The cell cycle distribution of cultured human retinal pigmented epithelial cells under exposure of anti-proliferative drugs

Intraocular application of Mitomycin C to prevent proliferative vitreoretinopathy in perforating and severe intraocular foreign body injuries

AIM

To assess the long-term anatomical and functional outcomes in addition to complications of a new surgical technique of localized intraocular application of mitomycin C (MMC) to prevent proliferative vitreoretinopathy (PVR) in eyes with open globe trauma.

METHODS

Prospective non-comparative interventional case series of 16 consecutive eyes with perforating and deep choroidal impact foreign body injuries presenting over a 2-year period. Patients underwent vitrectomy with intraocular application of MMC at the site of the chorioretinal injury and were followed-up for 1 year. The primary outcome measure was the rate of postoperative PVR. Secondary outcome measures were number of vitreoretinal surgeries (VRS) required, best corrected visual acuity (BCVA), final anatomical success rate and globe survival rate (GSR).

RESULTS

Patients underwent VRS at a mean time of 8.5 ± 4.6 days after the injury. Postoperative PVR developed in 2 (13 %) eyes and required only one additional VRS each. One other eye underwent further peeling of an epimacular membrane. BCVA improved from mean LogMAR 3.08 ± 0.72 preoperatively to 0.66 ± 0.79 at 1 year. All 10 eyes without a macular injury had a final BCVA of LogMAR 0.40 or better. The final anatomical success rate was 94% and GSR rate was 100%. There were no complications related to the intraocular use of MMC.

CONCLUSIONS

Vitrectomy and intraocular application of Mitomycin C may have a potential role in reducing the rate of post traumatic PVR and improving anatomical and functional outcomes in eyes with perforating and deep choroidal impact foreign body injuries.

Steroids as an adjunct for reducing the incidence of proliferative vitreoretinopathy after rhegmatogenous retinal detachment surgery: a systematic review and meta-analysis

Background

This meta-analysis was performed to determine the effectiveness of steroids as an adjunct following rhegmatogenous retinal detachment (RRD) surgery.

Methods

RRD patients with or without proliferative vitreoretinopathy (PVR) were included. The treatment group included patients in whom steroids were used as an adjunct and a control group in which placebo was used. Only randomized controlled trials were included. We searched the main electronic databases and included studies published until July 2014. PVR odds ratio, visual acuity, retinal reattachment rate, and complications were evaluated in three trials.

Results

Three randomized controlled trials were included in the meta-analysis. There was no significant difference in the incidence of postoperative PVR between groups (heterogeneity I²=48%, P=0.14). However, the incidence of postoperative PVR was lower in the treatment group (I²=0%, P<0.0001) than in the control group when a PVR grade C study was excluded. There was no statistically significant difference in postoperative visual acuity between the treatment and control groups (odds ratio −0.18; 95% confidence interval −0.38, 0.02; P=0.08). The two groups had similar results for primary/final retinal reattachment and reoperation rate. There was no significant difference in postoperative intraocular pressure.

Conclusion

This systematic review demonstrates that steroids may significantly reduce the incidence of postoperative PVR grade B or lower following RRD surgery.

Pharmacological implications from the adhesion-induced signaling profiles in cultured human retinal pigment epithelial cells

Extracellular matrix (ECM) plays an active and complex role in regulating cellular behaviors, including proliferation and adhesion. This study aimed at delineating the adhesion-induced signaling profiles in cultured human retinal pigment epithelium (RPE) cells and investigating the antiadhesion effect of antiproliferative drugs in this context. RPE R-50 cells grown on various ECM molecules, such as type I and IV collagens, fibronectin, and laminin, were used for adhesion assay and for examining the phosphorylation profiles of signaling mediators including Akt, extracellular signal-regulated kinase (ERK) 1/2, and integrin-linked kinase (ILK) using Western blotting. The cells receiving antiproliferative drug treatment at subtoxic doses were used to evaluate their antiadhesive and suppressive effects on kinase activities. ECM coating enhanced adhesion and spreading of RPE cells significantly. The cellular attachment onto ECM-coated surfaces differentially induced Akt, ERK1/2, and ILK phosphorylation, and concomitantly increased p53 phosphorylation and cyclin D1 expression, but decreased Bcl-2/Bax ratios. Treatment with antiproliferative agents, including 5-fluorouracil, mitomycin C, and daunomycin, at subtoxic doses suppressed the ability of RPE cells to adhere to ECM substratum significantly. This suppression was in part mediated through reduction of integrin β1 and β3 expressions and interfering Akt-ILK signaling activity. Mechanistically, blockade of PI3K/Akt signaling resulted in the suppressed adhesion of RPE cells to ECM. These findings support the hypothesis that, in addition to their antimitogenic effect, antiproliferative agents also exhibit suppressive effect on the adhesiveness of cultured RPE cells. Moreover, inhibitors of the PI3K/Akt signaling mediator can potentially be used as therapeutic agents for proliferative vitreoretinopathy.

The effect of a preoperative subconjuntival injection of dexamethasone on blood-retinal barrier breakdown following scleral buckling retinal detachment surgery: a prospective randomized placebo-controlled double blind clinical trial

Background

Blood–retinal barrier breakdown secondary to retinal detachment and retinal detachment repair is a factor in the pathogenesis of proliferative vitreoretinopathy (PVR). We wished to investigate whether an estimated 700 to 1000 ng/ml subretinal dexamethasone concentration at the time of surgery would decrease the blood–retinal barrier breakdown postoperatively.

Methods

Prospective, placebo-controlled, double blind clinical trial. In 34 patients with rhegmatogenous retinal detachment scheduled for conventional scleral buckling retinal detachment surgery, a subconjunctival injection of 0.5 ml dexamethasone diphosphate (10 mg) or 0.5 ml placebo was given 5–6 hours before surgery. Differences in laser flare photometry (KOWA) measurements taken 1, 3 and 6 weeks after randomisation between dexamethasone and placebo were analysed using mixed model ANOVA, while correcting for the preoperative flare measurement.

Results

Six patients did not complete the study, one because of recurrent detachment within 1 week, and five because they missed their postoperative laser flare visits. The use of dexamethasone resulted in a statistically significant decrease in laser flare measurements at the 1-week postoperative visit.

Conclusion

The use of a preoperative subconjunctival injection of dexamethasone decreased 1-week postoperative blood–retina barrier breakdown in patients undergoing conventional scleral buckling retinal detachment surgery. This steroid priming could be useful as a part of a peri-operative regime that would aim at decreasing the incidence of PVR.