1. Eli and Edythe Broad CIRM Center, Department of Stem Cell Biology and Regenerative Medicine, Keck School of Medicine, University of Southern California, Los Angeles, California 90033-9080, United States
2. Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089-0484, United States
3. Department of Biomedical Engineering, Viterbi School of Engineering, University of Southern California, Los Angeles, California 90089-1111, United States