Theranostics 2018; 8(22):6233-6247. doi:10.7150/thno.27941

Research Paper

Multimodal analysis of aged wild-type mice exposed to repeated scanning ultrasound treatments demonstrates long-term safety

Daniel G. Blackmore1,3, Fabrice Turpin2,3, Abdalla Z Mohamed2, Fangrong Zong2, Rucha Pandit1, Matthew Pelekanos1, Fatima Nasrallah2, Pankaj Sah2, Perry F. Bartlett1, Jürgen Götz1✉

1. Clem Jones Centre for Ageing Dementia Research, Queensland Brain Institute, The University of Queensland, Brisbane QLD 4072, Australia;
2. Queensland Brain Institute, The University of Queensland, Brisbane QLD 4072, Australia
3. These authors contributed equally to this paper.

Abstract

The blood-brain barrier presents a major challenge for the delivery of therapeutic agents to the brain; however, it can be transiently opened by combining low intensity ultrasound with microbubble infusion. Studies evaluating this technology have largely been performed in rodents, including models of neurological conditions. However, despite promising outcomes in terms of drug delivery and the amelioration of neurological impairments, the potential for long-term adverse effects presents a major concern in the context of clinical applications.

Methods: To fill this gap, we repeatedly treated 12-month-old wild-type mice with ultrasound, followed by a multimodal analysis for up to 18 months of age.

Results: We found that spatial memory in these aged mice was not adversely affected as assessed in the active place avoidance test. Sholl analysis of Golgi impregnations in the dentate gyrus of the hippocampus did not reveal any changes to the neuronal cytoarchitecture. Long-term potentiation, a cellular correlate of memory, was still achievable, magnetic resonance spectroscopy revealed no major changes in metabolites, and diffusion tensor imaging revealed normal microstructure and tissue integrity in the hippocampus. More specifically, all measures of diffusion appeared to support a neuroprotective effect of ultrasound treatment on the brain.

Conclusion: This multimodal analysis indicates that therapeutic ultrasound for blood-brain barrier opening is safe and potentially protective in the long-term, underscoring its validity as a potential treatment modality for diseases of the brain.

Keywords: active place avoidance test, blood-brain barrier, diffusion tensor imaging, focused ultrasound, long-term potentiation

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How to cite this article:
Blackmore DG, Turpin F, Mohamed AZ, Zong F, Pandit R, Pelekanos M, Nasrallah F, Sah P, Bartlett PF, Götz J. Multimodal analysis of aged wild-type mice exposed to repeated scanning ultrasound treatments demonstrates long-term safety. Theranostics 2018; 8(22):6233-6247. doi:10.7150/thno.27941. Available from http://www.thno.org/v08p6233.htm