Unveiling the Cellular and Molecular Mechanisms of Diabetic Retinopathy with Human Retinal Organoids

Diabetic retinopathy (DR) is a leading cause of vision impairment worldwide, driven by chronic hyperglycaemia and its complex metabolic consequences. While animal models have been widely used to study DR, they often fail to replicate human retinal physiology. To address this limitation, we utilized human retinal organoids as a model to investigate hyperglycaemia-induced changes, focusing on late-stage organoids (D150+28), where we performed next-generation sequencing (NGS). Transcriptomic analysis revealed significant disruptions in photoreceptor maturation, with a marked downregulation of genes associated with phototransduction and sensory perception. Oxidative stress-related pathways were upregulated, suggesting an enhanced reactive oxygen species (ROS) response. While photoreceptors were particularly vulnerable to hyperglycaemia, other retinal cell types, including bipolar cells, ganglion cells, and Müller glia, exhibited greater resilience. Additionally, glial activation, evidenced by increased expression of astrocyte markers (CD44, GFAP, TGFBR2), suggested a reactive gliosis response. Overall design: Human-induced pluripotent stem cells (hiPSCs) were differentiated into retinal organoids following an established protocol. Retinal organoids were cultured for 150 days (D150) to achieve an advanced stage of differentiation. To investigate the effects of hyperglycaemia, organoids were exposed for 28 days to one of the following conditions: 1) Control: Standard maintenance medium containing 17.5 mM D-Glucose. 2) Hyperglycaemia (D-Glucose): Maintenance medium supplemented with additional 7.5 mM D-Glucose for a final concentration of 25 mM D-Glucose.