Abstract
Purpose :
To characterize the cellular composition of proliferative vitreoretinopathy (PVR) membranes surgically removed from human patients by single-cell genome wide expression profiling and to investigate the role of RUNX1 in PVR.
Methods :
Three PVR membranes were obtained from three different patients with grade C PVR undergoing surgery. After tissue dissociation, PVR cells were submitted for 3’ v2 Single Cell Gene Expression for analysis using the 10x Chromium Platform. Single cells, reagents, and a single Gel Bead containing barcoded oligonucleotides were encapsulated into nanoliter-sized GEMs (Gel Bead-in-Emulsion) using the GemCode platform. Lysis and barcoded reverse transcription of RNAs from single cells was performed. Full-Length barcoded cDNA was amplified by polymerase chain reaction to generate sufficient mass for library construction. Read counts were then loaded into Partek Flow software.
Results :
Four main clusters of cells defined by differential gene expression were found and, although there was some variability, these clusters accounted for ≥90% of the cells in each sample. RUNX1 expression was robust in the first two clusters of cells across all three samples. Cluster 1, one of the RUNX1-expressing cell clusters, encompassing 47.1% of all cells, was clearly distinguished as microglial cells due to their robust expression of hallmark genes. This dominant microglial population was found in similar size in the other samples as well. Clusters 2 and 3 expressed gene sets characteristic of fibroblasts and mesenchymal cells, and less so epithelial cells. Only a very small percentage of cells were classified as differentiated RPE suggesting that the majority of cells have undergone epithelial to mesenchymal transition (EMT) or are of immune origin. Importantly, most cells that skewed towards a mesenchymal phenotype had higher summed RUNX1 and Snail 1 expression, suggesting potential cooperation between these transcription factors in driving EMT.
Conclusions :
scRNAseq analysis revealed the preponderance of immune cells and cells with fibroblastic phenotypes in PVR membranes. The majority of the cell clusters from PVR membranes showed robust RUNX1 expression levels, which correlated with a shift towards mesenchymal gene expression and away from an epithelial phenotype. This finding suggests that RUNX1 may play an essential role in EMT.
This is a 2020 ARVO Annual Meeting abstract.