Fibrinogen αC-subregions critically contribute blood clot fibre growth, mechanical stability and resistance to fibrinolysis

Fibrinogen is essential for blood coagulation. The C-terminus of the fibrinogen -chain (C-region) is composed of an C-domain and C-connector. Two recombinant fibrinogen variants (390 and 220) were produced to investigate the role of subregions in modulating clot stability and resistance to lysis. The 390 variant, truncated before the C-domain, produced clots with a denser structure and thinner fibres. In contrast, the 220 variant, truncated at the start of the C-connector, produced clots that were porous with short stunted fibres and visible fibre ends. These clots were mechanically weak and susceptible to lysis. Our data demonstrate differential effects for the C-subregions in fibrin polymerisation, clot mechanical strength, and fibrinolytic susceptibility. Furthermore, we demonstrate that the C-subregions are key for promoting longitudinal fibre growth. Together, these findings highlight critical functions of the C-subregions in relation to clot structure and stability, with future implications for development of novel therapeutics for thrombosis.