Section of Periodontology, Department of Hard Tissue Engineering, Graduate School, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo, 113-8549, Japan.
Lasers Med Sci. 2010 Jul;25(4):559-69. doi: 10.1007/s10103-010-0761-5. Epub 2010 Feb 26.
Although the use of high-level Er:YAG laser irradiation has been increasing in periodontal and peri-implant therapy, the effects of low-level Er:YAG laser on surrounding tissues and cells remain unclear. In the present study, the effects of low-level Er:YAG laser irradiation on osteoblast proliferation were investigated. Cells of the osteoblastic cell line MC3T3-E1 were treated with low-level Er:YAG laser irradiation with various combinations of laser settings (fluence 0.7-17.2 J/cm(2)) and in the absence or presence of culture medium during irradiation. On day 1 and/or day 3, cell proliferation and death were determined by cell counting and by measurement of lactate dehydrogenase (LDH) levels. Further, the role of mitogen-activated protein kinase (MAPK) pathways in laser-enhanced cell proliferation was investigated by inhibiting the MAPK pathways and then measuring MAPK phosphorylation by Western blotting. Higher proliferation rates were found with various combinations of irradiation parameters on days 1 and 3. Significantly higher proliferation was also observed in laser-irradiated MC3T3-E1 cells at a fluence of approximately 1.0-15.1 J/cm(2), whereas no increase in LDH activity was observed. Further, low-level Er:YAG irradiation induced the phosphorylation of extracellular signal-regulated protein kinase (MAPK/ERK) 5 to 30 min after irradiation. Although MAPK/ERK 1/2 inhibitor U0126 significantly inhibited laser-enhanced cell proliferation, activation of stress-activated protein kinases/Jun N-terminal kinase (SAPK/JNK) and p38 MAPK was not clearly detected. These results suggest that low-level Er:YAG laser irradiation increases osteoblast proliferation mainly by activation of MAPK/ERK, suggesting that the Er:YAG laser may be able to promote bone healing following periodontal and peri-implant therapy.
虽然在牙周病和种植体周围病的治疗中，高强度铒：YAG 激光的应用越来越多，但低强度铒：YAG 激光对周围组织和细胞的影响尚不清楚。本研究旨在探讨低强度铒：YAG 激光照射对成骨细胞增殖的影响。采用不同激光参数（能量密度 0.7-17.2 J/cm(2))组合，在有无培养液的情况下，对成骨细胞系 MC3T3-E1 细胞进行低强度铒：YAG 激光照射。在第 1 天和/或第 3 天，通过细胞计数和乳酸脱氢酶（LDH）水平的测定来确定细胞的增殖和死亡。进一步通过抑制丝裂原活化蛋白激酶（MAPK）通路，然后通过 Western blot 测定 MAPK 磷酸化，来研究激光增强细胞增殖中 MAPK 通路的作用。结果发现，在第 1 天和第 3 天，各种辐照参数组合均可提高细胞增殖率。在大约 1.0-15.1 J/cm(2)的能量密度下，激光照射的 MC3T3-E1 细胞的增殖率也明显提高，而 LDH 活性没有增加。此外，低强度铒：YAG 激光照射后 30 min 可诱导细胞外信号调节激酶（MAPK/ERK）5 的磷酸化。虽然 MAPK/ERK1/2 抑制剂 U0126 显著抑制了激光增强的细胞增殖，但应激激活蛋白激酶/Jun N-末端激酶（SAPK/JNK）和 p38 MAPK 的激活并不明显。这些结果表明，低强度铒：YAG 激光照射主要通过激活 MAPK/ERK 来增加成骨细胞的增殖，提示铒：YAG 激光可能有助于牙周病和种植体周围病治疗后的骨愈合。
