Human vs. dog platelet adhesion to Cuprophane under controlled conditions of whole blood flow

It is commonly assumed that a candidate biomaterial to which nonhuman (especially dog) platelets do not readily adhere is promising for human use. This assumption has been tested in a lucite chamber in which Cuprophane membrane (Bemberg PT-150), comprising one of the chamber surfaces, is exposed to citrated or heparinized flowing dog or human blood for 10 or 20 minutes and flowing buffer for 1 minute. Following exposure, membrane specimens are carefully removed, fixed in glutaraldehyde, and mounted on a slide. Platelets at a particular axial location are counted by phase-contrast microscopy (625 X). At a shear rate of 986 sec.-1 and at 10 minutes, platelets per square millimeter (mean +/- S.E.(N) in citrate were 28,400 +/- 5,000 (6), dog; 18 +/- 3.8 (4), human. Under the same conditions, platelets per squar millimeter in heparin were 32,600 +/- 8,400 (4), dog; 7.6 +/- 1.0 (3), human. A qualitatively similar species difference was found in citrate at one shear rate and at one other exposure time. Those observations suggest that evaluations of candidate human biomaterials carried out with dog (and perhaps other nonhuman) blood must be interpreted with caution.