Inhibitory effect of indocyanine green on biological behavior and transdifferentiation of human lens epithelial cells and its mechanism

Objective

To investigate the inhibitory effect of indocyanine green (ICG) on biological behavior and transdifferentiation of human lens epithelial cells (HLECs) and its mechanism.

Methods

HLECs were divided into blank control group, 5% glucose solution (GS) group and 0.5% ICG group, 1.5% ICG group and 2.5% ICG group, which were treated with balanced salt solution, 5% GS and 0.5%, 1.5% and 2.5% ICG solutions for 3 minutes, respectively, and then were incubated in fresh medium for 24 hours.The apoptosis level of HLECs was detected by flow cytometry.The expression levels of apoptosis-related proteins, Bcl-2-associated X protein (Bax), B-cell lymphoma-2 (Bcl-2), caspase-3 and caspase-9 were detected by Western blot.Cell proliferation was detected via the cell counting kit-8 (CCK-8) assay and 5-ethynyl-2′-deoxyuridine (EdU) incorporation assay.The migration ability of HLECs was detected by cell scratch assay.Cell migration and invasion were determined by Transwell assays.The expression levels transdifferentiation-related proteins, α-smooth muscle actin (α-SMA), nerve calcium adhesion protein (N-cadherin), fibronectin (FN) and vimentin were assessed by Western blot.

Results

The apoptosis rates of blank control group, 5% GS group, 0.5% ICG group, 1.5% ICG group and 2.5% ICG group were (4.35±0.60)%, (4.63±0.19)%, (8.17±0.69)%, (13.90±0.33)% and (23.08±1.12)%, with a statistically significant difference in the overall comparison (F=412.74, P<0.05). The apoptosis rate was significantly higher in 0.5% ICG group, 1.5% ICG group and 2.5% ICG group than in blank control group and 5% GS group (all at P<0.05). The relative expressions of caspase-3, caspase-9 and Bax proteins were significantly higher in 0.5% ICG group, 1.5% ICG group and 2.5% ICG group than in blank control group and 5% GS group, and the relative expression of Bcl-2 protein was lower in 1.5% ICG group and 2.5% ICG group than in blank control group and 5% GS group, and the differences were statistically significant (all at P<0.05). The rate of EdU-positive cells was significantly lower in 0.5% ICG group, 1.5% ICG group and 2.5% ICG groups than in blank control group and 5% GS group (all at P<0.05). The survival rate of cells was significantly lower in 0.5% ICG group, 1.5% ICG group and 2.5% ICG group than in blank control group and 5% GS group (all at P<0.05). The migration rates of scratch cells were significantly lower in 0.5% ICG group, 1.5% ICG group and 2.5% ICG group than in blank control group and 5% GS group, and the differences were statistically significant (all P<0.05). The number of migrating cells and the number of invading cells were significantly lower in 0.5% ICG group, 1.5% ICG group and 2.5% ICG group than in blank control group and 5% GS group (all at P<0.05). The relative expressions of α-SMA, N-cadherin and FN were significantly lower in 0.5% ICG group, 1.5% ICG group and 2.5% ICG group than in blank control group and 5% GS group, and the relative expression of vimentin was lower in 1.5% ICG group and 2.5% ICG group than in blank control group and 5% GS group, and the differences were statistically significant (all at P<0.05).

Conclusions

ICG can promote HLECs apoptosis and inhibit HLECs proliferation, migration, invasion and transdifferentiation in a concentration-dependent manner.

Cataract; Capsule opacification; Indocyanine green; Lens epithelial cells; Biological behavior; Transdifferentiation