BIORESORBABLE, HEPARINIZED POLYMERS FOR STENT COATING - IN-VITRO STUDIES ON HEPARINIZATION EFFICIENCY, MAINTENANCE OF ANTICOAGULANT PROPERTIES AND IMPROVEMENT OF STENT HEMOCOMPATIBILITY
B. Seifert et al., BIORESORBABLE, HEPARINIZED POLYMERS FOR STENT COATING - IN-VITRO STUDIES ON HEPARINIZATION EFFICIENCY, MAINTENANCE OF ANTICOAGULANT PROPERTIES AND IMPROVEMENT OF STENT HEMOCOMPATIBILITY, Journal of materials science. Materials in medicine, 7(8), 1996, pp. 465-469
Biodegradable poly-(D,L-lactide) RESOMER(R) R208 and poly(D,L-lactide-
co-glycolide) RESOMER(R) RG756 were heparinized to improve the blood c
ontacting properties of the materials. The immobilization of heparin w
as performed with glutaraldehyde as coupling agent. The efficacy of th
e surface modification was monitored with respect to the total amount
of bound heparin measured by a toluidine blue assay, the anticoagulant
potential estimated by a factor Xa assay, and the activation of plate
lets estimated by a GMP140 assay. It was found that a reaction at ambi
ent temperature for 2 h resulted in optimal heparin binding, with high
anticoagulant activity and low thrombogenicity. The storage of hepari
nized polylactide in saline solutions up to 8 days demonstrated the re
lease of small quantities of heparin into the fluid. A further finding
was that with prolonged storage the anticoagulant potential was impro
ved, whereas the thrombogenicity decreased. Comparison of platelet act
ivation on RESOMER(R) R208 as unmodified and heparinized material with
polypropylene and Pellethane(R) revealed that heparinization of R208
substantially improved the haemocompatibility. Coating and subsequent
heparinization of intravascular stents were carried out with RESOMER(R
) RG756 because of its more appropriate mechanical properties. in vitr
o studies with blood under flow conditions demonstrated that platelet
activation on Palmaz(TM) stents was considerably diminished after poly
mer coating and heparinization.