Department of Orthopaedic Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150081, Heilongjiang, China.
Lasers Med Sci. 2022 Dec;37(9):3509-3516. doi: 10.1007/s10103-022-03624-x. Epub 2022 Sep 6.
Low-level laser therapy (LLLT) also known as photobiomodulation is a treatment to change cellular biological activity. The exact effects of LLLT remain unclear due to the different irradiation protocols. The purpose of this study was to investigate the effects of LLLT by three different irradiation methods on the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in vitro. BMSCs were inoculated in 24-well plates and then irradiated or not (control) with a laser using three different irradiation methods. The irradiation methods were spot irradiation, covering irradiation, and scanning irradiation according to different spot areas (0.07 cm or 1.96 cm) and irradiation areas (0.35 cm or 1.96 cm), respectively. The laser was applied three times at energy densities of 4 J/cm. The cell proliferation by CCK-8. ALP activity assay, alizarin red, and quantitative real-time polymerase chain reaction (RT-PCR) were performed to assess osteogenic differentiation and mineralization. Increases in cell proliferation was obvious following irradiation, especially for covering irradiation. The ALP activity was significantly increased in irradiated groups compared with non-irradiated control. The level of mineralization was obviously improved following irradiation, particularly for covering irradiation. RT-PCR detected significantly higher expression of ALP, OPN, OCN, and RUNX-2 in the group covering than in the others, and control is the lowest. The presented results indicate that the biostimulative effects of LLLT on BMSCs was influenced by t he irradiation method, and the covering irradiation is more favorable method to promote the proliferation and osteogenic differentiation of BMSCs.
低水平激光疗法（LLLT）也称为光生物调节，是一种改变细胞生物活性的治疗方法。由于不同的辐照方案，LLLT 的确切效果仍不清楚。本研究旨在通过三种不同的辐照方法来研究 LLLT 对体外骨髓间充质干细胞（BMSCs）增殖和成骨分化的影响。BMSCs 接种于 24 孔板中，然后用激光进行辐照或不辐照（对照），采用三种不同的辐照方法。根据不同的光斑面积（0.07cm 或 1.96cm）和照射面积（0.35cm 或 1.96cm），照射方法分别为点照射、覆盖照射和扫描照射。激光以 4 J/cm 的能量密度应用三次。通过 CCK-8 法、ALP 活性测定、茜素红和实时定量聚合酶链反应（RT-PCR）评估成骨分化和矿化，以评估细胞增殖。辐照后细胞增殖明显增加，特别是覆盖照射。与未辐照对照相比，辐照组的 ALP 活性显著增加。照射后矿化水平明显提高，特别是覆盖照射。RT-PCR 检测到覆盖组中 ALP、OPN、OCN 和 RUNX-2 的表达明显高于其他组，而对照组最低。结果表明，LLLT 对 BMSCs 的生物刺激作用受辐照方法的影响，覆盖辐照更有利于促进 BMSCs 的增殖和成骨分化。
