Conflict/competing interest: No stated conflict of interest.
Investigation of nanoparticles using magnetic resonance imaging after intravitreal injection
Version of Record online: 19 SEP 2011
© 2011 The Authors. Clinical and Experimental Ophthalmology © 2011 Royal Australian and New Zealand College of Ophthalmologists
Clinical & Experimental Ophthalmology
Volume 40, Issue 1, pages 100–107, January/February 2012
How to Cite
Raju, H. B., Hu, Y., Padgett, K. R., Rodriguez, J. E. and Goldberg, J. L. (2012), Investigation of nanoparticles using magnetic resonance imaging after intravitreal injection. Clinical & Experimental Ophthalmology, 40: 100–107. doi: 10.1111/j.1442-9071.2011.02651.x
Funding sources: We gratefully acknowledge funding support from the National Eye Institute (EY-017971 to JLG, and P30 EY014801 to UM), the Department of Defense (W81XWH-09-1-0674), Hope For Vision and the Seigal Foundation (JLG), and an unrestricted grant from Research to Prevent Blindness (University of Miami).
- Issue online: 5 FEB 2012
- Version of Record online: 19 SEP 2011
- Accepted manuscript online: 11 JUL 2011 06:25AM EST
- Received 27 January 2011; accepted 15 June 2011.
- imaging systems;
Background: Magnetic nanoparticles may be used for focal delivery for cells, plasmids or drugs, and other applications. Here we asked whether magnetic nanoparticles could be detected in vivo at different time points after intravitreal injection by magnetic resonance imaging.
Methods: Adult Sprague-Dawley rats received intravitreal injections of 50-nm or 4-µm magnetic particles into the left eye, with an equal volume of phosphate-buffered saline into the right eye (as controls). Animals were examined by magnetic resonance imaging at 1 h, 1 day and 5 weeks after injection. Eyes, brain, liver, spleen and kidney were also imaged with high-resolution ex vivo magnetic resonance imaging scanning.
Results: In vivo magnetic resonance imaging at the 1 h and 1 day time points more clearly detected magnetic particles in the 4 µm group compared with the 50-nm group, although 50-nm magnetic nanoparticles were easily visualized with high-resolution magnetic resonance imaging ex vivo. Five weeks after intravitreal injection magnetic resonance imaging clearly detected 4-µm particles inside the eye, but by this time point the 50-nm magnetic nanoparticles could not be detected by either in vivo or ex vivo high-resolution magnetic resonance imaging. No magnetic particles were detected in any other organ.
Conclusions: Magnetic resonance imaging could be used to track magnetic nanoparticles in the eye with the dosing selected for this study. Clearance varies by size, with 50-nm magnetic nanoparticles cleared more quickly than 4-µm particles. Thus, nanoparticles may provide advantages over micron-scale particles when considering risks associated with long-term persistence.