The effect of single low-power CO2 laser irradiation on human PDL fibroblast proliferation & differentiation

Abstract

[한글]이 논문은 단일조사 저출력 CO2 laser조사가 치주인대 섬유아세포의 증식과 분화에 미치는 영향을 살펴보고 가장 효과적인 에너지와 파워밀도(power density)를 알아보기 위하여 다음과 같이 실험하였다.0.5W 출력, 10.6 ㎛ 파장, 50 Hz 연속형 CO2 laser를 사용하여, 실험군은 laser tip과 배양된 세포 사이의 거리를 2cm, 3cm으로 나누고, 조사시간을 1초, 3초로 나누어 4개의 군으로 설정하였고 대조군은 laser를 조사하지 않은 군으로 하였다. 치주인대 섬유아세포의 증식정도와 골모세포로의 분화정도를 보기 위하여 각각 MTT 실험과 ALP activity 실험을 시행하여 다음과 같은 결과를 얻었다.1. Laser를 조사하고 난 후 5일째에, 모든 군에서 유의하게 세포가 증식되는 것을 확인할 수 있었고 조사방법간에 유의한 차이가 없었다.2. 대조군과 실험군에서 0일째에 비하여 3일째, 5일째, 7일째, 10일째에 통계적으로 유의하게 ALP activity가 증가하였고, 이중 2cm,1sec 군을 제외하면 3일째에서 가장 높은 ALP activity 값을 보였다. 특징적으로 2Cm,1sec 군은 3일째부터 10일까지 통계적으로 유의하지는 않지만 시간이 지남에 따라서 ALP activity가 증가함을 보였다.7일과 10일째에는 2cm,1sec, 3cm,3sec군에서 다른 군에 비하여 큰 activity값을 보였다.이번실험에서 저출력 CO2 laser 조사는 세포의 증식보다는 분화에 더 큰 영향을 끼쳤고, 2cm,1sec, 3cm,3sec군이 치주인대 섬유아세포의 분화에 가장 효과적인 laser 조사방법으로 분석되었다.

[영문]Low-power laser therapy using CO2 lasers is known to activate surrounding cells and tissue. Shiozaki et al.(2005) achieved that low-power CO2 lasers induced not only mineralization but also osteoblast differentiation. And Tajima et al (2003). reported that low-power CO2 laser accelerates new bone formation within the marrow cavity subjacent to the laser treatment site. In spite of successful clinical and experimental results, the mechanisms underlying low-power CO2 laser effects are still poorly understood.The aim of this study is to evaluate the effect of low-power CO2 laser in growth and proliferation of cultured human PDL fibroblast in vitro and to understand better about the effect of laser on periodontal regeneration. The study also tried to find out the most effective degree of energy and power density where cell proliferation and differentiation to osteoblastic cells highly takes place after laser irradiation.The experimental groups were divided into 4 groups by applying different irradiating distances from cultured cell to laser tip; 2Cm (Focal spot=∅0.74mm), 3Cm (Focal spot=∅1.04mm) and different irradiating time; 1 second, 3 seconds. And they were applied to laser at a power of 0.5W with 50Hz under continuous mode. The control group was not applied to laser. MTT and ALP activity test were performed to observe the growth of PDL cells and cell differentiation to osteoblastic cells. The result are as follows.1. On the 5th day after laser irradiation, statistically significant increase of cells were found in all groups. But, no significant differences were found among groups.2. Statistically significant increase of ALP activity was seen on the 3rd, 5th, 7th, and 10th day after laser irradiation compared to the baseline. Among this, there were highest ALP activity on 3rd day except 2cm,1sec group. 2cm,1sec group showed increase of ALP activity not statistically significant from the 3rd day to 10th day.On the 7th and 10th day 3cm,1sec, 3cm,3sec and 2cm,1sec group showed significant high score of ALP activity compared to 2cm,3sec and control group.In this study, there was a weak effect of low-power CO2 laser on cell proliferation but there was a better effect on cell differentiation. 2cm,1sec irradiation was found to be the most effective condition for PDL cell differentiation in this study and 3cm, 3sec was found to be efficient.