The phototoxicity of aged human retinal melanosomes

Bartosz Rózanowski, Joyceline Cuenco, Sallyanne Davies, Farukh A. Shamsi, Andrzej Za̧dło, Pierrette Dayhaw-Barker, Małgorzata Rózanowska, Tadeusz Sarna, Michael E. Boulton

Research output: Contribution to journalArticlepeer-review

42 Scopus citations

Abstract

The purpose of this study was to determine whether an age-related increase in photoreactivity of human retinal melanosomes (MS) can cause phototoxicity to retinal pigment epithelium (RPE) cells. MS were isolated post mortem from young (20-30 years, young human melanosomes [YHMs]) and old (60-90 years, old human melanosomes [OHMs]) human eyes and from young bovine eyes (bovine melanosomes [BMs]). Confluent cultured ARPE-19 cells were fed equivalent numbers of OHMs or BMs and accumulated similar amounts of melanin as determined by electron paramagnetic resonance assay. Cells with and without MS were either maintained in the dark or exposed to blue light for up to 96 h and assessed for alterations in cell morphology, cell viability and lysosomal integrity. Incubation of cells in dark in the presence of internalized MS or irradiation of cells with blue light in the absence or presence of BMs did not significantly affect cell viability. However, exposures to blue light in the presence of OHMs resulted in abnormal cell morphology, up to ∼75% decrease in mitochondrial activity, loss of lysosomal pH and cell death. OHMs contained significantly less melanin than YHMs, supporting the hypothesis that melanin undergoes degradation during RPE aging. Our results demonstrate that aged MS can be phototoxic to human RPE cells and support a contributing role of MS in RPE aging and in the pathogenesis of age-related macular degeneration.

Original languageEnglish (US)
Pages (from-to)650-657
Number of pages8
JournalPhotochemistry and Photobiology
Volume84
Issue number3
DOIs
StatePublished - May 2008

ASJC Scopus subject areas

  • Biochemistry
  • Physical and Theoretical Chemistry

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