Monocyte Activation in Angiogenesis and Collateral Growth in the Rabbit Hindlimb

We have previously shown that monocytes adhere to the vascular wall during collateral vessel growth (arteriogene-sis) and capillary sprouting (angiogenesis). In this study we investigated the association of monocyte accumulation with both the production of the cytokines—basic fibroblast growth factor (bFGF) and TNF-a —and vessel proliferation in the rabbit after femoral artery occlusion. In particular, we studied the effects of an increase in monocyte recruit-ment by LPS on capillary density as well as collateral and peripheral conductance after 7 d of occlusion. Monocytes accumulated around day 3 in collateral arteries when maxi-mal proliferation was observed, and stained strongly for bFGF and TNF-a. In the lower limb where angiogenesis was shown to be predominant, macrophage accumulation was also closely associated with maximal proliferation (around day 7). LPS treatment significantly increased capil-lary density (424