Differential inhibition of capillary tube formation by factor XIIIa in γA/γA and γA/γ′ fibrin.

A 3-dimensional fibrin-based capillary tube formation assay was performed using either γA/γA fibrin (A, C, E, G, and I) or γA/γ′ fibrin (B, D, F, H, and J). Nuclei were stained with bis-benzimide after 2 days and photographed. HMEC-1 cells in γA/γA (A) and γA/γ′ (B) fibrin without factor XIIIa showed numerous capillary-like sprouts. The addition of 10 μg/mL factor XIIIa (C, D), 25 μg/mL (E, F), 50 μg/mL (G, H), and 100 μg/mL (I, J) inhibited sprouting significantly in γA/γA fibrin (C, E, G, I), but only partially in γA/γ′ fibrin (D, F, H, J). Bar, 100 μm.