In vitro and in vivo studies of heparinized‐collageno‐elastic tubes

Abstract

Heparin was covalently coupled to collageno-elastic grafts (CET) derived from lamb carotid arteries, by using the crosslinking agent 1-ethyl-3 (3-dimethyl-aminopropyl) carbodiimide (EDC). The collagenous grafts were pretreated with various aminating agents in order to enhance the number of available binding sites on the collagen surface. By varying the EDC/heparin weight ratio, the pH of the immobilization media, and the pretreatment agent, a global search pattern maximized heparin loading at 3.90 +/- 0.36 USP heparin/cm2 collagenous graft surface when the EDC/heparin ratio was 2:1 at a pH of 1.5 with 1 M hydroxylamine sulfate as the pretreatment agent. Heparinized CETs were superior to nonheparinized CETs by exhibiting both enhanced antiplatelet activity in using an in vitro differential recirculation reactor with chromium-51 tagged platelets and enhanced patency when interposed in canine carotid arteries. Both antiplatelet activity and patency duration for heparinized CETs were independent of heparin loading.

Thromboresistant and endothelialization effects of dopamine-mediated heparin coating on a stent material surface

“…Heparin is a selective inhibitor of blood coagulation. Furthermore, immobilization of heparin reportedly decreases in vitro and in vivo platelet adhesion and aggregation [38][39][40][41][42]. Platelet adhesion represents the main indicator to Fig.…”

Blood compatibility of surfaces with immobilized albumin-heparin conjugate and effect of endothelial cell seeding on platelet adhesion

“…39,40 Increased in vitro platelet binding to heparinized biomaterial surfaces, as described in this study, as well as decreased binding have been described in the literature. [37][38][39][42][43][44] These controversies may be due to the different effects of heparin on platelet activation induced by various agonists. 41 Heparin inhibits the activation of platelets by thrombin in the presence of plasma (or probably ATIII), whereas it is uneffective or sometimes stimulates activation in the absence of plasma.…”

Bovine Type I Collagen as an Endovascular Stent-Graft Material: Biocompatibility Study in Rabbits

“…Binding heparin to these collagen grafts improves their patency rate (21,22). A tube made of extruded collagen that was glued with gelatin to a Dacron outer tube was bound with heparin and was placed into dogs and pigs for as long as 4 1 ⁄2 years and into humans for as long as 4 years (23).…”

“…Another type of collagen tube for use as a vascular graft can be made by removing the carotid arteries of dogs and other animals, by digesting them with chymotrypsin, and by tanning them with glutaraldehyde to obtain an arterial heterograft that consists mostly of collagen and elastic fibers (21,22). Binding heparin to these collagen grafts improves their patency rate (21,22).…”