Maternal-Fetal Cholesterol Transport Mechanisms

Cholesterol is indispensable for fetal development, serving as a structural component of cell membranes and a precursor for steroid hormone synthesis. Maternal-to-fetal transfer occurs across the placental barrier, where specialised trophoblast cells mediate uptake, intracellular trafficking and efflux. Uptake is primarily driven by low-density lipoprotein receptor (LDLR)-mediated endocytosis of LDL particles and by scavenger receptor class B type I (SR-BI)-mediated selective cholesterol uptake from high-density lipoproteins (HDL). Once internalised, cholesterol may be esterified for storage, converted to steroid hormones in mitochondria, or effluxed back to maternal or fetal circulations via ATP-binding cassette transporters such as ABCA1 and ABCG1. This dynamic exchange supports placental steroidogenesis and fine-tunes fetal lipid supply. Dysregulation of these pathways underlies conditions such as maternal supraphysiological hypercholesterolaemia and pre-eclampsia, where altered receptor expression, impaired efflux and endothelial dysfunction contribute to increased cardiovascular risk for mother and offspring. Unravelling these mechanisms offers avenues for therapeutic intervention to safeguard fetal growth and long-term health.

Research from Nature Portfolio

Recent studies of primary human trophoblasts have revealed that maternal supraphysiological hypercholesterolaemia diminishes both LDL and HDL uptake by syncytiotrophoblasts, despite unchanged receptor abundance, and alters cholesterol efflux patterns. Increased ABCA1 expression contrasts with reduced ABCG1 and SR-BI levels, leading to elevated free cholesterol in trophoblasts and potential perturbation of maternal-to-fetal lipid delivery. Complementary work on placental secretory function demonstrates that the syncytiotrophoblast actively secretes apoA-I and apoE, with a directional bias favouring the maternal circulation. Placental cells release higher amounts of these anti-atherogenic apolipoproteins than hepatocytes, implicating the placenta in systemic cholesterol homeostasis and suggesting a protective mechanism against lipid-induced vascular damage.

Maternal-Fetal Cholesterol Transport Mechanisms publication trend

The graph below shows the total number of articles in maternal-fetal cholesterol transport mechanisms across all publications each year (not limited to Nature Index journals).

Technical terms

Syncytiotrophoblast: Multinucleated outer layer of the placental villus responsible for nutrient and gas exchange.

ABCA1/ABCG1: ATP-binding cassette transporters that export cellular cholesterol to lipid-poor apolipoproteins and HDL.

SR-BI: Scavenger receptor class B type I, a membrane protein mediating selective uptake of cholesterol from HDL.

Efflux: Active transport process by which cells export excess cholesterol to extracellular acceptors.

Hypercholesterolaemia: Elevated cholesterol levels in the maternal circulation that can influence placental transport dynamics.

References

1. Maternal Supraphysiological Hypercholesterolemia Is Accompanied by Shifts in the Composition and Anti-Atherogenic Functions of Maternal HDL along with Maternal Cardiovascular Risk Markers at Term of Pregnancy. Antioxidants (2023).
2. Cholesterol uptake and efflux are impaired in human trophoblast cells from pregnancies with maternal supraphysiological hypercholesterolemia. Scientific Reports (2020).
3. Placental secretion of apolipoprotein A1 and E: the anti-atherogenic impact of the placenta. Scientific Reports (2019).
4. Evidence for hypoxia‐induced dysregulated cholesterol homeostasis in preeclampsia: Insights into the mechanisms from human placental cells and tissues. The FASEB Journal (2024).
5. Physiology and Pathophysiology of Steroid Biosynthesis, Transport and Metabolism in the Human Placenta. Frontiers in Pharmacology (2018).