Abstract
Purpose: :
Mesenchymal stem cell (MSC) engraft into the retina is recently hot investigated for development of the new therapeutic strategy treating incurable neural retinal diseases. The present study was tested biodegradable hyaluronic acid (HA)-based hydrogel as a stem cell carrier, to upgrade the migratory potential of mesenchymal stem cells using a rat model of retina ischemia-reperfusion injury (IR).
Methods: :
IR was made by transient elevation of intraocular pressure raising hydrostatic pressure value of 120 mmHg for 1 hour via a needle cannulation into the anterior chamber of the right eyeball using Sprague-Dawley rats. After 1 week, DiI-labeled rat MSCs of 3 passages loaded on HA-based hydrogel were applied on a dose of 1x105 cells/10 μl into the vitreous body of both experimental and control eyeballs. HA-based hydrogels were prepared with two different pH modulations. As a control to hydrogel effect, MSCs were loaded on 0.01M phosphate buffered saline (pH 7.2, PBS) with the same dosage of the hydrogel loading. The whole-mount retinas were prepared from all eyeballs 1 week after MSC application. The results were evaluated by confocal laser scanning microscopy of triple immunofluorescence done by a combination DiI (red fluorochrome) with anti-Iba1 (Cy5) and anti-GFAP (Alexa488) antibodies.
Results: :
Among whole-mount retinas of the all experiments, MSCs were much more aggregated in the border between the inner limiting membrane and the vitreous body loaded on HA-based hydrogels than in on PBS. HA-based hydrogel modulated with basic pH showed higher localization of MSCs than that with neutral pH. DiI-labeled MSCs were rarely observed in the superficial nerve fiber layer of the IR retinas applied with basic pH modulated hydrogel-loaded MSCs. Additionally, dissolved DiI particles contained in the microglial cytoplasm were more frequently detected in the IR retinas applied with basic pH hydrogel than those with neutral one.
Conclusions: :
These findings demonstrate that biodegradable scaffold such a HA-hydrogel is excellent for MSC localization in MSC engraft into the vitreous body of the IR retina. In respect to penetration of the inner limiting membrane of the retina, the basic pH modulated HA-hydrogel seems likely more efficient.
Keywords: ischemia • retina • immunohistochemistry