The Effects of Low-Level Lasers on Adult versus Neonatal Human Retinal Pigment Epithelial Cells; an in vitro study
Mohammad Abolhosseini1 , Seyed Mohamadmehdi Moshtaghion1 , Mozhgan Rezaei Kanavi2 *, Fatemeh Suri1 , Faraj Tabeie3
- Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences
- Ocular Tissue Engineering Research Center, Shahid Beheshti University of Medical Sciences
- Department of Nuclear Medicine, Taleghani Hospital, School of Medicine, Shahid Beheshti University of Medical Sciences
Abstract: To investigate the short-term effects of low-level lasers (LLLs) on morphological, genotypic, and phenotypic characteristics of cultured adult versus neonatal human retinal pigment epithelial (hRPE) cells.
Methods: Cultivated neonatal and adult hRPE cells were irradiated with 2 wavelengths of LLL (630 nm and 780 nm) 1 min daily for 5 consecutive days. MTT assay, doubling time, real-time PCR for expression of PAX6, RPE65, nestin, and ACTA2 genes, and immunocytochemistry for ZO-1, PAX6, Na+-K+ ATPase, RPE65, cytokeratin 8/18, nestin, and alpha-smooth muscle actin (α-SMA) proteins were performed. Finally, the corresponding results were compared within and between the study groups.
Results: Cultured neonatal hRPE cells showed a predominant spindle-shaped morphology when irradiated with the 630 nm-laser in comparison with those irradiated with 780 nm-laser. Although cell proliferation assay did not show any significant change between the irradiated hRPE cells and the controls, an increase of doubling time was observed in 630 nm-irradiated adult hRPE cells (P = 0.032). Gene expression profile disclosed increased expressions of RPE65 (P < 0.01 for 630 nm-laser, P < 0.001 for 780 nm-laser) and nestin (P < 0.01 for 630 nm-laser) in neonatal hRPE cells, upregulation of RPE65 (P < 0.001 for 780 nm-laser) and PAX6 (P < 0.001 for 780 nm-laser) genes in adult hRPE cells, and reduced expression of ACTA2 in 780 nm-irradiated adult hRPE cells (P < 0.001). In irradiated neonatal hRPE cells, excepting the significant increase of ?-SMA, no significant change was noted in the expressions of other investigated proteins. In the irradiated adult hRPE cells, the expressions of all the investigated proteins remained unchanged.
Conclusion: Short term irradiation of neonatal and adult hRPE cells with LLLs may induce multipotency at the transcriptional level. Irradiation of neonatal hRPE cells with LLLs can be associated with an increased risk of myofibroblastic transformation; however, adult hRPE cells irradiated with the 780 nm-laser have minimal risk of myofibroblastic differentiation. It seems that the 780 nm-laser may be a promising option for future photobiomodulation in retinal degenerations in adults.
