Spatiotemporal coordination at the maternal-fetal interface promotes trophoblast invasion and vascular remodeling in the first half of human pregnancy

Abstract

Beginning in the first trimester, fetally derived extravillous trophoblasts (EVTs) invade the uterus and remodel its spiral arteries, transforming them into large, dilated blood vessels that lack smooth muscle and are partially lined with EVTs instead of vascular endothelium. Several mechanisms have been proposed to explain how EVTs coordinate with decidual cells to promote a tissue microenvironment conducive to spiral artery remodeling (SAR). However, it remains a matter of debate which immune and stromal cell types participate in these interactions, how this process evolves with respect to gestational age, and which anatomic routes are the predominate path of EVT invasion in humans. To elucidate this complex interplay, we used multiplexed ion beam imaging by time of flight with a 37-plex antibody panel to build the first spatio-temporal atlas of the human maternal-fetal interface in the first half of pregnancy at single-cell resolution. We analyzed ~500,000 cells and 588 spiral arteries within intact decidua from 66 patients between 6-20 weeks of gestation. Using custom machine learning algorithms for cell segmentation and classification, we evaluated the spatial distributions and phenotype of 20 maternal and five EVT populations with respect to gestational age and SAR. Gestational age substantially influenced the frequency of most maternal immune and stromal cells, with tolerogenic subsets expressing CD206, CD163, TIM-3, Galectin-9, and IDO-1 preferentially enriched at later time points. In contrast, SAR progression, and not gestational age, preferentially correlated with local invasion of EVTs. Lastly, by comparing spatial co-occurrence and phenotype of decidual interstitial, perivascular and intravascular EVTs with respect to SAR progression, we developed a statistical model suggesting an intravasation mechanism as the predominant route of EVT invasion in superficial decidua. Taken together, these results support a coordinated model of decidualization in which increasing gestational age drives a transition in maternal decidua towards a tolerogenic niche conducive to locally regulated, EVT-dependent SAR.

Monosodium glutamate (MSG) perturbs trophoblast differentiation and invasion program through a ROS-mediated pathway

“…Trophoblast invasion is a highly coordinated process that involves the remodeling of maternal vasculature and invasion of the endometrium. The success of this process heavily depends upon the orchestrated effort of pro and anti-invasive proteins in a tempo-spatial manner 65,66 . MSG tilts this delicate balance, thereby perturbing the trophoblast invasion and differentiation program.…”

Robust phenotyping of highly multiplexed tissue imaging data using pixel-level clustering

“…The decidua MIBI-TOF dataset was previously described in Greenbaum, Averbukh, Soon et al 34 Imaging parameters and pre-processing methodology (background subtraction, denoising) are described in the manuscript. To compare the full dataset against a subset dataset, we randomly subsampled 10% of the total number of pixels for each replicate run.…”

“…We hypothesized that for large datasets, a random subset of pixels is a representative sample and provides the SOM with enough information to generate accurate clusters. Using a large dataset of around 800 million total pixels 34 , we trained the SOM using a random 10% subset of pixels (Supplementary Fig. 10).…”

Single-cell Spatial Proteomic Imaging for Human Neuropathology

“…Here, we present a new generation of single-cell, spatial proteomic imaging, and analytical tools to capture the underlying cellular and phenotypic diversity in intricate neural tissues. In place of fluorophores and lasers, we employed multiplex ion beam imaging by time of flight (MIBI-TOF) mass spectrometry (MS) that has been used previously to study various archival human tissue types from tumors to placenta and granulomas in infectious disease (Greenbaum et al, 2021; Keren et al, 2018; Liu et al, 2021; McCaffrey et al, 2022; Risom et al, 2022). Based on secondary ion mass spectrometry (SIMS), MIBI-TOF images antigens targeted by antibodies labelled with elemental isotopic mass reporters that are spatially quantified with nanometer resolution.…”