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Title: The use of non-ionic surfactant vesicles to prevent radiocontrast media-associated damage
Author: Donaghey, Rachel
ISNI:       0000 0004 7972 2654
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2018
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Radiocontrast media administered during routine bio-imaging procedures represents a cause of hospital-associated, acute kidney injury or contrast-induced nephropathy. The exact mechanism of disease is not well characterised, although, a number of existing theories exist. The absence of adequate preventative or treatment measures poses a risk to poorly defined, susceptible patients. The initial goal is to formulate and characterise a novel iohexol-non-ionic surfactant vesicle (IOX-NIV) delivery system in line with FDA recommendations. This work adds to current knowledge of IOX-associated cytotoxicity and its influence on vessel function. IOX-NIVs were prepared using a 3: 3: 1 mol. ratio of surfactant VIII/ cholesterol/ dicetyl phosphate using high shear homogenisation. Dynamic light scattering was used to determine physical characteristics including size, polydispersity index (PDI) and particle distribution. Phase analysis light scattering was used to measure surface charge. NIVs were purified using ultracentrifugation prior to the quantification of IOX encapsulation efficiency and release using high performance liquid chromatography. Toxicity of IOX, empty-NIV and IOX-NIV was tested on renal and vascular cells using assays including the Resazurin metabolic indicator assay, thymidine-incorporation, CellTox Green™ assay and ApoToxGlo™ assay. IOX-NIVs were reproducibly produced (n = 3) with an average size of 204 ± 24 nm, low PDI of 0.13 ± 0.04, surface charge of -26 ± 1 mV and EE of 22 ± 3%. Vesicle processing through ultracentrifugation or sterile filtration did not significantly alter physical properties. IOX-NIVs maintained physicochemical stability throughout 37 weeks storage at 4 and 25 °C. A time- and temperature-dependent change in IOX-NIV colour was observed prior to an increase in size (1671 ± 1498 nm) and PDI (0.7 ± 0.31), followed by a loss in negativity (-15 ± 3 mV) and EE (4 ± 3 %), specifically at temperatures of 37 and 50°C (p < 0.001). Hydrated IOX-NIVs displayed a typical 'burst' release profile under physiological conditions in vitro, whereby 73 ± 2 % of IOX was released after 48 h. IOX exposure led to decreased renal and vascular metabolism where cells underwent rounding and a loss in adherence, features of which express similarities to cells undergoing apoptosis or as a result of exposure to hyperosmolar agents. In addition, IOX inhibited receptor-independent vasoconstriction, while IOX-NIV treated groups expressed a response similar to the control. Characterisation of IOX-NIVs showed the synthesis of a stable system with physical features desirable for administration as an intravenous contrast agent. IOX-NIVs expressed relatively low toxicity in vitro. Overall, IOX-NIV show great potential as a clinically compatible product, however, future in vivo safety and efficacy studies are required.
Supervisor: Ferro, Val ; Mullen, Alex Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral