Project description:Spatial localization is a key determinant of cellular fate and behavior, but spatial RNA assays traditionally rely on staining for a limited number of RNA species. In contrast, single-cell RNA-seq allows for deep profiling of cellular gene expression, but established methods separate cells from their native spatial context. Here we present Seurat, a computational strategy to infer cellular localization by integrating single-cell RNA-seq data with in situ RNA patterns. We applied Seurat to spatially map 851 single cells from dissociated zebrafish (Danio rerio) embryos, inferring a transcriptome-wide map of spatial patterning. We confirmed Seurat’s accuracy using several experimental approaches, and used it to identify a set of archetypal expression patterns and spatial markers. Additionally, Seurat correctly localizes rare subpopulations, accurately mapping both spatially restricted and scattered groups. Seurat will be applicable to mapping cellular localization within complex patterned tissues in diverse systems. We generated single-cell RNA-seq profiles from dissociated cells from developing zebrafish embryos (late blastula stage - 50% epiboly)
Project description:The process of cardiac morphogenesis in humans is incompletely understood. Its full characterization requires a deep exploration of the organ-wide orchestration of gene expression with a single-cell spatial resolution. Here, we present a molecular approach that reveals the comprehensive transcriptional landscape of cell types populating the embryonic heart at three developmental stages, and which maps cell type-specific gene expression to specific anatomical domains.
Spatial Transcriptomics identified unique gene profiles corresponding to distinct anatomical regions in each developmental stage. Human embryonic cardiac cell types identified by single-cell RNA-sequencing confirmed and enriched the spatial annotation of embryonic cardiac gene expression. In situ sequencing was then used to refine these results and create spatial subcellular map for the three developmental phases. Finally, we generated a publicly available web resource of the human developing heart to facilitate future studies on human cardiogenesis.
Project description:Profiling global gene expression of undifferentiated human embryonic stem cells, artificially derived cardiomyocytes, fetal ventricular cardiomyocytes, and adult ventricular cardiomyocytes to determine transcriptomic variation between these cell types. Total RNA extracted from 10 human samples representing four stages of cardiac development from undifferentiated stem cells to mature adult cardiac tissue.
Project description:Vascularization and efficient perfusion are long-standing challenges in cardiac tissue engineering. Here, we engineer perfusable microvascular constructs, wherein human embryonic stem cell-derived endothelial cells (hESC-ECs) are seeded both into patterned microchannels and the surrounding collagen matrix. In vitro, the hESC-ECs lining the luminal walls readily sprout and anastomose with de novo-formed endothelial tubes in the matrix under flow. When implanted on infarcted rat hearts, the perfusable microvessel grafts integrate with coronary vasculature to a greater degree than non-perfusable self-assembled constructs at 5 days post-implantation. Optical microangiography imaging reveal that perfusable grafts have 6-fold greater vascular density, 2.5-fold higher vascular velocities and >20-fold higher volumetric perfusion rates. Implantation of perfusable grafts containing additional hESC-derived cardiomyocytes show higher cardiomyocyte and vascular density. Thus, pre-patterned vascular networks enhance vascular remodeling and accelerate coronary perfusion, potentially supporting cardiac tissues after implantation. These findings should facilitate the next generation of cardiac tissue engineering design.
Project description:<p>During development of the human brain, multiple cell types with diverse regional identities are generated. Here we report a system to generate early human brain forebrain and mid/hindbrain cell types from human embryonic stem cells (hESCs), and infer and experimentally confirm a lineage tree for the generation of these types based on single-cell RNA-Seq analysis. We engineered <i>SOX2<sup>Cit/+</sup></i> and <i>DCX<sup>Cit/Y</sup></i> hESC lines to target progenitors and neurons throughout neural differentiation for single-cell transcriptomic profiling, then identified discrete cell types consisting of both rostral (cortical) and caudal (mid/hindbrain) identities. Direct comparison of the cell types were made to primary tissues using gene expression atlases and fetal human brain single-cell gene expression data, and this established that the cell types resembled early human brain cell types, including preplate cells. From the single-cell transcriptomic data a Bayesian algorithm generated a unified lineage tree, and predicted novel regulatory transcription factors. The lineage tree highlighted a prominent bifurcation between cortical and mid/hindbrain cell types, confirmed by clonal analysis experiments. We demonstrated that cell types from either branch could preferentially be generated by manipulation of the canonical Wnt/beta-catenin pathway. In summary, we present an experimentally validated lineage tree that encompasses multiple brain regions, and our work sheds light on the molecular regulation of region-specific neural lineages during human brain development.</p>
Project description:Adult cardioyocytes undergo remarkable dedifferentiation and cell cycle reprogramming/reentery when cultured in mitogen-rich medium, continuously, and give rise to cardiac progenitor cells (CPCs). Using microfluidic device for single-cell capture and whole-transcriptomic amplification, we analyze the whole-genome transcriptomic profile in adult mouse cardiomyocytes (Ctl) and in their derived CPCs, and validate the gene expression by single-cell PCR and PCR array. Using two platforms for DNA methylation profiling: NimbleGen DNA methylation array and CHARM array, the whole-genome DNA methylation profile in myocytes (Ctl) and CPCs were compared and their regulations in relationship to the transcriptomics profile were analyzed. The results demonstrated remarkable molecular reprogramming pertaining to dedifferentiation, loss of cardiac contractile, structure, and function molecules, and reactivation of cell cycle and proliferation genes, significant changes in metabolisms. The reduction of cardiac function and structure genes are highly related to their hypermethylation of the promoter regions. GO and Pathway enrichment analysis revealed distinct coordianted transcriptomic and epigenetic regulation in the CPCs derived from cardiomyocytes. Mouse single cardiomyocytes (Ctl) and their derievd single CPCs were captured using microfluidic deviced and cDNA synthesized and amplified and labelled using NuGENE kits, and regular Affymetrix hybridization and wash protocols were used to process the mouse whole-genome array GeneChip 430 2.0.