methylcellulose and Retinal-Degeneration

Retinitis pigmentosa (RP) is a group of genetic diseases that results in rod photoreceptor cell degeneration, which subsequently leads to cone photoreceptor cell death, impaired vision and eventual blindness. Rod-derived cone viability factor (RdCVF) is a protein which has two isoforms: a short form (RdCVF) and a long form (RdCVFL) which act on cone photoreceptors in the retina. RdCVFL protects photoreceptors by reducing hyperoxia in the retina; however, sustained delivery of RdCVFL remains challenging. We developed an affinity-controlled release strategy for RdCVFL. An injectable physical blend of hyaluronan and methylcellulose (HAMC) was covalently modified with a peptide binding partner of the Src homology 3 (SH3) domain. This domain was expressed as a fusion protein with RdCVFL, thereby enabling its controlled release from HAMC-binding peptide. Sustained release of RdCVFL was demonstrated for the first time as RdCVFL-SH3 from HAMC-binding peptide for 7 d in vitro. To assess bioactivity, chick retinal dissociates were harvested and treated with the affinity-released recombinant protein from the HAMC-binding peptide vehicle. After 6 d in culture, cone cell viability was greater when cultured with released RdCVFL-SH3 relative to controls. We utilized computational fluid dynamics to model release of RdCVFL-SH3 from our delivery vehicle in the vitreous of the human eye. We demonstrate that our delivery vehicle can prolong the bioavailability of RdCVFL-SH3 in the retina, potentially enhancing its therapeutic effects. Our affinity-based system constitutes a versatile delivery platform for ultimate intraocular injection in the treatment of retinal degenerative diseases. STATEMENT OF SIGNIFICANCE: Retinitis pigmentosa (RP) is the leading cause of inherited blindness in the world. Rod-derived cone viability factor (RdCVF), a novel protein paracrine factor, is effective in preclinical models of RP. To extend its therapeutic effects, we developed an affinity-controlled release strategy for the long form of RdCVF, RdCVFL. We expressed RdCVFL as a fusion protein with an Src homology 3 domain (SH3). We then utilized a hydrogel composed of hyaluronan and methylcellulose (HAMC) and modified it with SH3 binding peptides to investigate its release in vitro. Furthermore, we designed a mathematical model of the human eye to investigate delivery of the protein from the delivery vehicle. This work paves the way for future investigation of controlled release RdCVF.

Topics: Delayed-Action Preparations; Eye Proteins; Humans; Hyaluronic Acid; Methylcellulose; Retinal Cone Photoreceptor Cells; Retinal Degeneration; Retinitis Pigmentosa

The human retina is constantly affected by light of varying intensity, this being especially true for photoreceptor cells and retinal pigment epithelium. Traditionally, photoinduced damages of the retina are induced by visible light of high intensity in albino rats using the LIRD (light-induced retinal degeneration) model. This model allows study of pathological processes in the retina and the search for retinoprotectors preventing retinal photodamage. In addition, the etiology and mechanisms of retina damage in the LIRD model have much in common with the mechanisms of the development of age-related retinal disorders, in particular, with age-related macular degeneration (AMD). We have studied preventive and therapeutic effects of Visomitin eye drops (based on the mitochondria-targeted antioxidant SkQ1) on albino rat retinas damaged by bright light. In the first series of experiments, rats receiving Visomitin for two weeks prior to illumination demonstrated significantly less expressed atrophic and degenerative changes in the retina compared to animals receiving similar drops with no SkQ1. In the second series, the illuminated rats were treated for two weeks with Visomitin or similar drops without SkQ1. The damaged retinas of the experimental animals were repaired much more effectively than those of the control animals. Therefore, we conclude that Visomitin SkQ1-containing eye drops have pronounced preventive and therapeutic effects on the photodamaged retina and might be recommended as a photoprotector and a pharmaceutical preparation for the treatment of AMD in combination with conventional medicines.

Topics: Animals; Benzalkonium Compounds; Disease Models, Animal; Drug Combinations; Female; Light; Methylcellulose; Ophthalmic Solutions; Plastoquinone; Protective Agents; Rats, Wistar; Retina; Retinal Degeneration

Regenerative strategies for retinal degenerative diseases are limited by poor cellular survival, distribution and integration after transplantation to the sub-retinal space. To overcome this limitations a stem cell delivery system was developed, taking advantage of the minimally-invasive, injectable and biodegradable properties of a blend of hyaluronan and methylcellulose (HAMC). The physical and biological properties of this unique HAMC formulation were studied. HAMC supported retinal stem-progenitor cell (RSPC) survival and proliferation in vitro. The blend was a viscous solution, exhibiting properties ideal for delivery to the sub-retinal space. In vivo transplantation studies in mice were carried out to investigate both the biodegradability of HAMC in the sub-retinal space over 7 days and the potential of HAMC as a cell delivery vehicle. RSPCs delivered in HAMC were more evenly distributed in the sub-retinal space than those delivered in traditional saline solutions, suggesting that HAMC is a promising vehicle for cellular delivery to the degenerating retina overcoming previously reported barriers to tissue integration in the retina such as cellular aggregation and non-contiguous distribution.

Topics: Animals; Biocompatible Materials; Green Fluorescent Proteins; Hyaluronic Acid; Hydrogel, Polyethylene Glycol Dimethacrylate; Methylcellulose; Mice; Retinal Degeneration; Stem Cell Transplantation; Stem Cells

The effects of experimental hypertension on retinal cells were studied. Evaluation was made of IOP levels and degree of cell damage by cytochemical and DNA analysis, and degeneration modes: necrosis and apoptosis.

Topics: Acute Disease; Animals; Apoptosis; DNA; Follow-Up Studies; Intraocular Pressure; Male; Methylcellulose; Necrosis; Ocular Hypertension; Rats; Retina; Retinal Degeneration

Topics: Arginine Vasopressin; Carboxymethylcellulose Sodium; Chromatography; Humans; Methylcellulose; Oxytocin; Retinal Degeneration; Vasopressins