Diabetic retinopathy (DR) is a global problem due to an alarming increase in the number of individuals with diabetes. The lack of an early diagnostic tool predicting retinal vascular health is a critical barrier to progress. To this end, we have identified circulating angiogenic cells (CACs) as ideal reporter cells, which are most receptive to changes of diabetic milieu and retinopathy. Our preliminary studies suggest that CACs map a distinct RNA signature. We also found that a miRNA, miR-92a, is downregulated explicitly in CACs with DR, and its overexpression in CACs of people with diabetes decreased pro-inflammatory markers, such as IL-1β and CD14, emphasizing the importance of CACs for biomarker discovery of retinal vascular health. Our preliminary studies using machine learning models could accurately predict DR providing us a stronger rationale for developing this paradigm for our robust study design. Furthermore, using rodent models, we found a decrease in miR-92a in lineage-Sca1+c-kit+ (LSK; mouse equivalent of CACs) parallels with an increase in acellular capillaries, and miR- 92a inhibition in LSKs triggered a stronger inflammatory response. Therefore, this proposal's overarching goal is to study RNA (miRNA and mRNA) and inflammatory signature using a robust sequencing paradigm and differential modeling in individuals with different severities of DR and animal models to gain insights into retinal vascular health. Our central hypothesis is that RNA signature in CACs mirror DR severity, and miR-92a decrease within CACs serves as a candidate biomarker. We propose the following specific aims to test our hypothesis: Aim 1: To assess changes in RNA levels in CACs of patients with different severity of DR and validate miR-92a as a candidate biomarker. Aim 2: Determine whether the miR-92a loss in bone marrow cells is associated with the development of DR in rodents. We anticipate that our proposed studies will identify specific mRNA and miRNA changes of DR severity and validate miR-92a as a novel biomarker for retinal vascular health. Overall, our studies will help improve the standard of care of DR individuals by aiding in diagnosis, prognosis and providing mechanistic insights for future therapies.

While diabetic retinopathy (DR) cases are rising globally, and newer treatments are emerging, there is a lack of biomarkers reflecting retinal vascular health. We propose that the RNA levels (mRNA and miRNA) and inflammation in circulating angiogenic cells (CACs) will serve as a biomarker of DR. We will perform RNA sequencing of CACs in DR patients and study how a change in miRNA levels leads to retinopathy using rodent models.