Retinal ganglion cell survival and functional maturation in transiently vascularized human retinal organoids

Retinal organoids are widely used to model human retinal development and disease, but their utility is limited by the absence of vascular networks and stable axonal projections, which contribute to retinal ganglion cell degeneration and loss of function. To address these challenges, we incorporated stem cell-derived endothelial cells to induce transient vascular-like networks and used microfluidic devices to stabilize axonal growth. The resulting organoids showed reduced hypoxia, increased size, and decreased apoptosis, indicating improved long-term survival and maturation of retinal ganglion cells. Integration with microfluidic-microelectrode arrays enabled stable recordings of spontaneous and optogenetically evoked activity, which persisted beyond the time when control organoids lost function. At later stages, these transiently vascularized organoids displayed photoreceptor-driven ON, OFF, and ON-OFF light responses, indicating circuit-level retinal activity. This bioengineered platform establishes a long-term, functional model of the human retina as a transformative tool for retinal research and therapeutic innovation.