Effects of simulated bleeding in an in vitro nasal fibroblast wound healing model

We investigated the effect of simulated bleeding on plasminogen activity, matrix metalloproteinase (MMP) expression, and wound healing using a human fibroblast model.

Nasal fibroblasts from three chronic rhinosinusitis (CRS) patients with nasal polyps and three controls were grown in culture and a standardized injury was created using a punch. To mimic bleeding, fibroblasts were stimulated with plasminogen (100 microg/mL), plasminogen + tranexamic acid (TA; 100 microg/mL) or media only. At 24, 48, and 72 hours after injury, we measured urokinase plasminogen activator (uPA) and tissue-type plasminogen activator (tPA) activities and inactive and active MMP-2 and -9 expression.

Injury stimulated the nasal fibroblasts to express uPA and tPA and active and inactive MMP-2 and -9. In CRS patients, plasminogen significantly decreased MMP-9 expression after 48 hours (p < 0.04). In untreated fibroblasts, we observed a decrease in active MMP-9 expression, whereas plasminogen increased active MMP-9 expression after 48 hours (p < 0.04). At 24 hours, active MMP-9 expression was reduced by plasminogen +/- TA (p < 0.02). Plasminogen also stimulated uPA expression in CRS patient fibroblasts after 48 hours (p < 0.04). Fibroblast proliferation occurred when exposed to plasminogen and was strongly modulated by uPA and inactive and active MMP-2. The quality of wound healing was affected by inactive MMP-2, uPA and tPA, simulation, and inhibition of bleeding.

Activation of the plasminogen pathway and inactive MMP-2 expression tended to increase both proliferation of nasal fibroblasts and MMP-9 expression as a marker for deterioration of the quality of wound healing.