[1] Univ Wisconsin, Dept Biomed Engn, Madison, WI 53706 USA
[2] Univ Wisconsin, Dept Orthoped & Rehabil, Madison, WI 53706 USA
[3] Univ Wisconsin, Mat Sci Program, Madison, WI 53706 USA
[4] Univ Wisconsin, Stem Cell & Regenerat Med Ctr, Madison, WI 53706 USA
[5] Univ Calif San Francisco, Dept Bioengng & Therapeut Sci, San Francisco, CA 94143 USA
[6] Gladstone Inst, Roddenberry Ctr Stem Cell Biol & Med, San Francisco, CA USA