Effect of factor XIIIa and tissue TG on the formation of capillary-like tubular structures in fibrin.

Fibrin matrices prepared from normal fibrinogen and fibrinogen_Nieuwegein were cross-linked by the addition of different concentrations of factor XIIIa (A) and tissue TG (B). The hMVEC were seeded on top of the fibrin and stimulated with 5 ng/mL bFGF and 1 ng/mL TNF-α to form invasive capillary-like tubular structures. The total length of capillary-like tubular structures was quantified after 4 days and expressed as percent of control (normal fibrin). Data are mean ± SD of 8 cultures in 4 independent experiments (* represents P < 0.05). NS indicates not significant.