Advancing novel therapeutic approaches and a preclinical model for the treatment of preeclampsia and fetal growth restriction: Drug delivery systems

Abstract

Pregnancy complications such as preeclampsia (PE) and fetal growth restriction (FGR) remain major causes of maternal and perinatal morbidity, yet current therapies largely fail to address the underlying placental pathology. Drug delivery systems, particularly RNA-based therapeutics, offer a promising strategy to modulate placental dysfunction while limiting fetal exposure. This thesis aimed to advance the development of placental drug delivery systems for PE and FGR by addressing key translational barriers, combining critical evaluation of a relevant preclinical model with the development of passive and active delivery approaches. Part 1 focused on the Reduced Uterine Perfusion Pressure (RUPP) model as a model of placental ischemia–induced PE and FGR. Through a systematic review and meta-analysis, this work demonstrated that the RUPP model has high face validity for studying the hemodynamic and vascular consequences of placental ischemia, reflecting multiple maternal and fetal features of human disease. However, substantial heterogeneity in reported outcomes and experimental protocols highlighted the need for improved standardization to enhance reproducibility and translational relevance. Importantly, this thesis challenged the view that the RUPP model only reflects late-stage disease. Experimental data showed that acute reductions in uterine blood flow during mid-gestation impair early placental vascular development, partially mimicking disrupted placentation processes characteristic of early-onset PE. while RUPP does not model the etiological first triggers of PE, it does replicate critical consequences of ischemic placenta, offering a valuable tool for studying disease mechanisms and testing potential therapeutics when its limitations are recognized. Part 2 explored passive and active drug delivery strategies targeting the placenta. Passive delivery was investigated using liposomal encapsulation of nitric oxide precursor amino acids (L-arginine and L-citrulline) to overcome rapid systemic clearance. Liposomal delivery improved pharmacokinetics, reduced maternal blood pressure, and increased placental accumulation in the RUPP model, demonstrating proof of concept for placental nutrient supplementation. However, the absence of improved fetal growth underscored the need for further optimization of formulation, dosing, and targeting efficiency. Active delivery strategies focused on lipid nanoparticles (LNPs) functionalized with targeting ligands, particularly VHH nanobodies, to enable placenta- and vasculature-specific delivery of RNA therapeutics such as siRNA. Ex vivo human placental perfusion studies demonstrated enhanced placental uptake of targeted LNPs without transplacental transfer, supporting fetal safety. In vivo screening using a barcoded DNA-LNP library identified nanobody candidates that increased placental accumulation, although subsequent validation suggested that passive uptake still contributes substantially to delivery. These findings highlight both the promise and complexity of active targeting strategies in placental disease. Overall, this thesis demonstrates that effective placental therapeutics require an integrated approach combining robust, well-characterized preclinical models with tailored drug delivery systems. Future progress will depend on deeper molecular characterization of placental cell types, careful evaluation of immunogenicity, and the use of complementary animal and human-relevant models. Together, these advances are critical steps toward translating these technologies from bench to bedside.