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PubMed · 10102284

Conjunctival epithelial cell differentiation on amniotic membrane.

Abstract

PURPOSE: Amniotic membrane (AM)-reconstructed conjunctival surfaces recover the normal epithelial phenotype with a significantly higher cell density than the control. The present study was undertaken to examine how AM modulates rabbit conjunctival epithelial cell differentiation. METHODS: Rabbit conjunctival epithelial cells (RCEs) were cultured on the basement membrane side of dispase-pretreated AM, with or without seeding rabbit conjunctival fibroblasts (RCFs) on the stromal side. After 7 to 12 days, half of the cultures were raised to the air-liquid interface, and the remainder stayed submerged. A small group of air-lifted cultures containing RCFs was treated with retinoic acid. After 1, 2, and 4 weeks, cultures were terminated and processed for immunostaining with antibodies directed against distinct types of mucins (SMC and AM3), glycocalyx (AMEM2), keratin K3 (AE5), and K12 (AK2). Additionally, western blot analysis was performed for K3 keratin expression. Ultrastructural changes were evaluated by transmission electron microscopy. RESULTS: In general, RCEs grown on AM were uniformly small, negative to AE5 and AK2 antibodies, and positive to AMEM2 and ASPG1 antibodies. Epithelial stratification and cell polarity with prominent microvilli, tight junctions, and hemidesmosomes were more pronounced in air-lifted cultures. RCEs cocultured with RCFs showed scattered AM3-positive goblet cells, which were not increased by retinoic acid. CONCLUSIONS: RCEs cultured on AM primarily exhibit a nongoblet conjunctival epithelial phenotype. Epithelial stratification and cell polarity, features essential for epithelial differentiation, are promoted by air-lifting. This culture model will be useful for studying how growth and differentiation of conjunctival epithelial cells can be modulated further.

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BibTeXRIS

D Meller, S C Tseng. 1999. Conjunctival epithelial cell differentiation on amniotic membrane.. https://pubmed.ncbi.nlm.nih.gov/10102284/

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Intrathoracic pressure in congenital chylothorax: keystone for the rationale of thoracoamniotic shunting?

Thoracoamniotic shunting in fetal pleural effusion has poor results, with an overall survival of less than 50% when hydrops is associated. Those cases without hydrops presented the best evolution, but the indication in these cases remains controversial. We present a dichorionic diamniotic twin pregnancy at 29 weeks' with right pleural effusion and hydrops, in which one fetus presented diaphragm inversion and mediastinal shift, both considered as ultrasonographic signs of thoracic hypertension. A thoracoamniotic shunt reversed these signs immediately. Nevertheless, 1 week after, these signs and skin edema reappeared and the effusion increased, leading to a second thoracocenthesis for drainage and intrathoracic pressure measurement. Amniotic fluid and intrathoracic pressures were found at 21 and 39 mm Hg, respectively. A cesarean section was performed and the catheter was found to be obliterated by cellular detritus of leukocytes and fibrin. Our conclusion is that ultrasonographic signs of elevated thoracic pressure are a keystone for the shunt indication, and that this could be corroborated by direct measurements. This can be an important parameter for precise indication of thoracoamniotic shunting.

Amnion↗

Rate of epithelialisation and re-operations in corneal ulcers treated with amniotic membrane transplantation combined with botulinum toxin-induced ptosis.

OBJECTIVE: To examine the efficacy of amniotic membrane transplantation (AMT) and/or botulinum toxin type A-induced ptosis (Dysport) in the treatment of corneal ulcerations of different entities. METHODS: Retrospective evaluation of 137 cases of corneal ulcers which have been treated with AMT, botulinum toxin type A and perforating keratoplasty (pKP). Regarding corneal ulcerations the patients were divided into three groups: group A, patients initially having received an AMT (92 eyes eventually followed by AMT or pKP as a second intervention); group B, patients initially having received an AMT (32 eyes followed by botulinum toxin type A injection in the upper lid as a second intervention); group C, patients initially treated only by botulinum toxin type A injection (13 eyes followed occasionally by AMT or pKP or additional botulinum toxin type A injection). Additionally, we analysed the complete epithelialisation rate of the ocular surface in respect to different ocular and systemic diseases and compared the frequency of re-operations in each group. RESULTS: The overall follow-up was 14.2 (+/-14.7 months; range from 1 to 60 months). The total frequency of re-operations was 45.3% (overall time until complete epithelialisation 12.7 (+/-6.1) days). If the patient was initially treated with an AMT (group A), the re-operation rate was 44.6%. Treating affected eyes in this group with a subsequent amniotic membrane resulted in a reduction of re-operation rate to 30.4%. In cases with induced ptosis by injecting botulinum toxin type A in the M. levator palpebrae (group B), the re-operation frequency could be reduced to 34.4% with similar times of epithelialisation [group A: 12.0 (+/-6.5) days and group B: 11.7 (+/-5.5) days]. In group C, with botulinum toxin type A alone initially, the re-operation rate of 69.2% was the highest one compared with groups A and B; this rate could be drastically reduced by a following AMT to 23.1%. Surprisingly, in the few successful cases with botulinum toxin type A alone a quite low epithelialisation time of 6.5 (+/-1.3) days was achieved, but turned out to be similar after additional interventions if compared with the other groups (botulinum toxin type A + AMT: 15.7 (+/-4.9) day). CONCLUSION: AMT alone and combined with botulinum toxin type A-induced ptosis is an effective surgical approach for managing severe corneal ulcerations by promoting wound healing and stabilizing ocular surface homeostasis.

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