Uncovering the emergence of HSCs in the human fetal bone marrow by single-cell RNA-seq analysis.

During fetal development, human hematopoietic stem cells (HSCs) colonize the bone marrow (BM), where they self-renew and sustain hematopoiesis throughout life; however, the precise timepoint at which HSCs seed the BM is unclear. We used single-cell RNA-sequencing to map the transcriptomic landscape of human fetal BM and spleen hematopoietic stem/progenitor cells (HSPCs) and their microenvironment from 10 to 14 post-conception weeks (PCWs). We further demonstrated that functional HSCs capable of reconstituting long-term multi-lineage hematopoiesis in adult NOG mice do not emerge in the BM until 12 PCWs.

Single-Cell Analysis of the Pan-Cancer Immune Microenvironment and scTIME Portal.

Single-cell sequencing opens a new era for the investigation of tumor immune microenvironments (TIME). However, at single-cell resolution, a pan-cancer analysis that addresses the identity and diversity of TIMEs is lacking. Here, we first built a pan-cancer single-cell reference of TIMEs with refined subcell types and recognized new cell type-specific transcription factors.

tagHi-C Reveals 3D Chromatin Architecture Dynamics during Mouse Hematopoiesis.

Spatiotemporal chromatin reorganization during hematopoietic differentiation has not been comprehensively characterized, mainly because of the large numbers of starting cells required for current chromatin conformation capture approaches. Here, we introduce a low-input tagmentation-based Hi-C (tagHi-C) method to capture the chromatin structures of hundreds of cells. Using tagHi-C, we are able to map the spatiotemporal dynamics of chromatin structure in ten primary hematopoietic stem, progenitor, and differentiated cell populations from mouse bone marrow.

Targeting of apoptosis gene loci by reprogramming factors leads to selective eradication of leukemia cells.

Applying somatic cell reprogramming strategies in cancer cell biology is a powerful approach to analyze mechanisms of malignancy and develop new therapeutics. Here, we test whether leukemia cells can be reprogrammed in vivo using the canonical reprogramming transcription factors-Oct4, Sox2, Klf4, and c-Myc (termed as OSKM). Unexpectedly, we discover that OSKM can eradicate leukemia cells and dramatically improve survival of leukemia-bearing mice.

New paradigms on hematopoietic stem cell differentiation.

Ever since hematopoietic stem cells (HSCs) were first identified half a century ago, their differentiation roadmap has been extensively studied. The classical model of hematopoiesis has long held as a dogma that HSCs reside at the top of a hierarchy in which HSCs possess self-renewal capacity and can progressively give rise to all blood lineage cells. However, over the past several years, with advances in single cell technologies, this developmental scheme has been challenged.