Single-cell analyses to reveal hematopoietic stem cell fate decisions

Progress in the treatment of neonatal hypoxic-ischemic encephalopathy with umbilical cord blood mononuclear cells

Neonatal hypoxic-ischemic encephalopathy (HIE) is a common disease among newborns, which is a leading cause of neonatal death and permanent neurological sequelae. Therapeutic hypothermia (TH) is the only method for the treatment of HIE that has been recognized effective clinically at home and abroad, but the efficacy is limited. Recent research suggests that the cord blood-derived mononuclear cells (CB-MNCs), which the refer to blood cells containing one nucleus in the cord blood, exert anti-oxidative, anti-inflammatory, anti-apoptotic effects and play a neuroprotective role in HIE. This review focuses on safety and efficacy, the route of administration, dose, timing and combination treatment of CB-MNCs in HIE.

Limited Mitochondrial Activity Coupled With Strong Expression of CD34, CD90 and EPCR Determines the Functional Fitness of ex vivo Expanded Human Hematopoietic Stem Cells

Ex vivo expansion strategies of human hematopoietic stem cell (HSC) grafts with suboptimal stem cell dose have emerged as promising strategies for improving outcomes of HSC transplantation in patients with hematological malignancies. While exposure of HSCs to ex vivo cultures expands the number of phenotypically identifiable HSCs, it frequently alters the transcriptomic and metabolic profiles, therefore, compromising their long-term (LT) hematopoietic reconstitution capacity. Within the heterogeneous pool of expanded HSCs, the precise phenotypic, transcriptomic and metabolic profile and thus, the identity of HSCs that confer LT repopulation potential remains poorly described. Utilizing valproic acid (VPA) in ex vivo cultures of umbilical cord blood (UCB)-CD34⁺ cells, we demonstrate that expanded HSCs phenotypically marked by expression of the stem cell markers CD34, CD90 and EPCR (CD201) are highly enriched for LT-HSCs. Furthermore, we report that low mitochondrial membrane potential, and, hence, mitochondrial activity distinguishes LT-HSCs within the expanded pool of phenotypically defined HSCs. Remarkably, such reduced mitochondrial activity is restricted to cells with the highest expression levels of CD34, CD90 and EPCR phenotypic markers. Together, our findings reveal that high expression of CD34, CD90 and EPCR in conjunction with low mitochondrial activity is critical for identification of functional LT-HSCs generated within ex vivo expansion cultures.

The miR-532-3p/Chrdl1 axis regulates the proliferation and migration of amniotic fluid-derived mesenchymal stromal cells

BACKGROUND

Amniotic fluid-derived mesenchymal stromal cells (AFMSCs) are promising stem cells for regeneration medicine. However, AFMSCs isolated at different stages of pregnancy have different biological characteristics, and the therapeutic effects can differ in vivo and in vitro. The mechanisms underlying these differences have not been defined.

METHODS

Bioinformatics analysis of the AFMSC transcriptome identified Chrdl1 as one of the differentially expressed genes. We evaluated the effects of Chrdl1 overexpression or knockdown on the proliferation and migration of AFMSCs. Target prediction was performed using miRanda software to identify the upstream microRNA of Chrdl1. The interaction between Chrdl1 mRNA and its upstream microRNA was evaluated using a dual-luciferase reporter gene assay.

RESULTS

Chrdl1 was expressed at lower levels in AFMSCs derived from the early stages of pregnancy. It could suppress AFMSC proliferation and migration. miR-532-3p promoted AFMSC proliferation and migration by targeting the 3' UTR of Chrdl1 and downregulating its expression.

Applications of single cell RNA sequencing to research of stem cells

Stem cells (SCs) with their self-renewal and pluripotent differentiation potential, show great promise for therapeutic applications to some refractory diseases such as stroke, Parkinsonism, myocardial infarction, and diabetes. Furthermore, as seed cells in tissue engineering, SCs have been applied widely to tissue and organ regeneration. However, previous studies have shown that SCs are heterogeneous and consist of many cell subpopulations. Owing to this heterogeneity of cell states, gene expression is highly diverse between cells even within a single tissue, making precise identification and analysis of biological properties difficult, which hinders their further research and applications. Therefore, a defined understanding of the heterogeneity is a key to research of SCs. Traditional ensemble-based sequencing approaches, such as microarrays, reflect an average of expression levels across a large population, which overlook unique biological behaviors of individual cells, conceal cell-to-cell variations, and cannot understand the heterogeneity of SCs radically. The development of high throughput single cell RNA sequencing (scRNA-seq) has provided a new research tool in biology, ranging from identification of novel cell types and exploration of cell markers to the analysis of gene expression and predicating developmental trajectories. scRNA-seq has profoundly changed our understanding of a series of biological phenomena. Currently, it has been used in research of SCs in many fields, particularly for the research of heterogeneity and cell subpopulations in early embryonic development. In this review, we focus on the scRNA-seq technique and its applications to research of SCs.

Bone marrow hematopoietic dysfunction in untreated chronic lymphocytic leukemia patients

The consequences of immune dysfunction in B-chronic lymphocytic leukemia (CLL) likely relate to the incidence of serious recurrent infections and second malignancies that plague CLL patients. The well-described immune abnormalities are not able to consistently explain these complications. Here, we report bone marrow (BM) hematopoietic dysfunction in early and late stage untreated CLL patients. Numbers of CD34⁺ BM hematopoietic progenitors responsive in standard colony-forming unit (CFU) assays, including CFU-GM/GEMM and CFU-E, were significantly reduced. Flow cytometry revealed corresponding reductions in frequencies of all hematopoietic stem and progenitor cell (HSPC) subsets assessed in CLL patient marrow. Consistent with the reduction in HSPCs, BM resident monocytes and natural killer cells were reduced, a deficiency recapitulated in blood. Finally, we report increases in protein levels of the transcriptional regulators HIF-1α, GATA-1, PU.1, and GATA-2 in CLL patient BM, providing molecular insight into the basis of HSPC dysfunction. Importantly, PU.1 and GATA-2 were rapidly increased when healthy HSPCs were exposed in vitro to TNFα, a cytokine constitutively produced by CLL B cells. Together, these findings reveal BM hematopoietic dysfunction in untreated CLL patients that provides new insight into the etiology of the complex immunodeficiency state in CLL.