Fabrication of micropored elastomeric film‐covered stents and acute‐phase performances

Abstract

To prevent thrombus formation in the acute phase and restenosis in the subacute to chronic phase after stenting of atherosclerotic arteries, we developed a covered stent with a micropored elastomeric film, the blood-contacting surface of which was coated with a photocured gelatin layer immobilized with heparin. Segmented polyurethane (SPU) film (30 microm in wall thickness) as a cover material was multiply micropored by excimer laser-directed microprocessing (pore diameter, 30 microm; interpore distance, 125 microm). An aqueous mixed solution of benzophenone-derivatized gelatin and heparin was coated on the micropored SPU film. Upon ultraviolet light irradiation, a thin layer of a gelatin gel immobilized with heparin was formed and simultaneously fixed on the SPU film. The fully covered stents were assembled by wrapping a balloon-expandable stent with gelatin/heparin gel-layered SPU film and subsequently suturing and then gluing. To assess the validity of this covered stent in vivo, "half-covered" stents, in which half at the distal side was covered with the gel-layered SPU film, was implanted in rabbit common carotid arteries (about 3 mm in diameter). After 3 months of implantation, all the half-covered stents (n = 7) were patent. Regardless of the covered or noncovered region of the stents, the entire luminal surface of the stents was fully endothelialized and a thin neointimal tissue was formed. The potential advantages of a covered stent as designed above are discussed.

Development of a polymeric matrix metalloproteinase inhibitor as a bioactive stent coating material for prevention of restenosis

“…This raises questions on how PMMPI interacts with MMPs at the liquid-solid interface or whether the MMPI binding to the zinc ion located at the active site of the MMP is a reversible reaction or not. Irrespective of these processes, however, the present results support the reasonable application of PMMPI as a coating for metal stents and polymer-covered stents 32,33 to prevent restenosis after stent implantation. An additional advantage is the extremely low drug concentrations in blood and high local concentration at the treatment site provided by this polymer, which is a potentially significant prerequisite for DES.…”

Development of self‐expandable covered stents

“…Second, the cover film was micropored using a KrF excimer laser apparatus (L4500, Hamamatsu Photonics, Shizuoka, Japan). [22][23][24][25] The pore diameter and the interpore distance were fixed at 100 and 250 mm, respectively. Finally, the luminal and outer surfaces of the microporous covered stents were coated with argatroban (500 mg/cm 2 ) and FK506 (140 mg/cm 2 ), respectively.…”

Layer-by-layer biofabrication of coronary covered stents with clickable elastin-like recombinamers

“…Unfortunately, the synthetic materials originally used for covering small-caliber stents (Table 1) display limited hemocompatibility, and their use has resulted in restenosis, thrombotic [8,9] and inflammatory events [10,11]. Table 1: Materials employed for the fabrication of covered coronary stents and clinical outcomes.…”