1. Department of Stem Cell Biology and Regenerative Medicine, Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.
2. Department of Biomedical Engineering, University of Southern California, Los Angeles, CA 90089, USA.
3. Department of Medicine, University of Southern California, Los Angeles, CA 90033, USA.
4. Leonard Davis School of Gerontology, University of Southern California, Los Angeles, CA 90089, USA.