Abstract
Purpose: :
To ascertain if canine lens epithelial cells (LEC) contain the hyaluronic acid (HA) receptors CD44 and CD168, and if surgical viscoelastics with higher HA content can negatively impact posterior capsular opacification (PCO) formation in vitro.
Methods: :
Canine LEC from normal (n=12) and cataractous (n=12) lenses were evaluated using immunohistochemistry and RT-PCR for expression of CD44 and CD168. Two in vitro models of PCO formation were used to determine if various HA concentrations altered LEC migration and proliferation. In the first model, a one millimeter scratch was created in cultures of confluent canine LEC. Cells were treated with 0, 0.2, or 1.0 mg/mL (n=6) of HA dissolved in unsupplemented DMEM. Migration of LEC into the scratch was monitored over 24 hours and quantified using ImageJ. In the second model, mock cataract surgery was performed on canine cadaver eyes. Following removal of lens fibres, capsules were re-distended using one of the following treatments (n=6): no viscoelastic (DMEM only), 0% HA viscoelastic, 1.2% HA viscoelastic, or 2.0% HA viscoelastic. The treatment remained in the lens capsule for 5 minutes before removal by irrigation and aspiration. Capsules were monitored daily and the rate of migration and proliferation onto the posterior capsule was evaluated.
Results: :
Both normal and cataractous LEC were positive for CD44 and CD168 protein and mRNA. There was a significant increase in the rate of migration in LEC treated with 0.2 and 1.0 mg/mL of HA compared to LEC receiving 0 mg/mL of HA (p=0.001). LEC treated with either 1.2% or 2.0% HA viscoelastics reached confluence on the posterior capsule significantly faster than LEC receiving no or 0% HA viscoelastic (p=0.003).
Conclusions: :
Canine LEC possess the appropriate receptors to respond to HA signaling and treatment with various HA concentrations significantly increased the rate of LEC migration. In addition, acute exposure to viscoelastics containing HA significantly increased the rate of LEC migration onto the posterior capsule. The introduction of exogenous HA in the form of viscoelastics during cataract surgery may promote LEC migration and thus contribute to PCO formation.
Keywords: posterior capsular opacification (PCO) • EMT (epithelial mesenchymal transition)