title: Low-level laser therapy induces the expressions of BMP-2, osteocalcin, and TGF-β1 in hypoxic-cultured human osteoblasts.
abstract: The aim of this study was to examine the effect of low-level laser therapy (LLLT) on the cell viability and the expression of hypoxia-inducible factor-1s (HIF-1s), bone morphogenic protein-2 (BMP-2), osteocalcin, type I collagen, transforming growth factor-β1 (TGF-β1), and Akt in hypoxic-cultured human osteoblasts. Human fetal osteoblast cells (cell line 1.19) were cultured under 1 % oxygen tension for 72 h. Cell cultures were divided into two groups. At the experimental side, low-level laser (808 nm, GaAlAs diode) was applied at 0, 24, and 48 h. After irradiation, each cell culture was incubated 24 h more under hypoxia. Total energy was 1.2, 2.4, and 3.6 J/cm(2), respectively. Non-irradiated cultures served as controls. Comparisons between the two groups were analyzed by t test; a p value <0.05 was considered statistically significant. Hypoxia resulted in a decrease in the expression of type I collagen, osteocalcin, and TGF-β1 (p < 0.001, p < 0.001, and p < 0.01, respectively). Cell viability and BMP-2 expression were not decreased by hypoxic condition. On the other hand, LLLT on hypoxic-cultured osteoblast promoted the expression of BMP-2, osteocalcin, and TGF-β1 (p < 0.05, p < 0.01, and p < 0.001, respectively). Cell proliferation was also increased time-dependently. However, hypoxia decreased in type I collagen expression (p < 0.001), and LLLT did not affect type I collagen expression in hypoxic-cultured osteoblasts. Furthermore, LLLT inhibited HIF-1 and Akt expression in hypoxic conditioned osteoblasts. We concluded that LLLT induces the expression of BMP-2, osteocalcin, and TGF- β1 in 1 % hypoxic-cultured human osteoblasts.
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Dentistry, Pusan National University, Beomeo, Mulgum, Yangsan, 626-770, Republic of Korea.
authors.forename: Se-Jeong
authors.initials: SJ
authors.lastname: Pyo
authors.forename: Won-Wook
authors.initials: WW
authors.lastname: Song
authors.forename: In-Ryoung
authors.initials: IR
authors.lastname: Kim
authors.forename: Bong-Soo
authors.initials: BS
authors.lastname: Park
authors.forename: Cheul-Hong
authors.initials: CH
authors.lastname: Kim
authors.forename: Sang-Hun
authors.initials: SH
authors.lastname: Shin
authors.forename: In-Kyo
authors.initials: IK
authors.lastname: Chung
authors.forename: Yong-Deok
authors.initials: YD
authors.lastname: Kim
mesh_terms: D051784:Aryl Hydrocarbon Receptor Nuclear Translocator / Q000235:genetics / Q000378:metabolism; D055396:Bone Morphogenetic Protein 2 / Q000378:metabolism*; D015687:Cell Hypoxia; D049109:Cell Proliferation / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D002478:Cells, Cultured; D024042:Collagen Type I / Q000378:metabolism; D005786:Gene Expression Regulation / Q000528:radiation effects; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D028022:Low-Level Light Therapy; D010006:Osteoblasts / Q000378:metabolism* / Q000528:radiation effects*; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism*; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000235:genetics / Q000378:metabolism*
chemical_list: C497396:ARNT protein, human; C525718:BMP2 protein, human; D055396:Bone Morphogenetic Protein 2; D024042:Collagen Type I; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D053773:Transforming Growth Factor beta1; D015675:Osteocalcin; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D051057:Proto-Oncogene Proteins c-akt