research experience.

Undergraduate students participating in the UCLA Undergraduate Research Consortium for Functional Genomics (URCFG) have conducted a two-phased screen using RNA interference (RNAi) in combination with fluorescent reporter proteins to identify genes important for hematopoiesis in Drosophila. This screen disrupted the function of approximately 3500 genes and identified 137 candidate genes for which loss of function leads to observable changes in the hematopoietic development. Targeting RNAi to maturing, progenitor, and regulatory cell types identified key subsets that either limit or promote blood cell maturation. Bioinformatic analysis reveals gene enrichment in several previously uncharacterized areas, including RNA processing and export and vesicular trafficking. Lastly, the participation of students in this course-based undergraduate research experience (CURE) correlated with increased learning gains across several areas, as well as increased STEM retention, indicating that authentic, student-driven research in the form of a CURE represents an impactful and enriching pedagogical approach

A functional genomics screen identifying blood cell development genes in Drosophila by undergraduates participating in a course-based research experience.

Undergraduate students participating in the UCLA Undergraduate Research Consortium for Functional Genomics (URCFG) have conducted a two-phased screen using RNA interference (RNAi) in combination with fluorescent reporter proteins to identify genes important for hematopoiesis in Drosophila. This screen disrupted the function of approximately 3500 genes and identified 137 candidate genes for which loss of function leads to observable changes in the hematopoietic development. Targeting RNAi to maturing, progenitor, and regulatory cell types identified key subsets that either limit or promote blood cell maturation. Bioinformatic analysis reveals gene enrichment in several previously uncharacterized areas, including RNA processing and export and vesicular trafficking. Lastly, the participation of students in this course-based undergraduate research experience (CURE) correlated with increased learning gains across several areas, as well as increased STEM retention, indicating that authentic, student-driven research in the form of a CURE represents an impactful and enriching pedagogical approach