scEye-Map: Developmental trajectories of progenitor cell populations in the human eye at single cell resolution

We wish to understand how the human eye develops at single cell resolution for two related reasons. Firstly we would like to use the single cell 'omic data to identify cells within the adult eye that retain the ability to replace damages tissue . Secondly to help understand the timing and cellular basis of severe birth defects affecting the eyes, particularly complete absence of both eyes and similar conditions which result in blindness from birth. There are many different types of cell in the adult eye and each developed from a progenitor cell during early development. There is evidence for the existence of rare cells - known as progenitor-like cells - in the adult eye, which, in other species, can be stimulated to replace specialist cells that have died. We have access to both adult eyes and human embryonic eye tissue. Our aim is to identify all the major cell types in the embryonic eye and map the progress of these cell populations through development to know what their fate is in the adult eye. We will use an important new technology called single cell analysis which allows us to look at which genes are turned on in each cell in the population. Gene expression is a very reliable tool for the precise categorisation of cells and allows us to identify types of cells that are not noticeable but looking under the microscope at their shape or position. The use of advanced data analysis techniques then allow us to match cell types across development to predict their ultimate fate. The information will be available to all scientists and clinicians to help their understanding of eye development and disease.

Cell types within the adult eye have been extensively studied and categorised. Single cell transcriptomic of the adult retina has been used to define novel cell types (e.g. macroglia) and confirm that these have progenitor-like cell characteristics. From cell culture experiment there is also evidence for multiple progenitor-like cells within the iris and ciliary apparatus in particular but the molecular markers for most of these cells are not yet available. The cell populations within the embryonic human eye are much less well defined and the developmental trajectories of the different populations across developmental time are largely unknown. We have access to early embryonic material via HDBR and to adult eye tissue via the Moorfields tissue bank. We propose to use single cell technologies to map all of the major cell populations within the embryonic eye across critical periods of morphogenesis/early retinal development and compartments of the adult eye known to be enriched in progenitor-like cells. The main aims of this project are to help understand major developmental disorders affecting the eyes and identify cell populations within the adult eye that have regenerative potential.

A major focus of this project is the identification and localisation of molecularly defined progenitor-like and stem cell-like cells in the adult eye. By identifying the transcription factors which uniquely define these cells and the cell surface antigens that will allow their purification from live tissue we will generate resources that will be of great use in regenerative medicine. We will utilise informatic analyses that will allow ranking of their regenerative potential which will have a significant impact in tissue engineering.

Our ability to explain the effects of the genetic variants that cause major eye malformations and early retinal dysplasias will have a very beneficial impact on both the affected individuals and their carers. An understanding of the developmental mechanisms and the precise timing of the pathogenic effects will help interpret the effects of drug and viral exposures on the eye during pregnancy . Mapping the differentiation potential and site of different cell types within the embryonic eye will also allow testing of the validity of eye-relevant organoid systems.