Corneal reconstruction with tissue-engineered cell sheets composed of human immature dental pulp stem cells.

PURPOSE: To determine the outcome of the use of a tissue-engineered cell sheet composed of human undifferentiated immature dental pulp stem cells (hIDPSC) for ocular surface reconstruction in an animal model of total limbal stem cell deficiency (LSCD). METHODS: LSCD was induced by the application of 0.5 M NaOH to the right eye of rabbits for 25 seconds (mild chemical burn [MCB]) and for 45 seconds (severe chemical burn [SCB]). After 1 month, a superficial keratectomy was performed to remove the fibrovascular pannus that covered the animals' burned corneas. A tissue-engineered hIDPSC sheet was transplanted onto the corneal bed and then covered with deepithelialized human amniotic membrane (AM). In the respective control groups, the denuded cornea was covered with AM only. After 3 months, a detailed analysis of the rabbit eyes was performed with regard to clinical aspect, histology, electron microscopy, and immunohistochemistry. RESULTS: Corneal transparency of the rabbit eyes that underwent hIDPSC transplantation was improved throughout the follow-up, while the control corneas developed total conjunctivalization and opacification. Rabbits from the MCB group showed clearer corneas with less neovascularization. The clinical data were confirmed by histologic analysis that showed healthy uniform corneal epithelium, especially in the MCB group. The presence of hIDPSC was detected using an anti-hIDPSC antibody. The corneal tissue also showed positive immunostaining with anti-human antibodies. In the control corneas, none of these antigens were detected. CONCLUSIONS: Overall, these data showed that transplantation of a tissue-engineered hIDPSC sheet was successful for the reconstruction of corneal epithelium in an animal model of LSCD.

Sensory nerve endings in the rat cheek mucosa: an electron microscopic study / Terminações nervosas sensitivas na mucosa da bochecha de ratos: estudo ao microscópio eletrônico

The sensory nerve endings of the rat cheek mucosa were studied using the transmission electron microscopy. The specimens were fixed in modified Karnovsky solution and embedded in Epon resin. The sensory nerve endings showed a central terminal axon containing numerous mitochondria, neurofilaments, microtubules and clear vesicles. The proximal part of corpuscle revealed the cytoplasmic extensions of lamellar cells and the perineural cells. The fine bundles of collagen fibers are identified in the interlamellar spaces and the external part of corpuscle. Numerous concentric lamellae showed caveolae, interlamelar spaces filled with amorphous material, desmosome-type junctions between adjacent lamellae and the inner lamellar cells and the axoplasmic membrane. These fine structures are important to recognise and understand the morphological characteristics in the oral mucosa.

As terminações nervosas sensitivas da mucosa da bochecha de ratos foram estudadas utilizando-se microscopia eletrônica de transmissão. As amostras foram fixadas em solução de Karnovsky modificada e inclusas em resina do tipo Epon. As terminaçãos nervosas sensitivas mostraram um axônio central terminal contendo numerosas mitocôndiras, neurofilamentos, microtúbulos e vesículas claras. A porção proximal dos corpúsculos revelaram projeções citoplasmáticas de células lamelares e células perineurais. Delgados feixes de fibras colágenas foram identificados nos espaços interlamelares e na região externa dos corpúsculos. Numerosas lamelas concêntricas apresentavam caveolas, espaços interlamelares preenchidos por material amorfo, desmossomos do tipo juncional entre lamelas adjacentes e células lamelares internas e membrana axolplásmatica. Essas estruturas delgadas mostram-se importantes na identificação e estudo das características da mucosa oral.