Lymphatic vessels identified in failed human corneal transplants
Author Disclosure Block: S. Chan: None. M. Diamond: None. X. Zhou: None. Y. Yucel: None. N. Gupta: Senju, Valeant, Alcon, International Council of Ophthalmology, Pan-American Academy of Ophthalmology, American Academy of Ophthalmology, African Ophthalmology Council, The Glaucoma Foundation, Human Eye Biobank for Research, World Glaucoma Association.
Abstract Body:
Purpose: Failed corneal transplant is the most common indication for full-thickness corneal transplants (1). Abnormal corneal blood vessels contribute to graft failure and understanding the nature of these vessels may help monitor and prevent failing grafts. In mouse models, there are reports of lymphatic vessels in the corneas of failed corneal transplants. Here we systematically investigated the presence of abnormal lymphatic vessels in patients with failed corneal grafts.
Study Design: Experimental pathological study.
Methods: After institutional REB approval, 9 failed corneal transplants with neovascularization were selected from the University of Toronto Ophthalmic Pathology database. Paraffin-embedded sections of 8 μm thickness were stained with hematoxylin and eosin (H & E) and re-examined for the presence of neovascularization. This was followed by immunofluorescence staining to identify lymphatics with antibodies to podoplanin (D2-40, monoclonal mouse, Cedarlane Laboratories (CL3730)) and to identify blood vessels with antibodies to CD31 (polyclonal rabbit, Abcam (ab28364)). Immunofluorescence stained sections were analyzed by confocal scanning laser microscopy for the presence of lymphatics and blood vessels and compared to negative controls obtained by omitting the primary antibody. Additionally, these findings were compared to age-matched normal corneas.
Results: In all 9 cases showing neovascularization of the cornea and blood vessels by H & E, immunostaining for CD31 showed clear positivity for blood vessels distributed in varying stromal layers. Most cases (7/9) showed numerous podoplanin immune-positive profiles, either in the form of a lumen (4) or as elongated-stained profiles (7). This was different from CD31-positive blood vessels most often in the form of lumen.
Conclusions: This is the first study to systematically evaluate lymphatic vessels in failed human corneal grafts with neovascularization. The presence of abnormal lymphatic vessels in these failed corneal grafts suggests a role for lymphatics in the graft rejection process, with implications as a new treatment target for failing grafts. (1) Le R, Yucel N, Khattak S, Yucel YH, Prud’homme GJ, Gupta N. Current indications and surgical approaches to corneal transplants at the University of Toronto: A clinical-pathological study. Can J Ophthalmol 2015:1-6. doi:10.1016/j.jcjo.2016.07.005.
