Derivation of functional retinal endothelial cells from human pluripotent stem cells for therapeutics and modelling.

Retinal microvascular diseases involve a compromised inner blood-retina barrier (iBRB), which remains poorly understood. A renewable source of human iBRB endothelium is thus vital for advancing eye research and treatment development. Here we differentiated human induced pluripotent stem cells into retinal endothelial cells (iRECs) via the Wnt-β-catenin pathway, namely Norrin-Frizzled4 signalling. These iRECs show genetic, protein and functional fidelity as well as unique retinal features. When injected into oxygen-induced retinopathy mice, iRECs integrated into the host vascular network and revascularized the ischaemic eye, rescuing the tissue. In microphysiological models, iRECs form perfusable microvascular networks that recapitulate iBRB morphology and phenotype in both healthy and diabetic states while also physiologically organizing and interacting with induced pluripotent stem cell-derived retinal pericytes. Our study establishes functional human iRECs and microphysiological iBRB models that facilitate mechanistic studies aimed at identifying therapeutic targets and promoting the revascularization of injured retinas, thereby supporting treatment advancement.