Hemocompatibility of polymers for use in vascular endoluminal implants

Implanted polymers for cardiovascular applications may function as structural supports, barriers, or provide a means for local drug delivery. Several thermoplastic biodegradable drug delivery polymers are potential candidates for blood-contacting implant applications. For intravascular applications specifically, a criterion for material selection is the intrinsic hemocompatibility of the baseline polymer. As an initial screening approach for selection of polymers for in vivo use, thin films of polyesters: poly(e-caprolactone) (PCL), poly(lactic acid) (PLA), poly(lactic-co-glycolic acid) (PLGA); polyanhydrides: poly(fatty acid dimer-co-sebacic acid) (PFAD:SA) and poly(biscarboxyphenoxypropane-co-sebacic acid) (PCPP:SA); and poly(ethylene glycol) (PEG)-ylated polyesters: PLA:PEG, PCL:PEG and PCL:PLA:PEG polymers were spin-cast on glass cover slips and placed in an in vitro flow system exposing them at a controlled shear to overflowing human whole blood. Platelet adherence, aggregate formation, and thrombus formation, as well as leukocyte adherence were assessed following 5 min of flow. At 5 min of flow the rank order of materials, in terms of least to most thrombogenic was: PCL < PFAD:SA < PCPP:SA < PLGA < PLA. All PEGylated materials, in general, had less thrombus formation than baseline unmodified materials.

Automated summary

Implanted polymers for cardiovascular applications serve as structural supports, barriers, or means for drug delivery. In vitro studies show that PEGylated materials have less thrombus formation and are preferred for implantation.