Related Experiment Video
Updated: Jun 18, 2026
Examination of Anatomical Features of Retinal Ganglion Cells Under N-methyl-D-aspartic Acid (NMDA)-induced Excitotoxicity
Published on: September 19, 2025
Triamcinolone attenuates macrophage/microglia accumulation associated with NMDA-induced RGC death and facilitates
S Singhal1, J M Lawrence, T E Salt
1Department of Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, 11 Bath Street, London EC1V 9EL, UK.
Abstract:
Retinal ganglion cell (RGC) death in glaucoma models is associated with accumulation of activated microglia, a sign of neural degeneration which has been shown to constitute a barrier for transplant cell survival and migration. This study investigated the use of triamcinolone (TA) to control macrophage/microglia accumulation in a model of RGC depletion to create a permissive environment for stem cell grafting. Intravitreal NMDA alone or in combination with TA was used to induce rapid onset of RGC death in 3-4 week old Lister hooded (LH) rat eyes prior to Müller stem cell transplantation into the vitreoretinal space. The effect of NMDA on RGC death and microglial accumulation was assessed immuno-histochemically, whilst electroretinography (ERG) was used to assess RGC function. Post transplantation, survival of grafted cells and their association with microglia were also examined by immunohistochemical methods. Intravitreal injection of NMDA alone resulted in severe macrophage/microglia accumulation associated with extensive RGC death 4-7 days post-treatment. Combination of NMDA with TA significantly reduced microglial numbers in the RGC when compared to NMDA only treated eyes while still depleting the retina of RGC. At the same time, NMDA/TA treatment also caused functional RGC loss as demonstrated by reduction of the scotopic threshold response. Upon transplantation with Müller stem cells, NMDA/TA treatment caused significant reduction in the number of transplant associated macrophage/microglia compared to eyes treated with NMDA alone. On this basis it is proposed that intravitreal injection of TA may be useful as an effective anti-inflammatory agent to control macrophage/microglia accumulation induced by RGC death, thereby creating a retinal environment permissive to cell transplantation studies.
Insights
Triamcinolone (TA) reduces microglia accumulation in retinal ganglion cell (RGC) death models. This creates a more permissive environment for Müller stem cell transplantation, aiding future regenerative therapies.
Area of Science:
- Ophthalmology
- Neuroscience
- Regenerative Medicine
Background:
- Glaucoma models show retinal ganglion cell (RGC) death is linked to activated microglia accumulation.
- This microglial buildup creates a barrier to successful stem cell transplantation and survival.
- Developing strategies to manage microglia is crucial for retinal cell-based therapies.
Purpose of the Study:
- To investigate the efficacy of triamcinolone (TA) in controlling macrophage/microglia accumulation in an RGC depletion model.
- To determine if TA treatment can create a permissive environment for Müller stem cell transplantation.
- To assess the impact of TA on RGC survival, function, and microglial response post-transplantation.
Main Methods:
- Induction of RGC death using intravitreal NMDA, alone or combined with TA, in Lister hooded rats.
- Immunohistochemical analysis to assess RGC death and microglial accumulation.
- Electroretinography (ERG) to evaluate RGC function.
- Examination of transplanted Müller stem cell survival and interaction with microglia.
Main Results:
- NMDA injection alone caused significant RGC death and severe macrophage/microglia accumulation.
- Combination of NMDA with TA markedly reduced microglial numbers compared to NMDA alone, while still causing RGC depletion.
- NMDA/TA treatment led to reduced transplant-associated macrophage/microglia compared to NMDA-only treatment.
- Functional RGC loss was observed with NMDA/TA treatment, indicated by reduced scotopic threshold response.
Conclusions:
- Intravitreal triamcinolone (TA) effectively reduces NMDA-induced macrophage/microglia accumulation in the retina.
- TA treatment creates a less inhibitory retinal environment for Müller stem cell transplantation.
- TA shows potential as an anti-inflammatory agent to facilitate cell transplantation in retinal degeneration models.
