1. Department of Pathology, Institute for Stem Cell and Regenerative Medicine, School of Medicine, University of Washington, Seattle, WA 98109, USA
2. Department of Clinical Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand
3. Department of Oral Biology, School of Dentistry, University of Washington, Seattle, WA 98195, USA
4. Department of Anatomy, Faculty of Dentistry, Mahidol University, Bangkok 10400, Thailand