Vulnerability of primitive human placental trophoblast to Zika virus

Infection of pregnant women by Asian lineage strains of Zika virus (ZIKV) has been linked to brain abnormalities in their infants, yet it is uncertain when during pregnancy the human conceptus is most vulnerable to the virus. We have examined two models to study susceptibility of human placental trophoblast to ZIKV: cytotrophoblast and syncytiotrophoblast derived from placental villi at term and colonies of trophoblast differentiated from embryonic stem cells (ESC). The latter appear to be analogous to the primitive placenta formed during implantation. The cells from term placentas, which resist infection, do not express genes encoding most attachment factors implicated in ZIKV entry but do express many genes associated with antiviral defense. By contrast, the ESC-derived trophoblasts possess a wide range of attachment factors for ZIKV entry and lack components of a robust antiviral response system. These cells, particularly areas of syncytiotrophoblast within the colonies, quickly become infected, produce infectious virus and undergo lysis within 48 h after exposure to low titers (multiplicity of infection > 0.07) of an African lineage strain (MR766 Uganda: ZIKVU) considered to be benign with regards to effects on fetal development. Unexpectedly, lytic effects required significantly higher titers of the presumed more virulent FSS13025 Cambodia (ZIKVC). Our data suggest that the developing fetus might be most vulnerable to ZIKV early in the first trimester before a protective zone of mature villous trophoblast has been established. Additionally, MR766 is highly trophic toward primitive trophoblast, which may put the early conceptus of an infected mother at high risk for destruction

Research Notes : U.S.S.R. : Subunit composition of glycinin from various samples of cultivated and wild soybean

The major storage protein of llS class of soybean seeds, glycinin, has a complex subunit structure. Each of the six subunits is composed of two pro-tein molecules (acidic and basic), linked via disulphide bonds (Badley et al., 1975). Depending on subunit, the acidic moiety molecular weight varies from 37,000 to 42,000, with one exception (m.w. 10,000)

216 EMBRYONIC AND INDUCED PLURIPOTENT STEM CELLS ANALOGOUS TO INNER CELL MASS-DERIVED LIF-DEPENDENT MOUSE EMBRYONIC STEM CELLS ESTABLISHED FROM THE DOMESTIC PIG, SUS SCROFA

Authentic embryonic stem cells (ESC) may never have been successfully derived from the inner cell mass (ICM) of pig and other ungulates, despite over 25 years of effort. Recently, porcine induced pluripotent stem cells (piPSC) were generated by reprogramming somatic cells with a combination of four factors OCT4, SOX2, KLF4 and c-MYC (OSKM) delivered by lentiviral transduction. The established piPSC are analogous to FGF2-dependent human (h) ESC and murine “epiblast stem cells,” and are likely to advance swine as a model in biomedical research. Here, we report for the first time, the establishment of LIF-dependent, so called naïve type pluripotent stem cells (1) from the inner cell mass (ICM) of porcine blastocysts by up-regulating the expression of KLF4 and POU5F1; and (2) from umbilical cord mesenchyme (Wharton's jelly) by transduction with OSKM factors and subsequent culture in the presence of LIF-based medium with inhibitors that substitute for low endogenous expression of c-MYC and KLF4 and promote pluripotency. The 2 compounds that have been used in this study are, CHIR99021 (CH), which substitutes c-MYC by inhibiting GSK3B and activating WNT signalling and Kenpaullone (KP), which inhibits both GSK3B and CDK1 and supplants KLF4 function. The lentiviral vectors employed for introducing the re-programming genes were modified for doxycycline-mediated induction of expression (tet-on) and are ‘floxed’ for Cre-mediated recombination and removal of transgenes following complete reprogramming. Two LIF-dependent cell lines have been derived from the ICM cells of late d 5.5 in vitro produced blastocysts and four from umbilical cord mesenchyme recovered from fetuses at d 35 of pregnancy. The derived stem cell lines are alkaline phosphatase-positive, resemble mouse embryonic stem cells in colony morphology, cell cycle interval, transcriptome profile and expression of pluripotent markers, such as POU5F1, SOX2 and surface marker SSEA1. They are dependent on LIF signalling for maintenance of pluripotency, can be cultured over extended passage (&gt;50) with no senescence. Of importance, the ICM-derived lines have been successful in their ability to form teratomas. The cells could be cultured in feeder free conditions on a synthetic matrix in the presence of chemically defined medium and can be coaxed to differentiate under xeno-free conditions. Currently, the piPSC lines are being investigated for their ability to give rise to teratomas and to produce a live offspring by nuclear transfer. Supported by Addgene Innovation Award, MO Life Sciences Board Grant 00022147 and NIH grant HD21896. </jats:p

Differentiation of trophoblast cells from human embryonic stem cells: to be or not to be?

It is imperative to unveil the full range of differentiated cell types into which human pluripotent stem cells (hPSCs) can develop. The need is twofold: it will delimit the therapeutic utility of these stem cells and is necessary to place their position accurately in the developmental hierarchy of lineage potential. Accumulated evidence suggested that hPSC could developin vitrointo an extraembryonic lineage (trophoblast (TB)) that is typically inaccessible to pluripotent embryonic cells during embryogenesis. However, whether these differentiated cells are truly authentic TB has been challenged. In this debate, we present a case for and a case against TB differentiation from hPSCs. By analogy to other differentiation systems, our debate is broadly applicable, as it articulates higher and more challenging standards for judging whether a given cell type has been genuinely produced from hPSC differentiation.</jats:p