Hypoxia-induced Response in Mitochondria DNA Biogenesis in Retinal Organoids Derived from Pluripotent Stem Cells from Leber Hereditary Optic Neuropathy

This study evaluated the impact of hypoxia on mitochondrial DNA (mtDNA) biogenesis in retinal organoids of patients with Leber hereditary optic neuropathy (LHON) with an mtDNA G11778A mutation. The induced pluripotent stem cells derived from the peripheral blood mononuclear cells of LHON patients and a healthy individual were differentiated into three-dimensional retinal organoids with confirmed morphology and retinal ganglion cell (RGC) markers. The retinal organoids were cultured in alternating hypoxic and normoxic states. The ratio of the mtDNA copy number in an organoid to the mtDNA copy number in the white blood cells was calculated. Under both conditions, the control and LHON organoids had similar morphology and RGC marker patterns. Under the normoxic condition, the LHON organoids had a smaller but similar mtDNA copy number ratio as the controls. Hypoxic exposure significantly reduced the mtDNA copy number ratio in both groups. However, the magnitude of reduction was significantly smaller in LHON organoids than in the controls. One LHON patient had a similar and relative mtDNA copy number in the white blood cells to the controls, but the other patient had a much higher number. Therefore, the hypoxic response of retinal mtDNA biogenesis was reduced in LHON patients.