Purpose: Sialidosis is a lysosomal storage disease caused by mutations of the lysosomal enzyme neuraminidase-1 (NEU1) gene. Patients with this condition develop symptoms of cherry red spot in retina, often with a complication of visual loss. In this study, we investigated embryoid body (EB) -like structures induced from patient blood cell-derived induced pluripotent stem cells (iPS cells) and induced retinal pigment epithelium (RPE).
Subjects and methods: We induced iPS cells established from patient blood mononuclear cells into EB-like structures by 3D culture. Some EB-like structures were observed via optical and transmission electron microscopy, and others were shifted to a culture on a flat surface to isolate RPE-like sheet. Establishment of RPE and autophagic reaction in the patient RPE was confirmed by immunofluorescent LC3 staining, quantitative real-time polymerase chain reaction, and Western blot analysis.
Results: Patient EB resulted in irregular shapes and formation of vacuoles filled with lipid droplets and cellular components such as damaged mitochondria. The patient and control RPE exhibited epithelial sheet-like morphology, had tight junctions, and expressed RPE markers. The sialic acid containing glycoconjugate accumulated in patient RPE. In patient RPE, autophagic reaction in starvation condition declined to 22.7% of control in the same condition, and the number and area of LC3 puncta decreased in normal (39.1% vs. 30.1%) and starvation (72.4% vs. 66.6%) conditions compared with those in control.
Conclusions: The patient RPE cells exhibited remarkable impaired autophagy. We also observed the characteristic failure of these cells in the treatment process of waste products during differentiation induction. This suggests that visual disturbances of sialidosis are related to the autophagic dysfunction in RPE
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 123: 373-382, 2019.