Absence of scar formation in human donor cornea with prior laser in situ keratomileusis.
OBJECTIVE
To investigate transglutaminases (enzymes capable of cross-linking extracellular matrix proteins to proteolysis-resistant complexes during scar tissue formation) in a human donor cornea after successful laser in situ keratomileusis (LASIK) without clinical complications and to compare with the results in a human donor cornea with corneal scarring after corneal injury.


METHODS
Department of Ophthalmology, Ludwig-Maximilians University, Munich, Germany.


METHODS
A donor cornea with prior uneventful LASIK treatment and 1 with corneal scarring after penetrating injury were investigated. Cryostat sections were stained immunohistochemically for tissue transglutaminase (tTG), keratocyte transglutaminase (kTG), and their reaction product epsilon-(gamma-glutamyl)-lysine.


RESULTS
With light microscopy, the flap interface of the LASIK-treated eye could hardly be detected, while in the injured eye, infiltration of cells and a clear margin next to the scar formation were present. Immunohistochemistry demonstrated a distinct staining for tTG, kTG, and epsilon-(gamma-glutamyl)-lysine in the corneal scar. In contrast, neither transglutaminase nor epsilon-(gamma-glutamyl)-lysine staining could be observed at the flap margin or in the interface of the LASIK-treated donor eye.


CONCLUSIONS
Irreversible protein cross-linking of transglutaminases via epsilon-(gamma-glutamyl)-lysine connections seem to be indicators for scarring in corneal wound healing. The absence of transglutaminases and their reaction product epsilon-(gamma-glutamyl)-lysine in a LASIK-treated cornea supports the idea of missing scar tissue formation after LASIK surgery.
Priglinger
Siegfried G
SG
Department of Ophthalmology, Ludwig Maximilians University, Munich, Germany.
May
Christian-Albrecht
CA
Alge
Claudia S
CS
Wolf
Armin
A
Neubauer
Aljoscha S
AS
Kampik
Anselm
A
Welge-Luessen
Ulrich
U
D000328:Adult; D002921:Cicatrix / Q000378:metabolism*; D003315:Cornea / Q000378:metabolism*; D065306:Corneal Injuries; D004151:Dipeptides / Q000378:metabolism*; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D015807:Eye Injuries, Penetrating / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D015948:Keratoplasty, Penetrating; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D014019:Tissue Donors; D011503:Transglutaminases / Q000378:metabolism*; D014945:Wound Healing / Q000502:physiology*
D004151:Dipeptides; D016326:Extracellular Matrix Proteins; C001299:epsilon-(gamma-glutamyl)-lysine; D000091345:Protein Glutamine gamma Glutamyltransferase 2; D011503:Transglutaminases; D019204:GTP-Binding Proteins