Various approaches have been taken to improve our knowledge of the microenvironmental regulation of limbal epithelial stem cells. Researchers have extensively investigated the roles of growth factors, survival factors, cytokines, enzymes, and permeable molecules secreted by the limbal cells. However, recent evidence suggests that stem cell fate (i.e., self-renewal or differentiation) can also be influenced by biophysical and mechanical cues related to the supramolecular organization and the liquid crystalline (mesophase) nature of the stromal extracellular matrix. These cues can be sensed by stem cells and transduced into intracellular biochemical and functional responses, a process known as mechanotransduction. The objective of this review is to offer perspectives on the supramolecular microenvironmental regulation of limbal epithelial stem cells and the differentiation of their progeny.

The objective of this study was to establish ophthalmic parameters in the Pomeranian dog breed. Schirmer tear test (STT), tear breakup time test (TBUTT), Jones test (JT), aesthesiometry, biomicroscopy, tonometry, non-contact specular microscopy (SM), ophthalmoscopy and ultrasonography (US) were carried out 48 eyes of 24 male and female Pomeranian dogs from a breeding kennel. Descriptive statistics was applied for data analysis. Means and standard errors found for STT, TBUT, JT, esthesiometry and tonometry were 24.310±0.448mm/min, 14.570±0.406s., 8.420±1.571min, 3.667±0.157cm and 17.960±0.697mmHg, respectively. For biomicroscopy, 43.75% of the eyes presented caruncle trichiasis, 25% chromodacryorrhea, 25% medial entropion and 10,42% distichiasis. SM showed endothelial cells density of 1958.285±36.760 cells/mm². For hexagonality, endothelial cells area and central corneal thickness were 62.229±2.183%, 519.231±9.853mm², 0.567±0.006mm, respectively. Ophthalmoscopy presented a pattern described in other breeds. Amelanotic fundus was reported in 8.33% of the eyes. The US means and standard errors for axial length of the eyeball, lens thickness, anterior and vitreous chamber depth were 16.859±0.148mm, 6.651±0.081mm, 2.673±0.091mm and 7.485±0.101mm. Mild changes in the lacrimal evaluation parameters were influenced by eyelid changes in STT type I. Increased corneal sensitivity was observed in the breed.

Our results show that KCS promotes chromatin remodeling in epithelial cells and lymphocytes on the conjunctival surface of dogs. The changes described in this study are different from those reported for conjunctival cell nuclei of human KCS patients.

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