1. Stem Cell Research Center, University of Pittsburgh, Pittsburgh, Pennsylvania.
2. Department of Biomedical Engineering, University of Texas, Austin, Texas.
3. Center for Cardiovascular Research, Washington University School of Medicine, St. Louis, Missouri.
4. Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania.
5. McGowan Institute for Regenerative Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania.