Development of novel radiolabels for long-term in vitro stem cell tracking

Al-Luaibi, Reem 2024. Development of novel radiolabels for long-term in vitro stem cell tracking. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Introduction: This thesis has focussed on the development of a novel cell labelling technology that has longer-term potential for deep tissue imaging of cells over a protracted time course. These investigations have centred on a specific radiolabel, namely the separation and complexation of a Positron Emission Tomography (PET) isotope of vanadium,48V, which has a long half-life (~16 days; potential analysis for many months). Methods: 48V was produced in a cyclotron from a Ti disc, utilising a novel methodology involving an electrochemical technique developed for the dissolution of the 48V containing Ti at room temperature under mild acidic conditions. The 48V was extracted from aqueous solutions using various strategies, beginning with a variety of ligands but subsequently focussing on the Salen ligands. Biological assays (OranguTM for cell proliferation; 2D scratch assay for wound repopulation) were utilised to evaluate their cellular cytotoxicity. To finesse the large-scale radiolabelling of cells, labelling of attached cells and cells in solution was investigated. PET/computed tomography (CT) scanning was utilised to explore minimum labelled cell detection limits. Results: The non-radioactive ligands L1 -L 4 exhibited higher extraction percentages compared to L5 -L 6 , indicating their potential as extractants for vanadium. Assessment of the cytotoxicity of the non-radiolabelled ligands/complexes on oral stem cells, revealed that for the ligands only very high concentrations were cytotoxic whereas for the complexes there was a broader range of cytotoxicity. Choosing a low concentration (15.6µg/mL; no effect of cell proliferation) of the ligands/complexes had no effect on cellular wound repopulation in vitro, whereas as a high concentration (250µg/mL; detrimental effect on cell proliferation) prevented cell migration. Investigations into radiolabelling of the complexes revealed the best results for L 5 and L6 which were able to extract 48V with 20% and 57% efficiency respectively. Assessment of cell proliferation demonstrated that cells could tolerate up to 0.00139 MBq of [VOL5 (Cl)] without showing significant reductions in viability but this was even greater for [VOL6 (Cl)] – cells could tolerate up to 0.00556 MBq of 48V. [VOL6 (Cl)] also proved the better complex in respect of allowing wound repopulation. Experimentation with [VOL6 (Cl)] and cell labelling in solution demonstrated that 68% of the activity could be retained by the cells and that they appeared healthy after five weeks. PET/CT scanning detected radiolabel in cell numbers as low as 6000 cells. Conclusions: 48V Salen complexes were successfully synthesised and their III cellular biocompatibility demonstrated. This represents the first example of 48V labelling of stem cells opening up the possibility of long-term tracking for regenerative medicine.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Chemistry
Date of First Compliant Deposit:	20 June 2024
Last Modified:	20 Jun 2024 10:40
URI:	https://orca.cardiff.ac.uk/id/eprint/169937

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