In Vitro Characterisation of Endothelial Colony-Forming Cells (ECFCs) from a Cohort of Patients with Diabetic Retinopathy

Abstract

Purpose : There is currently no approved treatment for diabetic macular ischaemia; novel regenerative therapies such as endothelial colony-forming cells (ECFCs) may offer therapeutic potential. However, ECFCs isolated from people with diabetes (PWD) have previously demonstrated dysfunctional growth and repair, and the underlying mechanisms remain unclear. We characterised ECFCs isolated from the peripheral blood of PWDs with varying levels of retinopathy in addition to control subjects.

Methods : 38 PWDs were recruited from the diabetic eye clinic at St Pauls Eye Unit, Liverpool, UK in addition to four age-matched controls without diabetes. PWDs were categorised into four different groups (diabetes with no retinopathy, mild-moderate pre-proliferative retinopathy, maculopathy without ischaemia, and ischaemic retinopathy). ECFCs were isolated from peripheral blood. A positive control group consisting of ECFCs from umbilical cord blood (UCB-ECFCs) was included. ECFCs were characterised via tube formation and resazurin assays. Clinical data were collected at the time of blood sampling and two years later.

Results : The median age of the PWDs and controls was 63 (IQR=16.5) and 59.5 years (IQR=1.8), respectively. A higher proportion of patients with severe retinopathy had systemic complications of diabetes at both baseline and follow-up. ECFCs could be successfully isolated and expanded from two out of four healthy controls (50%) and five out of 38 PWDs (13.1%); these ECFCs were from the maculopathy without ischaemia and ischaemic retinopathy groups. ECFCs from PWDs with either no or mild retinopathy could not be successfully cultured. The maculopathy without ischaemia group and UCB-ECFCs demonstrated a greater percentage area covered by ECFC tubes, compared to ECFCs from the ischaemic retinopathy group or age-matched controls (p <0.0001). ECFCs from the maculopathy without ischaemia and ischaemic retinopathy groups showed a trend of having higher metabolic activity compared to ECFCs from the age-matched controls.

Conclusions : Successful culture of circulating ECFCs was more likely to occur in people with more severe retinopathy than in those with no or mild DR. The variance in tube formation and metabolic activity observed between people with different levels of retinopathy (and other complications of diabetes) is in keeping with the “activation phase” hypothesis.

This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.