Proliferative vitreoretinopathy

Vitreoschisis-induced vitreous cortex remnants in proliferative vitreoretinopathy: A comprehensive review from basic research to clinical practice

Proliferative vitreoretinopathy (PVR) significantly impacts the prognosis of rhegmatogenous retinal detachment (RRD), one of the most critical and increasing causes of vision loss in the Western world. Despite advancements in surgical instruments and techniques, the failure rate due to PVR remains substantial, necessitating additional surgeries and often leading to unsatisfactory visual outcomes. This comprehensive review explores the role of vitreoschisis-induced vitreous cortex remnants (VCR) as a critical, previously under-recognised factor contributing to PVR. Vitreoschisis, a phenomenon where the inner lamellae of the posterior vitreous cortex detach while the outermost layers remain attached to the retina, creates VCR that may contain hyalocytes and serve as scaffolds for fibrocellular proliferation. These remnants are difficult to visualise without triamcinolone acetonide (TA) staining, leading to their frequent lack of recognition in clinical practice. Moreover, removing VCR can be challenging and time-consuming, often requiring meticulous surgical techniques to avoid retinal damage and ensure complete elimination. This review consolidates insights from basic research and clinical practice, emphasising the importance of complete vitreous removal and effective VCR detection and removal to mitigate PVR risks. It highlights the histopathological and clinical evidence supporting the hypothesis that VCR, containing hyalocytes, play a pivotal role in preretinal membrane formation. The review also discusses epidemiological data, surgical management strategies and potential future directions, including improved visualisation techniques and the development of new surgical tools and methods. This review aims to improve surgical outcomes and reduce the frequency and burden of RRD-related complications by addressing VCR as a critical factor in PVR.

Tricetin suppresses the cell migration and BMP-6 expression through p38 signaling pathways in human retinal pigment epithelium cells

Proliferative vitreoretinopathy (PVR) is a visual-threatening disease, which cause from the migration of retinal pigment epithelium (RPE). Tricetin, a family of flavonoids, can inhibit the metastasis of several cancers. Herein, we aim to evaluate the possible effect of tricetin on inhibiting ARPE-19 cells migration. The Boyden chamber assay, wound healing assay, RNA sequencing, and Western blot analysis were applied in our experiment. The results revealed that tricetin inhibited the cell migration abilities of ARPE-19 cells. Moreover, using RNA sequencing technology, we revealed that tricetin repressed bone morphogenetic protein-6 (BMP-6) gene expressions in ARPE-19 cells. Overexpression of BMP-6 resulted in significant restoration of cell migration capabilities of tricetin-treated ARPE-19 cells. Furthermore, tricetin suppressed the phosphorylation of the p38 signaling pathway. Moreover, blocking the p38 pathway also inhibits BMP-6 expression and migration in the ARPE-19 cells. In conclusion, this study revealed that tricetin inhibits the ARPE-19 cell migration mainly via the suppression of BMP-6 expression and p38 signaling pathway.

Enantiomeric Agonists of the Type 2 Cannabinoid Receptor Reduce Retinal Damage during Proliferative Vitreoretinopathy and Inhibit Hyperactive Microglia In Vitro

Microglia are resident immune cells of the central nervous system (CNS) and propagate inflammation following damage to the CNS, including the retina. Proliferative vitreoretinopathy (PVR) is a condition that can emerge following retinal detachment and is characterized by severe inflammation and microglial proliferation. The type 2 cannabinoid receptor (CB2) is an emerging pharmacological target to suppress microglial-mediated inflammation when the eyes or brain are damaged. CB2-knockout mice have exacerbated inflammation and retinal pathology during experimental PVR. We aimed to assess the anti-inflammatory effects of CB2 stimulation in the context of retinal damage and also explore the mechanistic roles of CB2 in microglia function. To target CB2, we used a highly selective agonist, HU-308, as well as its enantiomer, HU-433, which is a putative selective agonist. First, β-arrestin2 and Gαi recruitment was measured to compare activation of human CB2 in an in vitro heterologous expression system. Both agonists were then utilized in a mouse model of PVR, and the effects on retinal damage, inflammation, and cell death were assessed. Finally, we used an in vitro model of microglia to determine the effects of HU-308 and HU-433 on phagocytosis, cytokine release, migration, and intracellular signaling. We observed that HU-308 more strongly recruited both β-arrestin2 and Gαi compared to HU-433. Stimulation of CB2 with either drug effectively blunted LPS- and IFNγ-mediated signaling as well as NO and TNF release from microglia. Furthermore, both drugs reduced IL-6 accumulation, total caspase-3 cleavage, and retinal pathology following the induction of PVR. Ultimately, this work supports that CB2 is a valuable target for drugs to suppress inflammation and cell death associated with infection or sterile retinopathy, although the magnitude of effector recruitment may not be predictive of anti-inflammatory capacity.

Characteristics and surgery outcomes of macular hole diagnosed after rhegmatogenous retinal detachment repair

PURPOSE

To report the characteristics and the visual and anatomical outcomes of secondary macular holes (SMHs) diagnosed after rhegmatogenous retinal detachment (RRD) repair and their associated factors.

METHODS

Retrospective, interventional case series. All consecutive patients who were diagnosed with SMH after RRD repair at Beijing Tongren eye center from January 2016 to April 2021 were included. Patients who had their primary RRD repair in other hospitals and were referred to our center after diagnosis of SMH were also included. The minimum follow-up time after RRD repair was 6 months.

RESULTS

37 SMHs were diagnosed within a series of 5696 RRDs. Including 24 eyes referred from other hospitals after the diagnosis of SMH, 61 eyes were included. The type of primary RRD repair surgery included 22/61 (36%) eyes with scleral buckling procedure (SBP) and 39/61 (64%) eyes with pars plana vitrectomy (PPV). 21/61 (34%) eyes had recurrent RD. The median time to SMH diagnosis was 150 days (range, 7 ~ 4380 days). Macular hole (MH) closure was achieved in 77% eyes. Visual acuity (VA) improvement of at least 2 lines of Snellen's visual acuity was observed in 51% eyes. Final MH closure status was associated with preoperative MH diameter (for every 50 μm increment) (P = 0.046, OR = 0.875, 95%CI: 0.767 ~ 0.998). VA improvement was associated with final MH closure status (P = 0.009, OR = 8.742, 95%CI: 1.711 ~ 44.672). Final VA (logMAR) was associated with recurrent RD (P < 0.001, B = 0.663, 95%CI: 0.390 ~ 0.935), preoperative MH diameter (P = 0.001, B = 0.038, 95%CI: 0.017 ~ 0.058), VA at the time of SMH diagnosis (P < 0.001, B = 0.783, 95%CI: 0.557 ~ 1.009) and final MH closure status (P = 0.024, B = -0.345, 95%CI: -0.644 ~ -0.046). For patients without recurrent RD, VA improvement and final VA was associated with final MH closure status (P = 0.016 and P < 0.001, respectively), while for patients with recurrent RD, VA improvement or final VA did not associate with final MH closure status (P > 0.05).

CONCLUSION

For SMH diagnosed after RRD repair, final MH closure status was associated with preoperative MH diameter. Recurrent RD, larger preoperative MH diameter, worse VA at the time of SMH diagnosis and failed MH closure are predictive factors for worse final VA. Visual outcome is associated with final MH closure status in patients without recurrent RD, but not as so in patients with recurrent RD.

Novel insights into the pathophysiology of proliferative vitreoretinopathy: The role of vitreoschisis-induced vitreous cortex remnants

PURPOSE

We previously hypothesized a causal relationship between vitreoschisis-induced vitreous cortex remnants (VCR) and the development of proliferative vitreoretinopathy (PVR). This study aims to substantiate this association through histopathological analysis of surgical specimens in support of strategies to improve therapeutic outcomes.

METHODS

A descriptive, prospective, non-consecutive case series. Histopathological and immunohistochemical analyses were performed on membranes removed from the peripheral retinal surface during initial vitrectomy for primary rhegmatogenous retinal detachment (RRD) (n = 11) or recurrent retinal detachment (n = 12). The clinical aspect of the membranes ranged from loose-meshed membranes visualized with triamcinolone to more fibrotic membranes stained with trypan blue.

RESULTS

Consistent with the clinical presentation, histopathological analysis revealed membranes with different area characteristics. Paucicellular lamellar collagen-rich areas, suggestive of VCR, appeared to transition to areas of increased cellularity and eventually more fibrotic areas of low cellularity. Five different area characteristics could be identified that seemed to correspond to five histopathological stages in PVR formation, with lamellar VCR collagen acting as an essential precondition: 1. Lamellar collagen, low cellularity (hyalocytes). 2. Lamellar collagen, increased cellularity (hyalocytes, glial cells). 3. Lamellar collagen, high cellularity (macrophages, glial cells, RPE-cells). 4. Early fibrosis, decreased cellularity (myofibroblasts). 5. Fibrosis, low cellularity (myofibroblasts).

CONCLUSION

These findings confirm the role of VCR in preretinal PVR formation posterior to the vitreous base. We propose that the presence of VCR over the retinal surface should be qualified as a risk factor for PVR formation. Detection and adequate removal of VCR may improve the success rate of vitreoretinal surgeries.

Placental extract suppresses the formation of fibrotic deposits by tumor necrosis factor alpha and transforming growth factor beta-induced epithelial-mesenchymal transition in ARPE-19 cells

Objective

Epithelial–mesenchymal transition (EMT) is involved in the development of proliferative vitreoretinopathy (PVR) and subsequent fibrosis. Previously, we demonstrated that placental extract ameliorates fibrosis in a mouse model of non-alcoholic steatohepatitis. In this study, we evaluated whether placental extract influences EMT and fibrosis through cytokine-induced EMT in the retinal pigment epithelial cells, in vitro.

Results

Placental extract did not inhibit EMT, but it suppressed excessive mesenchymal reactions and the subsequent fibrosis. These results suggest that placental extract effectively ameliorates EMT-associated fibrosis in PVR. This beneficial effect could be partially attributed to the suppression of excessive mesenchymal reactions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05824-0.

The role of vitreous cortex remnants in proliferative vitreoretinopathy formation demonstrated by histopathology: A case report

Purpose

The pathogenesis of proliferative vitreoretinopathy (PVR), the most important cause of retinal detachment surgery failure, is still not fully understood. We previously hypothesized a causal link between vitreoschisis-induced vitreous cortex remnants (VCR) and PVR formation. The purpose of this case report is to demonstrate this association by showing the clinical occurrence of PVR in the presence of VCR across the retinal surface, illustrated by histopathological analysis.

Observations

A 69-year-old male was referred because of widespread epiretinal membrane formation after treatment of recurrent retinal detachments. During surgery with extensive membrane peeling, a large continuous membrane was peeled from the superior arcade towards the inferior temporal mid-periphery. Histopathological analysis of this membrane revealed areas with different characteristics: paucicellular laminar collagen-rich areas, suggestive for VCR, areas with increased cellularity, and more fibrotic areas with low cellularity.

The immunohistochemical analysis identified cell type variety in these areas: collagen-rich areas showed glial cells and hyalocytes, while in areas with high cellularity fibroblasts, macrophages and retinal pigment epithelial cells were found, which have previously been shown to play an important role in the development of PVR as they can transdifferentiate into myofibroblasts, which were seen in the more fibrotic areas.

Conclusions and importance

These findings support the theory that VCR have a role in PVR development, where VCR can act as a scaffold for fibrocellular proliferation. We suggest that the presence of VCR over the retinal surface should be qualified as a risk factor for PVR formation. Detection and adequate removal of VCR may improve the success rate of retinal detachment surgery.

Endoscopy-assisted vitrectomy vs. vitrectomy alone: comparative study in complex retinal detachment with proliferative vitreoretinopathy

Background

Recurrent retinal detachment (RD) is still a widespread event despite the therapeutic options available. Proliferative vitreoretinopoathy (PVR) is one of the main causes of redetachment. Little is known about the use of endoscopy-assisted vitrectomy (E-PPV) in complex recurrent RD with PVR. The purpose of this study was to identify the potential advantages of E-PPV in complex RD with PVR compared with pars plana vitrectomy (PPV) alone.

Methods

Single-center, retrospective, observational, descriptive study. The medical records of 293 patients were reviewed. Patients who underwent PPV for complex rhegmatogenous RD and associated PVR between 2009 and 2017 were included. Patients with diabetic tractional RD, trauma, uveitis or detachment postendophthalmitis were excluded. After 2013, an endoscopic visualization system was used in a nonrandomized fashion at the surgeon’s discretion. Outcome measures (reattachment rate, number of surgeries, lens status, PVR stage, intraocular pressure, phthisis rate) were compared between the E-PPV and PPV-only groups with independent samples t-tests (continuous variables) and Fisher’s exact test (categorical variables), as well as time-adjusted analyses. Postoperative time to retinal redetachment was assessed with Kaplan–Meier survival analysis.

Results

One hundred one eyes from 100 patients met the inclusion criteria. The mean participant age was 63.3 years old (95% CI 60.4–66.1 years), without a significant difference between groups. E-PPV was performed in 36.6% (n = 37) of eyes, and 63.4% (n = 64) underwent PPV only. The mean follow-up was significantly longer in the PPV-only group (31.9 vs. 21.1 months; p = 0.021). Upon adjustment for follow-up duration, the mean number of surgeries was significantly lower in the PPV-only group (2.6 vs. 4.3 number of surgeries; p < 0.001) than in the E-PPV group. A significantly higher risk for redetachment was observed in the PPV-only group (HR [95% CI] 4.1 [1.4–11.8]) than in the E-PPV group (p = 0.037). The evolution to phthisis was 7% (n = 4) in the PPV-only group and 2.7% (n = 1) in the E-PPV group (p > 0.05).

Conclusions

Compared to PPV alone, endoscopy-assisted vitrectomy seems to be advantageous in achieving better reattachment rates in complex RD with advanced PVR. Endoscopic visualization allows a thorough examination and extensive anterior PVR and vitreous base dissection.

Vitreous levels of Lipocalin-2 on patients with primary rhegmatogenous retinal detachment

Purpose

To measure vitreous levels of Lipocalin2 (LCN2) in patients with rhegmatogenous retinal detachment (RRD) and investigate potential association with presence of proliferative vitreoretinopathy (PVR).

Materials and methods

Collection of undiluted vitreous samples from 24 patients suffering from RRD and 10 control patients undergoing vitrectomy for: vitreomacular traction (VMT) (n = 2), idiopathic epiretinal membrane (iERM) (n = 6) and full thickness macular hole (FTMH) (n = 2). Quantitative analysis of LCN2 has been made with flow cytometry. Lens status, duration of symptoms, quadrants of detachment, as well as level of PVR, were assessed. Statistical analysis included Mann-Whitney test, Kruskal-Wallis test, t-test, Spearman’s correlation coefficient and Fisher's exact test.

Results

Median LCN2 was significantly higher in the RRD group as compared to control (p<0.001). Within the RRD group there was a positive correlation between LCN2 and PVR grade (r_s = 0.94, p<0.001). Median LCN2 was 35,759 pg/ml (IR = 55,347) in grade C PVR, 9,387 pg/ml (IR = 3721) in grade B, 4,917 pg/ml (IR = non computable) in grade A and 3,921 pg/ml (2132) in the no PVR group. Median LCN2 was also significantly higher in pseudophakic patients as compared to phakic patients (p = 0.007). LCN2 also correlates with the extend of detachment (≤2 vs >2 quadrants, p<0.001) as well as with duration of symptoms (r_s = 0.87, p<0.001). After multivariate linear regression analysis, only PVR was independently related with LCN2 concentration. In particular, increased PVR grading was associated with increased LCN2 concentration (coefficient b = 2.97, 95% confidence interval = 1.89 to 4.67, p<0.001).

Conclusion

A positive correlation between vitreous levels of LCN2 and PVR grading reveals a potential role in the pathogenesis and progression of PVR. Further studies could elucidate if LCN2 could be a therapeutic target.

Comparative transcriptomic analysis reveals adriamycin-induced apoptosis via p53 signaling pathway in retinal pigment epithelial cells

OBJECTIVE

This paper applied a transcriptomic approach to investigate the mechanisms of adriamycin (ADR) in treating proliferative vitreoretinopathy (PVR) using ARPE-19 cells.

METHODS

The growth inhibitory effects of ADR on ARPE-19 cells were assessed by sulforhodamine B (SRB) assay and propidium iodide (PI) staining using flow cytometry. The differentially expressed genes between ADR-treated ARPE-19 cells and normal ARPE-19 cells and the signaling pathways involved were investigated by microarray analysis. Mitochondrial function was detected by JC-1 staining using flow cytometry and the Bcl-2/Bax protein family. The phosphorylated histone H2AX (γ-H2AX), phosphorylated checkpoint kinase 1 (p-CHK1), and phosphorylated checkpoint kinase 2 (p-CHK2) were assessed to detect DNA damage and repair.

RESULTS

ADR could significantly inhibit ARPE-19 cell proliferation and induce caspase-dependent apoptosis in vitro. In total, 4479 differentially expressed genes were found, and gene ontology items and the p53 signaling pathway were enriched. A protein-protein interaction analysis indicated that the TP53 protein molecules regulated by ADR were related to DNA damage and oxidative stress. ADR reduced mitochondrial membrane potential and the Bcl-2/Bax ratio. p53-knockdown restored the activation of c-caspase-3 activity induced by ADR by regulating Bax expression, and it inhibited ADR-induced ARPE-19 cell apoptosis. Finally, the levels of the γ-H2AX, p-CHK1, and p-CHK2 proteins were up-regulated after ADR exposure.

CONCLUSIONS

The mechanism of ARPE-19 cell death induced by ADR may be caspase-dependent apoptosis, and it may be regulated by the p53-dependent mitochondrial dysfunction, activating the p53 signaling pathway through DNA damage.

Scutellarin protects human retinal pigment epithelial cells against hydrogen peroxide (H2O2)-induced oxidative damage

Background

Proliferative vitreoretinopathy (PVR) is a severe blinding complication of retinal detachment surgery. Increasing evidence demonstrate that PVR is associated with oxidative stress. Scutellarin is a natural flavone compound that has been reported to have anti-oxidative activity. However, the effect of scutellarin on PVR remains unknown. In the current study, we assessed the effect of scutellarin on hydrogen peroxide (H₂O₂)-induced oxidative injury in human retinal pigment epithelium cells (ARPE-19).

Methods

ARPE-19 cells were pretreated with different concentrations of scutellarin for 2 h, and then challenged with H₂O₂ (1 mM) for 24 h. The levels of reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD) and glutathione (GSH) activity were measured to assess the level of oxidative stress. Flow cytometry was performed to detect the apoptosis rate of ARPE-19 cells. Expression levels of bcl-2, bax, cleaved-caspase-3, p-JAK2, JAK2, p-STAT3, and STAT3 were measured using western blot.

Results

Our results revealed that scutellarin improved the cell viability of H₂O₂-induced ARPE-19 cells. Scutellarin alleviated the H₂O₂-induced oxidative stress in ARPE-19 cells, which was illustrated by reduced levels of ROS and MDA, accompanied by increased SOD activity and GSH level. The increased apoptosis rate of ARPE-19 cells caused by H₂O₂ induction was significantly decreased after scutellarin treatment. H₂O₂ treatment resulted in significant increase in bax expression and decrease in bcl-2 expression, while the changes in the expressions of bax and bcl-2 were reversed by scutellarin treatment. In addition, scutellarin promoted the activation of JAK2/STAT3 signaling pathway in H₂O₂-induced ARPE-19 cells. Suppression of JAK2/STAT3 signaling pathway abolished the protective effects of scutellarin on H₂O₂-induced ARPE-19 cells.

Conclusion

These findings suggested that scutellarin was capable for alleviating H₂O₂-induced oxidative damage in ARPE-19 cells, which might be ascribed to the activation of JAK2/STAT3 signaling pathway.

Electronic supplementary material

The online version of this article (10.1186/s13578-019-0276-0) contains supplementary material, which is available to authorized users.

Feline Neovascular Vitreoretinopathy and Anterior Segment Dysgenesis With Concurrent Glaucoma in Domestic Cats

Feline neovascular vitreoretinopathy (FNV) is a newly recognized rare condition affecting kittens and young domestic cats. This study investigated the clinical and pathologic findings in 22 cats with FNV. In affected cats, ophthalmoscopy of the fundus (when visible) revealed avascular peripheral retinae and epiretinal vascular membranes. Frequent nonspecific clinical findings were buphthalmos ( n = 21), medically uncontrollable glaucoma ( n = 22), and lenticular abnormalities ( n = 13). Anterior segment dysgenesis (ASD) was detected clinically in affected cats ( n = 6). The fellow eye was affected in 11 of 18 cats to a variable degree or appeared clinically normal in 7 of 18 cats. The globes were examined histologically and using immunohistochemistry for vimentin, glial fibrillary acidic protein (GFAP), synaptophysin, neurofilament, laminin, factor VIII-related antigen (FVIII-RA), and smooth muscle actin (SMA). Histologically, diagnostic features included laminin-positive epiretinal vascular membranes affecting the central retina, with an avascular peripheral retina and gliosis. Enucleated globes exhibited multiple additional abnormalities, including corneal disease ( n = 15), anterior segment dysgenesis ( n = 21), lymphoplasmacytic anterior uveitis ( n = 19), peripheral anterior synechiae ( n = 20), retinal degeneration ( n = 22), and retinal detachment ( n = 19). Gliotic retinae labeled strongly for GFAP and vimentin with reduced expression of synaptophysin and neurofilament, consistent with degeneration or lack of differentiation. While an avascular peripheral retina and epiretinal fibrovascular membranes are also salient features of retinopathy of prematurity, there is no evidence to support hyperoxic damage in cats with FNV. The cause remains unknown.

Suppressive effect of AMP-activated protein kinase on the epithelial-mesenchymal transition in retinal pigment epithelial cells

The epithelial-mesenchymal transition (EMT) in retinal pigment epithelial (RPE) cells plays a central role in the development of proliferative vitreoretinopathy (PVR). The purpose of this study was to investigate the effect of AMP-activated protein kinase (AMPK), a key regulator of energy homeostasis, on the EMT in RPE cells. In this study, EMT-associated formation of cellular aggregates was induced by co-stimulation of cultured ARPE-19 cells with tumor necrosis factor (TNF)-α (10 ng/ml) and transforming growth factor (TGF)-β₂ (5 ng/ml). 5-Aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR), a potent activator of AMPK, significantly suppressed TNF-α and TGF-β₂-induced cellular aggregate formation (p < 0.01). Dipyridamole almost completely reversed the suppressive effect of AICAR, whereas 5’-amino-5’-deoxyadenosine restored aggregate formation by approximately 50%. AICAR suppressed the downregulation of E-cadherin and the upregulation of fibronectin and α-smooth muscle actin by TNF-α and TGF-β₂. The levels of matrix metalloproteinase (MMP)-2, MMP-9, interleukin-6, and vascular endothelial growth factor were significantly decreased by AICAR. Activation of the mitogen-activated protein kinase and mammalian target of rapamycin pathways, but not the Smad pathway, was inhibited by AICAR. These findings indicate that AICAR suppresses the EMT in RPE cells at least partially via activation of AMPK. AMPK is a potential target molecule for the prevention and treatment of PVR, so AICAR may be a promising candidate for PVR therapy.

Strategic planning ensures surgical success in cases of proliferative vitreoretinopathy

For this Practical Retina column, Dr. Ross Lakhanpal from Baltimore was asked to comment on the current state of thinking and management options for proliferative vitreoretinopathy (PVR) after retinal detachment (RD) surgery.We are all aware that PVR continues to be an important cause of recurrent RD after successful repair. This feared complication has been reported to occur in up to 8% of patients after undergoing RD repair. Despite the historic progress made in managing various vitreoretinal diseases over the past decade, most retina specialists will agree that an unmet need remains in this landscape. Fortunately, advances in various surgical technologies such as instrumentation, lighting, and visualization have improved the outcomes after PVR management.Dr. Lakhanpal discusses causes of PVR, management goals, surgical techniques, and pearls to avoid complications after managing PVR. His experience working in an urban tertiary surgical retina practice enables him to offer insights that will be highly valued by our community.

The outcomes of primary scleral buckling during repair of posterior segment open-globe injuries

Objective. To compare visual outcomes of eyes which underwent primary scleral buckling (PSB) treatment during posterior segment open-globe injury (OGI) repair with eyes not treated with PSB. Methods. We retrospectively reviewed 38 eyes which underwent a posterior segment OGI repair with no preoperative evidence of retinal detachment (RD) at Soroka University Medical Center (1995–2010). 19 (50%) underwent scleral repair alone (control group) and the other 19 eyes were treated with PSB also (PSB group). We compared visual outcomes in these two groups and rates of subsequent postoperative complications. Results. Baseline characteristics of the groups were similar. Compared with the control group, the PSB group had statistically significant lower rates of proliferative vitreoretinopathy (PVR) (5.3% versus 38.4%, P < 0.05) and a trend towards lower rates of RD (15.8% versus 41.1%, P = 0.1). PSB group eyes had a statistically significant improvement of their best distance visual acuity (BDVA) with lower means of final BDVA-grade (P < 0.05) and logMAR vision (P < 0.05). Eyes in the control group had no improvement in these parameters. Conclusion. PSB procedure during posterior segment OGI repair may decrease the risk of subsequent retinal complications and improve final visual outcome.

Stem cells as source for retinal pigment epithelium transplantation

Inherited maculopathies, age related macular degeneration and some forms of retinitis pigmentosa are associated with impaired function or loss of the retinal pigment epithelium (RPE). Among potential treatments, transplantation approaches are particularly promising. The arrangement of RPE cells in a well-defined tissue layer makes the RPE amenable to cell or tissue sheet transplantation. Different cell sources have been suggested for RPE transplantation but the development of a clinical protocol faces several obstacles. The source should provide a sufficient number of cells to at least recover the macula area. Secondly, cells should be plastic enough to be able to integrate in the host tissue. Tissue sheets should be considered as well, but the substrate on which RPE cells are cultured needs to be carefully evaluated. Immunogenicity can also be an obstacle for effective transplantation as well as tumorigenicity of not fully differentiated cells. Finally, ethical concerns may represent drawbacks when embryo-derived cells are proposed for RPE transplantation. Here we discuss different cell sources that became available in recent years and their different properties. We also present data on a new source of human RPE. We provide a protocol for RPE differentiation of retinal stem cells derived from adult ciliary bodies of post-mortem donors. We show molecular characterization of the in vitro differentiated RPE tissue and demonstrate its functionality based on a phagocytosis assay. This new source may provide tissue for allogenic transplantation based on best matches through histocompatibility testing.

TGF-ß and RPE-derived cells in taut subretinal strands from patients with proliferative vitreoretinopathy

PURPOSE

To investigate the distribution of transforming growth factor-ß (TGF-ß) and cells derived from the retinal pigment epithelium (RPE) as a major source for TGF-ß in subretinal strands (SRSs), originating from patients with proliferative vitreoretinopathy (PVR) and proliferative diabetic vitreoretinopathy (PDVR).

METHODS

Nine SRSs (PVR: n=6 and PDVR: n=3) were obtained during pars plana vitrectomy. Specimens were processed for immunohistochemical analysis in paraffin wax or studied by transmission electron microscopy.

RESULTS

Staining for TGF-ß was consistent in all specimens. The content of RPE-derived cells identified by anticytokeratin staining revealed considerable differences, ranging from <10 to >90%.

CONCLUSIONS

The widespread immunoreactivity for TGF-ß in SRSs suggests a significant role of this group of cytokines in the pathologic course of PVR.

Expression of PDGFRα is a determinant of the PVR potential of ARPE19 cells

PURPOSE

Previous studies indicate that the expression of platelet-derived growth factor (PDGF) receptor α (PDGFRα) dramatically increases the ability of fibroblasts to induce experimental proliferative vitreoretinopathy (PVR). The purpose of this study was to determine whether PDGFRα contributed to the PVR potential of retinal pigment epithelial (RPE) cells, one of the most abundant cell types in PVR membranes.

METHODS

PDGFRα expression in human ARPE19 cells was increased or decreased by stably expressing the PDGFRα cDNA or short hairpin (sh) RNA directed at PDGFRα, respectively. The level of PDGFRα expression in the resulting panel of cell lines was either barely detectable (KD), standard (similar to the level of primary RPE cells), or overexpressed approximately 80-fold. Western blot analysis was used to assess the level of p53 and the activation state of PDGFRα and Akt. The following cellular responses were monitored: proliferation, apoptosis, and contraction. The PVR potential of cells was tested in a rabbit model of PVR in which cells were coinjected with platelet-rich plasma into the vitreous.

RESULTS

Comparison of KD and overexpressing cells indicated that high-level expression of PDGFRα dramatically augmented signaling events, cellular responses, and the PVR potential of ARPE19 cells. However, all these outcomes were also significantly increased, albeit not as robustly, by PDGFRα expression to the level typically present in RPE cells.

CONCLUSIONS

Even though RPE cells express substantially less PDGFRα than fibroblasts, it significantly boosts PVR-related signaling events, cellular responses, and the PVR potential of ARPE19 cells. These studies suggest that inhibiting activation, signaling, or both by PDGFRα has the potential to prevent the development of PVR.