dc.contributor.advisor |
Lau, Sandy |
|
dc.contributor.advisor |
Barrett, Carolyn |
|
dc.contributor.author |
Cheung, Sharon Wing Yin |
|
dc.date.accessioned |
2021-12-14T02:34:15Z |
|
dc.date.available |
2021-12-14T02:34:15Z |
|
dc.date.issued |
2021 |
en |
dc.identifier.uri |
https://hdl.handle.net/2292/57789 |
|
dc.description |
Full Text is available to authenticated members of The University of Auckland only. |
en |
dc.description.abstract |
Introduction: Maternal cardiovascular adaptations are essential for a successful pregnancy
and are characterised by a large decrease in systemic vascular resistance, complementing the
increases in cardiac output and blood volume. Both maternal and placental factors are thought
to contribute to these changes. Throughout gestation, placental extracellular vesicles (EVs) are
extruded directly into the maternal circulation, and EVs are known mediators of cell
communication. The anatomy of the placenta allows three types of EVs to be extruded,
classified by their size (macro-, micro-, and nanovesicles). We hypothesised that first-trimester
human placental EVs contribute to the decrease in systemic vascular resistance that occurs in
the first-trimester of pregnancy.
Aims:
1. To systematically review the current literature on the effects of EVs on vascular tone.
2. To determine the effects of first-trimester placental EVs on maternal vascular responses
to vasoactive stimuli and whether the effect is time-dependent.
Methods: Placental EVs were isolated from the conditioned media of first-trimester placental
explants via differential centrifugation to obtain each type of EV. Placental EVs were
administered into time-mated pregnant mice via tail-vein injection, and after 30-minutes or 24
hours, mesenteric arteries were collected for the wire myography experiments. Dose-response
curves to vasoconstrictors (phenylephrine, angiotensin II and endothelin-1) and vasodilators
(acetylcholine and sodium nitroprusside) were generated from the wire myography
experiments.
Results: A systematic review of the literature demonstrated that EVs could affect vascular tone
regardless of the origin of the EVs and the recipient species. In agreement, all three types of
placental EVs can affect the vessel responsiveness to vasoconstrictors and vasodilators after
30-minutes and 24 hours of exposure. Placental EVs had time-dependent effects, appearing
pro-constrictive and anti-dilatory at 30-minutes, whereas, after 24 hours, the effect was anticonstrictive
and pro-dilatory.
Discussion: First-trimester placental EVs can induce anti-constrictive and pro-dilatory effects
after 24 hours of exposure, consistent with the decrease in systemic vascular resistance seen in
the first-trimester of pregnancy. The time-dependent nature suggests that these effects are not
immediate but develop within the vasculature over time. Placental EVs may be one of the
contributors to maternal cardiovascular changes during normal pregnancy. |
|
dc.publisher |
ResearchSpace@Auckland |
en |
dc.relation.ispartof |
Masters Thesis - University of Auckland |
en |
dc.relation.isreferencedby |
UoA |
en |
dc.rights |
Restricted Item. Full Text is available to authenticated members of The University of Auckland only. |
en |
dc.rights |
Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. |
|
dc.rights.uri |
https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm |
en |
dc.title |
The effects of first-trimester placental extracellular vesicles on maternal vascular tone |
|
dc.type |
Thesis |
en |
thesis.degree.discipline |
Physiology |
|
thesis.degree.grantor |
The University of Auckland |
en |
thesis.degree.level |
Masters |
en |
dc.date.updated |
2021-11-19T00:07:30Z |
|
dc.rights.holder |
Copyright: the author |
en |
dc.identifier.wikidata |
Q112954994 |
|