Investigating the Impact of Hypoxia and Syncytialization on Lipid Nanoparticle-Mediated mRNA Delivery to Placental Cells

AbstractPlacental dysfunction leads to pregnancy-related disorders that affect up to 15% of pregnancies. Several of these, such as preeclampsia, are symptomatically managed but have no curative treatments other than preterm delivery. Placental dysfunction arises from improper placental development, leading to restricted blood vessel formation and a hypoxic placental microenvironment. The development of placental therapeutics is challenging due to the complex physiology that enables the placenta to have precise control over endocytosis and transport. Here, we use a simple culture system that combines hypoxia and trophoblast syncytialization to model the functional syncytiotrophoblast layer of the placenta under hypoxic stress. Using this model, we evaluate the impact of hypoxia on lipid nanoparticle (LNP)-mediated mRNA delivery. Our data shows that hypoxia hinders syncytiotrophoblast formationin vitro. Despite this, LNP delivery to syncytiotrophoblasts increases protein translation and secretion, particularly under hypoxic conditions. Further, we show delivery of a therapeutic mRNA, placental growth factor (PlGF), to syncytiotrophoblasts in hypoxia, which restored diminished PlGF levels back to normoxic controls. These findings provide an LNP platform for efficient mRNA delivery to hypoxic trophoblasts and demonstrate the importance of considering hypoxia towards the development of drug delivery platforms for placental therapeutics.Translational Impact StatementThis study investigates lipid nanoparticle (LNP)-mediated mRNA delivery to placental cells cultured in a simple hypoxia model, simulating the microenvironment of the placenta during pregnancy complications such as preeclampsia. We provide insights essential for developing LNP drug delivery platforms for treating disorders of the placenta. These findings will guide future design of LNP-based treatments for delivery to the diseased, hypoxic placenta, minimizing systemic exposure and improving outcomes in maternal and fetal health for conditions lacking effective, targeted interventions.