archives@tulane.edu / Placental insufficiency is a term used to describe the reduced transport of gases and nutrients across the placenta. As a result of placental insufficiency, preeclampsia and intrauterine growth restriction (IUGR) can develop. Preeclampsia is diagnosed by the onset of high blood pressure and proteinuria after 20 weeks of gestation and complicates 2-8% of all pregnancies. Having preeclampsia is also a risk-factor for developing IUGR, which is defined as an estimated fetal weight below the 10th percentile. These conditions can negatively impact the immediate outcomes of pregnancy by reducing placental perfusion and causing placental ischemia.
Currently, there is a need for reliable, inexpensive tools that can monitor placental function bedside. Spectral photoacoustic (PA) imaging presents a solution to this need.
Photoacoustic imaging uses nanosecond light pulses to excite photoabsorbers within tissue. These photoabsorbers undergo thermal expansion and relaxation, emitting a pressure wave that can then be read by an ultrasound transducer. In this study, the photoabsorbers of interest include hemoglobin, deoxyhemoglobin, and indocyanine green (ICG).
Various ultrasound contrast agents are available for clinical use; however, indocyanine green-loaded nanodroplets present various advantages over other contrast agents due to their smaller size and longer in vivo stability. Upon laser irradiation, these droplets experience a liquid-to-gas phase change and provide improved photoacoustic contrast.
These nanodroplets are a focus of this work, as they have the ability to be targeted to specific tissues and can act as oxygen carriers. In this case, they are targeted to folate receptor α, which is highly expressed on the placenta. Thus, the first aim of this work is to validate the folate receptor α targeting mechanism using an in vitro tissue phantom model. As oxygen carriers, they are able to release oxygen once activated by the laser. The second aim is to validate localized oxygen delivery via these nanodroplets by using multiplex imaging to determine ICG accumulation and measure their effect on placental oxygen saturation in vivo.
Another contrast agent, 2-Deoxy-D-Glucose (2DG-ICG), could be utilized in conjunction with photoacoustic imaging as a tool to monitor glucose transport, a major indicator of placental function. By conjugating ICG to 2DG, a glucose analog, it is possible to target glucose transporter 1, which is the primary glucose transporter on the placenta. The final aim of this work is to determine the feasibility of using 2DG-ICG as an indicator of glucose transport in the placenta using an in vitro model. / 1 / Sarah Nwia
| Identifer | oai:union.ndltd.org:TULANE/oai:http://digitallibrary.tulane.edu/:tulane_120416 |
| Date | January 2020 |
| Contributors | Nwia, Sarah (author), Bayer, Carolyn (Thesis advisor), School of Science & Engineering Biomedical Engineering (Degree granting institution) |
| Publisher | Tulane University |
| Source Sets | Tulane University |
| Language | English |
| Detected Language | English |
| Type | Text |
| Format | electronic, pages: 71 |
| Rights | No embargo, Copyright is in accordance with U.S. Copyright law. |
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