Abstract
Pathologic angiogenesis of the retina is a hallmark of frequent blinding conditions
among the elderly, such as proliferative diabetic retinopathy (PDR) and neovascular
age-related macular degeneration (nAMD). The underlying mechanisms are
complex. Currently, the approved therapies consist of intraocular injections of antivascular
endothelial growth factor (VEGF) agents, laser treatments, and intraocular
surgeries to cope with the complications, such as intravitreal bleeding. Although
these therapies are the cornerstone of ophthalmological care for the patients, they
are far from perfect. There is a clear need for understanding the intricate regulatory
mechanisms of different retinal angiogenic conditions and find novel prognostic and
therapeutic tools. Investigation of angiogenesis at the gene regulation level grants
the possibility of studying angiogenesis within the tissue of origin, finding biomarkers
of disease progression, and offering novel targets and therapy modalities, such as
gene therapy agents. This thesis provides further insight into the complexity and
heterogeneity of retinal angiogenesis by analyzing human endothelial cells from
retinal and choroidal vasculature. Furthermore, we show the biomarker potential of
specific microRNAs in PDR progression, focusing on recurrent vitreous hemorrhage.
Moreover, we show that hypoxia-inducible factor (HIF)-1α, a master regulator of
angiogenesis, is upregulated in retinal pigment epithelium (RPE) in hypoxia. HIFs
pathologic upregulation can be mitigated by overexpression of prolyl hydroxylase
domain (PHD)2, a prominent HIF regulatory protein. In vitro and in vivo experiments
with overexpression of PHD2 protein diminished hypoxia-induced molecular and
cellular angiogenesis. Gene therapy experiments in the choroidal neovascularization
(CNV) mouse model with PHD2 significantly reduced laser-induced CNV lesions.
Therefore, we provide a candidate molecule for anti-HIF gene therapy for sustained
and balanced inhibition of retinal angiogenic conditions.
