It has been reported that light-emitting diodes(LED) can be used in the treatment of oral diseases. Although bio-stimulatory effects of LED irradiation such as promotes stimulation of wound healing have been well known, there are few reports about molecular mechanism associated with cell cycle by LED irradiation. The purpose of present study was to examine the molecular event in cell cycle of LED irradiation on primary human gingival fibroblast(hGF) in vitro. The source of light for irradiation was a continuous-wave LED emitting at a wavelength of 635nm, and manufactured that energy density was 5mW/cm2 on sample surface. The hGF were irradiated for 1 hour at 37℃ in 5% CO2 humidified chamber. Experimental samples were acquired at 0 (right after irradiation), 8 and 24 hour after irradiation. To investigate the molecular mechanisms associated with cell cycle, growth phase was determined by flow cytometry and mRNA expression of cyclin A, cyclin B, cyclin D1, cyclin E, cdc2, PCNA, p18, p27, p21, and p53 were determined by real time RT-PCR. Flow cytometric analysis demonstrated the percentage of cells in the G1 and S phase were decreased, but the G2 phase increased, which showed cells irradiated by LED were transitioned from S to G2 phase. For mRNA expression, cyclin B, cdc2, PCNA and p53 were increased at 0 hour after irradiation, and most of cell cycle molecules were increased at 8 hour after irradiation. At 24 hour after irradiation, cyclin A, cyclin E, PCNA and p18 were increased. Taken together, LED irradiation induced proliferation of hGF cells through transition from S to G2 phase.

• Jung Hye Kim(Dental Research Institute, Department of Oral Pathology, School of Dentistry, Chonnam National University) | 김정혜
• Youn Young Jang(Dental Research Institute, Department of Oral Pathology, School of Dentistry, Chonnam National University) | 장윤영
• Kwon Jung(Dental Research Institute, Department of Oral Pathology, School of Dentistry, Chonnam National University) | 정권
• Mi Kyeong Ko(Dental Research Institute, Department of Oral Pathology, School of Dentistry, Chonnam National University) | 고미경
• Mi Sun Jang(Dental Research Institute, Department of Oral Pathology, School of Dentistry, Chonnam National University) | 장미선
• Eun Byul Kook(Dental Research Institute, Department of Oral Pathology, School of Dentistry, Chonnam National University) | 국은별
• Min A Chong(Dental Research Institute, Department of Oral Pathology, School of Dentistry, Chonnam National University) | 정민아
• Won Bong Lim(Dental Research Institute, Department of Oral Pathology, School of Dentistry, Chonnam National University) | 임원봉
• Chae Kwang Lim(Dental Research Institute, Department of Oral Pathology, School of Dentistry, Chonnam National University) | 임채광
• Ok Joon Kim(Dental Research Institute, Department of Oral Pathology, School of Dentistry, Chonnam National University) | 김옥준
• Hong Ran Choi(Dental Research Institute, Department of Oral Pathology, School of Dentistry, Chonnam National University) | 최홍란 Correspondence