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Patricia Gallego-Muñoz, Elvira Lorenzo-Martín, Cristina Herrero-Pérez, M. Carmen Martínez-García; Nidogen-2: location and mRNA expression during corneal wound healing.. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4347.
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© ARVO (1962-2015); The Authors (2016-present)
One of the main problems during corneal healing is the persistence of ulcers and, as a result, loss of transparency. Nidogen-2 (Nid2) is one component of the corneal epithelial basal membrane (BM) which is synthesized by epithelial and stromal cells. The aim of this study was to ascertain whether there are changes in Nid2 location and mRNA expression during the different stages of corneal healing.
Left eyes of 30 New Zealand rabbits were burned for 60 seconds with an 8-mm filter paper soaked in 0.5N NaOH (right eyes were used as a control group). Fifteen corneas were removed at different time points (7, 15 and 30 days) after injury. Nid2 location was assayed by immunohistochemical staining (Nid2 positive cells, Nid2+). The other 15 corneas were excised in wound (W) and periphery (P) and, Nid2 mRNA expression levels were determined by RT-PCR.
In control corneas, Nid2+ cells were located in all epithelial layers and, mainly, in the anterior and posterior stroma. Seven days after injury, in the W, Nid2+ epithelial cells were located only in the basal layer and the small number of stromal cells were mainly Nid2+. In the P, all the epithelial cells were Nid2+, and a high number of Nid2+ cells were observed in the stroma. At day 15, in the W, Nid2+ epithelial cell location was similar to day 7, although in the P, Nid2+ cells were located only in the external layers. Stromal repopulation was mainly performed with Nid2+ cells located everywhere in the W, although their number decreased in the P. Finally, one month later, the vast majority of the epithelial basal cells in W were Nid2-, and had detached from the stroma. In contrast, in P, Nid2+ epithelial cells were located in more basal layers. The number of Nid2+ stromal cells in the W was similar to day 15 whereas the number was seen to have increased in the P.These data concur with those obtained in the Nid2 mRNA expression levels. In the W, its levels increased steadily over time. In contrast, in the P, they were higher at day 7 but had decreased by day 15 before increasing again by day 30.
During corneal healing there are changes in Nid2 location and mRNA expression. The different cellular types implicated in this process synthesize and secrete Nid2. When Nid2 is absent in the epithelial basal layer, defects in re-epithelization occur, and its stromal contribution is not enough to restore the BM, which might then lead to loss of transparency.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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