Summary
Tissue factor (TF) is the primary initiator of the coagulation cascade and is thought
to play a key role in the generation of arterial thrombosis. Recent studies have suggested
that TF mediates inflammatory processes in the arterial wall and may be an important
regulator of intimal hyperplasia. We have employed genetically engineered mice (mTF−/−/hTF+) with markedly diminished TF activity (≈1% normal levels) to examine the role of
TF in mediating the response to arterial injury. mTF−/−/hTF+ displayed a marked reduction in intimal hyperplasia (46% decrease in intimal area,
60% decrease in intimal/medial ratio) in response to femoral artery injury when compared
to wild type controls. The decreased intimal hyperplasia seen in low TF mice was noted
in a model of vascular injury not associated with significant thrombosis, suggesting
that it may be mediated by non-procoagulant properties of TF. Smooth muscle cells
from mTF−/−/hTF+ mice grew normally in response to serum, but exhibited a marked defect in cell migration
in a modified Boyden chamber assay. In contrast, there was no difference in platelet
derived growth factorinduced migration, suggesting that the effect of TF on smooth
muscle cell migration is agonist dependent. These data suggest that TF may mediate
intimal hyperplasia by regulating smooth muscle cell migration.
Keywords
Vascular smooth muscle - cell migration - arterial injury - genetically altered mice
- tissue factor