## Unraveling the Mechanisms of Dry Age-Related Macular Degeneration and Potential Therapeutic avenues
Age-related macular degeneration (AMD) represents a leading cause of vision loss among the aging global population. While the “wet” form of AMD has established treatments, the more common “dry” form remains a important challenge due to a limited understanding of its underlying causes. Specifically, the precise molecular events leading to damage in retinal pigment epithelial cells (RPEs) and photoreceptor cells (PCs) in dry AMD are still being investigated [[1]]. This knowledge gap underscores the urgent need for advanced, human-relevant models to study and combat this debilitating disease.
### Modeling Dry AMD with Human Retinal Organoids
Recent research published in the journal *Genes and Diseases* details a novel approach to modeling dry AMD using human retinal organoids (ROs). A team of researchers from the Third Medical Center of the Chinese PLA General Hospital, the Faculty of Medicine of the General Hospital of Chinese PLA, and the Chinese Academy of medical Sciences & Peking Union Medical College successfully created a dry AMD model by exposing these ROs to sodium iodate [[3]].
This methodology builds upon prior work demonstrating the accomplished differentiation of ROs into RPEs and PCs after 186 days of development.By introducing sodium iodate into the culture medium, the researchers effectively replicated key pathological hallmarks of human dry AMD, offering a powerful tool for studying disease progression and testing potential therapies. The retina, a crucial part of the eye, converts light into signals the brain interprets as vision [[2]]. Any disruption to its function can lead to serious retinal diseases.
### Identifying Potential Protective Compounds
The study yielded promising results in the search for potential therapeutic interventions. Researchers identified two compounds – metformin, a commonly prescribed medication for type 2 diabetes, and TN1, a fetal hemoglobin inducer – as exhibiting protective effects against retinal degeneration. Both metformin and TN1 substantially reduced apoptosis (programmed cell death) triggered by sodium iodate in the ROs.
moreover, these compounds demonstrably lessened oxidative stress within photoreceptors and mitigated cellular damage to the RPEs, collectively providing a protective effect on the retina. This suggests a potential repurposing possibility for metformin, given its widespread use and established safety profile.
### The Role of HMOX1 in Retinal Protection
Further investigation using RNA sequencing revealed a key mechanism underlying the protective actions of metformin and TN1. Both compounds were found to positively regulate the expression of the HMOX1 gene. HMOX1 plays a critical role in cellular defense mechanisms, particularly in mitigating oxidative stress and inflammation. By upregulating HMOX1,metformin and TN1 appear to enhance the retina’s inherent resilience against the damaging effects of dry AMD. This revelation opens new avenues for developing targeted therapies aimed at bolstering HMOX1 expression and protecting the retina from degeneration.
As the global population ages, the prevalence of AMD is expected to rise dramatically. Continued research utilizing advanced models like human retinal organoids will be crucial in unraveling the complexities of this disease and developing effective treatments to preserve vision for millions.