Mouse models of retinal degeneration are useful tools to study therapeutic approaches for patients affected by hereditary retinal dystrophies. We have studied degeneration in the rd10 mice both by immunocytochemistry and TUNEL-labeling of retinal cells, and through electrophysiological recordings. The cell degeneration in the retina of rd10 mice produced appreciable morphological changes in rod and cone cells by P20. Retinal cell death is clearly observed in the central retina and it peaked at P25 when there were 800 TUNEL-positive cells per mm(2). In the central retina, only one row of photoreceptors remained in the outer nuclear layer by P40 and there was a remarkable deterioration of bipolar cell dendrites postsynaptic to photoreceptors. The axon terminals of bipolar cells also underwent atrophy and the inner retina was subject to further changes, including a reduction and disorganization of AII amacrine cell population. Glutamate sensitivity was tested in rod bipolar cells with the single cell patch-clamp technique in slice preparations, although at P60 no significant differences were observed with age-matched controls. Thus, we conclude that rod and cone degeneration in the rd10 mouse model is followed by deterioration of their postsynaptic cells and the cells in the inner retina. However, the functional preservation of receptors for photoreceptor transmission in bipolar cells may open new therapeutic possibilities.

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We designed niosomes based on three lipids that differed only in the polar-head group to analyze their influence on the transfection efficiency. These lipids were characterized by small-angle X-ray scattering before being incorporated into the niosomes which were characterized in terms of pKa, size, zeta potential, morphology and physical stability. Nioplexes were obtained upon the addition of a plasmid. Different ratios (w/w) were selected to analyze the influence of this parameter on size, charge and the ability to condense, release and protect the DNA. In vitro transfection experiments were performed in HEK-293, ARPE-19 and MSC-D1 cells. Our results show that the chemical composition of the cationic head-group clearly affects the physicochemical parameters of the niosomes and especially the transfection efficiency. Only niosomes based on cationic lipids with a dimethyl amino head group (lipid 3) showed a transfection capacity when compared with their counterparts amino (lipid 1) and tripeptide head-groups (lipid 2). Regarding cell viability, we clearly observed that nioplexes based on the cationic lipid 3 had a more deleterious effect than their counterparts, especially in ARPE-19 cells at 20/1 and 30/1 ratios. Similar studies could be extended to other series of cationic lipids in order to progress in the research on safe and efficient non-viral vectors for gene delivery purposes.

The development of novel non-viral delivery vehicles is essential in the search of more efficient strategies for retina and brain diseases. Herein, optimized niosome formulations prepared by oil-in water (o/w) and film-hydration techniques were characterized in terms of size, PDI, zeta potential, morphology and stability. Three ionizable glycerol-based cationic lipids containing a primary amine group (lipid 1), a triglycine group (lipid 2) and a dimethylamino ethyl pendent group (lipid 3) as polar head-groups were part of such niosomes. Upon the addition of pCMS-EGFP plasmid, nioplexes were obtained at different cationic lipid/DNA ratios (w/w). The resultant nioplexes were further physicochemically characterized and evaluated to condense, release and protect the DNA against enzymatic digestion. In vitro experiments were performed to evaluate transfection efficiency and cell viability in HEK-293, ARPE-19 and PECC cells. Interestingly, niosome formulations based on lipid 3 showed better transfection efficiencies in ARPE-19 and PECC cells than the rest of cationic lipids showed in this study. In vivo experiments in rat retina after intravitreal and subretinal injections together with in rat brain after cerebral cortex administration showed promising transfection efficiencies when niosome formulations based on lipid 3 were used. These results provide new insights for the development of non-viral vectors based on cationic lipids and their applications for efficient delivery of genetic material to the retina and brain.

Keywords:retinal degeneration rodent remodeling apoptosis protein kinase C calbindin recoverin parvalbumin transducin a b s t r a c t Aim of this study was to examine synaptic connectivity changes in the retina and the location and rate of apoptosis in transgenic S334ter line-3 and line-5 rats with photoreceptor degeneration. Heterozygous S334ter-line-3 and line-5 at P11-13, P30, P60, P90 and several control non-dystrophic rats (Long Evans and SpragueeDawley) at P60, were studied anatomically by immunohistochemistry for various cell and synaptic markers, and by PNA and TUNEL label.-S334ter line-3 exhibited the fastest rate of degeneration with an early loss of photoreceptors, with 1e2 layers remaining at P30, and only cones left at P60. Line-5 had 4e5 layers left at P30, and very few rods left at P60-90. In both lines, horizontal cell processes (including dendrites and axon) were diminished at P11-13, showing gaps in the outer plexiform layer (OPL) at P60, and at P90, almost no terminal tips could be seen. Bipolar cells showed a retraction of their dendrites forming clusters along the OPL. Synaptic terminals of A-II amacrine cells in the IPL lost most of their parvalbumin-immunoreactivity. The apoptosis rate was different in both lines. Line-3 rats showed many photoreceptors affected at P11, occupying the innermost part of the outer nuclear layer. Line-5 showed a lower number of apoptotic cells within the same location at P13. In summary, the S334ter line-3 rat has a faster progression of degeneration than line-5. The horizontal and bipolar terminals are already affected at P11-P13 in both models. Apoptosis is related to the mutated rhodopsin transgene; the first photoreceptor cells affected are those close to the OPL.

The adult mammalian retina has for long been considered to lack a neurogenerative capacity. However, retinal stem/progenitor cells, which can originate retinal neurons in vitro, have been recently reported in the ciliary body of adult mammals. Here we explored the possibility of retinal neurogenesis occurring in vivo in adult monkeys and humans. We found the presence of cells expressing molecular markers of neural and retinal progenitors in the nonlaminated retinal margin and ciliary body pars plana of mature primates. By means of immunohistochemistry and electron microscopy we also observed photoreceptors and other retinal cell types in different stages of morphological differentiation along the peripheral retinal margin. These findings allow us to extend to primates the idea of neurogenesis aimed at retinal cell turnover throughout life. J. Comp. Neurol. 511:557–580, 2008. © 2008 Wiley‐Liss, Inc.

Purpose: The P23H rhodopsin mutation is an autosomal dominant cause of retinitis pigmentosa (RP). The degeneration can be tracked using different anatomical and functional methods. In our case, we evaluated the anatomical changes using Spectral-Domain Optical Coherence Tomography (SD-OCT) and correlated the findings with retinal thickness values determined by immunocytochemistry.Methods: Pigmented rats heterozygous for the P23H mutation, with ages between P18 and P180 were studied. Function was assessed by means of optomotor testing and ERGs. Retinal thicknesses measurements, autofluorescence and fluorescein angiography were performed using Spectralis OCT. Retinas were studied by means of immunohistochemistry. Results: Between P30 and P180, visual acuity decreased from 0.500 to 0.182 cycles per degree (cyc/deg) and contrast sensitivity decreased from 54.56 to 2.98 for a spatial frequency of 0.089 cyc/deg. Only cone-driven b-wave responses reached developmental maturity. Flicker fusions were also comparable at P29 (42 Hz). Double flash-isolated rod-driven responses were already affected at P29. Photopic responses revealed deterioration after P29.A reduction in retinal thicknesses and morphological modifications were seen in OCT sections. Statistically significant differences were found in all evaluated thicknesses. Autofluorescence was seen in P23H rats as sparse dots. Immunocytochemistry showed a progressive decrease in the outer nuclear layer (ONL), and morphological changes. Although anatomical thickness measures were significantly lower than OCT values, there was a very strong correlation between the values measured by both techniques.Conclusions: In pigmented P23H rats, a progressive deterioration occurs in both retinal function and anatomy. Anatomical changes can be effectively evaluated using SD-OCT and immunocytochemistry, with a good correlation between their values, thus making SD-OCT an important tool for research in retinal degeneration.

Acid decorated diblock copolymer nano-objects were prepared by polymerization-induced self-assembly via RAFT dispersion polymerization of methyl methacrylate. Spheres were used to prepare thin film membranes.