1. Division of Hematology, Children's Hospital of Philadelphia, Philadelphia, PA;
2. Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA;
3. The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, Hubei, China; and
4. Department of Biomedical Sciences, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA