Wound healing modulation in glaucoma filtering surgery

The anti-scar effect of tyrosine-kinase inhibitor nintedanib in experimental glaucoma filtration surgery in rabbits

PURPOSE

To investigate the efficacy of nintedanib on preventing postoperative scar in formation following glaucoma filtering surgery (GFC) in rabbits in comparison with Mitomycin-C (MMC).

DESIGN

Experimental Animal Study.

METHODS

24 New Zealand rabbits were divided randomly into 3 groups as Sham, Nindetanib and MMC(n = 8). Limbal-based trabeculectomy was performed on the right eyes of the rabbits. Left eyes that did'nt undergo surgery were included in the control group (n = 8). Following surgery, Intraocular pressures (IOP), postoperative complications and morphological changes in the bleb were evaluated. On the 28th day, eight eyes from each group were enucleated and histologically and immunohistochemically analyzed. Matrix metalloproteinase-2 (MMP-2), Transforming Growth Factor-1 (TGF-B1) and alpha-smooth muscle actin (a-SMA) were evaluated.

RESULTS

It was observed that nintedanib has no side effects and reduces subconjunctival fibrosis. Postoperative IOP values in the Nindetanib group were lower than the other groups (p < 0.05). The longest bleb survival was observed in the Nintedanib group and the shortest in the Sham group (p < 0.001). Conjunctival vascularity and inflammation was reduced in the Nintedanib group compared to the Sham group (p < 0.05). The highest subconjunctival fibrosis was observed in the Sham group and the least in the Nintedanib group (p < 0.05). Although the fibrosis score was found lower in the Nintedanib group compared to the MMC(p > 0.05). α-SMA TGF-β1, MMP-2 expressions were similar in Nintedanib and MMC groups (p > 0.05), however, it was observed that significantly decreased in both groups compared to Sham group (p < 0.05).

CONCLUSION

It has been observed that Nindetanib suppress fibroblast proliferation Thus, It may be a drug that can prevent subconjunctival fibrosis in GFC.

Efficacy and Safety of the Intraoperative Application of Mitomycin in Glaucoma Patients with Trabeculectomy: A Systematic Review and Meta-Analysis

What Is Known and Objective. The primary cause of trabeculectomy failure in glaucoma surgery is the imperfect formation of the filter bubble, which blocks the filtration effect. This systematic review and meta-analysis aimed to compare the effects and safety of mitomycin C (MMC) or no antimetabolite in trabeculectomies cases that require needling revision. Methods. We searched PubMed, Cochrane, and EMBASE to identify randomized trials published between the time the databases were built and May 31, 2022. To compare the effectiveness and safety of mitomycin with or without mitomycin in trabeculectomy, intraocular pressure (IOP), the surgical failure rate, and functional follicle formation were used as efficacy indicators, and the occurrence of postoperative complications was used as a safety indicator. Meta-analyses were performed for comparisons. Results and Discussion. After trabeculectomy, MMC was significantly better than a placebo at lowering postoperative IOP (MD = −11.31 mmHg, 95% CI −19.73 to −2.88 mmHg). MMC outperformed the control group in terms of filtering blebs formation (relative risk (RR) = 1.18, 95% CI: 1.09 to 1.27). The surgical failure rate was significantly lower with MMC compared to placebo (RR = 0.35, 95% CI: 0.22 to 0.58). No significant difference was observed between MMC and placebo in terms of hypotony, anterior chamber bleeding, filter bubble leakage, and endophthalmitis, apart from the shallow anterior chamber (RR: 1.51, 95% CI: 1.02 to 2.25). What Is New and Conclusion. The use of MMC in glaucoma trabeculectomy can increase the success rate of the procedure and provide significant patient benefits. However, it is important to be extremely careful and aware of complications such as shallow anterior chambers.

ZD6474 attenuates TGF-β1-induced fibrosis in human Tenon fibroblasts and inhibits neovascularization via AKT-mTOR signaling pathway

PURPOSE

To investigate the anti-fibrotic effect of ZD6474 (a novel inhibitor of VEGF and EGF) in TGF-β1 stimulated human Tenon's capsule fibroblasts (HTFs) and the anti-angiogenetic role in HUVECs, compared to that of mitomycin C (MMC).

METHODS

The effects of ZD6474 on cell proliferation or migration in TGF-β1-stimulated HTFs and HUVECs were determined, using CCK8 or wound healing assay, respectively. The typical markers of fibrosis in TGF-β1-stimuated HTFs were detected, vimentin by immunofluorescence, α-SMA and snail by western blot. Tube formation was applied to validate the anti-angiogenesis effect in HUVECs following ZD6474 treatment. Furthermore, phosphorylated AKT and mTOR (p-AKT and p-mTOR) were evaluated, compared to the standardized total AKT and mTOR, using western blot.

RESULTS

There was almost no decreased cell viability in HTFs following ZD6474 (≤ 1 μM/mL) treatment, but MMC (> 50 μg/mL) significantly impaired cell viability. ZD6474 significantly inhibited TGF-β1-stimulated proliferation and migration in HTFs, compared to control group (**P < 0.01). ZD6474 also significantly attenuated the TGF-β1-stimulated expression of vimentin, α-SMA and snail in HTFs. Tube formation was notably interrupted in HUVECs following ZD6474 treatment (**P < 0.01). P-AKT and p-mTOR were significantly decreased in response to ZD6474 treatment in TGF-β1- induced HTFs and HUVECs.

CONCLUSIONS

ZD6474 exerts anti-proliferation and anti-fibrotic effects in TGF-β1-stimulated HTFs perhaps via regulating AKT-mTOR signaling pathway. ZD6474 also inhibited proliferation, migration and tube formation in HUVECs via the same signaling pathway. We concluded that ZD6474 may be potentially a novel agent in preventing bleb dysfunction following glaucoma filtration surgery (GFS).

Clinical Tear Fluid Proteomics—A Novel Tool in Glaucoma Research

Tear fluid forms the outermost layer of the ocular surface and its characteristics and composition have been connected to various ocular surface diseases. As tear proteomics enables the non-invasive investigation of protein levels in the tear fluid, it has become an increasingly popular approach in ocular surface and systemic disease studies. Glaucoma, which is a set of multifactorial diseases affecting mainly the optic nerve and retinal ganglion cells, has also been studied using tear proteomics. In this condition, the complete set of pathophysiological changes occurring in the eye is not yet fully understood, and biomarkers for early diagnosis and accurate treatment selection are needed. More in-depth analyses of glaucoma tear proteomics have started to emerge only more recently with the implementation of LC-MS/MS and other modern technologies. The aim of this review was to examine the published data of the tear protein changes occurring during glaucoma, its topical treatment, and surgical interventions.

Can bleeding in trabeculectomy be decreased? Effectiveness of brimonidine pre-treatment

PURPOSE

To evaluate the efficacy of preoperative topical brimonidine use to maintain visibility during trabeculectomy and control intraoperative bleeding and postoperative subconjunctival hemorrhage.

METHODS

The first group comprised 35 eyes of 34 patients administered brimonidine tartrate 0.15% (Brimogut, Bilim Ilac, Turkey) eye drops 6 and 3 min before surgery, and 33 eyes of 31 patients who received no medication for vasoconstriction formed the second group. Preoperative and postoperative photographs and operation video images were taken and vision analysis software used. Black-and-white images were obtained to identify the blood vessel and surface hemorrhage areas. The surface area of the hemorrhage was calculated by counting the black pixels with Image J software.

RESULTS

There was no significant difference between two groups in terms of baseline (preoperative) eye redness (p > 0.05). In the first group, the eye redness values were 344.7 ± 19.5 pixels preoperatively and 244.1 ± 23.3 pixels at the beginning of the surgery, respectively (p < 0.001). However, no significant change was observed in the second group in eye redness (348.2 ± 17.5 pixels preoperatively and 360.7 ± 26.8 pixels at the beginning of the surgery, p > 0.05). Cautery was used for an average of 11.91 ± 1.96 s in the first group and 25.57 ± 4.66 s in the second to control intraoperative bleeding (P < 0.001).

CONCLUSION

Preoperative topical brimonidine use in trabeculectomy surgery significantly decreased intraoperative bleeding and postoperative subconjunctival hemorrhage and facilitated bleeding control.

Trabeculectomy: is releasable suture trabeculectomy a cause of better bleb?

Purpose: To compare the outcome of fixed suture trabeculectomy with releasable suture trabeculectomy in terms of IOP control, bleb morphology, complications and need of antiglaucoma medication post-surgery.

Methods: This study enlisted 200 cases of open angle glaucoma, whose IOP was uncontrolled despite maximal medication. Trabeculectomy was performed using releasable suture in one group of 100 patients and fixed suture in another group of 100 with mitomycin 0.02% in both groups. The study was randomized, the method being the simple randomization. Fornix based trabeculectomy was done in both groups. Two 10-0 nylon releasable sutures were used at two corners of the rectangular flap and one fixed 10-0 vicryl suture was used in the center of the flap. Two mattress sutures (conjunctiva cornea) were also used. Essentially, all the sutures were removed postoperatively over a period of 2-4 weeks depending upon the level of IOP. Mitomycin c 0.02% was used in both groups.

Results: The mean preoperative intraocular pressure was 33 ± 12 mmHg in the single suture group and 39 ± 13 mmHg in the releasable suture group (p). We observed a highly significant reduction of intraocular pressure at all times in both groups compared with the preoperative intraocular pressure (P, 0.0001). There was an obvious difference between the bleb morphology between conventional trabeculectomy and releasable suture trabeculectomy. Blebs in releasable suture trabeculectomy were more diffuse, low lying and presented a more ideal vascularity.

Conclusion: Releasable suture trabeculectomy is a far much better technique than conventional trabeculectomy. Results are very good in terms of IOP control, post-operative complications, and bleb morphology. They may possibly have a role in wound modulation thereby achieving an ideal bleb, though more large sample studies need to be done.

The effect of halofugınone and pirfenidone on wound healing in experimental glaucoma filtration surgery

PURPOSE

To investigate the effects of halofuginone and pirfenidone on wound healing in experimental glaucoma filtration surgery (GFS).

STUDY DESIGN

Animal experimentation.

METHODS

A total of 42 male New Zealand albino rabbits were separated into 6 equal groups. A limbal-based trabeculectomy was performed on 5 groups, and Group I (control group) underwent no surgery and received no postoperative medication. For Group II (sham group), 1 drop 0.9% NaCl was instilled qid for 14 days. For Group III, 1% topical corticosteroid (prednisolone acetate) was instilled 1 drop qid for 14 days. For Group IV, 0.4mg/mL mitomycin-C (MMC) was applied intraoperatively to the region of the scleral flap. For Group V, 0.5% pirfenidone was instilled 1 drop qid for 14 days postoperatively. For Group VI, a sponge soaked in 10ng/mL halofuginone was applied to the surgical region for 3 mins. In addition, 1% topical corticosteroid was instilled ×1 drop qid for 14 days postoperatively for Groups IV, V and VI. After 14 days, sections prepared from the bleb regions of the enucleated eyes were evaluated histopathologically and immunohistochemically. Statistical analyses of the study were performed with Kruskal-Wallis variance analysis and the Mann-Whitney U test.

RESULTS

With regard to fibroblasts, suppression of the number of mononuclear cells and immunohistochemical staining intensity of transforming growth factor-b (TGF-β), fibroblast growth factor-b (FGF-β) and platelet derived growth factor (PDGF), the corticosteroid, MMC, pirfenidone and halofuginone groups were seen to exhibit more effect than the sham group (P<0.05). Compared to the pirfenidone and fuginone groups, inhibition of fibroblast and monocyte proliferation was determined to be lower in the MMC group (P<0.05). The intensity of TGF-β and FGF-β staining was seen to be lower in these two treatment groups than in the MMC group (P<0.05).

CONCLUSIONS

Halofuginone and pirfenidone may be used as effective alternative agents in delaying wound healing in glaucoma filtration surgery.

Effect of oral statin use on mitomycin-C augmented trabeculectomy outcomes

Purpose

The effect of statins on wound healing is controversial, and their effect on trabeculectomy outcomes remains unclear. This study aimed to examine the relationship between oral statin use and trabeculectomy outcomes.

Methods

Medical records of patients who underwent primary mitomycin-C augmented trabeculectomy with 2 years of follow-up were reviewed. Pre- and postoperative intraocular pressures (IOP) and numbers of medications, subconjunctival 5-fluorouracil (5-FU) injections, and bleb-needling procedures were compared between statin users and nonusers. Failure was defined as an eye that failed to achieve a 20% lowering of IOP from baseline or had an IOP > 21 mm Hg, as well as an eye that required further surgical intervention, developed hypotony, or had no light perception visual acuity.

Results

In total, 158 subjects were enrolled, with 47 eyes from statin users and 111 eyes from statin nonusers. The 24-month cumulative probability of failure was 78.7% for statin users and 60.4% for nonusers (P = .013). Cox proportional-hazards modeling showed a significantly higher hazard risk in statin users (adjusted hazard ratio 1.61, P = .026). There were no significant between-group differences in mean IOPs or number of medications (both P > .05) at 24 months. Multivariable Poisson regression analysis that statin use was associated with increased numbers of 5-FU injections (P = .014) and bleb-needling procedures (P = .031).

Conclusions

This study demonstrated that oral statin use was associated with higher rates of trabeculectomy failure and increased numbers of 5-FU injections and bleb-needling procedures.

Outcomes of trabeculectomy with polyvinylpyrrolidone collagen versus mitomycin in primary open angle glaucoma. 36-month follow-up

PURPOSE

Describe and compare the effects of intraoperative application of Polyvinylpyrrolidone Collagen (PVP) versus Mitomycin C (MMC) on the pattern of change in mean IOP reduction and mean number of medications over 36-months follow-up in patients with primary open angle glaucoma (POAG) undergoing trabeculectomy.

METHODS

Prospective, randomized, comparative study. Twenty-six eyes of 26 patients with POAG and no previous incisional glaucoma surgery underwent trabeculectomy and were randomized to PVP or MMC and completed a 36-month follow-up. Main outcome measures were IOP and number of glaucoma medications. Multivariate longitudinal analysis was performed by fitting a linear trend model adjusting for baseline response for the IOP outcome and a log-linear regression model with within-subject associations for the number of hypotensive medications outcome. Sensitivity analysis was performed to assess lower and higher order polynomial trends over time in IOP.

RESULTS

The univariate analysis revealed that the mean IOP reduction from baseline to 36 months was 7.62mmHg (3.05; 12.18) in the MMC group and 8.15mmHg (-0.64; 16.95) in the PVP group. Mean percentage IOP reduction from baseline was 37.09% (15.93; 58.17) and 36.08% (5.16; 67.20) in the PVP group. Mean change in number of medications from baseline to 36 months was -0.92 medications (-3.38; +1.54) for the MMC group and -1 medication (-3.12; +1.12) for the PVP group. Both groups had a statistically significant decline in mean IOP over the follow-up period (p<0.001) but there was no discernible difference between the two exposure groups in the rate of change in IOP (p=0.5975). Sensitivity analysis showed that a linear trend model is adequate to describe the IOP reduction over the follow-up period. Both groups had a statistically significant change in the number of hypotensive medications used between baseline and month 36 (p<0.05) but there was no discernible difference between exposure groups (p=0.2917). Both the PVP and MMC groups showed an initial reduction in number of medications until month 12 and a relatively linear increase towards month 36. A longer follow-up may be warranted to reveal differences in the number of medications between the two exposure groups. Postoperative complications were less frequent in the PVP group.

CONCLUSIONS

The use of PVP during trabeculectomy achieves and maintains a statistically significant IOP reduction from baseline to 36 months and decreases the number of glaucoma medications. Secondary outcome measures showed a lower incidence of adverse events in the PVP group.

Medical anti-glaucoma therapy: Beyond the drop

Barriers to effective medical therapy are numerous and include difficulties with effective and sustained control of intraocular pressure (IOP) and adherence to prescribed anti-glaucoma drop regimens. In an effort to circumvent these challenges, a number of new anti-glaucoma therapies with sustained effects have emerged. Methods for sustained delivery of prostaglandin analogs are being intensely investigated and many are in human clinical trials. Intracameral devices include the following: Allergan's Durysta^™ Bimatoprost SR, Envisia Therapeutics' ENV515 travoprost implant, Glaukos' iDose^™ , Ocular Therapeutix's OTX-TIC travoprost implant, and Santen's polycaprolactone implant with PGE2-derivative DE-117. Other prostaglandin-based technologies include Allergan's bimatoprost ring (placed in the conjunctival fornix), Ocular Therapeutics' OTX-TP intracanalicular travoprost implant, subconjunctival latanoprost in a liposomal formulation, and the PGE2 derivative PGN 9856-isopropyl ester that is applied to the periorbital skin. Exciting breakthroughs in gene therapy include using viral vectors to correct defective genes such as MYOC or to modulate gonioimplant fibrosis, CRISPR technology to edit MYOC or to alter aquaporin to reduce aqueous humor production, and siRNA technology to silence specific genes. Stem cell technology can repopulate depleted tissues or, in the case of Neurotech's Renexus® NT-501 intravitreal implant, serve as a living drug delivery device that continuously secretes neurotrophic factors. Other unique approaches involve nanotechnology, nasal sprays that deliver drug directly to the optic nerve and noninvasive alternating current stimulation of surviving cells in the optic nerve. Over time these modalities are likely to challenge the preeminent role that drops currently play in the medical treatment of glaucoma in animals.

All‑trans‑retinoic acid modulates TGF‑β‑induced apoptosis, proliferation, migration and extracellular matrix synthesis of conjunctival fibroblasts by inhibiting PI3K/AKT signaling

Conjunctival fiber generation is implicated in a wide spectrum of ocular diseases. Conjunctival wound healing is characterized by inflammation followed by re‑epithelialization, synthesis of new extracellular matrix (ECM), wound contraction and subconjunctival scar formation. The primary cause for the failure of glaucoma filtration surgery results from the excessive scarring of the filtering bleb. All‑trans‑retinoic acid (ATRA), a derivative of vitamin A, is a potent regulator of ECM synthesis, growth and differentiation. Following a previous study, which revealed that ATRA could inhibit transforming growth factor‑β‑induced human conjunctival fibroblast (HConF)‑mediated collagen gel contraction, the present study aimed to investigate the effects of ATRA on HConF migration, apoptosis, proliferation and ECM synthesis. To achieve this, the present study used Transwell migration, wound healing and Cell Counting Kit‑8 assays, flow cytometry and western blot analysis. In addition, the present study aimed to elucidate the mechanism of ATRA in mediating resistance to conjunctival scar formation. ATRA treatment resulted in an increased level of HConF apoptosis, reduced proliferation and migration, decreased collagen I and fibronectin expression, and decreased phosphorylation of PI3K and AKT. Thus, the present study showed a role for ATRA in inhibiting HConF migration, proliferation and ECM synthesis, and in promoting HConF apoptosis through the inhibition of the PI3K/AKT signaling pathway.

The effect on wound healing of pazopanib and bevacizumab compared with corticosteroid in experimental glaucoma filtration surgery

AIM

To compare the effects of bevacizumab and pazopanib with corticosteroids on wound healing after trabeculectomy.

METHODS

In the study, 35 New Zealand white rabbits were randomly divided into five groups. Apart from the first group, limbus-based trabeculectomy was performed for the eyes of rabbits. No postoperative treatment was administered for group I. Topically administered saline, prednisolone acetate (1%), bevacizumab 5 mg/mL, pazopanib 5 mg/mL for group II, III, IV and V respectively were applied for groups 6h daily for 28d. On day 28 of the experiment, eyes were enucleated and histologically and immunohistochemically analyzed.

RESULTS

The fibroblast counts of groups IV and V were determined to be lower than those of groups II and III (P<0.05). In the mononuclear cell (MNC) count evaluation, no statistically significant difference was determined between the treatment groups (P>0.05). The immunohistochemical staining intensity of fibroblast growth factor β (FGF-β) and vascular endothelial growth factor (VEGF) was determined to be lower in groups IV and V than in groups II and III (P<0.05). No statistically significant difference was determined between groups IV and V in respect of fibroblast count, MNC count, FGF-β and VEGF staining intensity (P>0.05). The platelet derived growth factor β (PDGF-β) intensity was lower in group V than in groups II, III and IV (P<0.05). While the PDGF-β staining intensity was significantly lower in group IV than in group II, the difference compared with group III was not statistically significant (P>0.05).

CONCLUSION

Bevacizumab and pazopanib might be good alternatives of corticosteroid treatment on delaying wound healing in glaucoma surgery.

A feasibility study of using biodegradable magnesium alloy in glaucoma drainage device

Technological advances in glaucoma have challenged the traditional treatment paradigm. Historically incisional surgery has been used in cases of advanced disease and/or uncontrolled intraocular pressures resistant to medical or laser interventions. More recently, perhaps due to advancements in imaging, surgery has been suggested to be beneficial earlier in the treatment paradigm. Despite these trends, surgical manipulation of the tissues and unpredictability of wound healing continue to result in surgical failure. Magnesium is an essential element for human body and plays a critically important role in maintaining the functional and structural integrity of several tissues, including the eye. Due to several of its advantageous properties such as non-toxicity, biodegradability, and high biological compatibility, magnesium alloy has attracted great attention as a novel biomaterial. Biodegradable cardiovascular stents made of magnesium alloy have already been introduced into clinical practice. The purpose of this review is to determine if bioabsorbable magnesium alloys can be utilized as a promising candidate for the development of a new generation of glaucoma surgical assistive devices.

NPPB modulates apoptosis, proliferation, migration and extracellular matrix synthesis of conjunctival fibroblasts by inhibiting PI3K/AKT signaling

When treating glaucoma, excessive scar tissue reactions reduce the postoperative survival rate of the filtering bleb. Accumulating evidence has demonstrated that the proliferation, migration and extracellular matrix (ECM) synthesis of fibroblasts are important molecular mechanisms underlying scar formation. Recent evidence has demonstrated that chloride channels play an important role in controlling cell proliferation, apoptosis, migration and the cell cycle process in several cell types, but the effects of chloride channels on conjunctival fibroblasts have not be studied. The aim of the present study was to investigate the effects of the chloride channel blocker 5-nitro-2-(3-phenylpropylamino) benzoic acid (NPPB) on cell proliferation, apoptosis, migration, cell cycle progression and ECM synthesis in human conjunctival fibroblasts (HConFs), and to further investigate the mechanism of resistance to scar formation following glaucoma filtration surgery. HConFs were exposed to NPPB or lubiprostone. Cell proliferation and viability was evaluated using the Cell Counting Kit-8. Cell migration was measured using Transwell migration and scratch‑wound assays. Flow cytometry was used to study apoptosis and cell cycle progression. Quantitative polymerase chain reaction and western blot analyses were performed to determine mRNA and protein expression levels, respectively. Following NPPB treatment, HConFs exhibited reduced proliferation and migration, along with increased apoptosis. NPPB also inhibited cell cycle progression by arresting cells in the G0̸G1 phase and reducing collagen I and fibronectin expression, as well as the phosphorylation of phosphoinositide 3-kinase (PI3K) and protein kinase B (AKT). However, lubiprostone treatment exerted the opposite effects on HConFs. Therefore, NPPB treatment inhibited proliferation, migration, cell cycle progression and synthesis of the ECM, while promoting apoptosis in HConFs, by inhibiting the PI3K̸AKT signaling pathway.

5-Aza-2'-deoxycytidine induces human Tenon's capsule fibroblasts differentiation and fibrosis by up-regulating TGF-β type I receptor

The principle reason of high failure rate of glaucoma filtration surgery is the loss of filtration function caused by postoperative scar formation. We investigated the effects of 5-aza-2'-deoxycytidine (5-Aza-dc), a DNA methyltransferases inhibitor, on human Tenon's capsule fibroblasts (HTFs) differentiation and fibrosis and its mechanism of action, especially in relation to transforming growth factor (TGF)-β1 signaling. TGF-β1 was used to induce differentiation of cultured HTFs. 5-Aza-dc suppressed DNA methyltransferases (DNMTs) activity 6 h after treatment with a course corresponding to that of TGF-β1-induced reduction of DNMT activity without affecting cell viability as measured by Cell Counting Kit-8 assay. 5-Aza-dc also reduced DNMT1 and DNMT3a protein expression from 24 to 48 h. HTFs migration evaluated by scratch-wound assay were significantly increased 24 h after 5-Aza-dc treatment, a time course similar to that of TGF-β1. Treatment with 5-Aza-dc significantly increased the mRNA and protein levels of α-smooth muscle actin (α-SMA), collagen-1A1 (Col1A1), fibronectin (FN) and TGF-β type I receptor (TGFβRI). Furthermore, the effects of 5-Aza-dc on DNMT activity suppression, cell migration, and fibrosis were all reversed by a TGFβRI inhibitor- SB-431542. Meanwhile, knockdown of DNMT1 upregulated TGFβRI expression and had the same fibrosis-inducing effect in HTFs, which was also inhibited by SB-431542. Thus, the results indicate that DNA hypomethylation induces HTFs differentiation and fibrosis through up-regulation of TGFβRI. DNA methylation status plays an important role in subconjunctival wound healing.

Oxidized low-density lipoprotein, lipid and calcium aggregates reveal oxidative stress and inflammation in the conjunctiva of glaucoma patients

PURPOSE

Conjunctival specimens from primary open-angle glaucoma (POAG), exfoliation glaucoma (ExG) patients and controls were histologically analysed for oxidized low-density lipoprotein (ox-LDL), lipid and calcium aggregates. Our goal was to use them as biomarkers of oxidative stress and inflammation and to evaluate their correlation with glaucoma and impact on surgical outcome.

METHODS

Conjunctival samples were obtained from POAG (n = 14) and ExG (n = 17) patients and from control subjects (n = 11) operated for macular hole, retinal detachment or strabismus. Immunohistochemistry was performed using the antibody against ox-LDL. Lipids and calcium were analysed by histochemical stainings with Nile red and Alizarin red S, respectively.

RESULTS

Immunoreaction for ox-LDL was significantly increased in POAG (p = 0.049) and the number of lipid aggregates was significantly higher in ExG (p = 0.009) when compared to control. When POAG and ExG patients were grouped according to the outcome of deep sclerectomy (DS) surgery, the number of lipid (p < 0.001) and calcium aggregates (p = 0.014) were significantly higher in the conjunctival stroma of patients whose surgery failed within a three-year follow-up period.

CONCLUSIONS

The lipid-mediated alterations suggested the presence of oxidative stress and inflammation in the conjunctiva of glaucoma patients. The present data further support the role of oxidative stress and inflammation in the wound healing process leading to excessive scarring and failure in DS surgery.

Pirfenidone Induces G1 Arrest in Human Tenon's Fibroblasts In Vitro Involving AKT and MAPK Signaling Pathways

PURPOSE

To investigate the underlying mechanism by which pirfenidone blocks the transition from the G1 to S phase in primary human Tenon's fibroblasts.

METHODS

Primary human Tenon's fibroblasts were characterized by immunocytofluorescence staining with vimentin, fibroblast surface protein, and cytokeratin. After treating Tenon's fibroblasts with pirfenidone under proliferation conditions (10% fetal bovine serum), cell proliferation was measured using a WST-1 assay. Progression through the cell cycle was analyzed by flow cytometry. The expression of CDK2, CDK6, cyclinD1, cyclinD3, and cyclinE and the phosphorylation of AKT, ERK1/2/MAPK, JNK/MAPK, and p38 MAPK were estimated using western blot analysis.

RESULTS

Under proliferative conditions, pirfenidone inhibited Tenon's fibroblasts proliferation and arrested the cell cycle at the G1 phase; decreased the phosphorylation of AKT, GSK3β, ERK1/2/MAPK, and JNK/MAPK; increased the phosphorylation of p38 MAPK; and inhibited CDK2, CDK6, cyclin D1, cyclin D3, and cyclin E in a dose-dependent manner. Inhibitors of AKT (LY294002), ERK1/2 (U0126), and JNK (SP600125) arrested the G1/S transition, similar to the effect of pirfenidone. The p38 inhibitor (SB202190) decreased the G1-blocking effect of pirfenidone. The expression of CDK2, CDK6, cyclin D1, and cyclin D3 were inhibited by LY294002, U0126, and SP600125. SB202190 attenuated the pirfenidone-induced reduction of CDK2, CDK6, cyclin D1, cyclin D3, and cyclin E.

CONCLUSIONS

Pirfenidone inhibited HTFs proliferation and induced G1 arrest by downregulating CDKs and cyclins involving the AKT/GSK3β and MAPK signaling pathways.

Bevacizumab Inhibits Angiogenesis and Inflammation in Rat Filtration Surgery Model

Bevacizumab can be potentially applied in filtration surgery in glaucoma patients. However, its mechanism remains unclear. In order to explore it, here, we established rat filtration surgery model and treat rat with Bevacizumab. At different time points after surgery, filtering blebs were collected and subjected to angiogenesis and inflammation genes analysis. Our results found that Bevacizumab significantly improved the outcome of filtration surgery and reduced complications (P < 0.05). Furthermore, angiogenesis factor, VEGF, and inflammation factors, TGFβ1 and TGFβ2, were dramatically inhibited by Bevacizumab treatment according to analysis of real-time PCR and western blot. Altogether, our findings suggested that Bevacizumab's beneficial effects on filtration surgery were not limited to antiangiogenesis effect and anti-inflammation effects may be also involved.

Direct Effects of Bevacizumab on Rat Conjunctival Fibroblast

Successful cases of treatment of Bevacizumab for preventing scar after trabeculectomy in glaucoma patients encourage us to explore its mechanism. In this study, we primarily isolated conjunctival fibroblast from rat. RT-PCR analysis for the cells implicated that conjunctival fibroblast expressed vascular endothelial growth factor (VEGF) and its receptors. Immunofluorescence staining also showed positive staining for VEGFR-1. Furthermore, growth of fibroblast was significantly inhibited by Bevacizumab at dose of 2.5 mg/ml. Real time PCR results showed after 48 h intervention of 2.5 mg/ml Bevacizumab, the mRNA expressions of VEGF and its receptors decreased compared to the control group (P < 0.05) and Bevacizumab also decreased expression of TGFβ1 and TGFβ2 (P < 0.05). In summary, our finding demonstrated that Bevacizumab could directly act on fibroblast and inhibit VEGF, TGFβ1, and TGFβ2 expression.

A histopathological investigation of Tenon's capsule in diabetic eyes

The aim of this study is to investigate the histopathological features of Tenon's capsule in eyes with diabetic macular oedema and to compare them between diabetic eyes and healthy subjects. The study included 26 eyes with diabetic oedema and 17 healthy eyes as healthy controls. Tenon's capsule biopsy specimens were processed with the routine electron microscopic analysis technique. Type I and III collagen fibres were labelled immunohistochemically to determine the amounts of predominating collagen fibres. Leica Q-Win program was used to calculate the amounts of collagen fibres type I and type III and independent-t test was utilized to compare the obtained results between the groups. Statistical significance was set at p < 0.05. Demographic characteristics of both groups were similar (p > 0.05). Collagen type I and type III immunoreactivity was observed both in the control and the diabetic groups. The Amounts of collagen fibres type I and type III were significantly higher in the diabetic group than in the control group (mean collagen type I area: 13.410 ± 0.99 and mean collagen type III area: 23.692 ± 0.17 in the control group; mean collagen type I area: 25.270 ± 6.48 and mean collagen type III area: 28.192 ± 0.82 in the diabetic group. p = 0.0037 for type I and p = 0.0000 for type III). In light of the findings of this study, it can be assumed that diabetes mellitus may engender increased amounts of collagen in Tenon's capsule. This alteration affecting the success of filtration surgery should be kept in mind especially in diabetic eyes with glaucoma.

Current and Future Techniques in Wound Healing Modulation after Glaucoma Filtering Surgeries

Filtering surgeries are frequently used for controlling intraocular pressure in glaucoma patients. The long-term success of operation is intimately influenced by the process of wound healing at the site of surgery. Indeed, if has not been anticipated and managed accordingly, filtering surgery in high-risk patients could end up in bleb failure. Several strategies have been developed so far to overcome excessive scarring after filtering surgery. The principal step involves meticulous tissue handling and modification of surgical technique, which can minimize the severity of wound healing response at the first place. However, this is usually insufficient, especially in those with high-risk criteria. Thus, several adjuvants have been tried to stifle the exuberant scarring after filtration surgery. Conventionally, corticosteroids and anti-fibrotic agents (including 5-fluorouracil and Mitomycin-C) have been used for over three decades with semi-acceptable outcomes. Blebs and bleb associated complications are catastrophic side effects of anti-fibrotic agents, which occasionally are encountered in a subset of patients. Therefore, research continues to find a safer, yet effective adjuvant for filtering surgery. Recent efforts have primarily focused on selective inhibition of growth factors that promote scarring during wound healing process. Currently, only anti-VEGF agents have gained widespread acceptance to be translated into routine clinical practice. Robust evidence for other agents is still lacking and future confirmative studies are warranted. In this review, we explain the importance of wound healing process during filtering surgery, and describe the conventional as well as potential future adjuvants for filtration surgeries.

A novel antiproliferative drug coating for glaucoma drainage devices

PURPOSE

The implantation of a glaucoma drainage device (GDD) is often necessary for intractable cases of glaucoma. Currently, the success rate of GDD implants is relatively low because fibrosis that develops during the wound-healing process ultimately blocks fluid drainage. We describe herein a novel porous coating for Ahmed glaucoma valves based on biodegradable poly(lactic-co-glycolic acid) (PLGA).

MATERIALS AND METHODS

Thin films of PLGA were fabricated using a spin-coating technique. The procedure led to an asymmetric pore structure that was exploited to control the rate of dissolution. Double-layered porous films were constructed to achieve continuous drug release. A cell culture system was used to test the efficacy of these coatings.

RESULTS

Double-layered films were manufactured to provide a burst of mitomycin C (MMC) release followed by a slow release of 5-fluorouracil (5-FU), which together prevented fibrosis over the most active period of postoperative wound healing (0 to 28 d). Double-layered films containing 5-FU only in the bottom layer showed a 3- to 5-day delay in drug release, followed by a sharp increase that continued for ~28 days. MMC was stable only when surface-loaded, and this drug was therefore surface-loaded onto the top PLGA layer to provide a continuous release of antifibrotics over the wound-healing period.

CONCLUSIONS

The combined use of both MMC and 5-FU in a biodegradable device inhibits cell proliferation in a tissue culture model and has the potential to reduce fibrosis and increase the success rate of GDD implants. The design is simple and can be scaled for commercial production.

Impact of trastuzumab on wound healing in experimental glaucoma surgery

BACKGROUND

To investigate the effects of subconjunctivally administered trastuzumab on wound healing in experimental glaucoma filtration surgery.

DESIGN

Comparative, experimental study.

SAMPLES

Twenty eight eyes.

METHODS

Twenty-eight male New Zealand white rabbits were randomly assigned to four groups, each including seven rabbits: The rabbits in the control group were not operated on and did not receive any treatment. The rabbits in the sham group underwent trabeculectomy and had one drop of saline instilled four times a day for 14 days. The rabbits in the mitomycin-C group underwent trabeculectomy, and a sponge soaked in 0.4 mg/mL mitomycin-C was applied intraoperatively to the scleral surgical site for 3 min. The rabbits in the trastuzumab group underwent trabeculectomy and were injected subconjunctivally once with 1.2 mg/0.1 mL of the drug. On day 14 of the experiment, the operated and control eyes were enucleated and immunohistochemically analyzed.

MAIN OUTCOME MEASURES

Mean values of fibroblast, mononuclear cell and immunostaining intensities of the transforming growth factor-β, fibroblast growth factor-β, and platelet derived growth factor.

RESULTS

The mean cell numbers and immunostaining intensities in the sham group were higher than those of the control group (P < 0.01). The mean cell numbers and immunostaining intensities in the mitomycin-C group and trastuzumab group were statistically significantly lower than those of the sham group (P < 0.01) while mean cell numbers and immunostaining intensities in the mitomycin-C group and trastuzumab group were similar (P > 0.05).

CONCLUSION

Subconjunctival trastuzumab injection effectively suppressed subconjunctival scarring after experimental glaucoma filtration surgery.

Functional characteristics of connective tissue growth factor on human tenon's capsule fibroblast

PURPOSE OF THE STUDY

To explore the characteristic of connective tissue growth factor (CTGF) on the phenotype transition, extracellular matrix (ECM) synthesis and proliferation of human Tenon's capsule fibroblasts (HTFs).

MATERIALS AND METHODS

HTFs were obtained from patients during cataract surgery and induced by CTGF (1 to 100 µg/L). Western blot and immunofluorescence were performed to observe the expression of alpha smooth muscle actin (α-SM-actin) protein. The levels of mRNAs were quantified by real-time PCR. Col I and FN expression at both protein and RNA levels were tested after induction by CTGF and transforming growth factor β (TGF-β), respectively. Statistical significance was assumed if p < 0.05.

RESULTS

CTGF upregulated the expression of α-SM-actin in cultured HTFs. Its maximum effect at protein level attained under the optimal concentration of 50 μg/L at the peak time of 48 hours, though still weaker than the effect of TGF-β1 (10 μg/L, p < 0.05). The expression of Col I and FN at both protein and mRNA levels was elevated by the induction of CTGF (50 μg/L) (p < 0.01) and TGF-β1 (10 μg/L) (p < 0.05), while CTGF (50 μg/L) showed a greater effect than the latter (p < 0.05). CTGF (1 to100 μg/L) increased the proliferation of HTFs significantly (p < 0.05).

CONCLUSIONS

CTGF induced the phenotype transition of HTFs individually and significantly promoted their proliferation. Moreover, it promoted ECM synthesis, thus demonstrating its role as a crucial factor in fibrosis. Thus, CTGF could potentially be a safer and more efficient target than TGF-β at suppressing scar formation after filtering surgery.

Bleb morphology and vascularity after trabeculectomy with intravitreal ranibizumab: a pilot study

PURPOSE

To investigate outcomes after trabeculectomy using intraoperative intravitreal ranibizumab and topical mitomycin C (MMC) vs MMC alone.

DESIGN

Prospective randomized single-site pilot study.

METHODS

Patients diagnosed with primary open-angle glaucoma were randomized 1:1 to either combination intravitreal ranibizumab 0.5 mg and topically applied MMC (0.4 mg/mL for 2 min) or MMC (0.4 mg/mL for 2 min) therapy alone at time of trabeculectomy surgery. The primary endpoint measured was bleb morphology and vascularity using the Moorfields Bleb Grading System. Unqualified success was defined as postoperative intraocular pressure (IOP) of >5 and <22 mm Hg and a 30% decrease from baseline without use of postoperative hypotensive drops. Qualified success was defined as postoperative IOP of >5 and <22 mm Hg and a 30% decrease from baseline with use of postoperative hypotensive drops.

RESULTS

Ten patients were randomized to either standard trabeculectomy with MMC (Group A) or trabeculectomy with intravitreal ranibizumab and MMC (Group B). All patients completed the study and were classified as unqualified successes. There were statistically significant differences in peripheral bleb area (P = .02), peripheral bleb vascularity (P = .02), and non-bleb-related peripheral conjunctiva vascularity (P = .0003), with Group B exhibiting more diffuse blebs with a lower degree of vascularity.

CONCLUSIONS

Combination intravitreal ranibizumab and topical MMC at time of trabeculectomy resulted in more diffuse blebs with less vascularity when compared to use of topical MMC alone. Further studies are planned to better understand the utility of anti-vascular endothelial growth factor agents as modulators of wound healing post trabeculectomy.

Regulation of Tenon's capsule fibroblast cell proliferation by the opioid growth factor and the opioid growth factor receptor axis

PURPOSE

Glaucoma filtration surgery often fails because of the fibrotic reaction from Tenon's capsule fibroblasts (TCFs). This study examined whether the interaction of the opioid growth factor (OGF) [Met(5)]-enkephalin with its receptor (OGFr) is a regulator of TCF proliferation.

METHODS

The presence of OGF and its receptor (OGFr) was determined in rabbit TCFs (RTCFs) by immunocytochemistry. The kinetics of OGFr were established in receptor binding assays. The ability of OGF to inhibit RTCF proliferation was assessed with dose-response, receptor mediation, and reversibility studies. Dependence on OGF and OGFr was ascertained by antibody neutralization and siRNA studies, respectively. The mechanism of action of the OGF-OGFr axis on survival (apoptosis, necrosis) and DNA synthesis of RTCFs was elucidated.

RESULTS

OGF and OGFr were detected in RTCF cells, and specific and saturable binding to OGFr was recorded. Exogenous OGF had a dose-dependent, reversible, and receptor-mediated inhibitory effect on cell proliferation. Endogenous OGF was found to be constitutively produced and tonically active in cell replication, with neutralization of this peptide causing acceleration of cell proliferation. The silencing of OGFr by using siRNA technology stimulated cell replication, validating OGFr's integral role. The mechanism of OGF-OGFr action was not related to cell survival, but rather to DNA synthesis-specifically, the cyclin-dependent kinase inhibitory pathway. Knockdown of p16 or p21 eliminated OGF's inhibitory effect on growth.

CONCLUSIONS

The OGF-OGFr system is a native biological regulator of cell proliferation in RTCFs and may offer a means of improving the success of glaucoma filtration surgery in a safe and nontoxic manner.

Aberrant wound-healing response in mitomycin C-treated leaking blebs: a histopathologic study

OBJECTIVE

To characterize histopathologic features of leaking mitomycin C-treated blebs and aberrant wound healing that may lead to persistent conjunctival thinning and leakage.

METHODS

Forty mitomycin C-treated filtering blebs excised for persistent leaks from 40 patients were examined histopathologically using hematoxylin-eosin, periodic acid-Schiff, Masson trichrome, and Alcian blue histochemical stains.

RESULTS

Ninety percent of the leaking blebs contained epithelial-stromal domes with areas of acellular stroma covered by attenuated epithelium. Seventy-five percent of the blebs demonstrated varying degrees of fibrovascular repair growing from the bleb margin, either beneath or interdigitating with the acellular zone. A novel observation in 65% of specimens was Alcian blue-positive myxoid stroma at the interface between the fibrovascular proliferation and the epithelial-stromal dome. The association between the presence of fibrovascular proliferation and Alcian blue-staining myxoid stroma was significant by Fisher exact test (P = .002).

CONCLUSIONS

A desirable filtration bleb requires a sufficient reparative fibrovascular response to maintain an epithelial-stromal barrier to prevent leakage. Fibroblasts must lay down a continuous collagen-rich fibrous layer, rather than merely myxoid stroma, beneath the conjunctival epithelium to promote bleb stability. Surgical techniques and postsurgical care should aim to attain this desired outcome.

The effect of paclitaxel on conjunctival wound healing: a pilot study

PURPOSE

To compare the effects of mitomycin C (MMC) and paclitaxel entrapped within Carbopol 980 hydrogel (CH) on conjunctival wound healing.

METHODS

Twenty rabbits were randomized into 2 groups. In group 1, limbal-based conjunctival flaps were created in both eyes. In this stage, eyes were randomized for 4 different processes. In process 1, a dry cellulose sponge soaked with 0.2 mg/mL of MMC was applied to the scleral surface. A cellulose sponge soaked with balanced saline solution was applied in the same manner in process 2. In process 3, paclitaxel 1 mg/mL entrapped within CH was placed between the conjunctiva and sclera. In process 4, CH without paclitaxel was applied in the same manner. The conjunctiva was then sutured. All procedures were applied in the same manner in both eyes of animals in group 2. Eyes from group 1 were sampled at the seventh day, and the sampling was also carried out in group 2 on day 14. The inflammatory response and fibrosis were evaluated with light microscopy.

RESULTS

Among 4 different processes, lower cell counts and fibrosis scores were found in eyes treated with MMC and paclitaxel compared with balanced saline solution and CH groups (P<0.05). There was no difference between eyes treated with MMC and paclitaxel in terms of these histopathologic parameters (P>0.05).

CONCLUSIONS

Paclitaxel was shown to provide MMC-like antifibrotic effects during conjunctival wound healing, particularly when delivered with CH and might be a promising alternative as an adjunctive antimetabolite in glaucoma filtration surgery.

Focus on triamcinolone acetonide as an adjunct to glaucoma filtration surgery

Glaucoma is one of the most common causes of irreversible blindness worldwide. Despite continued advances in medical and laser therapy, incisional surgery still appears to be an important and for many cases the only option by which intraocular pressure is controlled. Unlike many other types of surgery in which complete healing of tissue would be a desirable outcome, glaucoma surgery seeks to achieve incomplete healing to allow aqueous humor to escape the eye. Pharmacologic modulation of wound healing is a hot topic in glaucoma filtration surgery. Although routine antifibrotic medications are associated with good results in modulating wound healing in glaucoma surgery, they carry with them the possibility for significant morbidity due to the adverse effects of treatment. Challenge continues to be to find a safe and effective agent for this purpose. Because of beneficial effects of triamcinolone acetonide in some conditions which are associated with secondary glaucoma and also potential effects of this agent in modulating wound healing process, we propose it as a useful adjunct to glaucoma filtration surgery. This approach may allow modulation of wound healing with less of the toxicity associated with commonly used antifibrotics (5-FU and mitomycin C).

Photodynamic treatment in a rabbit model of glaucoma surgery

PURPOSE

To evaluate the safety and efficacy of postoperative verteporfin photodynamic treatment as an adjunct to glaucoma experimental filtration surgery in rabbits.

METHODS

Dutch belted (n = 15) rabbits underwent full thickness sclerectomy in one eye. The experimental group (group 1, n = 7) underwent i.v. injection of verteporfin and subsequent photoactivation at the operative site on postoperative day 1 (POD 1). Control groups of animals received either light exposure (group 2, n = 4) or verteporfin (group 3, n = 2), or no intervention (group 4, n = 2). Intraocular pressure (IOP) was measured prior to the procedure (POD 0) and daily thereafter for the first week after sclerectomy (PODs 1-7) and every other day for the second week (PODs 9, 11, 13, 15). Percentage IOP reductions of operated over contralateral control eyes were compared among the various groups. Success rates (percentage IOP reduction > 15%) were also compared between the experimental and control groups. Eyes were histologically examined for evaluation of fibrosis.

RESULTS

Rabbits in the experimental group (group 1) had a mean +/- SEM percentage IOP reduction of 25 +/- 3% during the follow-up period. In contrast, groups 2, 3 and 4 had IOP reductions of 4 +/- 5%, 12 +/- 7% and 4 +/- 6%, respectively (p < 0.005, anova among all four groups). Successful IOP reduction (> or = 15%) over the contralateral eye at POD 15 was achieved in six of seven experimental animals, but only in one of eight control animals (p < 0.02, chi-squared test). Bleb failure occurred significantly earlier in the control eyes compared with eyes receiving PDT (p < 0.003, log rank test). Blebs in the experimental group differed from those in the control groups histologically, lacking significant collagen deposition in the area of the sclerostomy.

CONCLUSIONS

Wound healing in glaucoma surgery may be successfully modulated postoperatively using photodynamic therapy with i.v. administered photosensitizer.