Examining the Role of Placental-derived MicroRNA Secretions in Response to Gestational Hypoxia on Foetal Neurodevelopment

  • Ashleigh L Bignell

Student thesis: Master's ThesisMaster of Science (MSc)

Abstract

Neurological disorders affect 1 in 6 individuals worldwide, yet their complex aetiology cannot be determined by classic Mendelian genetics alone and is thought to be the result of multifaceted epigenetic regulation in utero. Utilising the premise of the ‘Advanced Foetal Programming Hypothesis’, our research aim was to uncover the mechanism behind intrauterine gestational hypoxia as seen in obstetric complications in the aetiology of neurological disease progression. We explore microRNAs, small noncoding RNA molecules (19-22 nt), as potential biological factors released from the perturbed placental barrier as signalling molecules which can elicit altered foetal programming.

In order to replicate the effects of gestational hypoxia in utero, we exposed an, in vitro trophoblastic cell line (BeWo), ex vivo (human) and ex vivo (rodent) placental barrier model to hypoxic conditions and examined the release of miRNAs into conditioned media. Qualitative and quantitative analysis of the miRNAs was performed using a small RNA Agilent bioanalyser followed by NanoString technology. Bioinformatics to determine predicted target genes of differentially expressed miRNAs was implemented using mirPath v3.0 platform across the experimental parameters to determine if there was enrichment in relative neurological pathways.

We observed differential miRNA expression profiles in the conditioned media obtained across the placental models exposed to oxidative stress. Our model of gestational hypoxia resulted in increased expression of neurodevelopmental-associated-miRNAs; miR-132, miR-34a, miR-520, miR-124 and miR149 to be released from the placental barrier towards the foetal circulation. Furthermore, the direct application of an antioxidant drug-loaded nanoparticle treatment (MQ-NP) to the placental barrier was found to partially reverse the expression of differentially expressed miRNAs under conditions of gestational hypoxia which were found to be enriched in two neurological pathways, axon guidance and TGF-β signalling.

With a view to bridge the gap in knowledge surrounding the mechanisms behind oxidative stress and the prevalence of neurological disorders, our findings provide a platform for exploring the potential role for oxidative-stress induced miRNAs to act as signalling molecules released from the perturbed placenta into foetal circulation where they can elicit post-transcriptional regulation upon neuropathological pathways.
Date of Award23 Jan 2020
Original languageEnglish
Awarding Institution
  • The University of Bristol
SupervisorC P Case (Supervisor), Claire M Perks (Supervisor), James B Uney (Supervisor) & Tudor A. Fulga (Supervisor)

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