CD203c is expressed by human fetal hepatoblasts and distinguishes subsets of hepatoblastoma.

Background & Aims: Hepatocytic cells found during prenatal development have unique features compared to their adult counterparts, and are believed to be the precursors of pediatric hepatoblastoma. The cell-surface phenotype of hepatoblasts and hepatoblastoma cell lines was evaluated to discover new markers of these cells and gain insight into the development of hepatocytic cells and the phenotypes and origins of hepatoblastoma.

Methods: Human midgestation livers and four pediatric hepatoblastoma cell lines were screened using flow cytometry.

Human fetal liver cultures support multiple cell lineages that can engraft immunodeficient mice.

During prenatal development the liver is composed of multiple cell types with unique properties compared to their adult counterparts. We aimed to establish multilineage cultures of human fetal liver cells that could maintain stem cell and progenitor populations found in the developing liver. An aim of this study was to test if maturation of fetal hepatocytes in short-term cultures supported by epidermal growth factor and oncostatin M can improve their ability to engraft immunodeficient mice.

Higher Serum Alanine Transaminase Levels in Male Urokinase-Type Plasminogen Activator-Transgenic Mice Are Associated With Improved Engraftment of Hepatocytes but not Liver Sinusoidal Endothelial Cells.

The effects of sex on the degree of liver damage and human cell engraftment were investigated in immunodeficient urokinase-type plasminogen activator-transgenic (uPA-NOG) mice. Liver damage, measured by serum alanine transaminase (ALT) levels, was compared in male and female uPA-NOG mice of different ages. Male mice had significantly higher ALT levels than females with a median of 334 versus 158 U/L in transgenic homozygous mice, respectively.

The human chorion contains definitive hematopoietic stem cells from the fifteenth week of gestation.

We examined the contribution of the fetal membranes, amnion and chorion, to human embryonic and fetal hematopoiesis. A population of cells displaying a hematopoietic progenitor phenotype (CD34 CD45) of fetal origin was present in the chorion at all gestational ages, associated with stromal cells or near blood vessels, but was absent in the amnion. Prior to 15 weeks of gestation, these cells lacked hematopoietic engraftment potential.

Reduced alloimmunization in mice following repeated transfusion with pathogen-reduced platelets.

Background: Allogeneic transfusion can result in alloimmunization, leading to platelet (PLT) refractoriness and rejection of solid organ transplants. Previously we demonstrated that pathogen reduction using UV light and riboflavin (UV + R) eliminates the immunogenicity of white blood cells (WBCs) in vitro, blocks alloimmunization from transfusion in mice, and results in reduced ex vivo cytokine responses to subsequent untreated transfusions. We sought to determine if repeated transfusion with pathogen-reduced PLT-rich plasma (PRP) would eventually cause breakthrough alloimmunization or enhanced tolerance.

Neutralizing Monoclonal Antibodies Block Chikungunya Virus Entry and Release by Targeting an Epitope Critical to Viral Pathogenesis.

We evaluated the mechanism by which neutralizing human monoclonal antibodies inhibit chikungunya virus (CHIKV) infection. Potently neutralizing antibodies (NAbs) blocked infection at multiple steps of the virus life cycle, including entry and release. Cryo-electron microscopy structures of Fab fragments of two human NAbs and chikungunya virus-like particles showed a binding footprint that spanned independent domains on neighboring E2 subunits within one viral spike, suggesting a mechanism for inhibiting low-pH-dependent membrane fusion.

A quantitative assessment of the content of hematopoietic stem cells in mouse and human endosteal-bone marrow: a simple and rapid method for the isolation of mouse central bone marrow.

Background: Isolation of bone marrow cells, including hematopoietic stem cells, is a commonly used technique in both the research and clinical settings. A quantitative and qualitative assessment of cell populations isolated from mouse and human bone marrow was undertaken with a focus on the distribution of hematopoietic cells between the central bone marrow (cBM) and endosteal bone marrow (eBM).

Methods: Two approaches to cBM isolation from the hind legs were compared using the C57BL/6J and BALB/cJ strains of laboratory mice.

Whole-genome fingerprint of the DNA methylome during human B cell differentiation.

We analyzed the DNA methylome of ten subpopulations spanning the entire B cell differentiation program by whole-genome bisulfite sequencing and high-density microarrays. We observed that non-CpG methylation disappeared upon B cell commitment, whereas CpG methylation changed extensively during B cell maturation, showing an accumulative pattern and affecting around 30% of all measured CpG sites. Early differentiation stages mainly displayed enhancer demethylation, which was associated with upregulation of key B cell transcription factors and affected multiple genes involved in B cell biology.

Fresh frozen plasma and spray-dried plasma mitigate pulmonary vascular permeability and inflammation in hemorrhagic shock.

Background: In retrospective and prospective observational studies, fresh frozen plasma (FFP) has been associated with a survival benefit in massively transfused trauma patients. A dry plasma product, such as spray-dried plasma (SDP), offers logistical advantages over FFP. Recent studies on FFP have demonstrated that FFP modulates systemic vascular stability and inflammation.

Epigenetic remodeling in B-cell acute lymphoblastic leukemia occurs in two tracks and employs embryonic stem cell-like signatures.

We investigated DNA methylomes of pediatric B-cell acute lymphoblastic leukemias (B-ALLs) using whole-genome bisulfite sequencing and high-definition microarrays, along with RNA expression profiles. Epigenetic alteration of B-ALLs occurred in two tracks: de novo methylation of small functional compartments and demethylation of large inter-compartmental backbones. The deviations were exaggerated in lamina-associated domains, with differences corresponding to methylation clusters and/or cytogenetic groups.

The adult livers of immunodeficient mice support human hematopoiesis: evidence for a hepatic mast cell population that develops early in human ontogeny.

The liver plays a vital role in hematopoiesis during mammalian prenatal development but its hematopoietic output declines during the perinatal period. Nonetheless, hepatic hematopoiesis is believed to persist into adulthood. We sought to model human adult-liver hematopoiesis by transplantation of fetal and neonatal hematopoietic stem cells (HSCs) into adult immunodeficient mice.

Production of factor VIII by human liver sinusoidal endothelial cells transplanted in immunodeficient uPA mice.

Liver sinusoidal endothelial cells (LSECs) form a semi-permeable barrier between parenchymal hepatocytes and the blood. LSECs participate in liver metabolism, clearance of pathological agents, immunological responses, architectural maintenance of the liver and synthesis of growth factors and cytokines. LSECs also play an important role in coagulation through the synthesis of Factor VIII (FVIII).

A global DNA methylation and gene expression analysis of early human B-cell development reveals a demethylation signature and transcription factor network.

The epigenetic changes during B-cell development relevant to both normal function and hematologic malignancy are incompletely understood. We examined DNA methylation and RNA expression status during early B-cell development by sorting multiple replicates of four separate stages of pre-B cells derived from normal human fetal bone marrow and applied high-dimension DNA methylation scanning and expression arrays. Features of promoter and gene body DNA methylation were strongly correlated with RNA expression in multipotent progenitors (MPPs) both in a static state and throughout differentiation.

Cellular therapies supplement: the peritoneum as an ectopic site of hematopoiesis following in utero transplantation.

Background: In utero transplantation (IUT) has the potential to treat birth defects early before full development of the immune system. Relatively small grafts, which are not matched for major histocompatibility antigens, can be delivered even before onset of disease symptoms. IUT of hematopoietic stem cells is usually performed via intraperitoneal injection, yet the fate of donor cells in the peritoneal cavity is not fully understood.

Detection of human hematopoietic stem cell engraftment in the livers of adult immunodeficient mice by an optimized flow cytometric method.

Immunodeficient NOD.Cg-Prkdc(scid) Il2rg(tm1Wjl)/SzJ (NSG) mice are a valuable resource to study human hematopoietic stem cells. Prolonged multilineage hematopoiesis indicates stem cell engraftment and generally is measured by flow cytometry.

Coexpression of CD14 and CD326 discriminate hepatic precursors in the human fetal liver.

The molecular and cellular profile of liver cells during early human development is incomplete, complicating the isolation and study of hepatocytes, cholangiocytes, and hepatic stem cells from the complex amalgam of hepatic and hematopoietic cells, that is, the fetal liver. Epithelial cell adhesion molecule, CD326, has emerged as a marker of hepatic stem cells, and lipopolysaccharide receptor CD14 is known to be expressed on adult hepatocytes. Using flow cytometry, we studied the breadth of CD326 and CD14 expression in midgestation liver.

Identification of a critical control element directing expression of the muscle-specific transcription factor MRF4 in the mouse embryo.

Skeletal muscle development in the vertebrate embryo critically depends on the myogenic regulatory factors (MRFs) including MRF4 and Myf5. Both genes exhibit distinct expression patterns during mouse embryogenesis, although they are genetically closely linked with multiple regulatory elements dispersed throughout the common gene locus. MRF4 has a biphasic expression profile, first in somites and later in foetal skeletal muscles.