Toxicity of Indocyanine Green (ICG) in Combination with Light on Retinal Pigment Epithelial Cells and Neurosensory Retinal Cells

Neuroretinal Cell Culture Model as a Tool for the Development of New Therapeutic Approaches for Oxidative Stress-Induced Ocular Diseases, with a Focus on Glaucoma

Glaucoma is a heterogeneous group of optic neuropathies characterized by a progressive degeneration of the retinal ganglion cells (RGCs), leading to irreversible vision loss. Nowadays, the traditional therapeutic approach to glaucoma consists of lowering the intraocular pressure (IOP), which does not address the neurodegenerative features of the disease. Besides animal models of glaucoma, there is a considerable need for in vitro experimental models to propose new therapeutic strategies for this ocular disease. In this study, we elucidated the pathological mechanisms leading to neuroretinal R28 cell death after exposure to glutamate and hydrogen peroxide (H2O2) in order to develop new therapeutic approaches for oxidative stress-induced retinal diseases, including glaucoma. We were able to show that glutamate and H2O2 can induce a decrease in R28 cell viability in a concentration-dependent manner. A cell viability of about 42% was found after exposure to 3 mM of glutamate and about 56% after exposure to 100 µM of H2O2 (n = 4). Label-free quantitative mass spectrometry analysis revealed differential alterations of 193 and 311 proteins in R28 cells exposed to 3 mM of glutamate and 100 µM of H2O2, respectively (FDR < 1%; p < 0.05). Bioinformatics analysis indicated that the protein changes were associated with the dysregulation of signaling pathways, which was similar to those observed in glaucoma. Thus, the proteomic alteration induced by glutamate was associated with the inhibition of the PI3K/AKT signaling pathway. On the other hand, H2O2-induced toxicity in R28 cells was linked to the activation of apoptosis signaling and the inhibition of the mTOR and ERK/MAPK signaling pathways. Furthermore, the data show a similarity in the inhibition of the EIF2 and AMPK signaling pathways and the activation of the sumoylation and WNT/β-catenin signaling pathways in both groups. Our findings suggest that the exposure of R28 cells to glutamate and H2O2 could induce glaucoma-like neurodegenerative features and potentially provide a suitable tool for the development of new therapeutic strategies for retinal diseases.

Revolutionizing lymph node metastasis imaging: the role of drug delivery systems and future perspectives

The deployment of imaging examinations has evolved into a robust approach for the diagnosis of lymph node metastasis (LNM). The advancement of technology, coupled with the introduction of innovative imaging drugs, has led to the incorporation of an increasingly diverse array of imaging techniques into clinical practice. Nonetheless, conventional methods of administering imaging agents persist in presenting certain drawbacks and side effects. The employment of controlled drug delivery systems (DDSs) as a conduit for transporting imaging agents offers a promising solution to ameliorate these limitations intrinsic to metastatic lymph node (LN) imaging, thereby augmenting diagnostic precision. Within the scope of this review, we elucidate the historical context of LN imaging and encapsulate the frequently employed DDSs in conjunction with a variety of imaging techniques, specifically for metastatic LN imaging. Moreover, we engage in a discourse on the conceptualization and practical application of fusing diagnosis and treatment by employing DDSs. Finally, we venture into prospective applications of DDSs in the realm of LNM imaging and share our perspective on the potential trajectory of DDS development.

Looking into the Eyes—In Vitro Models for Ocular Research

Animal research undoubtedly provides scientists with virtually unlimited data but inflicts pain and suffering on animals. Currently, legislators and scientists alike are promoting alternative in vitro approaches allowing for an accurate evaluation of processes occurring in the body without animal sacrifice. Historically, one of the most infamous animal tests is the Draize test, mainly performed on rabbits. Even though this test was considered the gold standard for around 50 years, the Draize test fails to mimic human response mainly due to human and rabbit eye physiological differences. Therefore, many alternative assays were developed to evaluate ocular toxicity and drug effectiveness accurately. Here we review recent achievements in tissue engineering of in vitro 2D, 2.5D, 3D, organoid and organ-on-chip ocular models, as well as in vivo and ex vivo models in terms of their advantages and limitations.

Triazole-derivatized near-infrared cyanine dyes enable local functional fluorescent imaging of ocular inflammation

Near-infrared (NIR) chemical fluorophores are promising tools for in-vivo imaging in real time but often succumb to rapid photodegradation. Indocyanine green (ICG) is the only NIR dye with regulatory approval for ocular imaging in humans; however, ICG, when employed for applications such as labelling immune cells, has limited sensitivity and does not allow precise detection of specific inflammatory events, for example leukocyte recruitment during uveitic flare-ups. We investigated the potential use of photostable novel triazole NIR cyanine (TNC) dyes for detecting and characterising activated T-cell activity within the eye. Three TNC dyes were evaluated for ocular cytotoxicity in-vitro using a MTT assay and optimised concentrations for intraocular detection within ex-vivo porcine eyes after topical application or intracameral injections of the dyes. TNC labelled T-cell tracking experiments and mechanistic studies were also performed in-vitro. TNC-1 and TNC-2 dyes exhibited greater fluorescence intensity than ICG at 10 μM, whereas TNC-3 was only detectable at 100 μM within the porcine eye. TNC dyes did not demonstrate any ocular cell toxicity at working concentrations of 10 μM. CD4⁺T-cells labelled with TNC-1 or TNC-2 were detected within the porcine eye, with TNC-1 being brighter than TNC-2. Detection of TNC-1 and TNC-2 into CD4⁺T-cells was prevented by prior incubation with dynole 34-2 (50 μM), suggesting active uptake of these dyes via dynamin-dependent processes. The present study provides evidence that TNC dyes are suitable to detect activated CD4⁺T-cells within the eye with potential as a diagnostic marker for ocular inflammatory diseases.

Surgical Outcomes of Primary RRD With and Without Concurrent Full-Thickness Macular Hole (PRO Study Report No. 7)

BACKGROUND AND OBJECTIVE

Non-causal macular holes (MHs) can occur concurrently with rhegmatogenous retinal detachments (RRDs). The visual outcomes and surgical approach for these eyes are variable.

PATIENTS AND METHODS

This was a multi-institutional, retrospective review of all primary retinal detachment surgeries from January 1, 2015, through December 31, 2015. Pre-, intra-, and postoperative metrics were recorded.

RESULTS

There were 2,242 eyes that had pars plana vitrectomy for primary RRD, 43 (1.9%) of which had a MH at the time of surgery. The mean postoperative logMAR visual acuity (VA) for the MH cohort was 0.87 ± 0.64 (20/148) and for eyes without a MH was 0.47 ± 0.63 (20/59; P < .0001). The single-surgery re-attachment rate for the MH cohort and no MH cohort was 86.1% and 84.9%, respectively (P = 1.0000).

CONCLUSIONS

Patients with noncausal MHs and RRD had significantly worse VA than patients without a MH. Preoperative counseling is imperative in patients with both RRD and MH. [Ophthalmic Surg Lasers Imaging Retina. 2020;51:500-505.].

Cyanine Dyes for Photo-Thermal Therapy: A Comparison of Synthetic Liposomes and Natural Erythrocyte-Based Carriers

Cyanine fluorescent dyes are attractive diagnostic or therapeutic agents due to their excellent optical properties. However, in free form, their use in biological applications is limited due to the short circulation time, instability, and toxicity. Therefore, their encapsulation into nano-carriers might help overcome the above-mentioned issues. In addition to indocyanine green (ICG), which is clinically approved and therefore the most widely used fluorescent dye, we tested the structurally similar and cheaper alternative called IR-820. Both dyes were encapsulated into liposomes. However, due to the synthetic origin of liposomes, they can induce an immunogenic response. To address this challenge, we proposed to use erythrocyte membrane vesicles (EMVs) as “new era” nano-carriers for cyanine dyes. The optical properties of both dyes were investigated in different biological relevant media. Then, the temperature stability and photo-stability of dyes in free form and encapsulated into liposomes and EMVs were evaluated. Nano-carriers efficiently protected dyes from thermal degradation, as well as from photo-induced degradation. Finally, a hemotoxicity study revealed that EMVs seem less hemotoxic dye carriers than clinically approved liposomes. Herein, we showed that EMVs exhibit great potential as nano-carriers for dyes with improved stability and hemocompatibility without losing excellent optical properties.

Human Retinal Pigment Epithelium: In Vivo Cell Morphometry, Multispectral Autofluorescence, and Relationship to Cone Mosaic

Purpose

To characterize in vivo morphometry and multispectral autofluorescence of the retinal pigment epithelial (RPE) cell mosaic and its relationship to cone cell topography across the macula.

Methods

RPE cell morphometrics were computed in regularly spaced regions of interest (ROIs) from contiguous short-wavelength autofluorescence (SWAF) and photoreceptor reflectance images collected across the macula in one eye of 10 normal participants (23–65 years) by using adaptive optics scanning light ophthalmoscopy (AOSLO). Infrared autofluorescence (IRAF) images of the RPE were collected with AOSLO in seven normal participants (22–65 years), with participant overlap, and compared to SWAF quantitatively and qualitatively.

Results

RPE cell statistics could be analyzed in 84% of SWAF ROIs. RPE cell density consistently decreased with eccentricity from the fovea (participant mean ± SD: 6026 ± 1590 cells/mm² at fovea; 4552 ± 1370 cells/mm² and 3757 ± 1290 cells/mm² at 3.5 mm temporally and nasally, respectively). Mean cone-to-RPE cell ratio decreased rapidly from 16.6 at the foveal center to <5 by 1 mm. IRAF revealed cells in six of seven participants, in agreement with SWAF RPE cell size and location. Differences in cell fluorescent structure, contrast, and visibility beneath vasculature were observed between modalities.

Conclusions

Improvements in AOSLO autofluorescence imaging permit efficient visualization of RPE cells with safe light exposures, allowing individual characterization of RPE cell morphometry that is variable between participants. The normative dataset and analysis of RPE cell IRAF and SWAF herein are essential for understanding microscopic characteristics of cell fluorescence and may assist in interpreting disease progression in RPE cells.

Outer Retinal Defects Represent a Normal Recovery Pathway Following Internal Limiting Membrane Peeling in Macular Hole Surgery

BACKGROUND AND OBJECTIVE

To examine perioperative factors associated with the development of outer retinal defects (ORDs) following surgical repair of macular holes (MHs).

PATIENTS AND METHODS

An institutional review board-approved, retrospective, interventional cohort study was conducted. Patients who underwent MH repair during a 5-year period were identified. Statistical analysis was conducted to detect significant perioperative associations to ORD development.

RESULTS

One hundred twenty-four eyes were included, and 54% developed an ORD following surgery. These defects correlated with lower preoperative stage (P = .0057), preoperative phakia (P = .036), and lack of prior macular surgery (P = .0016). Patients in the ORD group had significantly better preoperative and postoperative visual acuity (P = .031 and P = .0004, respectively), but there was no difference in change in acuity from preoperatively to 3 months postoperatively when compared with control patients (P = 42). The majority (89%) of ORDs resolved by 24 months postoperatively.

CONCLUSION

The development of ORDs appears to be correlated with several factors indicative of favorable overall eye health and less advanced pathology and may represent a normal state of recovery after MH repair with internal limiting membrane peeling. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:e1-e8.].

Liposome-Indocyanine Green Nanoprobes for Optical Labeling and Tracking of Human Mesenchymal Stem Cells Post-Transplantation In Vivo

Direct labeling of human mesenchymal stem cells (hMSC) prior to transplantation provides a means to track cells after administration and it is a powerful tool for the assessment of new cell-based therapies. Biocompatible nanoprobes consisting of liposome-indocyanine green hybrid vesicles (liposome-ICG) are used to safely label hMSC. Labeled hMSC recapitulating a 3D cellular environment is transplanted as spheroids subcutaneously and intracranially in athymic nude mice. Cells emit a strong NIR signal used for tracking post-transplantation with the IVIS imaging system up to 2 weeks (subcutaneous) and 1 week (intracranial). The transplanted stem cells are imaged in situ after engraftment deep in the brain up to 1 week in living animals using optical imaging techniques and without the need to genetically modify the cells. This method is proposed for efficient, nontoxic direct cell labeling for the preclinical assessment of cell-based therapies and the design of clinical trials, and potentially for localization of the cell engraftment after transplantation into patients.

Streamlined duplex live-dead microplate assay for cultured cells

A duplex fluorescence assay to assess the viability of cells cultured in multi-well plates is described, which can be carried out in the original culture plate using a plate reader, without exchanges of culture or assay medium, or transfer of cells or cell supernatant. The method uses freshly prepared reagents and does not rely on a proprietary, commercially supplied kit. Following experimental treatment, calcein acetoxymethyl ester (CaAM) is added to each well of cultured cells; after 30 min, the fluorescence intensity (emission λ_max ∼ 530 nm) is measured. The signal is due to formation of calcein, which is produced from CaAM by action of esterase activity found in intact live cells. Since live cells may express plasma membrane multidrug transport proteins, especially of the ABC transporter family, the CaAM incubation is carried out in the presence of an inhibitor of this efflux process, thereby improving the dynamic range of the assay. Next, SYTOX^® Orange (SO) is added to the culture wells, and, after a 30-min incubation, fluorescence intensity (emission λ_max ∼ 590 nm) is measured again. SO is excluded from cells that have an intact plasma membrane, but penetrates dead/dying cells and can diffuse into the nucleus, where it binds to and forms a fluorescent complex with DNA. The CaAM already added to the wells causes no interference with the latter fluorescent signal. At the conclusion of the duplex assay, both live and dead cells remain in the culture wells and can be documented by digital imaging to demonstrate correlation of cellular morphology with the assay output. Two examples of the application of this method are provided, using cytotoxic compounds having different mechanisms of action.

Postoperative eccentric macular holes after vitrectomy and internal limiting membrane peeling

The purpose of this study was to describe the incidence, clinical characteristics, and outcome of eccentric macular holes presenting after vitrectomy and internal limiting membrane (ILM) peeling for the treatment of macular pathology and discuss the pathogenesis of holes formation. A retrospective, noncomparative, interventional case-series study of five patients who developed eccentric macular holes postoperatively following vitrectomy in 198 consecutive patients who underwent ILM peeling for idiopathic macular hole and epiretinal membrane formation between 2008 and 2015. Five patients (2.5 %) developed full-thickness eccentric macular holes postoperatively. Three patients presented with a single eccentric macular hole, one patient had an eccentric hole after a failed idiopathic macular hole surgery and one patient developed four eccentric macular holes. The mean diameter of the holes was 584 μm (range 206-1317 μm) and the average time of holes formation after vitrectomy was 27.7 weeks (range 1-140 weeks). Postoperative best-corrected visual acuity ranged from "counting fingers" to 20/25. The eyes with the holes distant from the fovea had the best final visual acuity. No further intervention was attempted and no complications occurred. The mean follow-up time was 26.8 months. The postoperative macular holes after vitrectomy and ILM peeling were variable in number, size, and time of appearance but remained stable and were not associated with any complications. The pathogenesis of macular holes is most consistent with contraction of the residual ILM or secondary epimacular proliferation probably stimulated by ILM peeling.

Evaluation of antimicrobial photodynamic therapy with indocyanine green and curcumin on human gingival fibroblast cells: An in vitro photocytotoxicity investigation

Recent investigations have suggested that antimicrobial photodynamic therapy (aPDT) can be an alternative treatment for the management of periodontal infections. However, currently there is very limited data regarding the photocytotoxicity of this method on human gingival fibroblast (HuGu) cells.

AIM

The in vitro optimal concentrations of indocyanine green (ICG) and curcumin as photosensitizers (PSs) and the irradiation time of diode laser emission were evaluated by assessing the photocytotoxicity of the treatment on HuGu cells.

MATERIALS AND METHOD

Monolayers of HuGu cells were incubated with various final concentrations of ICG (500, 750, 1000, 1250, 1500, 1750, and 2000μg/ml) and curcumin (3, 4, 5, 10, and 20mM). Three exposure times of the diode laser (30s, 60s, and 2×30s irradiation with an interval of 1min between each) and one of exposure time of 5min for LED were tested; cell viability was determined using neutral red assay. Chlorhexidine (CHX) as a gold standard antimicrobial agent for periodontal disease was considered as a control group.

RESULTS

ICG and curcumin significantly reduced HuGu cell viability at concentrations below 1000μg/ml and 10mM, respectively (P<0.01). Cytotoxicity was higher when the cells were treated for 2×30s irradiation with an interval of 1min and then again exposed to the laser for 30s (2% and 0.1%). CHX demonstrated no significant reduction in HuGu cell survival.

CONCLUSION

Photocytotoxicity is influenced by PS concentration, exposure time of PS, and time of irradiation. High doses of ICG and curcumin with lowest exposure time of light source and without cytotoxic effects may be an effective strategy for aPDT as an alternative treatment for periodontal disease.

Effect of distance and duration of illumination on retinal ganglion cells exposed to varying concentrations of brilliant blue green

Background

The objective of the study was to determine the safety parameters of using brilliant blue green (BBG) for chromovitrectomy by assessing the cytotoxicity of BBG on cultured retinal ganglion cells (RGCs) exposed to illumination.

Methods

RGCs were exposed to two concentrations of BBG (0.25 and 0.5 mg/mL) under metal halide illumination at varying distances (1 and 2.5 cm), intensities (990 and 2,000 Fc), and durations (1, 5 and 15 minutes). Cell viability was assessed using the WST-1 and CellTiter 96^® AQueous One solution cell proliferation assays.

Results

Using the WST-1 assay, with high-intensity illumination, viability of RGCs ranged from 97.5±16.4% of controls with minimum BBG and light exposure (0.25 mg/mL BBG and illuminated for 1 minute at 2.5 cm distance) to 53.1±11.3% of controls with maximum BBG and light exposure (0.50 mg/mL and illuminated for 15 minutes at 1 cm distance; P < 0.01). With medium-intensity illumination, RGCs showed better viability, ranging from 95.1±7.2% of controls with minimum BBG and light exposure to 72.3±12.8% of controls with maximum BBG and light exposure. CellTiter 96^® AQueous One assay showed similar results.

Conclusion

RGCs seem to safely tolerate up to 5 minutes of exposure to 0.5 mg/mL BBG under diffuse medium-intensity illumination (990 Fc).

Lutein and zeaxanthin toxicity with and without brilliant blue in rabbits

PURPOSE

To evaluate the safety profile of solutions containing lutein and zeaxanthin alone or associated with brilliant blue (BB).

METHODS

Twenty-eight New Zealand rabbits were used to evaluate 4 concentrations of the various dye solutions: 0.5% lutein/zeaxanthin; 0.5% lutein/zeaxanthin associated with 0.0125% BB; 0.3% lutein/zeaxanthin associated with 0.025% BB; and 0.25% lutein/zeaxanthin associated with 0.05% BB. The pHs of the dye solutions ranged from 6.5 to 7.2 and the osmolarities from 280 to 320 mOsm/mL. Each rabbit had 0.1 mL of one of the dyeing solutions injected into the vitreous cavity of the right eye, while balanced salt solution (BSS) was injected into the left eye as the control. Scotopic electroretinography responses were recorded in all eyes at different time points. The animals were sacrificed at 1 and 7 days after injection; the eyes were analyzed by light and transmission electron microscopy.

RESULTS

No significant (P>0.05) differences were seen in the a- and b-wave amplitudes among groups at any given point in time. Light and electron microscopy findings showed no significant abnormalities either, and were similar to the histological findings after intravitreal BSS injection.

CONCLUSIONS

Lutein and zeaxanthin alone or in association with BB showed a good safety profile in this experimental model.

In vitro evidence for mycophenolic acid dose-related cytotoxicity in human retinal cells

PURPOSE

Mycophenolic acid (MPA) is an immunosuppressive agent that controls noninfectious uveitis. Intravitreal MPA delivery may be a potential adjuvant therapy in patients who have to discontinue steroid or immunosuppressive systemic therapy because of side effects. The aims of this study are to evaluate the in vitro effects of MPA over human retinal pigment epithelium (ARPE-19) and human Muller cells (MIO M-1).

METHODS

ARPE-19 cells and MIO M-1 cells were exposed to 25, 50, and 100 µg/mL of MPA (Roche Bioscience, Palo Alto, CA) for 24 hours. Toxicity was evaluated by trypan blue dye-exclusion cell viability assay, caspase-3/7 apoptosis-related assay, and JC-1 mitochondrial membrane potential assay.

RESULTS

The MPA (25 µg/mL and 50 µg/mL) did not cause reduction in cell viability or significant change in caspase-3/7 activity in both cell lines tested. Mycophenolic acid (100 µg/mL) caused a significant decrease in cell viability (P < 0.01) and higher caspase-3/7 activity (P < 0.05) in both cell lines compared with untreated cells. The JC-1 mitochondrial membrane potential did not show statistically significant differences for both cell lines and all concentration tested when compared with untreated controls (P > 0.05).

CONCLUSION

Intraocular delivery may be a potential alternative for the treatment of noninfectious uveitis, either by intravitreal injection or sustained-release drug-delivery systems, in doses of 50 µg/mL or lower.

Indocyanine green increases light-induced oxidative stress, senescence, and matrix metalloproteinases 1 and 3 in human RPE cells

PURPOSE

Indocyanine green (ICG) is a commonly used vital dye for macular surgery. Recent reports implicate that its use might be associated with less favourable results regarding postoperative visual outcome and damage of retinal cells, and atrophic degeneration of the retinal pigment epithelium (RPE) has been described. This study investigates the effects of ICG on light-induced senescence of RPE cells.

METHODS

Primary human RPE cells were either pre-incubated with ICG in concentrations of 0.005% and 0.05% or not and then exposed to white light. After 10 min of irradiation viability, induction of intracellular reactive oxygen species (ROS) and senescence-associated β-galactosidase activity (SA β-Gal) were determined. Expression and secretion of matrix metalloproteinases (MMPs) 1 and 3 and their mRNA were determined by RT-PCR and ELISA.

RESULTS

Light exposure decreased RPE cell viability by 46%. Treatment with 0.005% and 0.05% ICG alone decreased RPE cell viability by 7% and 21%. In addition, expression of ROS, SA β-Gal, and MMP-1 and 3 was significantly increased. When 0.005% and 0.05% ICG treatments were combined with light exposure, viability decreased by 69% and 82% compared to the untreated control. Effects on the expression of ROS, SA β-Gal, and MMP-1 and 3 were, depending on the ICG dose, significantly increased when cells were pre-incubated with ICG and then illuminated.

CONCLUSION

In this study, pretreatment with ICG significantly increased light-induced oxidative stress and senescence. This might indicate a potential, supplementary mechanism that could explain RPE alterations and reduced functional results after ICG-assisted internal limiting membrane peeling.

Functional and structural effect of intravitreal indocyanine green, triamcinolone acetonide, trypan blue, and brilliant blue g on rat retina

PURPOSE

The purpose of this study was to evaluate the functional and structural damage of the retina after intravitreal injections of four different dyes in the rat.

METHODS

Rats were injected intravitreally with indocyanine green (ICG), trypan blue, triamcinolone acetonide, or brilliant blue G in the right eye. The other eye was injected with saline and served as a control. Simultaneous bilateral electroretinograms were recorded before injection and 7 and 28 days after injection. Histology and immunohistochemistry analyses with antibodies recognizing glial fibrillary acidic protein and protein kinase C were performed 28 days after the initial injection on both eyes.

RESULTS

Seven days after dye injection, the electroretinogram response of the treated eyes was altered in each group. At 1 month, eyes injected with triamcinolone acetonide, trypan blue, or brilliant blue G fully recovered, whereas eyes treated with ICG had A-wave and B-wave reduction of 65% and 63%, respectively. The inner nuclear layer thickness was statistically decreased in the ICG group (P = 0.003) but not with other dyes. Protein kinase C staining was decreased in the ICG group only, but no abnormal qualitative staining was found with either glial fibrillary acidic protein or protein kinase C antibodies with any dye.

CONCLUSION

Among the four tested dyes, only ICG led to functional and structural retinal damage.

Blood-assisted internal limiting membrane peeling for macular hole repair

PURPOSE

To evaluate the efficacy of autologous heparinized whole blood in assisting internal limiting membrane (ILM) peeling by coating the ILM for macular hole (MH) repair.

DESIGN

Prospective, interventional case series.

PARTICIPANTS

Twenty-nine patients (32 eyes) who underwent blood-assisted ILM peeling for MH repair.

METHODS

Patients in whom stage 2-4 idiopathic MHs had developed and who desired surgery were enrolled in this study. After core vitrectomy, autologous heparinized whole blood was applied to cover the macula and to coat the surface of the macular area in the fluid-filled vitreous cavity. The redundant blood was removed and only a very thin film of blood was left on the macular area. The blood-coated ILM was removed by forceps in a circular fashion. To confirm the removed membrane was the ILM, the first 10 specimens were examined by electron microscopy (EM).

MAIN OUTCOME MEASURES

The MH closure rate, the interval mean visual acuity (before and after surgery), retinal changes, and the EM results of the ILM specimens.

RESULTS

All 32 eyes in 29 patients completed 12 months of follow-up. The ILM were coated by autologous heparinized whole blood, removed without difficulty, and confirmed by EM. The whole blood highlighted the contrast of the coated and noncoated areas during the ILM peeling procedure. The MHs were closed in all surgical eyes with a single surgery (100%). Compared with study entry, the mean logMAR best-corrected visual acuity 12 months after surgery improved significantly (1.02 and 0.53, respectively; P<0.001). At 12 months of follow-up, 31 eyes (96.9%) had stable or improved vision. No toxic fundus changes were observed during follow-up.

CONCLUSIONS

Autologous heparinized whole blood coated the ILM and facilitated visibility during ILM peeling. Autologous heparinized whole blood is a cost-effective and useful tool for assisting MH surgery.

Evaluation of in vitro effects of bevacizumab (Avastin) on retinal pigment epithelial, neurosensory retinal, and microvascular endothelial cells

PURPOSE

To evaluate the short-term in vitro safety of bevacizumab (Avastin) in human retinal pigment epithelial (ARPE-19), rat neurosensory retinal (R28), and human microvascular endothelial (HMVECad) cells.

METHODS

ARPE-19 and R28 cells were treated with 0.125 mg/mL, 0.25 mg/mL, 0.50 mg/mL, and 1 mg/mL of bevacizumab for 2, 6, and 24 hours. HMVECad cells were treated with 5 ng/mL of vascular endothelial growth factor (VEGF) and 0.125 mg/mL, 0.25 mg/mL, 0.50 mg/mL, and 1 mg/mL of either bevacizumab for 2, 6, and 24 hours or a nonspecific human purified immunoglobulin (IgG) for 24 hours. Cell viability was measured using trypan blue dye exclusion assay.

RESULTS

The cell viabilities of ARPE-19 cells, R28 cells, and HMVECad cells treated with bevacizumab were not significantly different (P > 0.05) from that of untreated controls. There was no significant difference (P > 0.05) between viabilities of HMVECad cells treated with bevacizumab and IgG.

CONCLUSION

This study suggests that bevacizumab, at concentrations at or above the dose normally used in clinical practice, is not toxic to human retinal pigment epithelial, rat neurosensory retinal, or human microvascular endothelial cells in vitro. This report is consistent with the recent report of lack of toxicity of intravitreal bevacizumab in rabbits as well as the lack of apparent toxicity in clinical use.