Summary
Cultured porcine aortic endothelial cells (PAEC) constitutively produce and secrete
in their culture medium mitogens collectively called endothelial cell-derived growth
factors (EDGFs). Incubation of PAEC with fibrinogen-degradation products (FDPs) obtained
by plasmin digestion of highly purified fibrinogen caused an increased release of
EDGFs, as assessed by [3H]-thymidine incorporation in 3T3 mouse fibroblasts. The effect was time-dependent
and correlated with the degree of fibrinogenolysis. It was accompanied by elongation
of the cells. Neither increase in EDGFs release nor cell damage was observed when
non-degraded fibrinogen was incubated with endothelial cells. Low molecular weight
fibrinogen degradation products (LMWFDPs) (M
r ≤ 10,000), and the higher molecular weight fibrinogen fragments D and E were tested
under the same conditions. Only the LMWFDPs caused elongation and damage to PAEC and
a marked stimulation (up to 12 fold) of EDGFs release. A low density growth assay
revealed that the released EDGFs were mitogenically active on the same PAEC. The activity
of the released EDGFs was time and dose dependent on both 3T3 fibroblasts and PAEC,
indicating that LMWFDPs caused enhanced release of EDGFs that can act in paracrine
and autocrine fashion. This study suggests an additional role for fibrinogenolysis
contributing to wound healing, and possibly to atherosclerosis.