PROJECT SUMMARY Opioids are medically used for safe pain relief and management. However, illicit opioid use has substantially increased across the US in the past decade, with further worsening during the COVID-19 pandemic, leading to a profound impact on human health. Specifically, opioid use disorder (OUD) during pregnancy poses an increased risk of pregnancy-associated maternal morbidity and mortality, fetal growth restriction (FGR) and related complications, neonatal opioid withdrawal syndrome, and long-term neurobehavioral effects. Some of these risks persist despite the use of safer opioids, such as buprenorphine and methadone, medications for OUD (MOUD) patients. Whereas current studies center mainly on transplacental opioid transport to the fetus and the adverse effects of opioids on infants, the direct impact of illicit and prescription opioids on placental development, differentiation, and function are largely unexplored. The placental floating villi mediate maternal- fetal gas exchange, nutrient uptake, waste release immune defense and the production of hormones and extracellular vesicles (EVs). These villi are covered by a layer of multinucleated, terminally differentiated syncytiotrophoblasts (STBs), which forms the feto-placental frontline that is directly exposed to opioids in the maternal blood. Subjacent to this layer are mononucleated, progenitor cytotrophoblasts (CTBs), which replenish the STB layer through the process of differentiation and fusion. Importantly, injuries to the STB and CTB layers are implicated in pregnancy-associated complications, including FGR and stillbirth. Here we seek to investigate opioid-dependent placental injury, focusing on the most critical and unique layer of placental trophoblasts. We will enroll participants with OUD, including illicit opioids and MOUD (buprenorphine, methadone), examine their pregnancy course and their children’s health through the first year postpartum. Using biospecimens from each participant, including maternal plasma and urine across the three trimesters, placental biopsies and fetal cord blood at delivery, we will employ multimodal cutting-edge technologies, including single-cell RNAseq, spatial transcriptomics, protein chip cytometry and placenta EV RNA profiling, and explore the molecular and cellular processes affected by opioids in the maternal-placental-fetal trio- ecosystem. To gain mechanistic insights into the functional changes in gene expression and EV cargo, we will use an array of model systems, including human trophoblast stem cells and cultured primary human trophoblasts, and mechanistically interrogate pathways underlying opioid injury. We will further correlate key molecular signatures with clinical assessment, including maternal gestational disorders, perinatal and infant neurodevelopmental outcomes. Together, our strategic plan, bolstered by our transdisciplinary team, enables us to address critically important knowledge gaps related to human placenta biology in opioid-affected pregnancies.

PROJECT NARRATIVE Our proposal centers on the adverse impact of illicit opioid use during pregnancy and its devastating consequences on the mother, fetus, and the placenta. By integrating multimodal technologies and assessments, including single-cell RNA transcriptomics, spatial transcriptomics and chip-cytometric methods, and analysis of placental extracellular vesicle, we will shed new light on mechanisms underlying opioid- dependent placental dysfunction and diseases during pregnancy and infancy.