Positron emission tomography reporter gene strategy for use in the central nervous system

Abstract

There is a growing need for monitoring or imaging gene therapy in the central nervous system (CNS). This can be achieved with a positron emission tomography (PET) reporter gene strategy. Here we report the development of a PET reporter gene system using the PKM2 gene with its associated radiotracer [ 18 F]DASA-23. The PKM2 reporter gene was delivered to the brains of mice by adeno-associated virus (AAV9) via stereotactic injection. Serial PET imaging was carried out over 8 wk to assess PKM2 expression. After 8 wk, the brains were excised for further mRNA and protein analysis. PET imaging at 8 wk post-AAV delivery showed an increase in [ 18 F]DASA-23 brain uptake in the transduced site of mice injected with the AAV mice over all controls. We believe PKM2 shows great promise as a PET reporter gene and to date is the only example that can be used in all areas of the CNS without breaking the blood-brain barrier, to monitor gene and cell therapy.reporter gene | positron emission tomography (PET) | PKM2 | [18F]DASA-23 | adeno-associated virus

Positron emission tomography imaging of novel AAV capsids maps rapid brain accumulation

“…Finally, the PET method developed here to monitor binding and pharmacokinetics will be paired with PET reporter gene imaging in future work. A PET reporter gene based on pyruvate kinase (PKM2) has been shown to have low background in the brain and can be packaged within AAVs 49 . PKM2 can be used with the reporter probe [ 18 F]DASA-23 49 , which is permeable to the blood-brain barrier in order to monitor brain transduction over months or years.…”

“…A PET reporter gene based on pyruvate kinase (PKM2) has been shown to have low background in the brain and can be packaged within AAVs 49 . PKM2 can be used with the reporter probe [ 18 F]DASA-23 49 , which is permeable to the blood-brain barrier in order to monitor brain transduction over months or years. In the future, we will couple this tracer with the PET tag described here.…”

Options for imaging cellular therapeutics in vivo: a multi-stakeholder perspective

“…NIS has also been widely used for cell tracking in other fields. Other particularly promising host reporter genes for PET imaging in this context are a prostate-specific membrane antigen derivative, which was recently used to track CAR T cells in mouse models [112], and pyruvate kinase M2, which has been used to track cells in the brain because of the ability of its radiotracer, 1-((2-fluoro-6-(fluoro-[ 18 F])phenyl)sulfonyl)-4-((4-methoxyphenyl)sulfonyl)piperazine, to cross the bloodÀbrain barrier [174].…”

Genetically targeted reporter imaging of deep neuronal network in the mammalian brain

“…Several groups have attempted PET with mutant forms of dopamine and cannabinoid receptors, but these methods have suffered from poor signal-to-noise ratio due to ligand interaction with endogenous proteins 11,12 . A recent study reported brain PET imaging with an isoform of pyruvate kinase, PKM2, and its associated radiotracer [ 18 F]DASA-23 13 . Our laboratory has also demonstrated that a designer receptor exclusively activated by designer drugs (DREADD) and its artificial ligands, such as clozapine-N-oxide (CNO) and deschloroclozapine (DCZ), labeled with 11 C could be employed for PET of neurons and transplanted iPS cells in animal brains 14-16 .…”

“…Our laboratory has also demonstrated that a designer receptor exclusively activated by designer drugs (DREADD) and its artificial ligands, such as clozapine-N-oxide (CNO) and deschloroclozapine (DCZ), labeled with 11 C could be employed for PET of neurons and transplanted iPS cells in animal brains 14-16 . Nonetheless, these compounds cannot be applied to bimodal imaging, and they may also suffer from undesired effects on endogenous substrates 13,17 .…”