1. a Biomaterials, Cell and Tissue Engineering Laboratory, Department of Biomedical Engineering, Case Western Reserve University, Wickenden Bldg. 504, 10900 Euclid Avenue, Cleveland, OH 44106-7207, USA
2. b Biomaterials, Cell and Tissue Engineering Laboratory, Department of Biomedical Engineering, Case Western Reserve University, Wickenden Bldg. 504, 10900 Euclid Avenue, Cleveland, OH 44106-7207, USA
3. c Biomaterials, Cell and Tissue Engineering Laboratory, Department of Biomedical Engineering, Case Western Reserve University, Wickenden Bldg. 504, 10900 Euclid Avenue, Cleveland, OH 44106-7207, USA
4. d Sulzer-Carbomedics, 1300 B East Anderson Lane, Austin, TX 78752, USA
5. e Biomaterials, Cell and Tissue Engineering Laboratory, Department of Biomedical Engineering, Case Western Reserve University, Wickenden Bldg. 504, 10900 Euclid Avenue, Cleveland, OH 44106-7207, USA