Phototoxicity and cytotoxicity of fullerol in human lens epithelial cells

Abstract

The water-soluble, hydroxylated fullerene [fullerol, nano-C 60 (OH) [22][23][24][25][26] ] has several clinical applications including use as a drug carrier to bypass the blood ocular barriers. We have assessed fullerol's potential ocular toxicity by measuring its cytotoxicity and phototoxicity induced by UVA and visible light in vitro with human lens epithelial cells (HLE B-3). Accumulation of nano-C 60 (OH) [22][23][24][25][26] in the cells was confirmed spectrophotometrically at 405 nm and cell viability estimated using MTS and LDH assays. Fullerol was cytotoxic to HLE B-3 cells maintained in the dark at concentrations higher than 20 µM. Exposure to either UVA or visible light in the presence of >5 µM fullerol induced phototoxic damage. When cells were pretreated with non-toxic antioxidants: 20 µM lutein, 1 mM N-acetyl cysteine, or 1 mM L-ascorbic acid prior to irradiation, only the singlet oxygen quencher lutein significantly protected against fullerol photodamage. Apoptosis was observed in lens cells treated with fullerol whether or not the cells were irradiated, in the order UVA > visible light > dark. Dynamic light scattering (DLS) showed that in the presence of the endogenous lens protein α-crystallin, large aggregates of fullerol were reduced. In conclusion, fullerol is both cytotoxic and phototoxic to human lens epithelial cells. Although the acute toxicity of water soluble nano-C 60 (OH) 22-26 is low, these compounds are retained in the body for long periods, raising concern for their chronic toxic effect. Before fullerols are used to deliver drugs to the eye, they should be tested for photo-and cytotoxicity in vivo.

Antioxidative nanofullerol prevents intervertebral disk degeneration

“…[58][59][60][61] Before evaluating the therapeutic utility of fullerol, we wanted to define the therapeutic window of dose availability for our studies using NP cells. Upon performing a dose-dependent LDH cytotoxicity assay as a measure of toxicity, we observed no apparent cytotoxicity up to 10 µM, tenfold higher than what we chose for our studies (Figure 2A).…”

Role of Zucchini and Its Distinctive Components in the Modulation of Degenerative Processes: Genotoxicity, Antigenotoxicity, Cytotoxicity and Apoptotic Effects

“…On the other hand, similar negative effects to ours were obtained by Fernández-Bedmar and Alonso-Moraga [15]when HL60 cells were treated with this carotenoid. Roberts et al [69] demonstrated that when the human lens epithelial cells (HLE B-3) were pretreated with lutein (20 µM added 2 h prior to irradiation with UVA), the singlet oxygen quencher-lutein significantly protected against fullerol photodamage, phototoxic damage decreased by half.…”

“…Dehydroascorbic acid did not show cytotoxicity in our studies at 0.7 mM, but Park et al [72] informed that L-ascorbic acid (the reduced form of dehydroascorbic acid) showed cytotoxicity and induces apoptosis of malignant cells (HL60, NB4 and NB4-R1) in vitro, when they used higher concentrations than ours (0.25-1 mM). Moreover, dehydroascorbic acid (0.5-1 mM) was tested for its protective effect against phototoxic damage induced by fullerol, resulting in some activity against metabolic damage [69].…”

The Hypoxic Microenvironment of Stem Cells and their Progenies in the Heart

“…3 For instance, hypoxia does not regulate human ESC proliferation, but it has been shown to be critical for their differentiation into cardiac cells, mainly triggered under hypoxic conditions. 5 Yang et al, 6 showed that differentiation of myoblasts is favoured in a hypoxic microenvironment, with undifferentiated myoblasts presenting high levels of HIF1α, whereas differentiated myoblasts express high levels of HIF2α . The study by Kudová et al, 9 showed that HIF-1α deficiency significantly impaired the transcription of cardiac cell specific genes, and therefore the differentiation of ESCs into cardiomyocytes.…”