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A Novel Autologous Heart Valve with Growth Potential
Yoshiaki Takewa, MD, PhD1, Yasuhide Nakayama, PhD1, Hirohito Sumikura, PhD1,
Noritsugu Naito, MD1, EisukeTatsumi, MD, PhD1.
1.National Cerebral and Cardiovascular Center, Osaka, Japan.
We are developing a novel autologous heart valve prosthesis (Biovalve) with a unique in-body tissue engineering method. This enables us to select a tailor made valve replacement to fit the each patient and keep biocompatibility. In this study, we made 3 types of heart valve and tested the feasibility of them in a large animal model.
Materials & Methods
We created many kinds and sizes of molds for Biovalves using plastic rods with 3D printer easily and quickly considering the recipient character. In this study, we selected 3 types (a conventional type, a full-root type and a valve with a metalic stent for transcatheter implantation) and embedded them in the subcutaneous spaces of adult goats for 1-2 months. After extracting the molds with the tissue and removing the plastic rods only, Biovalve with tri-leaflets similar to those of the native valves were constituted from completely autologous connective tissues and fibroblasts.
Five cases of conventional Biovalves were implanted in the aorta under cardiopulmonary bypass, 8 cases of full-root type were implanted in the apico-aortic bypass or pulmonary position, and 22 stent valve type were implanted with transcatheter technique into in situ the aortic and pulmonary valves (15 and 7, respectively).
In each type, Biovalves were successfully implanted and showed smooth movement of the leaflets with a little regurgitation in angiogram.
In endoscopic view of in situ Biovalve 2 months after implantation, the leaflets have been opening and closing well.
After the experiments (The maximum 2 months in full root type and 6 months in stent valve type) the Biovalves were extracted and observed. The leaflets kept their shape and elasticity, and neither calcification nor thrombi were observed.
Histological examination showed the cell populations inside the valves and endothelial cells covering the laminar surface of the valve leaflets.
The Biovalve Stent satisfied the higher requirements of systemic and pulmonary circulation in goats for maximum 5 months with the potential for transcatheter implantation.