Human trophoblast contains an intracellular protein reactive with an antibody against CD133--a novel marker for trophoblast

Programmed cell death protein 1 promotes hepatitis B virus transmission through the regulation of ERK1/2-mediated trophoblasts differentiation

PURPOSE

The purpose of our research is to evaluate the mechanism of PD-1 in the promotion of HBV transmission.

METHODS

HBV was used to infect two human choriocarcinoma cell line, including JEG-3, as well as BeWo. We used PCR and western blotting to detect PD-1 gene and protein expression levels in cells. Stable knockdown of the PD-1 gene in JEG-3 cells was obtained by lentiviral transfection. Trophoblast cell proliferation was evaluated using CCK8 and flow cytometry. The concentration of HBV antibody in the cell supernatant was measured by ELISA. DNA was then extracted from the cells and the copy number of the HBV virus was detected by PCR. Finally, ERK1/2 expression was detected by western blot.

RESULTS

High PD-1 gene expression in HBV-infected trophoblasts and the knockdown of PD-1 gene can, respectively, improve the proliferation of HBV-infected trophoblasts and reduce viral replication in trophoblasts. In addition, PD-1 and ERK1/2 proteins were co-expressed in HBV-infected trophoblasts and inhibited the activation of ERK1/2 pathway in HBV-infected trophoblasts. ERK1/2 expression significantly increased after PD-1 knockdown. Therefore, PD-1 might be an important protein in trophoblast cells infected with HBV.

CONCLUSIONS

PD-1 promoted HBV transmission through regulating ERK1/2-mediated trophoblasts differentiation. Therefore, our research may provide new ideas and methods for preventing mother-to-child transmission of HBV infection during pregnancy.

Glucose-6-phosphate dehydrogenase plays a critical role in hypoxia-induced CD133+ progenitor cells self-renewal and stimulates their accumulation in the lungs of pulmonary hypertensive rats

Although hypoxia is detrimental to most cell types, it aids survival of progenitor cells and is associated with diseases like cancer and pulmonary hypertension in humans. Therefore, understanding the underlying mechanisms that promote survival of progenitor cells in hypoxia and then developing novel therapies to stop their growth in hypoxia-associated human diseases is important. Here we demonstrate that the proliferation and growth of human CD133(+) progenitor cells, which contribute to tumorigenesis and the development of pulmonary hypertension, are increased when cultured under hypoxic conditions. Furthermore, glucose-6-phosphate dehydrogenase (G6PD) activity was increased threefold in hypoxic CD133(+) cells. The increased G6PD activity was required for CD133(+) cell proliferation, and their growth was arrested by G6PD inhibition or knockdown. G6PD activity upregulated expression of HIF1α, cyclin A, and phospho-histone H3, thereby promoting CD133(+) cell dedifferentiation and self-renewal and altering cell cycle regulation. When CD133(+) cells were cocultured across a porous membrane from pulmonary artery smooth muscle cells (PASMCs), G6PD-dependent H2O2 production and release by PASMCs recruited CD133(+) cells to the membrane, where they attached and expressed smooth muscle markers (α-actin and SM22α). Inhibition of G6PD reduced smooth muscle marker expression in CD133(+) cells under normoxia but not hypoxia. In vivo, CD133(+) cells colocalized with G6PD(+) cells in the perivascular region of lungs from rats with hypoxia-induced pulmonary hypertension. Finally, inhibition of G6PD by dehydroepiandrosterone in pulmonary arterial hypertensive rats nearly abolished CD133(+) cell accumulation around pulmonary arteries and the formation of occlusive lesions. These observations suggest G6PD plays a key role in increasing hypoxia-induced CD133(+) cell survival in hypertensive lungs that differentiate to smooth muscle cells and contribute to pulmonary arterial remodeling during development of pulmonary hypertension.

Cancer stem cell: implications in cancer biology and therapy with special reference to lung cancer

The cancer stem cell (CSC) theory is currently central to the field of cancer research, because it is not only a matter of academic interest but also crucial in cancer therapy. CSCs share a variety of biological properties with normal somatic stem cells in terms of self-renewal, the propagation of differentiated progeny, the expression of specific cell markers and stem cell genes, and the utilization of common signaling pathways and the stem cell niche. However, CSCs differ from normal stem cells in their tumorigenic activity. Thus, CSCs are also termed cancer initiating cells. In this paper, we briefly review hitherto described study results and refer to some excellent review articles to understand the basic properties of CSCs. In addition, we focus upon CSCs of lung cancers, since lung cancer is still increasing in incidence worldwide and remains the leading cause of cancer deaths. Understanding the properties of, and exploring cell markers and signaling pathways specific to, CSCs of lung cancers, will lead to progress in therapy, intervention, and improvement of the prognosis of patients with lung cancer. In the near future, the evaluation of CSCs may be a routine part of practical diagnostic pathology.

Systemic delivery of umbilical cord blood cells for stroke therapy: a review

PURPOSE

This review paper summarizes relevant studies, discusses potential mechanisms of transplanted cell-mediated neuroprotection, and builds a case for the need to establish outcome parameters that are critical for transplantation success. In particular, we outline the advantages and disadvantages of systemic delivery of human umbilical cord blood (HUCB) cells in the field of cellular transplantation for treating ischemic stroke.

METHODS

A MEDLINE/PubMed systematic search of published articles in peer-reviewed journals over the last 25 years was performed focusing on the theme of HUCB as donor graft source for transplantation therapy in neurological disorders with emphasis on stroke.

RESULTS

Ischemic stroke remains a leading cause of human death and disability. Although stroke survivors may gain spontaneous partial functional recovery, they often suffer from sensory-motor dysfunction, behavioral/neurological alterations, and various degrees of paralysis. Currently, limited clinical intervention is available to prevent ischemic damage and restore lost function in stroke victims. Stem cells from fetal tissues, bone marrow, and HUCB has emerged in the last few years as a potential cell transplant cell source for ischemic stroke, because of their capability to differentiate into multiple cell types and the possibility that they may provide trophic support for cell survival, tissue repair, and functional recovery.

CONCLUSION

A growing number of studies highlight the potential of systemic delivery of HUCB cells as a novel therapeutic approach for stroke. However, additional preclinical studies are warranted to reveal the optimal HUCB transplant regimen that is safe and efficacious prior to proceeding to large-scale clinical application of these cells for stroke therapy.

Therapeutic potentials of human embryonic stem cells in Parkinson's disease

The loss of dopaminergic neurons of the substantia nigra is the pathological hallmark characteristic of Parkinson's disease (PD). The strategy of replacing these degenerating neurons with other cells that produce dopamine has been the main approach in the cell transplantation field for PD research. The isolation, differentiation, and long-term cultivation of human embryonic stem cells and the therapeutic research discovery made in relation to the beneficial properties of neurotrophic and neural growth factors has advanced the transplantation field beyond dopamine-producing cells. The present review addresses recent advances in human embryonic stem cell experimentation in relation to treating PD, as well as cell transplantation techniques in conjunction with alternative therapeutics.

Obesity in pregnancy stimulates macrophage accumulation and inflammation in the placenta

Obesity and pregnancy are associated with a combination of insulin resistance and inflammatory changes which exacerbate in combination. Based on the similarity between the inflammatory transcriptomes of adipose tissue and placenta, we hypothesized that the placenta develops exaggerated inflammation in response to obesity. The aim of this study was to characterize placental inflammatory mediators and macrophage accumulation in relation to peripheral inflammation in obesity. Placental macrophages and maternal peripheral blood mononuclear cells (PBMC) from 20 obese and 15 lean women were functionally and phenotypically characterized using immunohistochemistry, flow cytometry and expression for macrophage markers and inflammatory cytokines. The number of resident CD68+ and CD14+ cells was increased 2-3 fold in the placenta of obese as compared to lean women. The macrophage population was characterized by a marked phenotypic heterogeneity with complex subsets of CD14+, CD68+ and CD11b+ (mac-1) cells and by an increased expression of the pro-inflammatory cytokines IL-1, TNF-alpha, IL-6. Placental inflammation was associated with an activation of PBMC gene expression with an increase in the monocyte differentiation and maturation markers CD14 and CD68 in maternal but not fetal PBMC. The inflammatory changes were associated with higher plasma concentrations of C-reactive protein and IL-6 in obese compared to lean women. In conclusion, the chronic inflammation state of pre-gravid obesity is extending to in utero life with accumulation of a heterogeneous macrophage population and pro-inflammatory mediators in the placenta. The resulting inflammatory milieu in which the fetus develops may have critical consequences for short and long term programming of obesity.

Occult placenta accreta: the missing link in the diagnosis of abnormal placentation

Placenta creta (accreta, increta, or percreta) is a clinically symptomatic condition, usually diagnosed histologically on hysterectomy specimens. At a minimum, focal absence of decidua is the histological finding for this condition; however, excessive amounts of extravillous trophoblasts were recently documented on hysterectomy specimens. The histological finding of basal plate myometrial fibers (BPMF) without intervening decidua in spontaneously delivered placentas, which we term occult placenta accreta (OPA), is not infrequent, even in clinically asymptomatic cases. To prove that OPA is a missing link between normal placental implantation and clinical placenta accreta, CD146 immunohistochemical stains were performed on 25 sections of OPA (study group) and 25 placental sections without BPMF (control group). Implantation-site intermediate trophoblast (ISIT) cell number, thickness, and density were compared between the study and control groups. The ISIT micrometry thickness and cell number at BPMF sites were statistically significantly higher in OPA than in control group and same OPA placentas away from BPMF. There were no statistically significant differences in ISIT density. Therefore, although asymptomatic, OPA features the same histopathology as clinical placenta accreta and may share same pathogenesis, which may include decidual deficiency, abnormal trophoblast/decidua interaction, and/or hypoxia.

Brain tumor stem cells: identification and concepts

The study of human brain tumors has characteristically emphasized the molecular and cellular analysis of the bulk tumor. There is increasing evidence in brain tumors and other malignancies that the tumor clone is functionally heterogeneous, however, existing in a cellular hierarchy based on small subpopulations of stem cells. These concepts were first definitively demonstrated in human acute myelogenous leukemia, in which regeneration of a diversely heterogeneous human leukemia cell population in a xenograft mouse model occurred only after injection of a rare relatively homogeneous population of leukemic cells that expressed hematopoietic stem cell markers. Recently, through advances in understanding of normal neural stem cell biology, the use of techniques for cell purification by flow cytometry, and the development of cell functional assays in vivo, the time was made ripe for several groups to characterize brain tumor stem cells (BTSCs). The BTSC resides in the cell fraction expressing the neural precursor cell surface marker CD133.

A comparison of CFU-GM, BFU-E and endothelial progenitor cells using ex vivo expansion of selected cord blood CD133+ and CD34+ cells

BACKGROUND

CD133 is a newly developed hematopoietic stem cell marker but little is known about its function. Whether CD133(+) cell selection provides any advantage over CD34(+) selection for hematopoietic stem cell isolation and transplantation is unclear. The present study compared colony formation and endothelial cell differentiation of these two cell types from umbilical cord blood (UCB).

METHODS

Mononuclear cells from the same UCB samples were used for both CD133(+) and CD34(+) cell selection. Cells with 97.1% purity were incubated in semi-solid culture medium containing stem cell growth factor (SCGF) and G-CSF or erythropoietin (EPO). Purified cells were also cultured in M199 containing vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and insulin-like growth factor-1 (IGF-1).

RESULTS

CD34(+) and CD133(+) cells produced similar numbers of CFU-GM colonies (median 43.25 and 30.5, respectively; P>0.2). However, a greater than four-fold difference in BFU-E colony formation was observed from CD34(+) cells compared with CD133(+) cells (median 35 and 8, respectively; P<0.04). CD34(+) cells gave rise to endothelial-like cells when stimulated with VEGF, bFGF and IGF-1. CD133(+) cells were unable produce this cell type under the same conditions.

DISCUSSION

CD133(+) cells produced smaller BFU-E colonies and were unable to differentiate into mature endothelial cells. CD34(+) cells contained endothelial progenitors that could differentiate into mature cells of this lineage. Based on these data, it appears that CD133 offers no distinct advantage over CD34 as a selective marker for immunoaffinity-based isolation of hematopoietic stem cells and endothelial progenitor cells.

Identification of antibodies against HAI-1 and integrin alpha6beta4 as immunohistochemical markers of human villous cytotrophoblast

Syncytiotrophoblast and invasive extravillous trophoblast arise from a common stem cell, namely villous cytotrophoblast, but have very different characteristics. The study of the differentiation process relies on the availability of suitable markers for these different cell types of developing placenta. In this work, we have produced monoclonal antibodies that are specific to human villous cytotrophoblast. Monoclonal antibody (MAb) MG2 was specific to villous cytotrophoblast across gestation, and recognizes hepatocyte growth factor activator inhibitor type 1. MAb MD10 stained villous cytotrophoblast across gestation and also some endothelial cells, particularly in the second or third trimester. MAb MD10 recognizes human integrin alpha6beta4. As a test for specificity, the novel MAbs were also used for staining of frozen tissue from human colon carcinoma. The results show that the two antibodies can be used as tools to study human villous cytotrophoblasts and also human tumors. The MG2 antibody seems most specific and promising for the study of various aspects of human villous cytotrophoblast.

Somatic stem cell marker prominin-1/CD133 is expressed in embryonic stem cell-derived progenitors

Prominin-1/CD133 is a plasma membrane marker found in several types of somatic stem cells, including hematopoietic and neural stem cells. To study its role during development and with differentiation, we analyzed its temporal and spatial expression (mRNA and protein) in preimplantation embryos, undifferentiated mouse embryonic stem (ES) cells, and differentiated ES cell progeny. In early embryos, prominin-1 was expressed in trophoblast but not in cells of the inner cell mass; however, prominin-1 transcripts were detected in undifferentiated ES cells. Both ES-derived cells committed to differentiation and early progenitor cells coexpressed prominin-1 with early lineage markers, including the cytoskeletal markers (nestin, cytokeratin 18, desmin), fibulin-1, and valosin-containing protein. After spontaneous differentiation at terminal stages, prominin-1 expression was downregulated and no coexpression with markers characteristic for neuroectodermal, mesodermal, and endodermal cells was found. Upon induction of neuronal differentiation, some prominin-1-positive cells, which coexpressed nestin and showed the typical morphology of neural progenitor cells, persisted until terminal stages of differentiation. However, no coexpression of prominin-1 with markers of differentiated neural cells was detected. In conclusion, we present the somatic stem cell marker prominin-1 as a new parameter to define ES-derived committed and early progenitor cells.

Transplantation of human umbilical cord blood cells in the repair of CNS diseases

Cell transplantation therapies have been used to treat certain neurodegenerative diseases such as Parkinson's and Huntington's disease. However, ethical concerns over the use of fetal tissues, and the inherent complexities of standardising the procurement, processing and transplantation methods of this tissue, have prompted the search for a source of cells that have less ethical stigmatisations, are readily available and can be easily standardised. Several sources of human cells that meet these principles have been under investigation. Cells from human umbilical cord blood (HUCB) are one source that is consistent with these principles; therefore, they have become of great interest in the field of cellular repair/replacement for the treatment of CNS diseases and injury. This review will focus on the advantages of HUCB cells as a source for cellular transplantation therapies, recent studies that have examined the potential of these cells in vitro to be directed towards neural phenotypes, and in vivo studies that have investigated the functional recovery of animals in a number of models of CNS injury and disease following administration of HUCB cells.

Endocrine cell lines from the placenta

Cell-lines derived from human placenta and chorion have been used extensively to model the endocrine functions of human trophoblast. In general terms, the endocrine functions of the primary cells and tissues are at least partially replicated within the cell-lines, suggesting that they may be used as appropriate models. There are, however, two major provisos that compromise this generalisation. Firstly, the endocrine function of placenta represents a complex interaction between cytotrophoblast, syncytiotrophoblast and multiple regulators, so a single cell population digested from the normal environment is unlikely to represent this. Secondly, the characterisation of primary trophoblast populations and of cell-lines is incomplete, complicating the assignment of functions to trophoblast populations. Despite these difficulties, useful information has been obtained from the available cell-lines, regardless of whether they have arisen spontaneously, been transformed in vitro, or derived from cancers in vivo.

Identification of human brain tumour initiating cells

The cancer stem cell (CSC) hypothesis suggests that neoplastic clones are maintained exclusively by a rare fraction of cells with stem cell properties. Although the existence of CSCs in human leukaemia is established, little evidence exists for CSCs in solid tumours, except for breast cancer. Recently, we prospectively isolated a CD133+ cell subpopulation from human brain tumours that exhibited stem cell properties in vitro. However, the true measures of CSCs are their capacity for self renewal and exact recapitulation of the original tumour. Here we report the development of a xenograft assay that identified human brain tumour initiating cells that initiate tumours in vivo. Only the CD133+ brain tumour fraction contains cells that are capable of tumour initiation in NOD-SCID (non-obese diabetic, severe combined immunodeficient) mouse brains. Injection of as few as 100 CD133+ cells produced a tumour that could be serially transplanted and was a phenocopy of the patient's original tumour, whereas injection of 10(5) CD133- cells engrafted but did not cause a tumour. Thus, the identification of brain tumour initiating cells provides insights into human brain tumour pathogenesis, giving strong support for the CSC hypothesis as the basis for many solid tumours, and establishes a previously unidentified cellular target for more effective cancer therapies.

Probing the fetal genome: progress in non-invasive prenatal diagnosis

Progress in our understanding of the molecular basis of heritable diseases, through identification of specific mutations, has provided a foundation for the development of DNA-based prenatal diagnosis. Genetic analysis of fetal DNA is now routinely performed from chorionic villus samples obtained as early as the tenth week of gestation or by amniocentesis from week 15 onwards. However, both of these approaches involve invasive procedures with increased risk of fetal loss. To avoid such complications, attempts have been made to develop non-invasive tests through the identification, characterization and isolation of fetal cells or free fetal DNA from the maternal circulation. Recently, progress has been made towards the development of novel strategies that are expected to provide non-invasive means for early prenatal diagnosis in pregnancy.

A positive immunoselection method to isolate villous cytotrophoblast cells from first trimester and term placenta to high purity

We developed a method for isolating highly pure villous cytotrophoblast cells from first trimester and term placenta that excludes extravillous trophoblast and syncytiotrophoblast fragments. The method is based on positive immunoselection using an antibody (mAb C76/18) reacting with hepatocyte growth factor activator inhibitor 1, HAI-1, a membrane antigen on villous cytotrophoblast. As a comparison, we also immunopurified cells using an antibody against CD105, present on syncytiotrophoblast and some extravillous trophoblast cells. The isolates were characterized by flow cytometry. HAI-1-positive cells from first trimester and term placentae were highly pure (>98 per cent cytokeratin 7-positive) mononuclear trophoblast cells. These isolations were contaminated with only very small percentages of vimentin and CD45-positive cells. HAI-1-positive trophoblast cells lacked CD105 and also HLA class I, a marker for extravillous trophoblast. In culture HAI-1-positive cells adhered, displayed an epithelial morphology, and survived for more than three days. In contrast, CD105-positive cell fractions from first trimester placenta were a heterogeneous mixture of mononuclear and multinuclear elements consisting of syncytiotrophoblast fragments, extravillous trophoblast cells, as well as around 5 per cent non-trophoblastic contaminants. In conclusion, the positive immunoselection method using antibody C76/18 yielded highly pure villous cytotrophoblast cells devoid of elements derived from syncytiotrophoblast or extravillous trophoblast.

Human umbilical cord blood (HUCB) cells for central nervous system repair

Cellular therapy is a compelling and potential treatment for certain neurological and neurodegenerative diseases as well as a viable treatment for acute injury to the spinal cord and brain. The hematopoietic system offers alternative sources for stem cells compared to those of fetal or embryonic origin. Bone marrow stromal and umbilical cord cells have been used in pre-clinical models of brain injury, directed to differentiate into neural phenotypes, and have been related to functional recovery after engraftment in central nervous system (CNS) injury models. This paper reviews the advantages, utilization and progress of human umbilical cord blood (HUCB) cells in the neural cell transplantation and repair field.

Monoclonal antibody CD133-2 (AC141) against hematopoietic stem cell antigen CD133 shows crossreactivity with cytokeratin 18

CD133 is an antigen expressed on hematopoietic progenitor cells and on some epithelial cells. We previously reported that a commercially available antibody against CD133, CD133-2/AC141, also reacted with an intracellular protein in placental trophoblasts. Here we show by 2D electrophoresis and mass spectroscopy that this reactivity is with cytokeratin 18, a cytokeratin present in most simple epithelia. Immunohistochemistry (IHC) with CD133-2/AC141 on a trophoblast cell line displayed a staining pattern typical for the cytoskeleton. Cryostat sections of stratified epithelia lacking cytokeratin 18 did not react with CD133-2/AC141. In conclusion, care must be taken not to misinterpret staining patterns using CD133-2/AC141 in IHC.