Inhibition of hemangiogenesis and lymphangiogenesis after normal-risk corneal transplantation by neutralizing VEGF promotes graft survival.
OBJECTIVE
To evaluate the occurrence and time course of hem- and lymphangiogenesis after normal-risk corneal transplantation in the mouse model and to test whether pharmacologic strategies inhibiting both processes improve long-term graft survival.


METHODS
Normal-risk allogeneic (C57BL/6 to BALB/c) and syngeneic (BALB/c to BALB/c) corneal transplantations were performed and occurrence and time course of hem- and lymphangiogenesis after keratoplasty was observed, by using double immunofluorescence of corneal flatmounts (with CD31 as a panendothelial and LYVE-1 as a lymphatic vascular endothelium-specific marker). A molecular trap designed to eliminate VEGF-A (VEGF Trap(R1R2); 12.5 mg/kg) was tested for its ability to inhibit both processes after keratoplasty and to promote long-term graft survival (intraperitoneal injections on the day of surgery and 3, 7, and 14 days later).


RESULTS
No blood or lymph vessels were detectable immediately after normal-risk transplantation in either donor or host cornea, but hem- and lymphangiogenesis were clearly visible at day 3 after transplantation. Both vessel types reached donor tissue at 1 week after allografting and similarly after syngeneic grafting. Early postoperative trapping of VEGF-A significantly reduced both hem- and lymphangiogenesis and significantly improved long-term graft survival (78% vs. 40%; P < 0.05).


CONCLUSIONS
There is concurrent, VEGF-A-dependent hem- and lymphangiogenesis after normal-risk keratoplasty within the preoperatively avascular recipient bed. Inhibition of hem- and lymphangiogenesis (afferent and efferent arm of an immune response) after normal-risk corneal transplantation improves long-term graft survival, establishing early postoperative hem- and lymphangiogenesis as novel risk factors for graft rejection even in low-risk eyes.
Cursiefen
Claus
C
Schepens Eye Research Institute, Department of Ophthalmology, Harvard Medical School, Boston, Massachusetts 02114, USA.
Cao
Jingtai
J
Chen
Lu
L
Liu
Ying
Y
Maruyama
Kazuichi
K
Jackson
David
D
Kruse
Friedrich E
FE
Wiegand
Stanley J
SJ
Dana
M Reza
MR
Streilein
J Wayne
JW
D000818:Animals; D003315:Cornea / Q000378:metabolism; D016510:Corneal Neovascularization / Q000188:drug therapy*; D004305:Dose-Response Relationship, Drug; D019084:Fluorescent Antibody Technique, Indirect; D006023:Glycoproteins / Q000378:metabolism; D006085:Graft Survival / Q000502:physiology*; D015948:Keratoplasty, Penetrating; D042583:Lymphangiogenesis / Q000187:drug effects*; D008297:Male; D026901:Membrane Transport Proteins; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000378:metabolism; D017978:Receptors, Growth Factor; D011993:Recombinant Fusion Proteins / Q000494:pharmacology*; D012307:Risk Factors; D014184:Transplantation, Homologous; D014185:Transplantation, Isogeneic; D042461:Vascular Endothelial Growth Factor A / Q000037:antagonists & inhibitors*
D006023:Glycoproteins; D026901:Membrane Transport Proteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; D017978:Receptors, Growth Factor; D011993:Recombinant Fusion Proteins; D042461:Vascular Endothelial Growth Factor A; C460365:VEGF Trap R1R2 protein; C492273:LYVE1 protein, mouse