In vivo functional assessment of a novel degradable metal and elastomeric scaffold-based tissue engineered heart valve

Abstract

Objective: Ideal heart valve solutions aim to provide thrombosis-free durability. A scaffold-based polycarbonate urethane urea tissue-engineered heart valve designed to mimic native valve microstructure and function was used. This study examined the acute in vivo function of a stented tissue-engineered heart valve in a porcine model. Methods: Trileaflet valves were fabricated by electrospinning polycarbonate urethane urea using double component fiber deposition. The tissue-engineered heart valve was mounted on an AZ31 magnesium alloy biodegradable stent frame. Five 80-kg Yorkshire pigs underwent open tissue-engineered heart valve implantation on cardiopulmonary bypass in the pulmonary position. Tissue-engineered heart valve function was echocardiographically evaluated immediately postimplant and at planned study end points at 1, 4, 8, and 12 hours. Explanted valves underwent biaxial mechanical testing and scanning electron microscopy for ultrastructural analysis and thrombosis detection.Results: All 5 animals underwent successful valve implantation. All were weaned from cardiopulmonary bypass, closed, and recovered until harvest study end point except 1 animal that was found to have congenital tricuspid valve dysplasia and that was euthanized postimplant. All 5 cases revealed postcardiopulmonary bypass normal leaflet function, no regurgitation, and an average peak velocity of 2 m/s, unchanged at end point. All tissue-engineered heart valve leaflets retained microstructural architecture with no platelet activation or thrombosis by scanning electron microscopy. There was microscopic evidence of fibrin deposition on 2 of 5 stent frames, not on the tissueengineered heart valve. Biaxial stress examination revealed retained postimplant mechanics of tissue-engineered heart valve fibers without functional or ultrastructural degradation.Conclusions: A biodegradable elastomeric heart valve scaffold for in situ tissueengineered leaflet replacement is acutely functional and devoid of leaflet microthrombosis.

In Vitro and In Vivo Testing of Zinc as a Biodegradable Material for Stents Fabricated by Photo-Chemical Etching

“…Our patented alternative is based on photo-chemical etching to transfer a pattern of the stent struts onto a Mg sheet [13]. This type of Mg stent has been characterized in vitro and the results are published elsewhere [14][15][16][17][18][19]. In this study, we demonstrate that photo-chemical etching can be used to create stent materials out of pure Zn and that these materials are well tolerated by tissues in an initial in vivo study.…”

“…The work described here first examines the suitability of using photo-chemical etching to create Zn cardiovascular stent structures, using pure Zn, and then examines initial in vivo tissue compatibility studies of this Zn material. This investigation also compares the in vitro corrosion rate of uncoated Zn stents with that of stents coated with Parylene C. Among the many potential polymeric coatings [16,19], a chlorinated Parylene, known as Parylene C, was selected as a good candidate for improving metallic implant interactions with blood [26] and we further hypothesized that it would slow the corrosion rate of Zn, which is desired in some applications, as discussed above. It was reported by Fontaine et al [27], that Parylene C coated stents showed very low platelet attachment when compared to uncoated tantalum stents, thus hindering thrombogenicity.…”

Effect of Surface-Modification on In Vitro Corrosion of Biodegradable Magnesium-Based Helical Stent Fabricated by Photo-chemical Etching

“…In vitro and ex vivo corrosion behaviors of magnesium stents made of the AZ31 alloy by photo-chemical etching, have been reported by our group [19][20][21] . Other studies that have tested magnesium alloys as bone implants, such as screws, plates, or other orthopedic fixture devices, have reported that magnesium-based implants showed good biocompatibility, with no change in cancellous tissues and no inflammation [22][23][24] .…”

“…Details about stent fabrication using photochemical etching of biodegradable metal sheets have been published by our group [16][17][18][19][20]25 . The starting material was a rectangular sheet of AZ31 with dimensions of 250 mm × 250 mm and thickness of 250 μm, purchased from Goodfellow, USA (Oakdale, PA).…”

Biodegradable synthetic polymeric composite scaffold‐based tissue engineered heart valve with minimally invasive transcatheter implantation

“…Then they replaced the pulmonary valve of five pigs with TEHV by heart valve implantation. After 12 hours, all the valves showed normal valvular function without any reflux, and had an average peak velocity of 2 m/s 38,42 . Subsequently, they implanted biomimetic stentless tricuspid valves fabricated with poly(carbonate urethane) urea (PCUU) into five swine.…”