Investigation the effects of vitreous humor on proliferation and dedifferentiation of differentiated NTERA2 cells

Mammals have a limited capacity to regenerate their tissues and organs. One of the mechanisms associated with natural regeneration is dedifferentiation. Several small molecules such as vitamin C and growth factors could improve reprogramming efficiency. In this study, the NTERA2-D1 (NT2) cells were induced towards differentiation (NT2-RA) with 10-5 M retinoic acid (RA) for three days and then subjected to various amounts of vitreous humor (VH). Results show that the growth rate of these cells was reduced, while this rate was partly restored upon treatment with VH (NT2-RA-VH). Cell cycle analysis with PI method also showed that the numbers of cells at the S phase of the cell cycle in these cells were increased. The levels of SSEA3 and TRA-1-81 antigens in NT2-RA were dropped but they increased in NT2- RA-VH to a level similar to the NT2 cells. The level of SSEA1 had an opposite pattern. Expression of OCT4 gene dropped after RA treatment, but it was recovered in NT2-RA-VH cells. In conclusion, we suggest VH as a potent mixture for improving the cellular reprogramming leading to dedifferentiation.

Identification of Interphotoreceptor retinoid-binding protein in the Schisis cavity fluid of a patient with congenital X-linked Retinoschisis

Background This case report describes the surgical outcome in a patient with congenital X-linked retinoschisis (CXLRS) and the results of proteomic analysis of surgically extracted samples from both vitreous and intraschisis cavities by mass spectrometry. Case presentation A 3-month-old boy presented with extensive retinoschisis involving macula and retinal periphery in both eyes. Genetic analysis confirmed retinoschisin 1 mutation (c.554C > T), and an electroretinogram showed significant reduction of b-wave and decreased cone and rod responses, which led to a diagnosis of CXLRS. By performing pars plana vitrectomy, including inner wall retinectomy, clear visual axes with stable retinal conditions and functional vision in both eyes were obtained during the 4 years of follow-up. Proteomic analysis of surgically retrieved fluid from the intraschisis cavity revealed a higher expression of interphotoreceptor retinoid-binding protein (IRBP) than that from the vitreous humor. However, both samples showed equal levels of albumin, transferrin, and pigment epithelium-derived factor. Conclusions Cellular adhesive imperfection in CXLRS may cause IRBP diffusion from the interphotoreceptor matrix, resulting in the strong expression of IRBP in the intraschisis cavity. An impaired retinoid cycle caused by an absence of IRBP in the retina may potentially underlie the pathology of CXLRS.

Physical Characterization and In Vitro Toxicity Test of PDMS Synthesized from Low-Grade D4 Monomer as a Vitreous Substitute in the Human Eyes

Polydimethylsiloxane (PDMS) is one of the most superior materials and has been used as a substitute for vitreous humor in the human eye. In previous research, we have succeeded in producing PDMS with low and medium viscosity using octamethylcyclotetrasiloxane (D4) monomer with a low grade of 96%. Both have good physical properties and are comparable to commercial product PDMS and PDMS synthesized using D4 monomer with a high grade of 98%. An improvement of the synthesis process is needed to ensure that PDMS synthesized from a low-grade D4 monomer under specific synthesis conditions can repeatedly produce high-quality PDMS. Apart from good physical properties, the PDMS as a substitute for vitreous humor must also be safe and not cause other disturbances to the eyes. Here, we reported the process of synthesizing and characterizing the physical properties of low- and medium-viscosity PDMS using a low-grade D4 monomer. We also reported for the first time the in vitro toxicity test using the Hen’s Egg Test Chorioallantoic Membrane (HET-CAM) test method. We have succeeded in obtaining PDMS with viscosities of 1.15 Pa.s, 1.17 Pa.s, and 1.81 Pa.s. All samples have good physical properties such as refractive index, surface tension, and functional groups that are similar to commercial PDMS. The HET-CAM test results showed that all samples did not show signs of irritation indicating that samples were non-toxic. From the results of this study, it can be concluded that PDMS synthesized from a low-grade D4 monomer under specific synthesis conditions by the ROP method is very safe and has the potential to be developed as a substitute for vitreous humor in human eyes.

Successful bilateral phacoemulsification and vitrectomy in a Bennett’s wallaby (Macropus rufogriseus)

CASE DESCRIPTION A 7-month-old hand-reared female Bennett’s wallaby (Macropus rufogriseus) was evaluated for bilateral ocular opacity of 3 months’ duration. CLINICAL FINDINGS On physical examination, the wallaby was in good overall condition. An ophthalmic examination revealed mature cataracts in both eyes (OU). The cataracts were suspected to have a nutritional origin as it has been described in hand-reared macropods. Results of tonometry were normal OU. Results of CBC and serum biochemistry were unremarkable. The wallaby was premedicated with medetomidine and ketamine hydrochloride. Ocular ultrasonography performed while the wallaby was anesthetized revealed a thickened and opaque lens, mildly heterogeneous vitreous humor, and no sign of retinal detachment OU. An electroretinogram confirmed functional retinae OU. TREATMENT AND OUTCOME Surgery was considered necessary for welfare reasons. Phacoemulsification and vitrectomy were performed without intraoperative complication. The wallaby recovered uneventfully, and systemic NSAID, topical corticosteroid, and systemic and topical antimicrobial therapy were prescribed. One year later, the animal had vision OU. Physical examination did not show any vision-threatening postoperative complications. CLINICAL RELEVANCE The etiology of nutritional cataracts is not fully understood in macropods, but this condition is rather common in these species. To our knowledge, this is the first detailed report of a successful bilateral phacoemulsification and vitrectomy in a Bennett’s wallaby.

Mathematical Model of Macromolecular Drug Transport in a Partially Liquefied Vitreous Humor

The purpose of this study is to investigate the effect of partial liquefaction (due to ageing) of the vitreous humor on the transport of ocular drugs. In our model, the gel part of the vitreous is treated as a Darcy-type porous medium. A spherical region within the porous part of vitreous is in a liquid state which, for computational purposes, is also treated as a porous medium but with a much higher permeability. Using the finite element method, a time-dependent, three-dimensional model has been developed to computationally simulate (using the Petrov-Galerkin method) the transport of intravitreally injected macromolecules where both convection and diffusion are present. From a fluid physics and transport phenomena perspective, the results show many interesting features. For pressure-driven flow across the vitreous, the flow streamlines converge into the liquefied region as the flow seeks the fastest path of travel. Furthermore, as expected, with increased level of liquefaction, the overall flow rate increases for a given pressure drop. We have quantified this effect for various geometrical considerations. The flow convergence into the liquefied region has important implication for convective transport. One effect is the clear diversion of the drug as it reaches the liquefied region. In some instances, the entry point of the drug in the retinal region gets slightly shifted due to liquefaction. While the model has many approximations and assumptions, the focus is illustrating the effect of liquefaction as one of the building blocks towards a fully comprehensive model.

A Study on the Drug Concentration in Fellow Eyes After Unilateral Intravitreal Injection of Conbercept Into New Zealand Rabbit Eyes

Intravitreal injections of anti-vascular endothelial growth factor (VEGF) have become increasingly popular in the treatment of ocular diseases. However, few studies have determined the efficiency of unilateral intravitreal anti-VEGF injection in the fellow eye. Herein, we performed a study to investigate the drug concentration in fellow eyes and venous serum after unilateral intravitreal injection of conbercept into rabbit eyes. This is an experimental animal study. Thirty male New Zealand rabbits (60 eyes) were used. One eye of each rabbit was intravitreally injected with 0.5 mg of conbercept. Both eyes from six rabbits were enucleated on days 1, 3, 7, 14, and 30. Conbercept concentrations were measured in the serum, aqueous humor, and vitreous humor. We found conbercept was detected in the fellow eyes and serum of rabbits. Conbercept concentrations in the vitreous humor of the fellow eyes increased from 74.11 ng/ml on day 1 to 246.69 ng/ml on day 3 and then declined to 69.11 ng/ml after 30 days. The concentration in the aqueous humor peaked on day 1 with a concentration of 244.82 ng/ml and declined to 40.13 ng/ml after 30 days. The maximum conbercept concentrations in the aqueous humor and vitreous humor of fellow eyes were similar, which were 0.2 and 1.3% of those of the injected eye, respectively. A peak concentration of 102.49 ng/ml was achieved in the venous serum 1 day after intravitreal injection of conbercept, which was 0.08 and 0.5% of those of the maximum conbercept concentrations in the vitreous humor and aqueous humor of the injected eye, respectively, and 41.5 and 41.8% of the maximum conbercept concentrations in the vitreous humor and aqueous humor of the non-injected eye, respectively. In conclusion, after intravitreal injection of 0.5 mg of conbercept into rabbit eyes, very small amounts of conbercept were detected in the fellow non-injected eyes and venous serum.

Candida Endophthalmitis Treated Successfully with Isavuconazole - A Case Report

Candida endophthalmitis is a serious complication of candidemia. Diagnosis requires identification of ocular lesions on dilated fundoscopy, aided by isolation of the organism from blood and/or vitreous humor. However, the initial ophthalmological examination may be negative in some cases. Experience with isavuconazole for the treatment of Candida endophthalmitis is limited. We present a case of a 65-year-old woman with metastatic breast cancer on chemotherapy who developed Candida dubliniensis endophthalmitis with initial negative ophthalmological examination. She was treated with vitrectomy and 6 weeks of oral fluconazole. Despite vitrectomy and culture-directed antifungal treatment, management was complicated by lack of response to fluconazole and intolerance to other antifungals, necessitating the use of isavuconazole, which proved efficacious.