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3.  Pilot randomised controlled trial of face-down positioning following macular hole surgery 
Eye  2011;26(2):272-277.
Objective
This was a pilot randomised controlled trial (RCT) to investigate the effect of post-operative face-down positioning on the outcome of macular hole surgery and to inform the design of a larger definitive study.
Methods
In all, 30 phakic eyes of 30 subjects with idiopathic full-thickness macular holes underwent vitrectomy with dye-assisted peeling of the ILM and 14% perfluoropropane gas. Subjects were randomly allocated to posture face down for 10 days (posturing group) or to avoid a face-up position only (non-posturing group). The primary outcome was anatomical hole closure.
Results
Macular holes closed in 14 of 15 eyes (93.3% 95% confidence interval (CI) 68–100%) in the posturing group and in 9 of 15 (60% 95% CI 32–84%) in the non-posturing group. In a subgroup analysis of outcome according to macular hole size, all holes smaller than 400 μm closed regardless of posturing (100%). In contrast, holes larger than 400 μm closed in 10 of 11 eyes (91% 95% CI 58–99%) in the posturing group and in only 4 of 10 eyes (40% 95% CI 12–74%) in the non-posturing group (Fisher's exact test P=0.02).
Conclusion
Post-operative face-down positioning may improve the likelihood of macular hole closure, particularly for holes larger than 400 μm. These results support the case for a RCT.
doi:10.1038/eye.2011.221
PMCID: PMC3272183  PMID: 21941361
macular hole; face down positioning; prone; posturing
4.  Manipulation of the Recipient Retinal Environment by Ectopic Expression of Neurotrophic Growth Factors Can Improve Transplanted Photoreceptor Integration and Survival 
Cell transplantation  2012;21(5):871-887.
Degeneration of the neural retina is the leading cause of untreatable blindness in the developed world. Stem cell replacement therapy offers a novel strategy for retinal repair. Postmitotic photoreceptor precursors derived from the early postnatal (P) retina are able to migrate and integrate into the adult mouse retina following transplantation into the subretinal space, but it is likely that a large number of these cells would be required to restore vision. The adult recipient retina presents a very different environment to that from which photoreceptor precursor donor cells isolated from the developing postnatal retina are derived. Here we considered the possibility that modulation of the recipient environment by ectopic expression of developmentally regulated growth factors, normally present during photoreceptor development, might enhance the migration and integration of transplanted cells into the adult neural retina. Adeno-associated viral (AAV) vectors were used to introduce three growth factors previously reported to play a role in photoreceptor development, IGF1, FGF2, and CNTF, into the adult retina, prior to transplantation of P4 cells derived from the Nrl.GFP+ve neural retina. At 3 weeks posttransplantation the number of integrated, differentiated photoreceptor cells present in AAV-mediated neurotrophic factor-treated eyes was assessed and compared to control treated contralateral eyes. We show, firstly, that it is possible to manipulate the recipient retinal microenvironment via rAAV-mediated gene transfer with respect to these developmentally relevant growth factors. Moreover, when combined with cell transplantation, AAV-mediated expression of IGF1 led to significantly increased levels of cell integration, while overexpression of FGF2 had no significant effect on integrated cell number. Conversely, expression of CNTF led to a significant decrease in cell integration and an exacerbated glial response that led to glial scarring. Together, these findings demonstrate the importance of the extrinsic environment of the recipient retina for photoreceptor cell transplantation and show for the first time that it is possible to manipulate this environment using viral vectors to influence photoreceptor transplantation efficiency.
doi:10.3727/096368911X623871
PMCID: PMC3523316  PMID: 22325046
Photoreceptor; Retina; Transplantation; Neurotrophic factors; Gene therapy; Stem cell
5.  Cell transplantation strategies for retinal repair 
Progress in brain research  2009;175:3-21.
Cell transplantation is a novel therapeutic strategy to restore visual responses to the degenerate adult neural retina and represents an exciting area of regenerative neurotherapy. So far, it has been shown that transplanted postmitotic photoreceptor precursors are able to functionally integrate into the adult mouse neural retina. In this review, we discuss the differentiation of photoreceptor cells from both adult and embryonic-derived stem cells and their potential for retinal cell transplantation. We also discuss the strategies used to overcome barriers present in the degenerate neural retina and improve retinal cell integration. Finally, we consider the future translation of retinal cell therapy as a therapeutic strategy to treat retinal degeneration.
doi:10.1016/S0079-6123(09)17501-5
PMCID: PMC3272389  PMID: 19660645
stem cell; progenitor cell; photoreceptor; retina; transplantation; degeneration
6.  Targeted Disruption of Outer Limiting Membrane Junctional Proteins (Crb1 and ZO-1) Increases Integration of Transplanted Photoreceptor Precursors Into the Adult Wild-Type and Degenerating Retina 
Cell transplantation  2010;19(4):487-503.
Diseases culminating in photoreceptor loss are a major cause of untreatable blindness. Transplantation of rod photoreceptors is feasible, provided donor cells are at an appropriate stage of development when transplanted. Nevertheless, the proportion of cells that integrate into the recipient outer nuclear layer (ONL) is low. The outer limiting membrane (OLM), formed by adherens junctions between Müller glia and photoreceptors, may impede transplanted cells from migrating into the recipient ONL. Adaptor proteins such as Crumbs homologue 1 (Crb1) and zona occludins (ZO-1) are essential for localization of the OLM adherens junctions. We investigated whether targeted disruption of these proteins enhances donor cell integration. Transplantation of rod precursors in wild-type mice achieved 949 ± 141 integrated cells. By contrast, integration is significantly higher when rod precursors are transplanted into Crb1rd8/rd8 mice, a model of retinitis pigmentosa and Lebers congenital amaurosis that lacks functional CRB1 protein and displays disruption of the OLM (7,819 ± 1,297; maximum 15,721 cells). We next used small interfering (si)RNA to transiently reduce the expression of ZO-1 and generate a reversible disruption of the OLM. ZO-1 knockdown resulted in similar, significantly improved, integration of transplanted cells in wild-type mice (7,037 ± 1,293; maximum 11,965 cells). Finally, as the OLM remains largely intact in many retinal disorders, we tested whether transient ZO-1 knockdown increased integration in a model of retinitis pigmentosa, the rho−/− mouse; donor cell integration was significantly increased from 313 ± 58 cells without treatment to 919 ± 198 cells after ZO-1 knockdown. This study shows that targeted disruption of OLM junctional proteins enhances integration in the wild-type and degenerating retina and may be a useful approach for developing photoreceptor transplantation strategies.
doi:10.3727/096368909X486057
PMCID: PMC2938729  PMID: 20089206
Stem cell; Migration; Transplantation; Degeneration; Müller glia
7.  Pharmacological disruption of the outer limiting membrane leads to increased retinal integration of transplanted photoreceptor precursors 
Experimental Eye Research  2008;86(4):601-611.
Retinal degeneration is the leading cause of untreatable blindness in the developed world. Cell transplantation strategies provide a novel therapeutic approach to repair the retina and restore sight. Previously, we have shown that photoreceptor precursor cells can integrate and form functional photoreceptors after transplantation into the subretinal space of the adult mouse. In a clinical setting, however, it is likely that far greater numbers of integrated photoreceptors would be required to restore visual function. We therefore sought to assess whether the outer limiting membrane (OLM), a natural barrier between the subretinal space and the outer nuclear layer (ONL), could be reversibly disrupted and if disruption of this barrier could lead to enhanced numbers of transplanted photoreceptors integrating into the ONL. Transient chemical disruption of the OLM was induced in adult mice using the glial toxin, dl-alpha-aminoadipic acid (AAA). Dissociated early post-natal neural retinal cells were transplanted via subretinal injection at various time-points after AAA administration. At 3 weeks post-injection, the number of integrated, differentiated photoreceptor cells was assessed and compared with those found in the PBS-treated contralateral eye. We demonstrate for the first time that the OLM can be reversibly disrupted in adult mice, using a specific dose of AAA administered by intravitreal injection. In this model, OLM disruption is maximal at 72 h, and recovers by 2 weeks. When combined with cell transplantation, disruption of the OLM leads to a significant increase in the number of photoreceptors integrated within the ONL compared with PBS-treated controls. This effect was only seen in animals in which AAA had been administered 72 h prior to transplantation, i.e. when precursor cells were delivered into the subretinal space at a time coincident with maximal OLM disruption. These findings suggest that the OLM presents a physical barrier to photoreceptor integration following transplantation into the subretinal space in the adult mouse. Reversible disruption of the OLM may provide a strategy for increasing cell integration in future therapeutic applications.
doi:10.1016/j.exer.2008.01.004
PMCID: PMC2394572  PMID: 18294631
retinal transplantation; Müller cell; outer limiting membrane; cell integration; photoreceptor; stem cells; mouse
8.  Skull X-ray after head injury: the recommendations of the Royal College of Surgeons Working Party report in practice. 
Archives of Emergency Medicine  1993;10(3):138-144.
In 1986 a Royal College of Surgeons Working Party published guidelines, based on over 15 years of clinical research both here and in the U.S.A., on when to perform skull X-rays on a head injury patient. In this retrospective study the recorded details of 405 patients who presented to an accident and emergency (A&E) department over a 3-month period in 1991 are analysed, and the Report criteria applied to each one to assess whether the guidelines are being followed in performing a skull X-ray. According to these guidelines, 191 of these patients (47.2%) should have been X-rayed, however, only 83 were. Only one patient was thought to have been X-rayed inappropriately. The Report criteria most commonly thought by the A&E doctors not to warrant skull X-ray, were loss of consciousness, amnesia, dizziness, blurred vision, headache, and alcohol intoxication. The reasons why these criteria are being ignored are examined, and together with reference to recent studies, slight alterations to the Working Party guidelines are suggested to make them more applicable to everyday situations of head injury encountered in a casualty department.
PMCID: PMC1285978  PMID: 8216584
9.  Development and role of retinal glia in regeneration of ganglion cells following retinal injury. 
AIMS/BACKGROUND: Recent observations have shown that the glial scar resulting from a surgical lesion of the immature retina differs from elsewhere in the central nervous system, in that it permits the through growth and reconnection of regenerating axons. This study in the opossum examines in detail the development and reaction to injury of retinal glia at different developmental stages, and specifically examines the distribution of the gliosis related inhibitory molecule, chondroitin sulphate proteoglycan (CSPG), making comparisons with a control site of gliosis in the cerebral cortex. METHODS: A linear slit was cut into the retina or cortex with a fine tungsten probe. After a variable time delay, immunocytochemistry of the resulting gliosis was employed to detect astrocytes with glial fibrillary acidic protein (GFAP), Müller cells with vimentin, and CSPG with CS-56 antibodies. GFAP was also used at different ages to examine the normal development of astrocytes in the retina of this species. RESULTS: Astrocytes entered the retina 12 days after birth (P12), closely associated with blood vessels in the nerve fibre layer. In experiments at all ages studied, cellular continuity was re-established across the lesioned retina, which did not result in a significant astrocyte proliferation or CSPG expression. In contrast, cortical injury led to the development of a cystic cavity surrounded by astrocytes and CSPG. Müller cells expressed GFAP but not CSPG in the lesioned retina. CONCLUSION: Successful regrowth of ganglion cells through a retinal lesion may be partly the result of the scarcity of astrocytes in the retina, which results in minimal gliosis, or of their apparent inability to express inhibitory molecules.
Images
PMCID: PMC505499  PMID: 8695569

Results 1-10 (10)