Abstract
Purpose:
Posterior capsule opacification (PCO) causes secondary visual loss in a significant number of patients following cataract surgery. New open bag IOL designs have been introduced that separate the anterior capsule (AC) and posterior capsules (PC) and these devices appear to further reduce PCO incidence relative to traditional IOL closed bag designs. One possible mechanism that affords this benefit is reduction in growth factor/cytokine availability due to improved irrigation of the bag. We therefore have explored the role of growth factor restriction on PCO using human cell and tissue culture models.
Methods:
To assess the effect of growth factors on cell progression, match-paired human capsular bags were cultured in different volumes (1.5ml versus 6ml) of Serum-Free (SF) EMEM. We employed a non-suspended model in which the bag was isolated from the ciliary body and secured to a culture dish with pins. We subsequently adapted the capsular bag system by making radial incisions in the AC, allowing the AC to be folded back and secured to a dish to create a fully open bag model. Using phase-contrast microscopy and ImageJ analysis software cell cover of the central posterior capsule was quantified. Bioplex suspended bead array analysis determined changes in cytokine levels at day 2 of culture. The myofibroblast marker αSMA, and chromatin were visualised using fluorescence microscopy. The effect of cytokines on human lens epithelial cell (FHL124) growth, over a 48 hour period, was evaluated using Coomassie blue staining, which was extracted from cells and absorbance measured at 550nm.
Results:
Dilution of cytokines by increasing culture media volume significantly reduced cell coverage on the central PC in both closed and open capsular bag models. Cell density was reduced in the peripheral PC and a decrease in αSMA expression was observed in cells on the central PC at end-point (Day 28) in 6ml cultures. Bioplex cytokine analysis of 1.5ml versus 6ml closed bag cultures established significant reductions in 9 of the 27 factors assessed. The cytokines IL-10, IL-12, IL-15, IP-10, MIP1β and MCP1 significantly increased cell proliferation of FHL124 cells.
Conclusions:
Reducing cytokine levels decreases cell growth and myofibroblast formation within the capsular bag. Separating anterior and posterior capsules following surgery could limit cytokine availability and therefore reduce PCO formation.