Oral Presentation ESA-SRB-APEG-NZSE 2022

Reduced placental (P)RR inhibits trophoblast growth and placental development (#184)

Lachlan Schofield 1 2 , Richard G.S Kahl 1 2 , Jacinta Martin 1 2 , Saije K Morosin 1 2 , Sarah J Delforce 1 2 , Eugenie R Lumbers 1 2 , Kirsty G Pringle 1 2
  1. Hunter Medical Research Institute (HMRI), Newcastle, NSW, Australia
  2. University of Newcastle, Newcastle, New South Wales, Australia

Introduction

The renin-angiotensin system (RAS) is vital for appropriate placental development. The (pro)renin receptor ((P)RR) plays a crucial role in activating the RAS. We have shown that (P)RR promotes trophoblast proliferation, migration, and invasion in vitro. In this study, we assess the role (P)RR plays in placental development in vivo.

 

Methods

GFP-expressing lentiviral packaged gene-constructs were used to specifically knockdown (P)RR expression in the trophectoderm of mouse blastocysts. Zygotes were collected from super-ovulated C57/BL6/CBA-F1 mice and cultured until the blastocyst stage. Following zona pellucida removal, blastocysts were incubated for 6h with either vehicle (no-virus), control virus (vehicle shRNA and GFP;1x108VP/ml), or (P)RR-knockdown virus ((P)RR shRNA and GFP;1x108VP/ml) before being transferred into recipient pseudo-pregnant Swiss CD1 female mice. Fetal and placental tissues were collected and assessed at embryonic days 10 and 18.

(P)RR levels were assessed in the labyrinth zone of day 18 placentae via qPCR and immunoblot. Additionally, stereological merz grid analysis was performed on placental tissue to assess the volumetric distribution of  trophoblasts, fetal capillaries, and the maternal blood space.

 

Results

Embryo viability and the fetal-placental weight ratio were decreased at term in the (P)RR-knockdown group compared with the control groups (P=0.034 and P=0.04, respectively). (P)RR-knockdown successfully reduced (P)RR mRNA and protein levels in the placental labyrinth zone (P=0.002 and P=0.034, respectively).

Trophoblast volume and surface density were decreased in (P)RR-knockdown placentae when compared with the control groups (both, P<0.0001). In contrast, maternal blood space was increased in (P)RR-knockdown placentae (both, P<0.0001). Furthermore, syncytiotrophoblast barrier thickness was reduced in the (P)RR-knockdown placentae (P=0.026).

 

Discussion

Reduced placental labyrinth (P)RR expression decreases placental trophoblast number and total surface area for exchange, thus decreasing trophoblast barrier thickness. Decreasing (P)RR expression also decreases fetal-placental weight. Taken together these data suggest that placental (P)RR is important for placental development and functional capacity.