Measurement of von Willebrand factor-specific mRNA and release and storage of von Willebrand factor from endothelial cells of dogs with type-I von Willebrand's disease.

OBJECTIVE

To characterize the cellular basis of the plasma von Willebrand factor (vWf) deficiency in Doberman Pinschers with type-1 von Willebrand's disease (vWd).

ANIMALS

Five Doberman Pinschers with type-I vWd and 5 clinically normal dogs used as controls.

PROCEDURE

Vascular endothelial cell cultures were used to measure constitutive vWf release, thrombin-stimulated vWf release, baseline intracellular vWf concentration, and vWf mRNA expression.

RESULTS

Cells cultured from vWd-affected dogs were morphologically indistinguishable from cells cultured from control dogs, but had reductions in constitutive vWf release (6.5-fold) and vWf mRNA content (fivefold) that correlated to the reduction in plasma vWf concentration (sixfold) in these dogs. The 9.0-kb, canine vWf message was identified, using a polymerase chain reaction-amplified segment of the canine vWf gene and was similar in size to the human vWf message. The vWd cells also had reductions in baseline intracellular vWf concentration (15.6-fold) and thrombin-stimulated vWf release (14.5-fold). Additionally, it was observed that normal canine endothelial cells from different anatomic locations were heterogeneous with respect to vWf expression.

CONCLUSIONS

These findings suggest that the plasma vWf deficit in dogs with type-I vWd results from decreased endothelial cell production of vWf resulting from either decreased transcription of the vWf gene or abnormalities in mRNA processing/stability. This is similar to findings in human beings with type-I vWd.