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. Methods Umbilical 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). Results Introduction 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. Conclusion We 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.

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The mitochondrial F1Fo‐ATP synthase uses a rotary mechanism to synthesise ATP. This mechanism can, however, also operate in reverse, pumping protons at the expense of ATP, with significant potential implications for mitochondrial and age‐related diseases. In a recent study, Acin‐Perez et al (2023) use an elegant assay to screen compounds for the capacity to selectively inhibit ATP hydrolysis without affecting ATP synthesis. They show that (+)‐epicatechin is one such compound and has significant benefits for cell and tissue function in disease models. These findings signpost a novel therapeutic approach for mitochondrial disease.