Ceratoplastia lamelar em cães utilizando membrana fetal eqüina como enxerto: estudo experimental

Abstract

Objetivo: Avaliar o emprego da membrana fetal (membrana amniótica, córion e alantóide) eqüina como enxerto em ceratoplastia lamelar em cães. Métodos: Foram utilizados 9 animais SRD, respeitando as normas para experimentos em animais da ARVO -Association for Research in Vision and Ophthalmology. Ceratectomia semipenetrante foi realizada com o auxílio de trépano de 5 mm de diâmetro em região temporal superior, com subseqüente fixação de fragmento de membrana fetal eqüina de 6 mm de diâmetro com fio mononylon 8-0. Realizou-se avaliação clínica durante 2, 7, 15 e 60 dias. Os animais foram sacrificados e os olhos enucleados submetidos a estudo histológico. Resultados: Observou-se clinicamente edema moderado nas áreas circunjacentes ao implante desde o início até a fase intermediária do experimento. A neovascularização apareceu de maneira progressiva, com maior intensidade no período intermediário, regredindo paulatinamente. Aos 60 dias, notava-se uma mácula no local da cirurgia. Os achados histológicos demonstraram epitelização e perfeita integração do enxerto ao tecido autóctone logo aos 7 dias de evolução, quando também evidenciou respostas celular e vascular mais intensas. Aos 15 dias, verificou-se diminuição dos elementos vasculares em relação à quantidade de matriz e elementos celulares proliferados. Constatou-se ausência quase total de infiltrado inflamatório no enxerto e nos pontos de sutura. Conclusão: O emprego da membrana fetal (membrana amniótica, córion e alantóide) eqüina como enxerto em ceratoplastia lamelar em cães é factível e produz bons resultados.Lamelar keratoplasty in dogs using equine fetal membrane as graft. Experimental study

Lamellar keratoplasty in rabbits using human and rabbit amniotic membrane grafts: a comparative study

“…Optical microscopy revealed epithelial regeneration and migration over the grafted tissue in the first days postsurgery. Complete epithelialization with paved stratified epithelium was noted at 15 days, as reported by other researchers . Epithelial hyperplasia was noted over the operated area in some specimens and may represent a compensation mechanism in areas of stromal thinning or reflect the rapid regeneration of rabbit corneal epithelium that is interrupted only when 200% of the initial thickness of the epithelial layer is reached .…”

“…Clinical signs were similar but milder than previously reported following the use of AM xenografts, AM allografts, and fetal membrane xenografts in dogs.…”

“…Much of the information regarding the properties and effects of this membrane on the ocular surface was gained through research in rabbits that are considered a good animal model for ophthalmological studies. Also, the successful use of AM xenografts in veterinary medicine has been reported in lamellar and penetrating keratoplasty . There are very few scientific reports on the use of RAM as a substrate for limbal cell culture with posterior implantation of the cultured tissue in corneal lesions in rabbits.…”

Clinical evaluation and induced corneal vascularization study by native and anionic collagen membranes in rabbits corneas

“…We opted to study the angiogenic capacity of NCM and ACM membrane in rabbit corneas because it is an original biomaterial, with excellent biocompatibility and weak antigenicity (9) . Several methods were described for the repair of corneal ulcers and perforations with autogenous and xenologous grafts (2)(3)(4)(5)(6)8,(15)(16) . Corneal opacification may be the final results (2,(15)(16) .…”

“…Nevertheless, it use induces corneal vascularization and the occurrence of late corneal pigmentation, fibrosis and cicatricial leukoma (2) that would result in a partial success of corneal regeneration, consisting only in a tectonic keratoplasty (3) . Despite the numerous surgical techniques that have been described, there are few reports on corneal vascularization, although corneal repair using different tissues has been well studied (2,(4)(5)(6) . Nowadays, the state-of-art ophthalmology has supplied ways for the treatment of many corneal diseases employing the artificial membranes produced in laboratory.…”