Kim Ha Yeong, Yu Yeonsil, Oh Se-Young, Wang Kang-Kyun, Kim Yong-Rok, Jung Sung-Chul, Kim Han Su, Jo Inho
Department of Molecular Medicine, College of Medicine, Ewha Womans University, Seoul, Republic of Korea.
Department of Otorhinolaryngology-Head and Neck Surgery, College of Medicine, Ewha Womans University, Seoul, Republic of Korea.
Cell Physiol Biochem. 2019;52(2):240-253. doi: 10.33594/000000018. Epub 2019 Feb 28.
BACKGROUND/AIMS: Far-infrared (FIR) irradiation has been reported to exhibit various biological effects including improvement of cardiovascular function. However, its effect on the differentiation of stem cells has not been studied. Using tonsil-derived mesenchymal stem cells (TMSC), we examined whether and how FIR irradiation affects adipogenic or osteogenic differentiation.
TMSC were exposed to FIR irradiation (3-25 μm wavelength) for various times (0, 30, or 60 min), and then adipogenic or osteogenic differentiation was induced for 14 days with its respective commercially available differentiation medium. At the end of the differentiation, the cells were stained using Oil red O or Alizarin red S solution, and the expression of differentiation-specific proteins was analyzed by western blotting.
FIR irradiation did not alter cell viability or the expression of MSC-specific surface antigens (CD14, CD34, CD45, CD73, CD90, and CD105) in TMSC. However, FIR irradiation significantly inhibited adipogenic differentiation of TMSC, as evidenced by decreased Oil red O staining as well as protein expression of peroxisome proliferator-activated receptor γ and fatty acid binding protein 4. In contrast, FIR irradiation induced osteogenic differentiation, as evidenced by increased Alizarin red S staining as well as protein expression of osteocalcin and alkaline phosphatase. Treatment with heat alone did not inhibit the adipogenic differentiation of TMSC, suggesting that the inhibitory effect on adipogenic differentiation was not due to heat induced by FIR irradiation. However, heat alone did stimulate osteogenic differentiation, but to a lesser extent than FIR irradiation. Furthermore, FIR irradiation increased intracellular Ca²⁺ levels and the activity of protein phosphatase 2B (PP2B) in TMSC. Treatment with cyclosporin A, a specific PP2B inhibitor, reversed the inhibitory effect of FIR irradiation on adipogenic differentiation of TMSC, but had no effect on osteogenic differentiation.
Our data demonstrate that FIR irradiation inhibits adipogenic differentiation but enhances osteogenic differentiation of TMSC; the inhibitory effect on adipogenic differentiation is non-thermal and mediated at least in part by activation of Ca²⁺-dependent PP2B.
背景/目的：据报道，远红外线（FIR）照射具有多种生物学效应，包括改善心血管功能。然而，其对干细胞分化的影响尚未得到研究。我们使用扁桃体来源的间充质干细胞（TMSC），研究了FIR照射是否以及如何影响成脂或成骨分化。
将TMSC暴露于FIR照射（波长3 - 25μm）不同时间（0、30或60分钟），然后用各自市售的分化培养基诱导成脂或成骨分化14天。分化结束时，用油红O或茜素红S溶液对细胞进行染色，并通过蛋白质印迹法分析分化特异性蛋白的表达。
FIR照射未改变TMSC的细胞活力或MSC特异性表面抗原（CD14、CD34、CD45、CD73、CD90和CD105）的表达。然而，FIR照射显著抑制了TMSC的成脂分化，油红O染色以及过氧化物酶体增殖物激活受体γ和脂肪酸结合蛋白4的蛋白表达降低证明了这一点。相反，FIR照射诱导了成骨分化，茜素红S染色以及骨钙素和碱性磷酸酶的蛋白表达增加证明了这一点。单独加热处理并未抑制TMSC的成脂分化，这表明对成脂分化的抑制作用不是由FIR照射产生的热量引起的。然而，单独加热确实刺激了成骨分化，但程度低于FIR照射。此外，FIR照射增加了TMSC内的Ca²⁺水平和蛋白磷酸酶2B（PP2B）的活性。用特异性PP2B抑制剂环孢素A处理可逆转FIR照射对TMSC成脂分化的抑制作用，但对成骨分化没有影响。
我们的数据表明，FIR照射抑制TMSC的成脂分化但增强其成骨分化；对成脂分化的抑制作用是非热性的，并且至少部分是由Ca²⁺依赖性PP2B的激活介导的。
