Expression of Dominant Negative K6W-Ubiquitin in the Lens Epithelium via an Adenoviral Vector Delays Posterior Capsule Opacification in a Rabbit Model

PURPOSE

Ubiquitin is involved in cell proliferation and differentiation, and the objective of this study is to investigate the potential of dominant negative Ubiquitin (Ub) with a lysine to tryptophan mutation at the 6 position (K6W) through an adenoviral expression vector in the prevention of posterior capsule opacification (PCO) in a rabbit PCO model.

METHODS

Recombinant dominant negative K6W-Ub adenovirus (RAd-K6W-Ub) with green fluorescent protein (RAd-K6W-Ub/GFP) and RAd-GFP viruses (control) were generated with QBI-HEK 293A cells. New Zealand rabbits receiving lens phacoemulsification were given an intraoperative anterior chamber injection of the viruses. The images of anterior segment photography taken by a slit lamp biomicroscopy were analyzed by posterior capsule opacification manual software (POCOman) for PCO grading. The intraocular pressure (IOP) was detected with a non-contact tonometer (NCT). The expression of α-smooth muscle actin (α-SMA) was assessed by Western blotting. Cell migration ability in cultured rabbit's lens epithelial cells (LECs) was evaluated by scratch healing assay.

RESULTS

The expression of GFP and Ub in the lens epithelium was markedly upregulated after 48 hours vector injection. Eyes injected with RAd-K6W-Ub showed a significantly lower PCO degree compared with controls. Meanwhile, higher IOP and corneal edema was observed in groups with a higher RAd-K6W-Ub virus dosage. The expression of α-SMA was down-regulated in the RAd-K6W-Ub eyes as compared to controls at the 15th day after injection. Cell migration was inhibited by RAd-K6W-Ub infection.

CONCLUSIONS

RAd-K6W-Ub at an appropriate dosage could inhibit the proliferation of LECs and the formation of PCO in rabbit models. However, a higher dosage of Rad- K6W-Ub viral vector caused toxic effects to the surrounding tissues, such as corneal edema and high IOP.

An Overview of Nd:YAG Laser Capsulotomy

It has been revealed that posterior capsule opacification (PCO) is the most common delayed complication of cataract surgery. On the other hand, Nd:YAG laser capsulotomy is accepted as standard treatment for PCO. Although, Nd:YAG laser capsulotomy is a noninvasive and safe treatment it carries risk of some complications. Using less total energy and performing smaller capsulotomies are effective choices to decrease complications after Nd:YAG capsulotomy. The purpose of this review is to look through the complications associated with Nd:YAG laser capsulotomy, and the effect of capsulotomy size and used total energy on such complications.