It is not yet clear to know how normal human osteoblasts(NHost) from oral and maxillofacial area deposit, stabilize, and configure their extracellular matrix on dental biomaterial surfaces. Therefore it is necessary to design biomaterials with improved biocompatibility that will promote earlier bone differentiation and mineralization. There is now increasing evidence that TGase 2 may play a role in the initiation and regulation of the mineralization processes and serves to cross-link osteocalcin and osteopontin, which are predominant substrates for TGase 2 expressed during bone mineralization. But it is still unclear as to which TGase 2 is expressed by NHost in vitro bone formation. The purpose of this s tudy was t o determine the level of TGase 2 expression associated with collagen I , osteopontin and osteocalcin in NHost cell lines from oral and maxillofacial area in vitro. We will investigate whether TGase 2 has an active role in the biocompatibility of dental biomaterials during differentiation and mineralization of NHost. NHost cell lines were cultured under DMEM with 10% FBS at 37ﾟC and 5% CO2. Collagen quantification, mineralization and calcium assay, ALP activity assay, and RT-PCR analysis during bone differentiation and mineralization were done. ALP levels showed higher activity under AA+hGP t han under AA. I nhibition o f T Gase 2 by cystamine showed d ecreased Ca++ concentration, c ollagen I deposition and ALP level during 11 days of differentiation. TGase 2 mRNA expression of NHost was constant during mineralization stage. TGase 2 enzyme activity was increased during differentiation. Osteopontin mRNA expression during mineralization was higher than that of osteocalcin and collagen I . It suggested that TGase 2 associated with collagen I, osteocalcin and osteonectin might play a role in the differentiation of NHost from oral and maxillofacial area, but a little involved in mineralization.

I. INTRODUCTION
 II. MATERIALS AND METHODS
  1. Cell Culture Condition
  2. Collagen Staining and Quantification
  3. Mineralization and Calcium Assay
  4. Alkaline Phosphatase Activity Assay
  5. mRNA Expression of Collagen I, Osteocalcin,Osteonectin, and Transglutaminase 2
  6. Inhibition of Transglutaminase 2 Activity
 III. RESULTS
 IV. DISCUSSION
 V. REFRENCES

• 강기철(단국대학교 치과대학 구강병리학교실, 구강노화연구소) | Gi Chul Kang
• 박경주(단국대학교 치과대학 구강병리학교실, 구강노화연구소) | Gyeong Ju Park
• 이종헌(단국대학교 치과대학 구강병리학교실, 구강노화연구소) | Chong Heon Lee correspondence