Firefly luciferase offers superior performance to AkaLuc for tracking the fate of administered cell therapies

Francesco Amadeo,Neill Liptrott,Bettina Wilm,Patricia Murray,Anitta Chacko,Antonius Plagge,Arthur Taylor,Vivien Hanson

doi:10.1007/s00259-021-05439-4

Abstract

IntroductionA novel, red-shifted bioluminescence imaging (BLI) system called AkaBLI has been recently developed for cell tracking in preclinical models and to date, limited data is available on how it performs in relation to existing systems.PurposeTo systematically compare the performance of AkaBLI and the standard Firefly luciferase (FLuc) systems to monitor the biodistribution and fate of cell therapies in rodents.MethodsUmbilical cord mesenchymal stromal cells (MSCs) were transduced to produce two genetically engineered populations, expressing either AkaLuc or the engineered FLuc luc2. The bioluminescence of AkaLuc+ and FLuc+ cells was assessed both in vitro (emission spectra, saturation kinetics and light emission per cell) and in vivo (substrate kinetics following intraperitoneal and subcutaneous administration and biodistribution of the cells up to day 7).ResultsIntroduction of the reporter genes has no effect on MSC phenotype. For BLI, the FLuc system is superior to AkaBLI in terms of (i) light output, producing a stronger signal after subcutaneous substrate delivery and more consistent signal kinetics when delivered intraperitoneally; (ii) absence of hepatic background; and (iii) safety, where the AkaLuc substrate was associated with a reaction in the skin of the mice in vivo.ConclusionWe conclude that there is no advantage in using the AkaBLI system to track the biodistribution of systemically administered cell-based regenerative medicine therapies in vivo.

Highlights

A novel, red-shifted bioluminescence imaging (BLI) system called AkaBLI has been recently developed for cell tracking in preclinical models and to date, limited data is available on how it performs in relation to existing systems
Mice were obtained from a colony managed by the Biomedical Services Unit at the University of Liverpool (UK) which had been established from the B6N-Tyrc−Brd/BrdCrCrl strain originally purchased from Charles River (Italy)
Expression of common mesenchymal markers was similar in all three populations, with a good overlap of the flow cytometry data (Fig. 1e), revealing that the marker expression was not altered by either of the reporter genes and that all cells were negative for CD45 and positive for CD44, CD73, CD90, and CD105 (Fig. 1e)

Summary

Introduction

A novel, red-shifted bioluminescence imaging (BLI) system called AkaBLI has been recently developed for cell tracking in preclinical models and to date, limited data is available on how it performs in relation to existing systems. Purpose To systematically compare the performance of AkaBLI and the standard Firefly luciferase (FLuc) systems to monitor the biodistribution and fate of cell therapies in rodents. For BLI, the FLuc system is superior to AkaBLI in terms of (i) light output, producing a stronger signal after subcutaneous substrate delivery and more consistent signal kinetics when delivered intraperitoneally; (ii) absence of hepatic background; and (iii) safety, where the AkaLuc substrate was associated with a reaction in the skin of the mice in vivo. Cells expressing a luciferase genetic reporter can be detected by BLI in vivo following the administration of the relevant substrate. Luciferase (FLuc) and the substrate D-Luciferin constitute one of the main BLI systems used in vivo in small animals [5,6,7]. A recently developed novel BLI system consists of a luciferin

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