Induction of angiogenic responses by joint homogenates from mice with collagen-induced arthritis (CIA). A) Arthritic joint homogenates significantly induced the migration of endothelial cells (HMEC-1) in vitro. Representative photographs of migrated HMEC-1 in response to different stimuli (original magnification × 200). B) Graph illustrates HMEC-1 migration in response to paw homogenates (100 µg protein/ml) of healthy (n = 5) or arthritic (n = 15) mice in comparison to 20 ng/ml recombinant human VEGF (hVEGF) (n = 6). The migration index was calculated by dividing the number of migrated cells in the presence of stimuli by the number of migrated cells in the presence of PBS (set as 1, dashed line). Results were expressed as mean ± SEM and analysed by unpaired t-test (**P < 0.01). C) Homogenates of arthritic paws induce angiogenesis in vivo. Representative images of Matrigel plugs comparing healthy (1, 3) with arthritic (2, 4) paw homogenate-containing plugs. Graph demonstrates the haemoglobin content of isolated Matrigel plugs. Recombinant murine fibroblast growth factor (FGF)-2 (mFGF-2, 30 ng/ml) was used as a positive control. Data expressed as mean ± SEM (healthy, n = 6; arthritic,n = 6; FGF-2, n = 3) and analysed by unpaired t-test: *P < 0.05.
Raatz et al. Arthritis Research & Therapy 2012 14:R169 doi:10.1186/ar3922