Abstract
Purpose:
Knowledge of the biological processes underlying formation of capsular opacification (CO) enables development of new methods for CO prevention. We performed an experimental study in which nanofiber-based hydrogels (nanogels) with attached peptides were used to simulate a more natural extracellular environment for the lens epithelial cells (LECs) in order to prevent CO in a porcine eye model.
Methods:
Fresh natural porcine (Sus domesticus) eyes were obtained from the local slaughterhouse. The lens content was removed and the empty capsules were refilled with nanogel. The lenses were divided into 14 groups (N=4 per group), refilled with nanogel without peptides and nanogels with 13 combinations of 5 different peptides: two laminin-derived, two fibronectin-derived, and one collagen IV-derived peptide. A control group of 4 lenses was refilled with sodium hyaluronate. After refilling, lenses were extracted and cultured for three weeks. The lenses were fixated with paraformadehyde, and LECs were stained with phalloidin and 4',6-diamidino-2-phenylindole, after which the complete lenses were assessed using confocal laser scanning microscopy (CLSM). Next the capsules were separated from the lens content and stained for alpha smooth muscle actin (αSMA), again followed by CLSM. Total number of cells and percentage of cells showing αSMA expression were counted. Differences between groups were evaluated using Wilcoxon rank-sum tests and analyses of variance (ANOVA) with Games-Howell post-hoc analyses.
Results:
Compared to controls, lenses filled with nanogel show less severe CO formation, indicated by a smaller αSMA expression (P=0.004). Microscopic images show differences in morphological cell response between the nanogel refilled groups. αSMA expression was highest in lenses refilled with nanogel alone (9.54±11.29%). The cell number for the nanogel without peptides group was significantly lower compared to almost all groups (P values ≤0.013) except for the groups with the two fibronectin-derived peptides (P=0.167) and the two laminin-derived peptides (P=0.530).
Conclusions:
Our results show that LEC respond to both the presence of nanogels and the incorporation of peptides. Nanomaterials targeting biological pathways, in our case interactions with adhesion molecules, can be promising for CO prevention. However, further research is needed to discover optimal nanogel/peptide combinations.