The pathogenesis of venous leg ulcers is still not known. One hypothesis states that pericapillary fibrin cuffs might play an important role. These fibrin cuffs might not be broken down because of an inadequate fibrinolytic activity.
To stimulate fibrinolysis, tissue type plasminogen activator (t-PA) containing ointment was applied over 12 weeks on chronic venous leg ulcers of six patients. Three of the six ulcers healed within this period. Biopsy specimens for immunofluorescence studies were taken from the ulcer base and margin before and at the end of treatment and, if the ulcer had healed, from the healed area.
Deposition of pericapillary fibrin was seen around the capillaries of all investigated ulcers at the start of the study. Pericapillary fibrin was still present with nearly undiminished intensity at the end of the study even though 3 of the ulcers healed.
It is most likely that the healing of these ulcers was not improved by the fibrinolytic activity of t-PA, but caused by other wound healing properties of t-PA.