Corneal opacities affect vision for millions of individuals worldwide. Fibrotic scar tissues accumulate in reaction to inflammatory responses and remain permanently in corneal stroma, and conventionally correctable only by donor corneal transplantation. Numerous studies have explored innovative approaches to reverse corneal scarring through non-surgical means; however, existing mouse models limit these studies, due to the lack of visibility of scar tissue in mouse corneas with steep curvature. Here, we reported that corneal scarring was modelled using a transgenic mouse line, Tg(Col3a1-EGFP)DJ124Gsat, in which enhanced green fluorescence protein (EGFP) reporter expression was driven by the promoter of collagen 3a1 (COL3a1), a stromal fibrosis gene. Similar to wildtype, Col3a1-EGFP transgenic corneas developed opacities after wounding by alkali burn and mechanical ablation, respectively, as examined under stereomicroscopy and Spectral Domain optical coherent tomography. The time course induction of EGFP was aligned with Col3a1 upregulation and matched with the elevated expression of other fibrosis genes (α-smooth muscle actin, fibronectin and tenascin C). Measured by flow cytometry and enzyme-linked immunosorbent assay, increased number of EGFP expressing cells and fluorescent intensities were correlated to corneal thickening and scar volume. After treatment with human corneal stromal stem cells or their exosomes, EGFP expression was downregulated together with the reduction of scar volume and fibrosis gene expression. These results have demonstrated that the transgenic mouse line, Tg(Col3a1-EGFP)DJ124Gsat, can be a valuable tool for the detection of corneal fibrosis and scarring in vivo, and will be useful in monitoring the changes of corneal fibrosis over time.

角膜混浊影响全球数百万人的视力。纤维化疤痕组织在炎症反应中积累并永久保留在角膜基质中，并且通常只能通过供体角膜移植来纠正。许多研究探索了通过非手术方式逆转角膜瘢痕形成的创新方法；然而，现有的小鼠模型限制了这些研究，因为在具有陡峭曲率的小鼠角膜中疤痕组织缺乏可见性。在这里，我们报道了使用转基因小鼠系 Tg(Col3a1-EGFP)DJ124Gsat 模拟角膜瘢痕形成，其中增强的绿色荧光蛋白 (EGFP) 报告基因表达由胶原蛋白 3a1 ( COL3a1)，一种间质纤维化基因。与野生型相似，Col3a1-EGFP 转基因角膜在分别被碱烧伤和机械烧蚀伤后出现混浊，在立体显微镜和光谱域光学相干断层扫描下进行检查。EGFP 的时间过程诱导与Col3a1一致上调并与其他纤维化基因（α-平滑肌肌动蛋白、纤连蛋白和生腱蛋白 C）的表达升高相匹配。通过流式细胞术和酶联免疫吸附测定法测量，EGFP 表达细胞数量和荧光强度的增加与角膜增厚和疤痕体积相关。用人角膜基质干细胞或其外泌体处理后，EGFP 表达下调，同时瘢痕体积和纤维化基因表达减少。这些结果表明，转基因小鼠品系 Tg(Col3a1-EGFP)DJ124Gsat 可以成为体内检测角膜纤维化和瘢痕形成的宝贵工具，并将有助于监测角膜纤维化随时间的变化。