Deciphering the consequences of mast cell mediated extracellular matrix (ECM) remodeling in age-related macular degeneration (AMD)

• Applicant: Professor Dr. Simon J. Clark
• Subject Area: Ophthalmology ; Biochemistry ; Cell Biology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 517349829

Age-related macular degeneration (AMD) is a peculiarly human disease. Therefore, understanding the disease can only be achieved by studying physiologically relevant human tissue models. Commonly scientists use animal models, or study retinal cell types in isolation, neither of which represent what is really happening in a human eye. The resilience and longevity of a healthy human retina relies on the complex interactions between all the different cell types and their underlying extracellular matrix (ECM). Here, we will combine leading bioengineering expertise (Prof. Loskill) and AMD/protein biochemistry (Prof. Clark) to create a novel, multi-cellular retinal model that includes the natural underlying ECM, termed Bruch’s membrane (BrM), in a Retina-on-Chip system. To achieve this, we will incorporate enriched human BrM, kindly provided through organ donations, human induced pluripotent stem cell (iPSC)-derived retinal organoids, and retinal pigmented epithelial cells, creating the retinas complex multi-cellular environment in the lab like never before. We will use this novel engineering feat to investigate the observed phenomenon of accumulating mast cells within the choroid (underneath BrM) during early AMD and their subsequent driving of ECM remodelling. Our model system allows us to perfuse human serum, and allows us to introduce mast cells to the underside of BrM. We will stimulate these mast cells to degranulate, spilling out their proteolytic enzymes that have been shown to accumulate on BrM in human donor eyes. Using immunofluorescent microscopy, we will study the physiological consequences of BrM remodelling by these proteases on the retinal cells, as well as delving into the genetic consequences. We will perform single-cell transcriptomics, where each individual cell type within the retinal organoid will be assessed. This will tell us, not only how individual retinal cells react to the environmental changes preceding early AMD, but how they react when in complex with all their neighbouring cells: something that has not been considered before. Cellular pathways that are altered in this scenario can be validated through specific targeting in our in-house repository of human donor eye material from individuals with and without AMD. Our results will help identify pathways and targets that may be used to slow the progression of early AMD into its later stages, and may well help prevent the formation of Dry AMD.

• DFG Programme: Research Grants
• Co-Investigator: Professor Dr. Peter Loskill