Differences in bovine placentome blood vessel density and transcriptomics in a mid to late-gestating maternal nutrient restriction model

Authors: REID, DANA - Mississippi State University; BURNETT, DERRIS - Mississippi State University; CONTRERAS-CORREA, ZULLY - Mississippi State University; LEMLEY, CALEB - Mississippi State University

Submitted to: Placenta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/2021
Publication Date: 1/1/2022
Citation: Reid, D.S., Burnett, D.D., Contreras-Correa, Z.E., Lemley, C.O. 2022. Differences in bovine placentome blood vessel density and transcriptomics in a mid to late-gestating maternal nutrient restriction model. Placenta. 117:122-130. https://doi.org/10.1016/j.placenta.2021.12.004.
DOI: https://doi.org/10.1016/j.placenta.2021.12.004

Interpretive Summary: Despite decades of research, much remains to be elucidated about pregnancy in livestock. Specifically, questions surrounding fetal and placental development in relation to offspring health and viability. Cattle have multiple placental contact sites and limited data exists on the variation and contribution of each site to developmental programming. Therefore, a major gap in knowledge exists in cattle placental performance, which contributes significantly to offspring growth and development, an important economic trait in cattle production. Researchers in the Animal and Dairy Science Department are characterizing the cow placenta during a period of intensive growth and development of the fetus. In this study different placentomes were collected and a novel technique was utilized to examine variation in the different sites of placental attachment within cow and across nutritional treatments. We observed limited variation of placental capacity within animal; however, compensatory responses were apparent in cows that were nutrient restricted during their pregnancy.

Technical Abstract: Prenatal development is reliant on a functioning placenta, which can be influenced by maternal nutrition. Moreover, the variation in cotyledonary capacity within an animal has not been fully examined to date. Therefore, the purpose of this study was to determine the effect of (1) placentome size and (2) maternal nutrient restriction on molecular, microscopic, and macroscopic features of bovine placentomes during late gestation. Pregnant cows (n = 6) were placed into one of 2 treatments: CON (100% NRC) vs RES (60% of NRC) from day 140 until slaughter at day 240 of gestation. Placentomes of various sizes were perfused to assess macroscopic blood vessel density of the cotyledon. Microscopic imaging and RNA extraction for sequencing was performed. Macroscopic blood vessel density relative to placentome weight was not different (P = 0.42) among small, medium, or large placentomes. Cotyledonary microscopic blood vessel number, area, and perimeter was increased (P < 0.005) in high versus low blood perfusion areas. Differential expressed gene (DEG) analysis showed 209 upregulations and 168 downregulations in the RES group (P = 0.0001). Gene Ontology (GO) analysis showed that downregulated enriched terms were involved in blood vessel and mesenchymal stem cells development, whereas upregulated enriched terms were involved with translation and ribosomal function. This study demonstrates that placentome function is uniform across various placentome sizes within an animal. However, microscopic heterogeneity exists within each placentome. Maternal nutrient constraints alter placental transcriptomics which may yield compensatory mechanisms involved in nutrient transport including increased perimeter.