Abstract
Purpose: :
To test the hypothesis that magnetomotive optic coherence tomography (MMOCT) and magnetic particles will enable imaging of posterior eye structures of live mouse eyes and to determine whether protein-bound magnetic nanoparticles has discernable toxicity.
Methods: :
A custom built, high speed and ultra-high resolution (~3 µm) MMOCT was developed for imaging biotin-coupled magnetic particles (100 nm and ~1 µm, 0.1 mM biotin in 0.7 µl injected volume) in mice eye by applying an external dynamic magnetic field gradient. The magnetomotive signals were acquired by subtracting the images obtained with and without magnetic filed. Magnetic beads were imaged in vitro by embedded within agarose gel (1.5%) and in vivo in a congenic DBA/2J (D2-Gpnmb+-Sj/J mice) mouse eye. To assess toxicity and metabolic enzymatic activities (aldolase, pyruvate kinase, and malate dehyrogenase) of cell extracts were determined after incubation of primary retinal ganglion cells with magnetic particles. Three batches of 5000 cells each with 1 mM estimated biotin containing particles were used for these experiments
Results: :
The MMOCT signals were successfully captured in the agarose gel with embedded magnetic beads. The MMOCT signals were also captured in the posterior segment of the mouse eyes after injecting the beads into the posterior chamber near the retina, and the signals were overlaid successfully onto the structural OCT image. The enzymatic assays of extracts from control and cells incubated with magnetic particles show no difference in activities suggesting lack of metabolic toxicity.
Conclusions: :
To our knowledge, this is the first demonstration on the detection of particles injected into the posterior chamber of the mouse eye using MMOCT. This modality of imaging has the promise in studying optical neuritis and other posterior segment diseases. The novel method is expected to advance translational research.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina • imaging/image analysis: non-clinical