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Zammit M, Tao Y, Olsen ME, Metzger J, Vermilyea SC, Bjornson K, Slesarev M, Block WF, Fuchs K, Phillips S, Bondarenko V, Zhang SC, Emborg ME, Christian BT. [ 18F]FEPPA PET imaging for monitoring CD68-positive microglia/macrophage neuroinflammation in nonhuman primates. EJNMMI Res 2020; 10:93. [PMID: 32761399 PMCID: PMC7410886 DOI: 10.1186/s13550-020-00683-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 07/29/2020] [Indexed: 12/13/2022] Open
Abstract
PURPOSE The aim of this study was to examine whether the translocator protein 18-kDa (TSPO) PET ligand [18F]FEPPA has the sensitivity for detecting changes in CD68-positive microglial/macrophage activation in hemiparkinsonian rhesus macaques treated with allogeneic grafts of induced pluripotent stem cell-derived midbrain dopaminergic neurons (iPSC-mDA). METHODS In vivo positron emission tomography (PET) imaging with [18F]FEPPA was used in conjunction with postmortem CD68 immunostaining to evaluate neuroinflammation in the brains of hemiparkinsonian rhesus macaques (n = 6) that received allogeneic iPSC-mDA grafts in the putamen ipsilateral to MPTP administration. RESULTS Based on assessment of radiotracer uptake and confirmed by visual inspection of the imaging data, nonhuman primates with allogeneic grafts showed increased [18F]FEPPA binding at the graft sites relative to the contralateral putamen. From PET asymmetry analysis of the images, the mean asymmetry index of the monkeys was AI = - 0.085 ± 0.018. Evaluation and scoring of CD68 immunoreactivity by an investigator blind to the treatment identified significantly more neuroinflammation in the grafted areas of the putamen compared to the contralateral putamen (p = 0.0004). [18F]FEPPA PET AI showed a positive correlation with CD68 immunoreactivity AI ratings in the monkeys (Spearman's ρ = 0.94; p = 0.005). CONCLUSION These findings reveal that [18F]FEPPA PET is an effective marker for detecting increased CD68-positive microglial/macrophage activation and demonstrates sufficient sensitivity to detect changes in neuroinflammation in vivo following allogeneic cell engraftment.
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Affiliation(s)
- Matthew Zammit
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Yunlong Tao
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Miles E Olsen
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA
| | - Jeanette Metzger
- Preclinical Parkinson's Research Program, Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI, 53715, USA
- Cellular and Molecular Pathology Training Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Scott C Vermilyea
- Preclinical Parkinson's Research Program, Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI, 53715, USA
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, USA
- Department of Neuroscience, University of Minnesota-Twin Cities, Minneapolis, MN, USA
| | - Kathryn Bjornson
- Preclinical Parkinson's Research Program, Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI, 53715, USA
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, USA
| | - Maxim Slesarev
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
| | - Walter F Block
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA
| | - Kerri Fuchs
- Preclinical Parkinson's Research Program, Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI, 53715, USA
| | - Sean Phillips
- Preclinical Parkinson's Research Program, Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI, 53715, USA
| | - Viktorya Bondarenko
- Preclinical Parkinson's Research Program, Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI, 53715, USA
| | - Su-Chun Zhang
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
- Department of Neuroscience, University of Wisconsin-Madison, Madison, WI, USA
| | - Marina E Emborg
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA.
- Preclinical Parkinson's Research Program, Wisconsin National Primate Research Center, University of Wisconsin-Madison, 1220 Capitol Court, Madison, WI, 53715, USA.
- Cellular and Molecular Pathology Training Program, University of Wisconsin-Madison, Madison, WI, USA.
- Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, USA.
| | - Bradley T Christian
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, USA
- Waisman Center, University of Wisconsin-Madison, Madison, WI, USA
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