Identification of modifications to the maternal-fetal interface transcriptome associated with placental insufficiency and a novel gene therapy for the treatment of fetal growth restriction (Subplacenta)

The etiology of fetal growth restriction (FGR) is multifactorial, although many cases often involve placental insufficiency. Placental insufficiency is associated with inadequate trophoblast invasion that results in an environment with high resistance to blood flow, decreased availability of nutrients to the placenta, and increased hypoxia. Despite accumulating knowledge linking inadequate trophoblast invasion with placental insufficiency and FGR, current treatment options are limited to iatrogenic delivery, usually preterm. We have developed a non-viral, polymer-based nanoparticle that facilitates transient human insulin-like 1 growth factor (hIGF1) gene delivery specifically to placental trophoblast. Using the established guinea pig maternal nutrient restriction (MNR) model of placental insufficiency and FGR, the aim of the study was to identify novel pathways in the sub-placenta/decidua that will provide insight into the underlying mechanism driving FGR, and may be corrected with hIGF1 nanoparticle treatment. Pregnant guinea pig dams underwent ultrasound-guided sham or hIGF1 nanoparticle treatment at mid-pregnancy, and sub-placenta/decidua tissue was collected 5 days later. Transcriptome analysis was performed using RNA Sequencing on the Illumina platform. Histological assessment of the sub-placenta/decidua demonstrated fewer maternal spiral arteries lined by trophoblast in the MNR sub-placenta/decidua which was associated with downregulation of genes involved in epithelium development and the regulation of cell migration. hIGF1 nanoparticle treatment results in marked changes to transporter activity in the MNR + hIGF1 sub-placenta/decidua when compared to sham MNR. Under normal growth conditions however, hIGF1 nanoparticle treatment in Control + hIGF1 sub-placenta/decidua was associated with downregulation of kinase signaling and increased proteolysis indicative of homeostasis. Overall, this study identified changes to the sub-placenta/decidua transcriptome that likely result in inadequate trophoblast invasion and that contribute to placental insufficiency. Additionally, this study has increased our understanding of pathways that hIGF1 nanoparticle treatment acts on in order to restore or maintain appropriate placenta function. Overall design: Female (dams) Dunkin-Hartley guinea pigs were assigned to either the control diet group (n = 6) or MNR diet group (n = 7). Control dams were provided food and water was ad libitum; MNR dams were provided water ad libitum however, food intake was restricted to 70% per kilogram body weight of the Control group. At GD30-33, dams underwent an ultrasound-guided, transuterine, intra-placental injection of either sham or hIGF1 nanoparticle. Dams were sacrificed five (GD35-38) days after hIGF1 nanoparticle treatment. Sub-placenta/decidua tissue from two fetuses per litter (one female and one male) were blunt dissected away from the rest of the maternal-fetal interface and snap-frozen in liquid nitrogen for RNA extraction. RNA-Seq Libraries for each gender and experimental group were generated using the Illumina Stranded mRNA Prep Kit. RNA-Seq Libraries were sequenced using the Illumina NovaSeq platform.