Abstract
Purpose: :
The aim of the study was to non-invasively follow the time course of sodium iodate-induced retinal degeneration using spectral-domain optical coherence tomography (SD-OCT). Furthermore, to use the technique to monitor the fate of subretinally transplanted bone marrow-derived stem cells (BMSC) in a degenerative environment.
Methods: :
C57BL/6 mice received a single i.v. injection of sterile sodium iodate (15 / 25 mg/ kg NaIO3) or NaCl. BMSC were freshly prepared from bone marrow of GFP mice using magnetic activated cell sorting to perform lineage depletion followed by separation of Lin- CD45+ and Lin- CD45- BMSC. 60’000 GFP+ BMSC or fibroblasts as controls were transplanted with a transscleral approach into the subretinal space seven days after NaIO3 treatment. Infrared and fundus autofluorescence (FAF) were recorded simultaneously and SD-OCT imaging was conducted at baseline (BL) and at day 7, 14, 21, 28 post NaIO3 injection (PI) or post transplantation (PT). Integrity of retinal layers and retinal thickness was analyzed using Heidelberg Eye Explorer software.
Results: :
Selective patchy loss of the RPE monolayer was observed in all treated mice after NaIO3 injection. Additionally, loss of the layer structure was visualized and significant thinning was measured in the sensory retina. The effect was concentration-dependent and progressed over time. In contrast, none of the control animals showed significant changes. After transplantation GFP+ cells (BMSC, fibroblasts) could be visualized using FAF and SD-OCT. The transplants appear as inhomogeneous, focal hyperfluorescent FAF signals and as subretinal deposit in the corresponding SD-OCT images in the same area over time. No differences between BMSC and fibroblasts were found.
Conclusions: :
SD-OCT is a useful tool to monitor and quantify the kinetics of pharmacologically induced retinal degeneration in individual mice. Additionally, it can also be used to visualize subretinal cell transplants up to 28 days.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • degenerations/dystrophies • transplantation