Amniotic membrane as a biological scaffold for dental pulp stem cell transplantation in ocular surface reconstruction / Membrana amniótica como substrato biológico para o transplante de células-tronco da polpa do dente de leite na reconstrução da superfície ocular

ABSTRACT Purpose: To evaluate the ability of human immature dental pulp stem cells, which are mesenchymal stem cells of neural crest origin, to differentiate into the corneal epithelium for purposes of corneal transplantation and tissue engineering when cultured on de-epithelized amniotic membranes. Methods: We compared the immunophenotypes (ABCG2, K3/12, and vimentin) of cells grown on amniotic membranes or plastic surfaces under serum-free conditions or in culture media containing serum or serum replacement components. Results: Immature dental pulp stem cells grown on amniotic membranes under basal conditions are able to maintain their undifferentiated state. Our data also suggest that the culture medium used in the present work can modulate the expression of immature dental pulp stem cell markers, thus inducing epithelial differentiation of these cells in vitro. Conclusions: Our results suggest that the amniotic membrane is a good choice for the growth and transplantation of mesenchymal stem cells, particularly immature dental pulp stem cells, in clinical ocular surface reconstruction.

RESUMO Objetivos: Avaliar a capacidade das células-tronco imaturas da polpa do dente de leite que são células-tronco mesenquimais de origem da crista neural, de se diferenciarem no epitélio corneano para fins de transplante de córnea e engenharia de tecidos quando cultivadas em membrana amnióticas desepitelizadas. Métodos: Foram comparamos so imunofenótipo (ABCG2, CK3/12 e vimentina) de células cultivadas em membranas amnióticas ou em superfícies plásticas sob condições livres de soro ou em meios de cultura contendo soro ou componentes de substituição de soro. Resultados: Células-tronco imaturas da polpa do dente de leite cultivadas sobre membrana amniótica em condições basais são capazes de manter seu estado indiferenciado. Nossos dados também sugerem que o meio de cultura utilizado no presente trabalho pode modular a expressão de marcadores de células-tronco imaturas da polpa do dente de leite, induzindo a diferenciação epitelial destas células in vitro. Conclusão: Nossos resultados sugerem que a membrana amniótica é uma boa escolha para o crescimento e transplante de células-tronco mesenquimais, particularmente as células-tronco imaturas da polpa do dente de leite, na reconstrução da superfície ocular.

Assessment of surgical outcomes of limbal transplantation using simple limbal epithelial transplantation technique in patients with total unilateral limbal deficiency / Avaliação dos resultados cirúrgicos do transplante de limbo utilizando a técnica SLET (simple limbal epithelial transplantation), em pacientes com deficiência límbica total unilateral

ABSTRACT This study aimed to evaluate the effectiveness of the novel simple limbal epithelial transplantation (SLET) technique, which reduces the risk of iatrogenic limbal stem cell deficiency in the donor eye. Four patients with total unilateral limbal stem cell deficiency received a limbal graft, measuring 4 mm × 2 mm, from the contralateral healthy eye in a single surgical procedure. The graft was divided into 10-20 pieces and distributed on the corneal surface. At 6-month follow-up, a completely avascular corneal epithelial surface was obtained in two patients, and there was improvement in visual acuity in one patient. The limbal grafts did not adhere to the cornea in one patient. No serious complications related to the surgery were observed in this study.

RESUMO Este trabalho tem como objetivo avaliar a eficácia de uma nova técnica cirúrgica denominada SLET (simple limbal epithelial transplantation), um procedimento promissor que reduz os riscos de indução de deficiência límbica iatrogênica no olho doador. Quatro pacientes com deficiência límbica total unilateral, secundária a queimadura química, receberam um enxerto de células límbicas, medindo 4 mm x 2 mm, do olho contralateral sadio, em apenas um tempo cirúrgico. Este foi divido em 10 a 20 fragmentos e distribuído sobre a superfície da córnea. Após 6 meses de cirurgia, superfície corneana totalmente epitelizada e avascular foi obtida em dois pacientes. Houve melhora da acuidade visual em um paciente. Não houve aderência dos enxertos de limbo na córnea em um paciente. Nenhum paciente apresentou efeitos colaterais graves decorrentes do procedimento cirúrgico.

HLA-matched living-related conjunctival limbal allograft for bilateral ocular surface disorders: long-term results / Transplante alogênico inter vivo de limbo conjuntival com pareamento HLA em doenças bilaterais da superfície ocular: resultados em longo prazo

PURPOSE: To evaluate the long-term outcome of HLA-matched lr-CLAL for bilateral ocular surface disorders. METHODS: A retrospective, non-comparative interventional case series study of 39 eyes of 32 patients with bilateral surface disorders and clinical diagnosis of limbal stem cell deficiency who underwent HLA-matched lr-CLAL. Visual acuity (VA), ambulatory vision (> 20/200) and ocular surface stability were evaluated as main outcomes. Donor limbus was obtained from a sibling or a parent of the patient, after an appropriate Class I and II HLA match. RESULTS: One year after surgery, VA improved in 46.2 percent, ambulatory vision was achieved in 48.7 percent and a stable corneal surface was achieved in 84.6 percent of the eyes. At the final follow-up (mean, 48.7 ± 30.6 months), 66.6 percent of the eyes that had gained VA one year after surgery maintained an improved VA (p=0.28), 94.7 percent of eyes that had achieved ambulatory vision one year after surgery maintained 20/200 or better (p<0.001) and 93.9 percent still had a stable corneal surface (p=0.043) at the final follow-up. CONCLUSIONS: HLA-matched lr-CLAL can be an adequate method of treatment for bilateral ocular surface disorders, with a reasonable percentage of success of long-term results.

OBJETIVO: Avaliar os resultados em longo prazo do transplante alogênico inter vivo de limbo conjuntival para doenças bilaterais da superfície ocular com compatibilidade HLA doador-receptor. MÉTODOS: Estudo retrospectivo, não comparativo e intervencionista de 39 olhos de 32 pacientes submetidos a transplante alogênico de limbo com compatibilidade HLA e diagnóstico de deficiência límbica. Foram analisados como desfechos principais acuidade visual, visão ambulatorial (> 20/200) e estabilidade da superfície ocular. Limbo doador foi obtido de parentes do paciente após estudo de compatibilidade HLA classe I e II. RESULTADOS: Com um ano de pós-operatório, a acuidade visual melhorou em 46,2 por cento, visão ambulatorial foi atingida em 48,7 por cento e estabilidade da superfície corneana em 84,6 por cento dos pacientes. Ao final do seguimento (média, 48,7 ± 30,6 meses), 66,6 por cento dos olhos que haviam ganho acuidade visual um ano após a cirurgia mantiveram esta melhora (p=0,28), 94,7 por cento dos olhos que haviam alcançado visão ambulatorial um ano após a cirurgia mantiveram visão de 20/200 ou melhor (p<0,001) e 93,9 por cento ainda tinham superfície corneana estável (p=0,043) ao final do seguimento. CONCLUSÕES: O transplante alogênico inter vivo de limbo conjuntival com compatibilidade HLA revelou-se método adequado no tratamento de doenças bilaterais da superfície ocular, com uma porcentagem significativa de sucesso a longo-prazo.

Phacoemulsification after penetrating keratoplasty with autologous limbal transplant and amniotic membrane transplant in chemical burns.

We report a patient who had earlier penetrating keratoplasty with amniotic membrane transplant and autologous limbal cell transplant for chemical injury who underwent cataract surgery by phacoaspiration. A posterior limbal incision with corneal valve was made superotemporally with extreme caution to avoid damage to the limbal graft. Aspiration flow rates and vacuum were kept low to avoid any turbulence during surgery. A 6.0 mm optic diameter acrylic foldable intraocular lens was inserted in the bag. The patient achieved a best-corrected visual acuity of 6/12 at 10 months' follow-up with a clear corneal graft. We conclude that caution during wound construction and phacoaspiration can help preserve corneal and limbal graft integrity in patients undergoing cataract surgery after corneal graft and limbal transplantation.

Amniotic membrane transplantation for reconstruction of corneal epithelial surface in cases of partial limbal stem cell deficiency.

PURPOSE: To assess the efficacy of amniotic membrane for treatment of partial limbal stem cell deficiency (LSCD). METHODS: Medical records of four patients with partial LSCD who underwent pannus resection and amniotic membrane transplantation (AMT) were reviewed for ocular surface stability and improvement in visual acuity. Clinico-histopathological correlation was done with the resected pannus tissue. RESULTS: All the eyes exhibited stable corneal epithelial surface by an average of 7 weeks postoperatively with improvement in subjective symptoms. Best corrected visual acuity improved from preoperative (range: 6/9p-6/120) to postoperative (range: 6/6p-6/15) by an average of 4.5 lines on Snellen visual acuity charts. Histopathological examination of excised tissue showed features of conjunctivalisation. CONCLUSION: Amniotic membrane transplantation appears to be an effective means of reconstructing the corneal epithelial surface and for visual rehabilitation of patients with partial limbal stem cell deficiency. It may be considered as an alternative primary procedure to limbal transplantation in these cases.

Conjunctival-limbal autografts for primary and recurrent pterygia: technique and results.

Our technique of pterygium excision with conjunctival-limbal autografting is described and the safety and efficacy of the procedure in India is analysed. Case records of 51 consecutive patients (53 eyes) who underwent surgery at our institute between November 1992 and September 1994 were retrospectively analysed. Recurrence was defined as fibrovascular tissue crossing the corneoscleral limbus onto clear cornea in the area of previous pterygium excision. 2 (3.8%) of the 53 pterygia (primary 36; recurrent 17) recurred, after a mean follow up of 18.9 +/- 12.1 months (range: 1.5-43 months). Both recurrences occurred within a year of follow up, in patients who were < or = 40 years of age. No major operative or postoperative complications were encountered. The inclusion of limbal tissue in conjunctival autografts following pterygium excision appears to be essential to ensure low recurrence rates. The technique is safe, simple and inexpensive and is recommended for the management of both primary and recurrent pterygia in Indian eyes.