Gestational related morphological abnormalities in placental villous trophoblast turnover in compromised pregnancies

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.Human placental villi are covered by a layer of trophoblast epithelia in direct contact with maternal blood, which exist in a constant steady-state of turnover and renewal ensuring both maternal and fetal health. The process of trophoblast turnover involves proliferation, differentiation and fusion of cytotrophoblast cells to form a terminally differentiated outer syncytiotrophoblast layer which functions as the active transport compartment between mother and fetus. Alterations in the balance between these three processes are thought to diminish both the structural and functional integrity of the syncytiotrophoblast, potentially leading to placental insufficiency associated with severe complications of pregnancy such as pre-eclampsia (PET), intrauterine growth restriction (IUGR) and sudden infant death syndrome (SIDS). Placentas from early (33 weeks) pregnancies complicated by PET, IUGR, SIDS and gestational age-matched controls were systematically uniform randomly sampled to assess the morphological basis of placental villous structure and trophoblast turnover (villi, cytotrophoblast, syncytiotrophoblast, apoptotic syncytial knots) using unbiased stereological techniques (volumes and numbers). Villous cytotrophoblast proliferation was assessed using double immunohistochemistry for Ki67 and cytokeratin 7 (CK-7). Severe early-onset IUGR placentas (n=5) were smaller displaying significant reductions in the total number of CT cells, within which the density of proliferating CT was further reduced by 50%. Syncytiotrophoblast volume and number was significantly reduced with an increase in apoptotic syncytial knots. Late-onset IUGR placentas (n=4) also displayed significant reductions in the total number of CT and proliferating CT, but were not associated with changes in the density of proliferating CT. SCT numbers were significantly reduced with an increase in apoptotic knots. Placentas from severe early-onset PET (n=11) were similar to preterm controls, except for a significant increase in apoptotic syncytial knots. However, late-onset PET (n=6) displayed a significant decrease in total CT number, the percentage of which undergoing proliferation was significantly increased for structural villi. There were increased numbers of apoptotic syncytial knots in peripheral villi

Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms

Uptake of system L amino acid substrates into isolated placental plasma membrane vesicles in the absence of opposing side amino acid (zero-trans uptake) is incompatible with the concept of obligatory exchange, where influx of amino acid is coupled to efflux. We therefore hypothesized that system L amino acid exchange transporters are not fully obligatory and/or that amino acids are initially present inside the vesicles. To address this, we combined computational modeling with vesicle transport assays and transporter localization studies to investigate the mechanism(s) mediating [14C]L-serine (a system L substrate) transport into human placental microvillous plasma membrane (MVM) vesicles. The carrier model provided a quantitative framework to test the 2 hypotheses that L-serine transport occurs by either obligate exchange or nonobligate exchange coupled with facilitated transport (mixed transport model). The computational model could only account for experimental [14C]L-serine uptake data when the transporter was not exclusively in exchange mode, best described by the mixed transport model. MVM vesicle isolates contained endogenous amino acids allowing for potential contribution to zero-trans uptake. Both L-type amino acid transporter (LAT)1 and LAT2 subtypes of system L were distributed to MVM, with L-serine transport attributed to LAT2. These findings suggest that exchange transporters do not function exclusively as obligate exchangers.—Widdows, K. L., Panitchob, N., Crocker, I. P., Please, C. P., Hanson, M. A., Sibley, C. P., Johnstone, E. D., Sengers, B. G., Lewis, R. M., Glazier, J. D. Integration of computational modeling with membrane transport studies reveals new insights into amino acid exchange transport mechanisms

Pandemic stress and SARS-CoV-2 infection are associated with pathological changes at the maternal-fetal interface

Introduction The reported effects of SARS-CoV-2 on pregnancy outcomes are conflicting; studies frequently overlook the placenta, which is critical for the health of the mother and infant(s). This study aimed to determine the effect of pandemic stress ± SARS CoV-2 infection on placental histopathology. Methods Women were recruited in Canada (n = 69); France (n = 21) or in the UK (n = 25), between March and October 2020. Historic controls (N = 20) were also included. Placenta and fetal membrane samples were collected rapidly after delivery and were fixed and stained for histopathological analysis. Maternal demographical data and obstetric outcomes were recorded. Results Over 80% of the placentas from SARS-CoV-2+ pregnancies had histopathological abnormalities: predominantly structural (71–86%) or inflammatory (9–22%), depending on geographical location. Excessive fibrin was seen in all sites, whereas deciduitis (Canada), calcifications (UK), agglutinations and chorangiosis (France) predominated in different locations. The frequency of abnormalities was significantly higher than in SARS-CoV-2 negative women (50%, p < 0.05). Demographic and obstetric data were similar in the SARS-CoV-2+ women across all sites - characterised by predominantly Black/Middle Eastern women, and women with elevated body mass index. Discussion Overall, the frequency of placental abnormalities is increased in SARS-CoV-2+ women, but the incidence of placental abnormalities is also higher in SARS-CoV-2- women that gave birth during the pandemic, which highlights the importance of appropriate control groups to ascertain the roles of pandemic stress and SARS-CoV-2 infection on the placenta and pregnancy outcomes

Saving Babies' Lives Project Impact and Results Evaluation (SPiRE):a mixed methodology study

Abstract Background Reducing stillbirth and early neonatal death is a national priority in the UK. Current evidence indicates this is potentially achievable through application of four key interventions within routine maternity care delivered as the National Health Service (NHS) England’s Saving Babies’ Lives care bundle. However, there is significant variation in the degree of implementation of the care bundle between and within maternity units and the effectiveness in reducing stillbirth and improving service delivery has not yet been evaluated. This study aims to evaluate the impact of implementing the care bundle on UK maternity services and perinatal outcomes. Methods The Saving Babies’ Lives Project Impact and Results Evaluation (SPiRE) study is a multicentre evaluation of maternity care delivered through the Saving Babies’ Lives care bundle using both quantitative and qualitative methodologies. The study will be conducted in twenty NHS Hospital Trusts and will include approximately 100,000 births. It involves participation by both service users and care providers. To determine the impact of the care bundle on pregnancy outcomes, birth data and other clinical measures will be extracted from maternity databases and case-note audit from before and after implementation. Additionally, this study will employ questionnaires with organisational leads and review clinical guidelines to assess how resources, leadership and governance may affect implementation in diverse hospital settings. The cost of implementing the care bundle, and the cost per stillbirth avoided, will also be estimated as part of a health economic analysis. The views and experiences of service users and service providers towards maternity care in relation to the care bundle will be also be sought using questionnaires. Discussion This protocol describes a pragmatic study design which is necessarily limited by the availability of data and limitations of timescales and funding. In particular there was no opportunity to prospectively gather pre-intervention data or design a phased implementation such as a stepped-wedge study. Nevertheless this study will provide useful practice-based evidence which will advance knowledge about the processes that underpin successful implementation of the care bundle so that it can be further developed and refined. Trial registration www.clinicaltrials.gov NCT03231007 (26th July 2017

Stillbirth rates, service outcomes and costs of implementing NHS England's Saving Babies' Lives care bundle in maternity units in England: A cohort study.

ObjectiveTo assess implementation of the Saving Babies Lives (SBL) Care Bundle, a collection of practice recommendations in four key areas, to reduce stillbirth in England.DesignA retrospective cohort study of 463,630 births in 19 NHS Trusts in England using routinely collected electronic data supplemented with case note audit (n = 1,658), and surveys of service users (n = 2,085) and health care professionals (n = 1,064). The primary outcome was stillbirth rate. Outcome rates two years before and after the nominal SBL implementation date were derived as a measure of change over the implementation period. Data were collected on secondary outcomes and process outcomes which reflected implementation of the SBL care bundle.ResultsThe total stillbirth rate, declined from 4.2 to 3.4 per 1,000 births between the two time points (adjusted Relative Risk (aRR) 0.80, 95% Confidence Interval (95% CI) 0.70 to 0.91, PConclusionsImplementation of the SBL care bundle increased over time in the majority of sites. Implementation was associated with improvements in process outcomes. The reduction in stillbirth rates in participating sites exceeded that reported nationally in the same timeframe. The intervention should be refined to identify women who are most likely to benefit and minimise unwarranted intervention.Trial registrationThe study was registered on (NCT03231007); www.clinicaltrials.gov