fibrin and Retinal-Degeneration

Retinal pigment epithelium (RPE) transplantation for the treatment of macular degeneration has been studied for over 30 years. Human clinical trials have demonstrated that RPE monolayers exhibit improved cellular engraftment and survival compared to single cell suspensions. The use of a scaffold facilitates implantation of a flat, wrinkle-free, precisely placed monolayer. Scaffolds currently being investigated in human clinical trials are non-degradable which results in the introduction of a chronic foreign body. To improve RPE transplant technology, a degradable scaffold would be desirable. Using human fibrin, we have generated scaffolds that support the growth of an RPE monolayer in vitro. To determine whether these scaffolds are degraded in vivo, we developed a surgical approach that delivers a fibrin hydrogel implant to the sub-retinal space of the pig eye and determined whether and how fast they degraded. Using standard ophthalmic imaging techniques, the fibrin scaffolds were completely degraded by postoperative week 8 in 5 of 6 animals. Postmortem histologic analysis confirmed the absence of the scaffold from the subretinal space at 8 weeks, and demonstrated the reattachment of the neurosensory retina and a normal RPE-photoreceptor interface. When mechanical debridement of a region of native RPE was performed during implantation surgery degradation was accelerated and scaffolds were undetectable by 4 weeks. These data represent the first in situ demonstration of a fully biodegradable scaffold for use in the implantation of RPE and other cell types for treatment of macular degeneration and other retinal degenerative diseases.

Topics: Absorbable Implants; Animals; Equipment Design; Female; Fibrin; Retina; Retinal Degeneration; Sus scrofa; Tissue Scaffolds

Zebrafish spontaneously regenerate the retina after injury. Although the gene expression profile has been extensively studied in this species during regeneration, this does not reflect protein function. To further understand the regenerative process in the zebrafish, we compared the proteomic profile of the retina during injury and upon regeneration. Using two-dimensional difference gel electrophoresis (2D-DIGE) and label-free quantitative proteomics (quadrupole time of flight LC-MS/MS), we analysed the retina of adult longfin wildtype zebrafish at 0, 3 and 18 days after Ouabain injection. Gene ontology analysis indicates reduced metabolic processing, and increase in fibrin clot formation, with significant upregulation of fibrinogen gamma polypeptide, apolipoproteins A-Ib and A-II, galectin-1, and vitellogenin-6 during degeneration when compared to normal retina. In addition, cytoskeleton and membrane transport proteins were considerably altered during regeneration, with the highest fold upregulation observed for tubulin beta 2 A, histone H2B and brain type fatty acid binding protein. Key proteins identified in this study may play an important role in the regeneration of the zebrafish retina and investigations on the potential regulation of these proteins may lead to the design of protocols to promote endogenous regeneration of the mammalian retina following retinal degenerative disease.

Topics: Animals; Apolipoproteins; Cell Membrane; Cytoskeletal Proteins; Eye Proteins; Fibrin; Gene Ontology; Histones; Injections; Ouabain; Proteomics; Regeneration; Reproducibility of Results; Retina; Retinal Degeneration; Zebrafish; Zebrafish Proteins

Subretinal blood within the macula may cause visual loss in a number of macular diseases. The clinical and histopathologic effects of experimental subretinal hemorrhage were evaluated in the cat. Subretinal hemorrhages were produced by creating a focal neurosensory retinal detachment with micropipette techniques, then inserting a needle tip transsclerally to allow choroidal blood to fill the bleb. Experimental lesions were examined clinically and with light and electron microscopy during a 14-day postoperative period. Initial observations included clot organization with retraction of fibrin strands. In six of nine clots more than 1 hour old, fibrin was associated with tearing of sheets of photoreceptor inner and outer segments. Later degeneration progressed to involve all retinal layers overlying the densest areas of fibrin in the clots. Hemorrhages into subretinal blebs containing tissue plasminogen activator did not form fibrin strands or cause photoreceptor tearing. These findings highlight the potential for improved retinal survival if organized subretinal clot can be eliminated soon after formation.

Topics: Animals; Cats; Disease Models, Animal; Fibrin; Fundus Oculi; Retina; Retinal Degeneration; Retinal Detachment; Retinal Hemorrhage

Topics: Animals; Antioxidants; Blindness; Choroid; Darkness; Diet; Fatty Acids; Fibrin; Hydrophthalmos; Light; Lipid Metabolism; Macrophages; Melanins; Oxidation-Reduction; Peroxides; Photochemistry; Retina; Retinal Degeneration; Retinal Detachment; Time Factors; Turkeys

Topics: Aneurysm; Basement Membrane; Blood Vessels; Cell Membrane Permeability; Cell Nucleus; Child; Cytoplasmic Granules; Dilatation; Eosinophils; Epithelium; Erythrocytes; Female; Fibrin; Gliosis; Histiocytes; Humans; Hyalin; Lipids; Macrophages; Microscopy, Electron; Phagocytosis; Pigments, Biological; Retina; Retinal Degeneration; Retinal Hemorrhage; Retinal Vessels; Retinitis; Staining and Labeling; Telangiectasis