Abstract
Purpose :
Choroidal involution is a common feature in ischemic retinopathies such as age-related macular degeneration (AMD). It is now well recognized that Endothelial Progenitor Cells (EPCs) are essential to endothelial repair processes and to maintain vascular integrity. However, the contribution of EPCs to age-related choroidal vascular degeneration and the role of senescence in this pathophysiology remain to be determined. In this study, we characterized in vivo the senescence status of EPCs in the choroid of young vs old rats, and assessed the effect of aging on EPC gene expression profiling.
Methods :
We isolated the retina of young (6 weeks) vs old (18 months) rats and assessed by immunostaining choroidal tightness and the number of EPCs in choroidal vessels. PCR analyses were performed to quantify the expression of senescence-associated genes and EPCs markers. In addition, we performed next generation sequencing (NGS) and bioinformatic analyses to compare the gene expression profile of EPCs derived from theses rats.
Results :
In old rats, we found a significant decrease of choroidal tightness compared to young rats. This was associated with reduced number of EPCs colocalizing in choroidal vessels, and downregulation of the EPC markers including CD34 and CD133. Importantly, old EPCs showed strong evidence of senescence as attested by increased levels of X-gal and P53, combined with a loss of Lamin-B1 expression, associated with impaired vasculogenesis ex-vivo. We next compared EPC gene expression profiling in young vs old rats using NGS. Globally we found that 802 genes modulated by aging in isolated EPCs, representing around 2% of the total genes expressed. Interestingly, using bioinformatic algorithms analyses, we found that these genes are predicted to affect key physiologic signals involved in the modulation of inflammation, g-coupled receptors and hematopoietic cell lineages, and senescence.
Conclusions :
Altogether, our results suggest that age-related choroidal involution is associated with reduced level of EPCs in choroidal vessels through the acquisition of a senescent . Novel approaches using bioengineered EPCs treated with senolytic agents could potentially represent an interesting strategy to preserve choroidal vascular integrity in age-dependent ischemic retinopathies.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.