Context: Fetal supply of maternally derived fatty acids requires lipase-mediated hydrolysis of lipoprotein-borne triglycerides and phospholipids at the placental surface.

Objective: To test the hypothesis that members of the triglyceride lipase gene (TLG) family are expressed in the human placenta at the materno-placental (syncytiotrophoblast) and feto-placental (endothelial cells) interface and that their expression is altered in pregnancy pathologies.

Design and Setting: Expression of TLG family members in primary placental cells (trophoblast and endothelial cells) and tissues of first trimester and term human placenta was analyzed by microarrays, RT-PCR, Western blotting and immunohistochemistry. Their expression was compared between normal pregnancies and those complicated with intrauterine growth-restriction (IUGR).

Participants: Women with uncomplicated pregnancies and pregnancies complicated by IUGR.

Results: Endothelial Lipase (EL) and Lipoprotein Lipase (LPL) were the only lipases among the TLG family expressed in key cells of the human placenta. In first trimester EL and LPL were expressed in trophoblasts. At term EL was detected in trophoblasts and endothelial cells, while LPL was absent in these cells. Both lipases were found at placental blood vessels, EL in vascular endothelial cells and LPL in the surrounding smooth muscle cells. In total placental tissue EL expression prevails in first trimester and at term. Compared with normal placentas, EL mRNA was decreased (30%; p<0.02), while LPL mRNA expression was increased (2.4-fold; p < 0.015) in IUGR.

Conclusion: EL is the predominant TLG family member in the human placenta present at both interfaces. EL and LPL are dysregulated in IUGR.