Surfactant incorporation markedly alters mechanical properties of a fibrin clot.

Intra-alveolar clot formation is a common finding in acute and chronic inflammatory lung diseases. Incorporation of lipophilic surfactant components into a growing fibrin clot has recently been reported (Am. J. Respir. Cell Mol. Biol. 1993; 9:213-220). In the present study, we investigated the influence of such surfactant incorporation on the elastic properties and water permeability of the fibrin polymer. Thrombelastography and compaction experiments were employed for assessment of the elastic properties, and the permeability characteristics of the clot material were addressed in fibrin-packed columns. Two calf lung surfactant extracts (CLSE and Alveofact), Curosurf, and a synthetic phospholipid mixture (dipalmitoylphosphatidylcholine, phosphatidylglycerol, and palmitic acid at a ratio of 68.5:22.5:9 [wt/wt]) were used. The presence of surfactant did not affect the cleavage of fibrinopeptide A upon incubation of fibrinogen with thrombin (enzyme-linked immunosorbent assay technique). Similarly, kinetics and extent of factor XIII-induced covalent crosslinkage of the fibrin network remained unchanged in the presence of surfactant (sodium dodecyl sulfate polyacrylamide gel electrophoresis and D-Dimer quantification upon subsequent clot lysis). All surfactants, however, dose-dependently decreased the elastic modulus of the arising fibrin polymer. The maximal amplitude in thrombelastography was reduced, and the recovery of fluid after centrifugation of the fibrin clot increased. Fibrin clots embedding natural surfactant material displayed reduced permeability for saline as compared with control fibrin polymers. Subsequent washout of lipids from these clots with Triton X-100 resulted in increased hydraulic conductivity. This was accompanied by an increase in pore size, suggesting altered architecture of the fibrin matrix generated in the presence of surfactant.(ABSTRACT TRUNCATED AT 250 WORDS)