Department of Obstetrics and Gynecology, Chang Gung Memorial Hospital, Linkou medical center and College of Medicine, Chang Gung University, Taoyuan, Taiwan.
BMC Pregnancy Childbirth. 2021 Mar 27;21(1):260. doi: 10.1186/s12884-021-03744-2.
In monochorionic twin (MC) gestations with selective fetal growth restriction (FGR), the discordant fetal growth usually is due to unequal placental sharing. Glucose, which is essential for oxidative metabolism in the growing placenta and fetus, is transferred from maternal blood by facilitated carrier-mediated diffusion via glucose transporters (GLUTs). How the GLUTs expression varies in the two placenta territories manifests discordant perfusion in MC twin pregnancy with selective FGR is unknown. This study evaluates the human placental GLUT1 and GLUT3 gene expression in MC twin gestations with selective FGR.
MC twin pregnancy with selective FGR was defined as the presence of inter-twin birth weight discordance of > 25% and the smaller twin with a birth weight less than the 10th percentile in third trimester. Fetal umbilical artery Doppler was checked within 1 week before delivery in the two fetuses. An abnormal umbilical artery Doppler was defined as persistently absent or reverse end-diastolic flow (UA-AREDF). GLUT1, GLUT3 and HIF-1α gene expression were assayed in each twin's placental territories. The inter-twin placental gene expression ratio was calculated as the placenta GLUTs or HIF-1α expression level of the selective FGR twin divided by expression level of the appropriate-for-gestational-age (AGA) cotwin. Higher gene expression ratio means elevated gene expression in the selective FGR twin's placenta territory compared to AGA twin's placenta territory.
15 MC twin gestations with selective FGR including nine with normal (group 1) and six with abnormal selective FGR twin UA Doppler (group 2) were included into this study. The GLUT3 and HIF-1α gene expression are significantly elevated in selective FGR twin's placenta territory in group 2 twin pregnancies (mean gene expression ratio as 2.23 and 1.65, p values as 0.015 and 0.045, respectively), but not in in group 1 twin pregnancies.
The upregulation of placental GLUT3 gene expression in selective FGR fetus with abnormal UA Doppler may be due to hypo-perfusion which is mediated by up -regulation of HIF-1α gene expression.
在单绒毛膜双胎（MC）妊娠中，选择性胎儿生长受限（FGR）通常是由于胎盘不均等分配导致的。葡萄糖是生长中的胎盘和胎儿氧化代谢所必需的，它通过葡萄糖转运体（GLUTs）介导的易化扩散从母体血液中转运。在 MC 双胎妊娠中，选择性 FGR 时两个胎盘区域的 GLUTs 表达如何变化尚不清楚。本研究评估了 MC 双胎妊娠中选择性 FGR 胎儿胎盘 GLUT1 和 GLUT3 基因的表达。
MC 双胎妊娠中选择性 FGR 的定义为两胎儿间出生体重差异>25%，且小胎儿在孕晚期的出生体重低于第 10 百分位。在分娩前 1 周内，对两个胎儿的胎儿脐动脉多普勒进行了检查。异常的脐动脉多普勒定义为持续无舒张末期血流（UA-AREDF）或反向舒张末期血流。在每个胎儿的胎盘区域检测 GLUT1、GLUT3 和 HIF-1α 基因的表达。计算双胎胎盘基因表达比，即选择性 FGR 胎儿胎盘 GLUTs 或 HIF-1α 表达水平除以相应的适于胎龄（AGA）同卵双胎的表达水平。较高的基因表达比值表示与 AGA 同卵双胎胎盘相比，选择性 FGR 胎儿的胎盘区域基因表达升高。
本研究共纳入 15 例 MC 双胎妊娠中选择性 FGR，其中 9 例脐动脉多普勒正常（组 1），6 例异常（组 2）。在组 2 双胎妊娠中，选择性 FGR 胎儿的胎盘 GLUT3 和 HIF-1α 基因表达明显升高（平均基因表达比值分别为 2.23 和 1.65，p 值分别为 0.015 和 0.045），而在组 1 双胎妊娠中则无此变化。
在伴有异常 UA 多普勒的选择性 FGR 胎儿中，胎盘 GLUT3 基因表达的上调可能是由于低灌注引起的，这种低灌注是由 HIF-1α 基因表达的上调介导的。
