Artificial Organ Made in vivo —Valve Leaflet of the Jellyfish Valve—

Abstract

Artificial materials used for artificial organs have sufficient strength and durability. However, their biocompatibility has not been improved yet to the level of tissue-derived biomaterials. On the other hand, there were some problems in artificial organs made of tissue-derived biomaterials; difficulty of forming the desired shapes, insufficiency of strength and durability, and infection control. It is necessary to build arbitrarily-shaped artificial organs that have sufficient strength and durability with tissue-derived biomaterials. In this study, we developed an in-vivo method to make a circle valve leaflet of a jellyfish valve using an insert molding technique. The jellyfish valve is an artificial valve developed at the University of Tokyo, and consists of the valve leaflet and a valve seat. The three types of molds for valve leaflets with different thickness (0.5 mm, 1.0 mm, and 1.2 mm) were made with an acrylic resin. A velour cloth was put inside each mold to ensure strength and durability. Two sets of molds were built; one with only suspended cell and another with both suspended cell and tissue fragments. Three types of molds were implanted under the skin of a goat. The performance and durability of jellyfish valves with tissue-engineered valve leaflets were assessed using a mock circulation circuit after the molds were extracted from the goats and the valve leaflets were fixed with formalin. Moreover, hematoxylin-and-eosin stained sections were observed. The results demonstrated that the valve leaflets covered with connective tissues have sufficient performance and durability of more than one month. In conclusion, we made a tissue-engineered circle valve leaflet with enough strength and durability to be used as heart valves in vivo using the insert molding technique.