Transplantation of Islets of Langerhans into the Anterior Chamber of the Eye for Longitudinal In Vivo Imaging.

Noninvasive in vivo imaging techniques are attractive tools to longitudinally study various aspects of islet of Langerhans physiology and pathophysiology. Unfortunately, most imaging modalities currently applicable for clinical use do not allow the comprehensive investigation of islet cell biology due to limitations in resolution and/or sensitivity, while high-resolution imaging technologies like laser scanning microscopy (LSM) lack the penetration depth to assess islets of Langerhans within the pancreas. Significant progress in this area was made by the combination of LSM with the anterior chamber of the mouse eye platform, utilizing the cornea as a natural body window to study cell physiology of transplanted islets of Langerhans. We here describe the transplantation and longitudinal in vivo imaging of islets of Langerhans in the anterior chamber of the mouse eye as a versatile tool to study different features of islet physiology in health and disease.

Descemet's membrane endothelial keratoplasty with a simplified technique and low complication rate: the samba technique.

PURPOSE: We report a simplified Descemet's membrane endothelial keratoplasty (DMEK) technique that involves safe and effective preparation and introduction, correct orientation, and easy unfolding of the donor graft inside the recipient anterior chamber. METHODS: In this retrospective study, we assessed the surgical outcomes of 26 eyes of 23 consecutive patients (mean age, 61.2 ± 11.4 yr; range, 39-82 yr) with Fuchs endothelial corneal dystrophy (n=19) or bullous keratopathy (n=7) who underwent the Samba technique, a simplified DMEK method, at the Sorocaba Ophthalmology Hospital, Sorocaba Eye Bank, Sorocaba, Brazil, between August 2011 and July 2012. RESULTS: Of the 26 operated eyes, only two (7.7%) experienced partial graft detachment requiring rebubbling, and in those eyes, the graft was reattached successfully with one air bubble. There were no cases of primary graft failure, tissue loss, or pupillary block. All patients with good visual potential achieved a best-corrected visual acuity of 20/30 or better at 6 months, and 82.6% achieved a best-corrected visual acuity of 20/30 or better 1 month postoperatively. CONCLUSION: In this retrospective study, the Samba technique, a simplified DMEK procedure, was safe and effective, with an acceptably low rebubbling rate and no incidence of primary graft failure or pupillary block. Moreover, rapid and nearly complete visual recovery was achieved. This simplified DMEK technique can be adopted by corneal surgeons worldwide as a primary treatment for endothelial dysfunction with a less steep learning curve and low rate of postoperative complications.

Descemet's membrane endothelial keratoplasty with a simplified technique and low complication rate: the samba technique / Ceratoplastia endotelial da membrana de Descemet com técnica simplificada e baixa taxa de complicação: a técnica de samba

ABSTRACT Purpose: We report a simplified Descemet's membrane endothelial keratoplasty (DMEK) technique that involves safe and effective preparation and introduction, correct orientation, and easy unfolding of the donor graft inside the recipient anterior chamber. Methods: In this retrospective study, we assessed the surgical outcomes of 26 eyes of 23 consecutive patients (mean age, 61.2 ± 11.4 yr; range, 39-82 yr) with Fuchs endothelial corneal dystrophy (n=19) or bullous keratopathy (n=7) who underwent the Samba technique, a simplified DMEK method, at the Sorocaba Ophthalmology Hospital, Sorocaba Eye Bank, Sorocaba, Brazil, between August 2011 and July 2012. Results: Of the 26 operated eyes, only two (7.7%) experienced partial graft detachment requiring rebubbling, and in those eyes, the graft was reattached successfully with one air bubble. There were no cases of primary graft failure, tissue loss, or pupillary block. All patients with good visual potential achieved a best-corrected visual acuity of 20/30 or better at 6 months, and 82.6% achieved a best-corrected visual acuity of 20/30 or better 1 month postoperatively. Conclusion: In this retrospective study, the Samba technique, a simplified DMEK procedure, was safe and effective, with an acceptably low rebubbling rate and no incidence of primary graft failure or pupillary block. Moreover, rapid and nearly complete visual recovery was achieved. This simplified DMEK technique can be adopted by corneal surgeons worldwide as a primary treatment for endothelial dysfunction with a less steep learning curve and low rate of postoperative complications.

RESUMO Objetivo: Relatar uma técnica simplificada de ceratoplastia endotelial da membrana de Descemet (DMEK) que envolve a preparação e a introdução seguras e eficazes, a orientação correta e o fácil desdobramento do enxerto doador dentro da câmara anterior receptora. Métodos: Neste estudo retrospectivo, foram revisados e avaliados os resultados cirúrgicos de 26 olhos de 23 pacientes consecutivos (idade média: 61,2 ± 11,4 anos, intervalo: 39 a 82 anos) com distrofia corneana endotelial de Fuchs (n=19) ou ceratopatia bolhosa (N=7) submetidos à técnica "Samba", método de DMEK simplificado, no Hospital Oftalmológico de Sorocaba, Banco de Olhos de Sorocaba, Sorocaba, Brasil, entre agosto de 2011 e julho de 2012. Resultados: Dos 26 olhos operados, apenas 2 olhos (7,7%) apresentaram descolamento parcial do enxerto que necessitou de nova injeção de ar na câmara anterior "re-bubble", e nesses olhos o enxerto foi posicionado com sucesso com o procedimento de "re-bubble". Nenhum dos 26 olhos apresentaram falência primária do enxerto ou perda de tecido, ou bloqueio pupilar. Todos os pacientes com bom potencial visual obtiveram a acuidade visual melhor corrigida de 20/30 ou melhor e 82,6% tinham acuidade visual melhor corrigida de 20/30 ou melhor com 1 mês de cirurgia. Conclusão: Neste estudo retrospectivo, a técnica de Samba, um procedimento de DMEK simplificado, mostrou-se segura e eficaz, com uma taxa de "re-bubble" aceitavelmente baixa e nenhuma incidência de falência primária ou complicação com bloqueio pupilar. Além disso, a recuperação visual rápida e completa foi rapidamente alcançada. Esta técnica DMEK simplificada pode ser adotada por cirurgiões de córnea em todo o mundo como um tratamento primário para disfunção endotelial com uma curva de aprendizado rápida e baixa taxa de complicações pós-operatórias.

Intraocular in vivo imaging of pancreatic islet cell physiology/pathology.

BACKGROUND: Diabetes mellitus has reached epidemic proportions and requires new strategies for treatment. Unfortunately, the efficacy of treatment regimens on maintaining/re-gaining functional beta cell mass can, at the present, only be determined indirectly. Direct monitoring of beta cell mass is complicated by the anatomy of the endocrine pancreas, which consists of thousands to a million of discrete micro-organs, i.e. islets of Langerhans, which are scattered throughout the pancreas. SCOPE OF REVIEW: Here, we review the progress made over the last years using the anterior chamber of the eye as a transplantation site for functional imaging of pancreatic islet cells in the living organism. Islets engrafted on the iris are vascularized and innervated and the cornea, serving as a natural body-window, allows for microscopic, non-invasive, longitudinal evaluation of islet/beta cell function and survival with single-cell resolution in health and disease. MAJOR CONCLUSIONS: Data provided by us and others demonstrate the high versatility of this imaging platform. The use of 'reporter islets' engrafted in the eye, reporting on the status of in situ endogenous islets in the pancreas of the same animal, allows the identification of key-events in the development and progression of diabetes. This will not only serve as a versatile research tool but will also lay the foundation for a personalized medicine approach and will serve as a screening platform for new drugs and/or treatment protocols. 'Metabolic' islet transplantation, in which islets engrafted in the eye replace the endogenous beta cells, will allow for the establishment of islet-specific transgenic models and 'humanized' mouse models as well as serving as the basis for a new clinical transplantation site for the cure of diabetes.

Descemet's stripping endothelial keratoplasty: is it an option for congenital hereditary endothelial dystrophy?

The purpose of this study was to report our experience of an attempted Descemet's stripping automated endothelial keratoplasty (DSAEK) in a patient with congenital hereditary endothelial dystrophy (CHED). A 7-year-old boy presented with the complaints of decreased vision in his right eye. The left eye had undergone penetrating keratoplasty at the age of 5 years. He was diagnosed as a case of CHED, and a DSAEK was planned for him. Due to technical difficulties during Descemet's membrane scoring and stripping and poor visualization, the procedure had to be abandoned and converted to a full thickness penetrating keratoplasty. To the best of our knowledge, this is the first reported case of an attempted DSAEK in a patient with CHED. Proper DSAEK case selection should include adequate visualization of the endothelium and anterior chamber. Severe stromal haze and edema may prevent necessary surgical observation during the procedure, and a full thickness penetrating keratoplasty may be required.

Immunity and immune privilege elicited by autoantigens expressed on syngeneic neonatal neural retina grafts.

Achieving the long-term goal of successful engraftment of retinal tissues into eyes blinded by endogenous retinal failure will depend, at least in part, on controlling the immune response to antigens expressed on retinal grafts. Since histoincompatible tissues will have to be used for such transplants, methods to control immune rejection directed at transplantation alloantigens must be devised. In addition, it has recently been observed in mice that developing neural retinal tissues express retina-specific antigens that have the potential to contribute to graft failure. To examine the potential risk of this contribution, syngeneic neonatal neural retinas were implanted into the anterior chamber, vitreous cavity, and subconjunctival space of adult BALB/c mice. During two weeks post-implantation, the fate of these grafts was observed clinically and histologically, and the retina-specific immune responses of the recipients were evaluated. Whereas grafts placed intraocularly thrived, carried out their inherent developmental potential, and were healthy and intact at the end of the observation interval. Grafts placed extraocularly expressed their differentiation program poorly. These grafts underwent rapid decline and attrition, although the process was not accompanied by significant inflammation. Recipients of subconjunctival, but not AC or VC, implants developed retina-specific delayed hypersensitivity. Alternatively, mice bearing AC and VC implants of neonatal neural retina developed retina-specific anterior chamber associated immune deviation. It is concluded that retinal autoantigens are expressed on developing neural retinal tissues and these antigens are highly immunogenic when retinal grafts are placed at conventional body sites. When similar grafts are placed in immune privileged compartments of the normal eye, they enjoy significant survival. Circumstantial evidence indicates that intraocular retinal grafts are protected and maintained in part by the emergence of systemic retinal auto-antigen-specific immune suppression.

Immunologic privilege evoked by histoincompatible intracameral retinal transplants.

In order to examine the fate of intraocular retinal transplants, we placed histoincompatible neural retinas from neonatal BALB/c mice into the anterior chamber (AC) or subconjunctival space of eyes of adult C57BL/6 mice. Clinical and histologic examinations revealed that grafts of developing neural retinal tissue placed within the AC acquired a blood supply, and differentiated into histologically recognizable retinal structures; there was no evidence of inflammation or rejection. By contrast, developing neural retinal allografts placed in the subconjunctival space failed to thrive, and were promptly rejected within 8 days. To examine the nature of the systemic immune response of mice bearing intracameral retinal allografts, C57BL/6 mice, bearing neural retinal allografts from BALB/c donors in their AC for 12 days, were tested for delayed hypersensitivity. When ear challenged with (C57BL/6 x BALB/c)F1 spleen cells, these mice failed to mount significant ear swelling responses, whereas a positive control group of C57BL/6 mice that received neonatal BALB/c retinas implanted in the subconjunctival space displayed vigorous BALB/c-specific delayed hypersensitivity. It is pertinent that, shortly after ear challenge with (C57BL/6 x BALB/c)F1 cells, the previously healthy AC retinal allografts underwent regression and degeneration. Finally, we showed that the spleens of C57BL/6 mice bearing healthy intraocular developing retinal allografts contained suppressor lymphocytes that were revealed in adoptive transfer assays. We conclude that immune privilege is extended to histoincompatible developing retinal transplants placed in the AC of the eye, and that these allografts induce a deviant systemic immune response characterized by impaired expression of delayed hypersensitivity and generation of splenic suppressor cells. We infer that the success of these transplants, compared to similar grafts which are rejected in the subconjunctival space, is predicated upon, and mediated by, the induction of active specific suppression of cell-mediated immunity.