AIM: To evaluate expression of proangiogenic matrix metalloproteinases (MMP) 2 
and 9 at distinct intervals after verteporfin photodynamic therapy (PDT) in 
human choroidal neovascular membranes (CNV) secondary to age-related macular 
degeneration (AMD).
METHODS: Retrospective review of an interventional case series of 49 patients 
who underwent removal of CNV. Twenty-six patients were treated with PDT 3 to 383 
days prior to surgery. Twenty-three CNV without previous treatment were used as 
controls. CNV were stained for CD34, cytokeratin 18, endostatin, MMP-2 and MMP-9 
by immunohistochemistry.
RESULTS: CNV without previous therapy disclosed MMP-2, MMP-9 in RPE-Bruch's 
membrane, vessels and stroma in different intensities. Three days after PDT, 
MMP-9 expression was significantly weaker in stroma (p = 0.0019). Endostatin was 
significantly reduced in vessels (p<0.001). At longer post-PDT intervals, a 
significant increase of MMP-9 in stroma (p = 0.037) and of endostatin in 
RPE-Bruch's membrane (p = 0.02), vessels (p = 0.005) and stroma (p<0.001) were 
disclosed. No significant changes in MMP-2 expression were detected.
CONCLUSIONS: PDT induced an early, temporary decrease in MMP-9 and endostatin 
expression. At longer intervals, MMP-9 increase is possibly associated with the 
angiogenic process responsible for recurrence after PDT. MMP-9, however, acts as 
a double-edged sword by concomitant induction of endostatin, an endogenous 
inhibitor of angiogenesis.