Precision medicine for age-related macular degeneration: current developments and prospects

Sirolimus loaded chitosan functionalized poly (lactic-co-glycolic acid) (PLGA) nanoparticles for potential treatment of age-related macular degeneration

The usefulness of sirolimus (SIR) in the treatment of diseases that involve retinal degeneration like age-related macular degeneration (AMD) has been well documented. However, the problem still remains probably owing to the peculiar environment of the eye and/or unfavourable physiochemical profile of SIR. In the present work, we aimed to fabricate sirolimus loaded PLGA nanoparticles (SIR-PLGA-NP) and chitosan decorated PLGA nanoparticles (SIR-CH-PLGA-NP) to be administered via non-invasive subconjunctival route. Both the nanoparticles were characterized in terms of size, zeta potential, DSC, FTIR and XRD analysis. Quality by Design (QbD) approach was employed during the preparation of nanoparticles and the presence of chitosan coating was confirmed through thermogravimetric analysis and contact angle studies. Cationic polymer modification showed sustained in-vitro SIR release and enhanced ex-vivo scleral permeation and penetration. Further, SIR-CH-PLGA-NP revealed enhanced cellular uptake and thus, reduced lipopolysaccharide (LPS)-induced free-radicals generation by RAW 264.7 cells. The prepared nanoparticles were devoid of residual solvent and were found to be safe in HET-CAM analysis, RBCs damage analysis and histopathology studies. Moreover, high anti-angiogenic potential was observed in SIR-CH-PLGA-NP compared with SIR-PLGA-NP in chorioallantoic membrane (CAM) test. Overall, the current work opens up an avenue for further investigation of CH-PLGA-NP as SIR nanocarrier in the treatment of AMD.

Metabolomics and Age-Related Macular Degeneration

Age-related macular degeneration (AMD) leads to irreversible visual loss, therefore, early intervention is desirable, but due to its multifactorial nature, diagnosis of early disease might be challenging. Identification of early markers for disease development and progression is key for disease diagnosis. Suitable biomarkers can potentially provide opportunities for clinical intervention at a stage of the disease when irreversible changes are yet to take place. One of the most metabolically active tissues in the human body is the retina, making the use of hypothesis-free techniques, like metabolomics, to measure molecular changes in AMD appealing. Indeed, there is increasing evidence that metabolic dysfunction has an important role in the development and progression of AMD. Therefore, metabolomics appears to be an appropriate platform to investigate disease-associated biomarkers. In this review, we explored what is known about metabolic changes in the retina, in conjunction with the emerging literature in AMD metabolomics research. Methods for metabolic biomarker identification in the eye have also been discussed, including the use of tears, vitreous, and aqueous humor, as well as imaging methods, like fluorescence lifetime imaging, that could be translated into a clinical diagnostic tool with molecular level resolution.