QUANTIFICATION OF TISSUE FIBRONECTIN FROM TERMINAL VILLI OF PLACENTA

Tissue fibronectin (TFn) was solubilized from the terminal villi of perfused human placentas by sequential chemical extractions and plasmin digestion. Alternatively, plasmin digestion of intact tissue solubilized all the TFn, which amounted to 1.8-2.9% of the dry weight of the villi. Concomitantly, 69% of the tissue was solubilized. The non-equilibrium competitive ELISA (enzyme-linked immunosorbent assay), in which the TFn was immunologically identical with plasma fibronectin (PFn), was used for the quantification of TFn. The bulk of TFn can be obtained in a form that can be quantified by ELISA and TFn is immunologically identical with PFn. Thus the fibronectin molecule is not significantly altered as it is incorporated into the connective-tissue matrix and could exchange with PFn.