Retinal Astrocytes: Key Coordinators of Developmental Angiogenesis and Neurovascular Homeostasis in Health and Disease.

Retinal astrocytes reside mainly in the nerve fiber layer and are central to shaping retinal vessels and maintaining neurovascular balance. Derived from the optic nerve head, they spread across the inner retina to form a meshwork that both supports and instructs the emerging superficial vascular plexus. Immature astrocytes supply vascular endothelial growth factor-A(VEGF-A) to guide endothelial sprouting, while signals from growing vessels promote astrocyte maturation and strengthen the blood-retinal barrier. In disorders such as diabetic retinopathy and neovascular age-related macular degeneration, these cells show marked plasticity. Reactive astrogliosis can sustain VEGF and inflammation, favoring fragile, leaky neovessels, whereas alternative astrocyte states help reinforce barrier function and release anti-angiogenic factors. Located at the core of the neurovascular unit, astrocytes communicate continuously with endothelial cells, pericytes and neurons. This review integrates data from single-cell profiling and advanced imaging to outline astrocyte development, morphology and key signaling pathways (VEGF, PDGF, Wnt/Norrin, Eph/ephrin), and considers how tuning astrocyte polarization might be exploited to preserve retinal vascular integrity.