Platelet deposition on polyethylene. Dependence of second layer platelet attachment on von Willebrand's disease plasma.

The role of von Willebrand's factor (VWF) was examined in platelet deposition on polyethylene by exposing 3/16 inch diameter discs of polyethylene to 111In labeled platelets re-suspended in citrated blood from normal and severe von Willebrand's disease donors. Discs were oscillated for 30 and 60 min, washed, fixed, counted for 111In, and examined by scanning electron microscopy (SEM). Total platelet deposition in the 0% VWF group was significantly greater than control discs at 30 min (7.0 x 10(6) +/- 0.5 compared with 3.29 x 10(6) +/- 0.6 platelets/cm2). The SEM examination revealed patches of spread platelets, with platelets adhering to platelets in controls. A dense, uniform monolayer of platelets was found on the 0% VWF discs. At 60 min, control discs had significant increases in the platelet deposition with SEM examination revealing uniform coverage of the disc with additional platelets.