1. Stem Cell Biology Laboratory, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA 70808, USA.
2. Center for Stem Cell Research & Regenerative Medicine, Department of Pharmacology, Tulane University Health Science Center, New Orleans, LA 70112, USA
3. Orthopedic Research Laboratory, Department of Orthopedic Surgery, Duke University Medical Center, Durham, NC 27710, USA