In vivo tracking of Cardiac Progenitor Cells following myocardial infarction

Abstract

Following a myocardial infarction (MI), various cell therapies have demonstrated reparative potential with moderate amelioration of cardiac function in vivo. Cell engraftment and survival in the damaged heart have been poor leading to the postulation that the reparative potential of the transplanted cells is their secretome, also referred to as the ‘paracrine effect’. The aim of this PhD research project is to develop and assess the ability to non-invasively track, using whole body multimodal imaging, transplanted human cardiac progenitor cells (CPCs) in vivo following myocardial infarction. This enabled the in vivo quantification of (i) the distribution of administered CPCs, (ii) their potential redistribution, and, importantly, (iii) their survival at the target site.

CPCs were lentivirally transduced with the human sodium iodide symporter fused to green fluorescent protein (NIS-GFP) and FACS purified to generate a homogenous population of traceable CPCs (NIS-GFP CPCs) using radionuclide imaging. In vitro characterisation experiments of NIS-GFP CPCs demonstrated the stable expression of the reporter and the functional uptake of ^99mTcO4-. The detection of NIS-GFP CPCs both in vitro and in vivo was validated using imaging phantoms and following intramuscular injection into healthy NSG mice, respectively. NIS-GFP CPCs were successfully tracked in vivo using NIS-afforded ^99mTcO4- SPECT/CT imaging following intramyocardial and intravenous administration in MI-mice. ^99mTcO4- uptake of injected NIS-GFP CPCs enabled their detection in vivo compared to parental CPCs lacking the reporter. NIS-GFP CPCs engrafted and survived within the myocardium up to 24 h following intramyocardial injection. In comparison, NIS-GFP CPCs injected intravenously following MI were located primarily and trapped in the lungs at 24 h post-injection. These results were corroborated by ex vivo biodistribution analysis and immunohistochemistry.

This study is the first to demonstrate the NIS-mediated in vivo tracking of human CPCs following the incorporation of the clinically compatible NIS reporter. Cell engraftment and survival was reported following intramyocardial and intravenous administration over 24 h, supporting the potential of these approaches for cell therapy regenerative therapies.

Date of Award	1 Mar 2022
Original language	English
Awarding Institution	King's College London
Supervisor	Georgina Ellison (Supervisor) & Gilbert Fruhwirth (Supervisor)