Placenta-tropic VEGF mRNA-LNPs demonstrate potential for treating pre-eclampsia

Pre-eclampsia, a condition characterized by gestational hypertension, is a leading cause of maternal and fetal morbidity that lacks a clinically approved therapeutic to slow disease progression. Ionizable lipid nanoparticles (LNPs) that can deliver messenger RNA (mRNA) to the placenta represent an attractive treatment option for pre-eclampsia. However, LNP library design is challenging as in vitro LNP delivery can be poorly predictive of in vivo fate. To overcome this problem, University of Pennsylvania researchers used high-throughput LNP barcoding as an in vivo screening approach. This enabled the identification of a placenta-tropic LNP formulation which, when used to deliver vascular endothelial growth factor (VEGF) mRNA to multiple mouse models of pre-eclampsia, alleviated maternal hypertension until the end of gestation with just a single intravenous dose.?

High-throughput in vivo LNP screening identifies a placenta-tropic formulation?

To identify a placenta-tropic LNP formulation, Swingle et al. designed a 98-LNP library, which included the industry standard C12-200 and clinically approved DLin-MC3-DMA ionizable lipids as liver-tropic LNP controls. A lipid phase encapsulating a unique 61 nucleotide DNA barcode (b-DNA) was prepared for each LNP, all of which were then pooled and administered intravenously to non-pregnant and pregnant mice (n=6 biological replicates).?

Following administration, b-DNA was extracted from various tissues for detection of LNP delivery using next-generation sequencing. 52 LNPs were found to mediate significantly greater delivery to the distal placentas than the C12-200 formulation, with results also indicating that LNP delivery to placentas and fetuses was unlikely to vary with their location in the uterine horn. Swingle et al. subsequently used luciferase mRNA to identify LNP 55 as a placenta-tropic formulation, based on findings that included a 30-fold improvement in placental mRNA delivery compared to C12-200 and a 183-fold improvement compared to DLin-MC3-DMA LNP.?

Placental targeting is based on β2-glycoprotein I adsorption?

The mechanism by which LNP 55 enables mRNA delivery to the placenta was investigated by formulating LNP 55 and DLin-MC3-DMA with luciferase mRNA and precoating the LNPs with either β2-glycoprotein I (β2-GPI) or apolipoprotein E (ApoE). β2-GPI is known to promote spleen tropism, which accompanies the placental tropism exhibited by LNP 55, while ApoE is liver-tropic. In vitro testing showed β2-GPI to enhance mRNA expression and promote greater cellular uptake of LNP 55 in both Jurkat and BeWo b30 cells, which respectively model major cell types in the spleen and placenta. These data suggest a role for β2-GPI in placental targeting.?

VEGF mRNA-LNP 55 resolves maternal hypertension in vivo?

The therapeutic application of LNP 55 was evaluated using VEGF mRNA, which was produced via in vitro transcription using a HiScribe T7 High Yield RNA Synthesis kit (NEB) in combination with TriLink’s N1-methylpseudouridine-5′-triphosphate and CleanCap Reagent AG. In both inflammation- and hypoxia-induced murine models of pre-eclampsia, a single intravenous injection of VEGF mRNA LNP 55 alleviated maternal hypertension until the end of gestation. Additional testing showed VEGF mRNA LNP 55 to partially restore the placental vasculature and shift the immune landscape closer to that of healthy mice, as well as reduce serum levels of soluble Fms-like tyrosine kinase-1 (sFlt-1), a pre-eclampsia biomarker.?

Conclusion?

By developing ionizable LNPs that enable placental mRNA delivery with a simple intravenous injection, Swingle et al. have opened up opportunities to treat pre-eclampsia and other placental disorders during pregnancy. Although further work is required to bring this technology to patients, this study promises to broaden the therapeutic application of LNPs for many other conditions.?

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Article reference: Swingle KL, Hamilton AG, Safford HC, et al. Placenta-tropic VEGF mRNA lipid nanoparticles ameliorate murine pre-eclampsia. Nature 637, 412–421 (2025). https://dx.doi.org/10.1038/s41586-024-08291-2?