Stem Cell Laboratory, Prof. Brien Holden Eye Research Center, L V Prasad Eye Institute, Hyderabad, Telangana, India; Center for Ocular Regeneration (CORE), LV Prasad Eye Institute, Hyderabad, Telangana, India.
Stem Cell Laboratory, Prof. Brien Holden Eye Research Center, L V Prasad Eye Institute, Hyderabad, Telangana, India; School of Life Sciences, University of Hyderabad, Hyderabad, Telangana, India; Center for Ocular Regeneration (CORE), LV Prasad Eye Institute, Hyderabad, Telangana, India.
Exp Eye Res. 2021 Apr;205:108526. doi: 10.1016/j.exer.2021.108526. Epub 2021 Mar 2.
Limbal Stem Cell Deficiency (LSCD), caused due to corneal injury, primarily by chemical/alkali burns, leads to compromised vision. Recently, several animal models of corneal alkali burn injury have become available. The majority of the studies with these animal models start interventions soon after the injury. However, in the clinical setting, there is a considerable delay before the intervention is initiated. Detailed knowledge of the molecular, histopathological, and clinical parameters associated with the progression of the injury leading to LSCD is highly desirable. In this context, we set out to investigate clinical, histopathological parameters of ocular surface alkali burn over a long period of time, post-injury. Limbal stem cell-deficient animal models of rabbits were created by alkali burn using sodium hydroxide, which was then assessed for their progression towards LSCD by grading the alkali burn, corneal haze, and vascularization. Additionally, cells present on the corneal surface after the burn was investigated by histology and immunophenotyping. Grading of rabbit eyes post-alkali burn had shown complete conjunctivalization in 80% (n = 12/15) of the rabbits with the alkali burn grade score of 3.88 ± 0.29 in three months and remained stable at four months (4.12 ± 0.24). However, ocular surface showed self-healing in 20% (n = 3/15) of the rabbits with a score of 1.67 ± 0.34 in four months irrespective of similar alkali injury. These self-healing corneas exhibited decreased opacity score from 2.51 ± 0.39 to 0.66 ± 0.22 (p = 0.002) and regressed vascularity from 1.66 ± 0.41 to 0.66 ± 0.33 in one to nine months, respectively. Restoration of the corneal phenotype (CK3+) was observed in central and mid-peripheral regions of the self-healing corneas, and histology revealed the localization of inflammatory cells to the peripheral cornea when compared to conjunctivalized and scarred LSCD eyes. Our study shows the essentiality to consider the time required for surgical intervention after the corneal alkali injury in rabbit models as evident from their tendency to self-heal and restore corneal phenotype without therapy. Such information on the possibility of self-healing should be useful in further studies as well as determining interventional timings and strategy during clinical presentation of corneal alkali burns.
角膜缘干细胞缺乏症（LSCD）由角膜损伤引起，主要由化学/碱性烧伤引起，导致视力受损。最近，出现了几种角膜碱烧伤动物模型。这些动物模型的大多数研究都在受伤后不久就开始进行干预。然而，在临床环境中，在开始干预之前会有相当长的延迟。非常需要详细了解与 LSCD 相关的损伤进展的分子、组织病理学和临床参数。在这种情况下，我们着手研究碱烧伤后很长一段时间内眼表碱烧伤的临床和组织病理学参数。我们使用氢氧化钠创建了兔的角膜缘干细胞缺陷动物模型，然后通过碱烧伤分级、角膜混浊和血管化来评估它们向 LSCD 的进展。此外，还通过组织学和免疫表型分析研究了烧伤后角膜表面的细胞。碱烧伤后兔眼分级显示，80%（n=12/15）的兔结膜完全化，碱烧伤等级评分为 3.88±0.29，三个月后稳定在四个月（4.12±0.24）。然而，20%（n=3/15）的兔眼出现自我愈合，四个月时评分 1.67±0.34，尽管有类似的碱损伤，但与结膜化和瘢痕化 LSCD 眼相比，其评分有所降低。这些自我愈合的角膜混浊评分从 2.51±0.39 降低到 0.66±0.22（p=0.002），血管化程度从 1.66±0.41 降低到 0.66±0.33，分别在 1 到 9 个月内。自我愈合角膜的中央和中周区域观察到角膜表型（CK3+）的恢复，与结膜化和瘢痕化 LSCD 眼相比，组织学显示炎症细胞定位于周边角膜。我们的研究表明，在兔模型中，从角膜碱损伤后进行手术干预所需的时间必须考虑在内，因为它们有自我愈合和恢复角膜表型的趋势，而无需治疗。这种关于自我愈合可能性的信息对于进一步的研究以及在角膜碱烧伤的临床表现中确定干预时机和策略都将非常有用。
