癌細胞轉移至骨組織常造成骨組織破壞及引起骨骼疼痛，目前常以游離輻射局部照射來加以處理，而由於低能量氦氖雷射已被發現可促進受傷骨組織進行修復作用，爲瞭解其作用機制，本研究利用低能量氦氖雷射評估其對破骨細胞分化的影響，並同時比對游離輻射對破骨細胞的影響。本研究採分離人類周邊幹細胞與造骨細胞共同培養之模式，以誘發破骨細胞的分化，進而給與不同條件刺激，觀察其差異。結果顯示接受雷射照射組，其破骨細胞分化的數目相對少於對照組，但對已分化之破骨細胞的活性則較無影響，顯示低能量氦氖雷射可經由抑制分化的方式抑制破骨細胞。此外，游離輻射(10Gy)照射組所得到的結果顯示其對破骨分化之抑制作用較氦氖雷射照組爲小，但對於已分化之破骨細胞，其抑制作用則很明顯。由此可知低能量氦氖雷射與游離輻射經由不同的機制抑制破骨細胞的分化；由RT-PCR分析破骨細胞分化因子的製造即可獲得証實。因此，低能量氦氖雷射與游離輻射均可抑制破骨細胞的分化數目，但前者是透過減少造骨細胞分泌破骨細胞分化因子來達成抑制破骨細胞的分化，就抑制破骨細胞數量方面效果較佳，但游離輻射照射對於破骨細胞的活性則有明顯的抑制作用。

Metastasis of cancer cell to bone tissues usually causes bone damages and bone aches. Presently, they are approached with ionizing radiation. On the other hand, low-energy He/Ne laser has been found able to enhancing restoration of damaged bone tissues. In order to investigate its mechanism, we utilized low-energy He/Ne laser to evaluate its influence on the differentiation of osteoclasts. Meanwhile, we compared the above results with those using ionizing radiation. In this study, we co-cultured peripheral stem cells of human with osteoblasts to initiate the differentiation of osteoclasts, and investigated the difference when giving various stimuli. The results shown that the number of differentiating osteoclasts was less under the irradiation of low-energy He/Ne laser than that of the control group. However, no apparent effect was found on the activity of differentiated osteoclasts. This represented that low-energy He/Ne laser were capable of suppressing osteoclasts by their differentiation. Besides, the suppressing ability of ionizing radiation (10 Gy) on osteoclast differentiation was less than that of low-energy He/Ne laser. Nevertheless, the suppression was apparent on the differentiated osteoclasts. From above investigations, the differentiation of osteoclasts were suppressed through different mechanisms by low-energy He/Ne laser and the ionizing radiation, which was corroborated by RT-PCR analysis of the production of osteoclast differentiation factors. Therefore, both low-energy He/Ne laser and ionizing radiation were capable of inhibiting osteoclast differentiation, however, the former worked through reducing the secretion of osteoclast differentiation fgctors from osteobalsts, which is more effective.