scholarly journals Inefficient Placental Virus Replication and Absence of Neonatal Cell-Specific Immunity Upon Sars-CoV-2 Infection During Pregnancy

2021 ◽  
Vol 12 ◽  
Author(s):  
Ann-Christin Tallarek ◽  
Christopher Urbschat ◽  
Luis Fonseca Brito ◽  
Stephanie Stanelle-Bertram ◽  
Susanne Krasemann ◽  
...  
Keyword(s):  
Pregnant Women ◽  
Vertical Transmission ◽  
Virus Replication ◽  
Ex Vivo ◽  
Acute Infection ◽  
Cell Responses ◽  
Viral Expression ◽  
Risk Of Progression

Pregnant women have been carefully observed during the COVID-19 pandemic, as the pregnancy-specific immune adaptation is known to increase the risk for infections. Recent evidence indicates that even though most pregnant have a mild or asymptomatic course, a severe course of COVID-19 and a higher risk of progression to diseases have also been described, along with a heightened risk for pregnancy complications. Yet, vertical transmission of the virus is rare and the possibility of placental SARS-CoV-2 infection as a prerequisite for vertical transmission requires further studies. We here assessed the severity of COVID-19 and onset of neonatal infections in an observational study of women infected with SARS-CoV-2 during pregnancy. Our placental analyses showed a paucity of SARS-CoV-2 viral expression ex vivo in term placentae under acute infection. No viral placental expression was detectable in convalescent pregnant women. Inoculation of placental explants generated from placentas of non-infected women at birth with SARS-CoV-2 in vitro revealed inefficient SARS-CoV-2 replication in different types of placental tissues, which provides a rationale for the low ex vivo viral expression. We further detected specific SARS-CoV-2 T cell responses in pregnant women within a few days upon infection, which was undetectable in cord blood. Our present findings confirm that vertical transmission of SARS-CoV-2 is rare, likely due to the inefficient virus replication in placental tissues. Despite the predominantly benign course of infection in most mothers and negligible risk of vertical transmission, continuous vigilance on the consequences of COVID-19 during pregnancy is required, since the maternal immune activation in response to the SARS-CoV2 infection may have long-term consequences for children’s health.

scholarly journals Reduced calcium storage blunts calcium signaling in Toxoplasma bradyzoites and impedes motility and egress

2021 ◽  
Author(s):  
Yong Fu ◽  
Kevin M Brown ◽  
Nathaniel G Jones ◽  
Silvia N J Moreno ◽  
L. David Sibley
Keyword(s):  
Developmental Stages ◽  
Ex Vivo ◽  
Acute Infection ◽  
Gliding Motility ◽  
Lytic Cycle ◽  
Calcium Storage ◽  
Calcium Atpases ◽  
Dual Reporter

Toxoplasma gondii has evolved different developmental stages of tachyzoites for disseminating during acute infection and bradyzoites for establishing chronic infection. Calcium ion (Ca2+) signaling tightly regulates the lytic cycle of tachyzoites by controlling microneme secretion and motility to drive egress. However, the roles of Ca2+ signaling pathways in bradyzoites remain largely unknown. Here we show that Ca2+ signals and egress by bradyzoites in response to agonists are highly restricted. Development of dual-reporter parasites revealed dampened calcium responses and minimal microneme secretion by bradyzoites induced in vitro or harvested from infected mice and tested ex vivo. Ratiometric Ca2+ imaging demonstrated lower Ca2+ basal levels, reduced magnitude, and slower Ca2+ kinetics in bradyzoites compared with tachyzoites stimulated with agonists. Diminished responses in bradyzoites were associated with down-regulation of calcium ATPases involved in intracellular Ca2+ storage in the endoplasmic reticulum (ER) and acidocalcisome. Once liberated from cysts by trypsin digestion, bradyzoites displayed weaker gliding motility associated with Ca2+ oscillations compared with tachyzoites, although gliding motility of bradyzoites was enhanced by uptake of exogenous Ca2+. Collectively, our findings indicate that bradyzoites exhibit dampened Ca2+ signaling due to a decreased amount of stored Ca2+, limiting microneme secretion and egress, likely constituting an adaptation to their long-term intracellular niche.

Strategies to Protect Hematopoietic Stem Cells from Culture-Induced Stress Conditions

2020 ◽  
Vol 15 ◽  
Author(s):  
Fatima Aerts-Kaya
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Ex Vivo ◽  
Stress Conditions ◽  
Stress Factors ◽  
Hematopoietic Stem ◽  
Induced Stress

: In contrast to their almost unlimited potential for expansion in vivo and despite years of dedicated research and optimization of expansion protocols, the expansion of Hematopoietic Stem Cells (HSCs) in vitro remains remarkably limited. Increased understanding of the mechanisms that are involved in maintenance, expansion and differentiation of HSCs will enable the development of better protocols for expansion of HSCs. This will allow procurement of HSCs with long-term engraftment potential and a better understanding of the effects of the external influences in and on the hematopoietic niche that may affect HSC function. During collection and culture of HSCs, the cells are exposed to suboptimal conditions that may induce different levels of stress and ultimately affect their self-renewal, differentiation and long-term engraftment potential. Some of these stress factors include normoxia, oxidative stress, extra-physiologic oxygen shock/stress (EPHOSS), endoplasmic reticulum (ER) stress, replicative stress, and stress related to DNA damage. Coping with these stress factors may help reduce the negative effects of cell culture on HSC potential, provide a better understanding of the true impact of certain treatments in the absence of confounding stress factors. This may facilitate the development of better ex vivo expansion protocols of HSCs with long-term engraftment potential without induction of stem cell exhaustion by cellular senescence or loss of cell viability. This review summarizes some of available strategies that may be used to protect HSCs from culture-induced stress conditions.

scholarly journals COVID-19 Infection during Pregnancy: Risk of Vertical Transmission, Fetal, and Neonatal Outcomes

2021 ◽  
Vol 11 (6) ◽  
pp. 483
Author(s):  
Marwa Saadaoui ◽  
Manoj Kumar ◽  
Souhaila Al Khodor
Keyword(s):  
Pregnant Women ◽  
Vertical Transmission ◽  
Current Knowledge ◽  
Limited Data ◽  
Pregnancy Risk ◽  
Public Health Challenge ◽  
Short And Long Term ◽  
Critical Public Health ◽  
The Impact

The COVID-19 pandemic is a worldwide, critical public health challenge and is considered one of the most communicable diseases that the world had faced so far. Response and symptoms associated with COVID-19 vary between the different cases recorded, but it is amply described that symptoms become more aggressive in subjects with a weaker immune system. This includes older subjects, patients with chronic diseases, patients with immunosuppression treatment, and pregnant women. Pregnant women are receiving more attention not only because of their altered physiological and immunological function but also for the potential risk of viral vertical transmission to the fetus or infant. However, very limited data about the impact of maternal infection during pregnancy, such as the possibility of vertical transmission in utero, during birth, or via breastfeeding, is available. Moreover, the impact of infection on the newborn in the short and long term remains poorly understood. Therefore, it is vital to collect and analyze data from pregnant women infected with COVID-19 to understand the viral pathophysiology during pregnancy and its effects on the offspring. In this article, we review the current knowledge about pre-and post-natal COVID-19 infection, and we discuss whether vertical transmission takes place in pregnant women infected with the virus and what are the current recommendations that pregnant women should follow in order to be protected from the virus.

Peculiarities of pregnancy and delivery course in women after the application of assisted reproductive technologies against obesity (Based on the retrospective analysis)

2018 ◽  
pp. 122-126
Author(s):  
I.A. Zhabchenko ◽  
◽  
O.R. Sudmak ◽  
Keyword(s):  
In Vitro Fertilization ◽  
Pregnant Women ◽  
Retrospective Analysis ◽  
Perinatal Outcomes ◽  
Reproductive Technologies ◽  
Ischemic Lesion ◽  
Vitro Fertilization ◽  
Pregnancy And Delivery

The objective: to study the structure and frequency of complications of pregnancy, deliveries and perinatal outcomes in three groups of women: women with infertility and obesity, treated by application of in vitro fertilization (hereinafter IVF), pregnant women after IVF application with normal body weight, and pregnant women on the background of obesity which did not have an infertility in past history. Materials and methods. A retrospective analysis of 221 case histories of pregnancies and labors in women who were treated and gave birth in the Pregnancy and delivery pathology Department of SI «Institute of Pediatrics, Obstetrics and Gynecology named after Acad. O. M. Lukyanova of NAMS of Ukraine» for 2012 – 2016 years was carried out. Results. The overwhelming majority of pregnant women after IVF on the background of obesity are primaparas, who have a complicated obstetric history, hormonal changes in the form of progesterone deficiency predominantly and chronic inflammatory processes. Pregnancy with a combination of infertility, treated by the means of IVF application, and obesity, in most cases is accompanied by a long-term threat of termination of pregnancy (48.8%), threatening preterm deliveries (56%), placental dysfunction (41.5%), premature rupture of the amniotic membranes (41.5%), other problems during pregnancy, at the same time, every second woman (58.5%) had a combination of several complications, and required a long-term and repeated inpatient treatment (53.7%). The specific gravity of surgical delivery was 90%, and 16.2% of such deliveries were complicated by pathological blood loss. The number of preterm deliveries was 17.1%, with perinatal losses up to 11.3‰. Among full-term newborns 21.3% of newborns had malnutrition of the I degree and 17% of them had hypoxic-ischemic lesion of CNS. Conclusion. The course of pregnancy, delivery and the postpartum period in the studied contingent of women has a significant frequency of complications, mainly the coinciding ones, which affects on the consequences of perinatal outcomes and requires further study of this problem and the development of differentiated algorithms for antenatal observation. Key words: pregnancy, obesity, in vitro fertilization, complications, delivery, newborn.

Long-Term Ex Vivo Maintenance and Expansion of Transplantable Human Hematopoietic Stem Cells

Blood ◽  
1999 ◽  
Vol 94 (5) ◽  
pp. 1623-1636 ◽  
Author(s):  
Chu-Chih Shih ◽  
Mickey C.-T. Hu ◽  
Jun Hu ◽  
Jeffrey Medeiros ◽  
Stephen J. Forman
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
In Vitro Culture ◽  
Culture System ◽  
Ex Vivo ◽  
Human Stem Cells ◽  
Hematopoietic Stem ◽  
In Vitro Culture System

Abstract We have developed a stromal-based in vitro culture system that facilitates ex vivo expansion of transplantable CD34+thy-1+ cells using long-term hematopoietic reconstitution in severe combined immunodeficient-human (SCID-hu) mice as an in vivo assay for transplantable human hematopoietic stem cells (HSCs). The addition of leukemia inhibitory factor (LIF) to purified CD34+ thy-1+ cells on AC6.21 stroma, a murine bone marrow–derived stromal cell line, caused expansion of cells with CD34+ thy-1+ phenotype. Addition of other cytokines, including interleukin-3 (IL-3), IL-6, granulocyte-macrophage colony-stimulating factor, and stem cell factor, to LIF in the cultures caused a 150-fold expansion of cells retaining the CD34+ thy-1+ phenotype. The ex vivo–expanded CD34+ thy-1+ cells gave rise to multilineage differentiation, including myeloid, T, and B cells, when transplanted into SCID-hu mice. Both murine LIF (cannot bind to human LIF receptor) and human LIF caused expansion of human CD34+ thy-1+ cells in vitro, suggesting action through the murine stroma. Furthermore, another human HSC candidate, CD34+ CD38− cells, shows a similar pattern of proliferative response. This suggests thatex vivo expansion of transplantable human stem cells under this in vitro culture system is a general phenomenon and not just specific for CD34+ thy-1+ cells.

Interleukin-3 supports expansion of long-term multilineage repopulating activity after multiple stem cell divisions in vitro

Blood ◽  
2000 ◽  
Vol 96 (5) ◽  
pp. 1748-1755 ◽  
Author(s):  
David Bryder ◽  
Sten E. W. Jacobsen
Keyword(s):  
Bone Marrow Cells ◽  
Ex Vivo ◽  
Calf Serum ◽  
Self Renewal ◽  
Hematopoietic Stem ◽  
Cell Divisions ◽  
Stem Cell Divisions

Abstract Although long-term repopulating hematopoietic stem cells (HSC) can self-renew and expand extensively in vivo, most efforts at expanding HSC in vitro have proved unsuccessful and have frequently resulted in compromised rather than improved HSC grafts. This has triggered the search for the optimal combination of cytokines for HSC expansion. Through such studies, c-kit ligand (KL), flt3 ligand (FL), thrombopoietin, and IL-11 have emerged as likely positive regulators of HSC self-renewal. In contrast, numerous studies have implicated a unique and potent negative regulatory role of IL-3, suggesting perhaps distinct regulation of HSC fate by different cytokines. However, the interpretations of these findings are complicated by the fact that different cytokines might target distinct subpopulations within the HSC compartment and by the lack of evidence for HSC undergoing self-renewal. Here, in the presence of KL+FL+megakaryocyte growth and development factor (MGDF), which recruits virtually all Lin−Sca-1+kit+ bone marrow cells into proliferation and promotes their self-renewal under serum-free conditions, IL-3 and IL-11 revealed an indistinguishable ability to further enhance proliferation. Surprisingly, and similar to IL-11, IL-3 supported KL+FL+MGDF-induced expansion of multilineage, long-term reconstituting activity in primary and secondary recipients. Furthermore, high-resolution cell division tracking demonstrated that all HSC underwent a minimum of 5 cell divisions, suggesting that long-term repopulating HSC are not compromised by IL-3 stimulation after multiple cell divisions. In striking contrast, the ex vivo expansion of murine HSC in fetal calf serum-containing medium resulted in extensive loss of reconstituting activity, an effect further facilitated by the presence of IL-3.

scholarly journals Assessment of Immunogenicity and Neutralisation Efficacy of Viral-Vectored Vaccines Against Chikungunya Virus

Viruses ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 322 ◽  
Author(s):  
César López-Camacho ◽  
Young Chan Kim ◽  
Joshua Blight ◽  
Marcos Lazaro Moreli ◽  
Eduardo Montoya-Diaz ◽  
...  
Keyword(s):  
Chikungunya Virus ◽  
Pacific Islands ◽  
High Capacity ◽  
Febrile Illness ◽  
Structural Proteins ◽  
Vaccine Platform ◽  
Cell Responses ◽  
Efficacious Vaccine

Chikungunya virus (CHIKV) has caused extensive outbreaks in several countries within the Americas, Asia, Oceanic/Pacific Islands, and Europe. In humans, CHIKV infections cause a debilitating disease with acute febrile illness and long-term polyarthralgia. Acute and chronic symptoms impose a major economic burden to health systems and contribute to poverty in affected countries. An efficacious vaccine would be an important step towards decreasing the disease burden caused by CHIKV infection. Despite no licensed vaccine is yet available for CHIKV, there is strong evidence of effective asymptomatic viral clearance due to neutralising antibodies against the viral structural proteins. We have designed viral-vectored vaccines to express the structural proteins of CHIKV, using the replication-deficient chimpanzee adenoviral platform, ChAdOx1. Expression of the CHIKV antigens results in the formation of chikungunya virus-like particles. Our vaccines induce high frequencies of anti-chikungunya specific T-cell responses as well as high titres of anti-CHIKV E2 antibodies with high capacity for in vitro neutralisation. Our results indicate the potential for further clinical development of the ChAdOx1 vaccine platform in CHIKV vaccinology.

scholarly journals Differential Maintenance of Primitive Human SCID-Repopulating Cells, Clonogenic Progenitors, and Long-Term Culture-Initiating Cells After Incubation on Human Bone Marrow Stromal Cells

Blood ◽  
1997 ◽  
Vol 90 (2) ◽  
pp. 641-650 ◽  
Author(s):  
Olga I. Gan ◽  
Barbara Murdoch ◽  
Andre Larochelle ◽  
John E. Dick
Keyword(s):  
Bone Marrow ◽  
Bone Marrow Stromal Cells ◽  
Cultured Cells ◽  
Ex Vivo ◽  
Hematopoietic Cells ◽  
Long Term Culture ◽  
Cell Engraftment ◽  
Ex Vivo Culture

Abstract Many experimental and clinical protocols are being developed that involve ex vivo culture of human hematopoietic cells on stroma or in the presence of cytokines. However, the effect of these manipulations on primitive hematopoietic cells is not known. Our severe combined immune-deficient mouse (SCID)-repopulating cell (SRC) assay detects primitive human hematopoietic cells based on their ability to repopulate the bone marrow (BM) of immune-deficient non-obese diabetic/SCID (NOD/SCID) mice. We have examined here the maintenance of SRC, colony-forming cells (CFC), and long-term culture-initiating cells (LTC-IC) during coculture of adult human BM or umbilical cord blood (CB) cells with allogeneic human stroma. Transplantation of cultured cells in equivalent doses as fresh cells resulted in lower levels of human cell engraftment after 1 and 2 weeks of culture for BM and CB, respectively. Similar results were obtained using CD34+-enriched CB cells. By limiting dilution analysis, the frequency of SRC in BM declined sixfold after 1 week of culture. In contrast to the loss of SRC as measured by reduced repopulating capacity, the transplanted inocula of cultured cells frequently contained equal or higher numbers of CFC and LTC-IC compared with the inocula of fresh cells. The differential maintenance of CFC/LTC-IC and SRC suggests that SRC are biologically distinct from the majority of these in vitro progenitors. This report demonstrates the importance of the SRC assay in the development of ex vivo conditions that will allow maintenance of primitive human hematopoietic cells with repopulating capacity.

Structurally Specific Heparan Sulfates Support Primitive Human Hematopoiesis by Formation of a Multimolecular Stem Cell Niche

Blood ◽  
1998 ◽  
Vol 92 (12) ◽  
pp. 4641-4651 ◽  
Author(s):  
Pankaj Gupta ◽  
Theodore R. Oegema ◽  
Joseph J. Brazil ◽  
Arkadiusz Z. Dudek ◽  
Arne Slungaard ◽  
...  
Keyword(s):  
Stem Cell ◽  
Cell Line ◽  
Stem Cell Niche ◽  
Ex Vivo ◽  
Recent Observation ◽  
Hematopoietic Progenitors ◽  
Platelet Factor ◽  
Cell Niche

Abstract Stem cell localization, conservation, and differentiation is believed to occur in niches in the marrow stromal microenvironment. Our recent observation that long-term in vitro human hematopoiesis requires a stromal heparan sulfate proteoglycan (HSPG) led us to hypothesize that such HSPG may orchestrate the formation of the stem cell niche. We compared the structure and function of HS from M2-10B4, a hematopoiesis-supportive cell line, with HS from a nonsupportive cell line, FHS-173-We. Long-term culture-initiating cell (LTC-IC) maintenance was enhanced by PG from supportive cells but not by PG from nonsupportive cells (P < .005). The supportive HS were significantly larger and more highly sulfated than the nonsupportive HS. Specifically, supportive HS contained higher 6-O-sulfation on the glucosamine residues. In agreement with these observations, purified 6-O-sulfated heparin and highly 6-O-sulfated bovine kidney HS similarly maintained LTC-IC. In contrast, completely desulfated heparin, N-sulfated heparin, and unmodified heparin did not support LTC-IC maintenance. Moreover, the supportive HS promoted LTC-IC maintenance but not differentiation of CD34+/HLA-DR−cells into colony-forming cells (CFCs) and mature blood cells. The supportive HS but not the nonsupportive HS bound both cytokines and matrix components critical for hematopoiesis, including interleukin-3 (IL-3), macrophage inflammatory protein-1 (MIP-1), and thrombospondin (TSP). Significantly more CD34+ cells adhered directly to immobilized O-sulfated heparin than to N-sulfated or desulfated heparin. Thus, hematopoiesis-supportive stromal HSPG possessing large, highly 6-O-sulfated HS mediate the juxtaposition of hematopoietic progenitors with stromal cells, specific growth-promoting (IL-3) and growth-inhibitory (MIP-1 and platelet factor 4 [PF4]) cytokines, and extracellular matrix (ECM) proteins such as TSP. We conclude that the structural specificity of stromal HSPG that determines the selective colocalization of cytokines and ECM components leads to the formation of discrete niches, thereby orchestrating the controlled growth and differentiation of stem cells. These findings may have important implications for ex vivo expansion of and gene transfer into primitive hematopoietic progenitors.

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