Abstract
Purpose: :
To evaluate the cytotoxicity of para-phenylendiamine (PPD) in main component of hair dyes on human corneal epithelial cells in vitro.
Methods: :
First, we investigate PPD level during hair washing in 1 to 7 days after hair dying using HPLC. Second, human corneal epithelial cells were exposed to PPD at a concentration of 1, 3, 6, 9, 12 ppm(ng/µl) for 5,10,20 minutes. Evaluations were conducted with MTT assay for measuring the metabolic activity, lactate dehydrogenase (LDH) leakage assay for cytotoxicity, flow cytometric analysis and fluorescent micrograph for assessing the apoptotic response, and inverted phase-contrast microscopy and electron microscopy for observing the morphologic changes.
Results: :
PPD was released during hair washing at 2.1 to 11.6 ppm. The inhibitory effect of human corneal epithelial cell proliferation and cytotoxicity showed a dose and time dependent response (P=0.02). The exposure of PPD 12 ppm for 20 minutes did not reach the lethal dose 50. Apoptosis was seen in flow cytometry and apoptotic cells were demonstrated in fluorescent micrograph after being treated with over 3 ppm concentration of PPD. Human corneal epithelial cells were more detached from the bottom of the dish and damaged cells show degenerative changes like microvilli disappearance, vacuoles formation, and chromatin of the nuclear remnant condensed along the nuclear periphery
Conclusions: :
PPD can induce toxic effect on human corneal epithelial cells with dose and time dependent pattern. This toxic effect can be also developed with PPD level during hair washing in early phase after hair dying.
Keywords: cornea: epithelium • apoptosis/cell death • cornea: clinical science