The Effect of a-Tocopherol and Selenium on Human Gingival Fibroblasts and Periodontal Ligament Fibroblasts In Vitro

• Localización: Journal of periodontology, ISSN 0022-3492, Nº. 4, 2014, págs. 636-644
• Idioma: inglés
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• Resumen

  • Background: The aim of the present study is to evaluate the effect of a-tocopherol and selenium on gingival fibroblasts (GFs) and periodontal ligament fibroblasts (PDLFs) in terms of proliferation, basic fibroblast growth factor (bFGF) release, collagen type I synthesis, and wound healing.

    Methods: Primary cultures of human GFs and PDLFs were isolated. Four test groups and a control group free of medication was formed. In group E, 60 µM a-tocopherol was used, and in groups ES1, ES2, and ES3, the combination of 60 µM a-tocopherol with 5 × 10-9 M, 10 × 10-9 M, and 50 × 10-9 M selenium was used, respectively. Viability, proliferation, bFGF, and collagen type I synthesis from both cell types were evaluated at 24, 48, and 72 hours, and healing was compared on a new wound-healing model at 12, 24, 36, 48, and 72 hours.

    Results: a-Tocopherol alone significantly increased the healing rate of PDLFs at 12 hours and increased bFGF and collagen type I release from GFs and PDLFs at 24, 48, and 72 hours. The a-tocopherol/selenium combination significantly enhanced the proliferation rate of both cells at 48 hours, decreased the proliferation of PDLFs at 72 hours, and increased the healing rate of GFs at 12 hours and PDLFs at 12 and 48 hours. bFGF and collagen type I synthesis was also increased in both cell types at 24, 48, and 72 hours by a-tocopherol/selenium combination.

    Conclusion: a-Tocopherol and a-tocopherol/selenium combination is able to accelerate the proliferation rate and wound-healing process and increase the synthesis of bFGF and collagen type I from both GFs and PDLFs.

    It is well known that all mammalian cells use oxygen to produce energy, and, as metabolic byproducts, reactive oxygen species (ROS) are formed continuously. ROS are essential for the normal function and metabolism of the cells,1 but they are also capable of initiating lipid peroxidation and damaging cell membrane and DNA.2,3 In normal physiology, there is a continuous balance between ROS activity and antioxidant defense capacity; however, when there is a reduction in the antioxidant defense or increase in ROS production or activity, oxidative stress results, leading to potential damage.1 Excessive production of ROS has been associated with pathogenesis of many inflammatory diseases, including periodontitis.1,2,4 Antioxidants can be classified as endogenous antioxidants, which are synthesized by the body, including catalase, superoxide dismutase, glutathione peroxidase, and exogenous antioxidants, which are obtained through the diet, such as carotenoids, ascorbic acid, and tocopherols. a-Tocopherol is one of the subspecies of vitamin E and regarded as the most important and effective lipid-soluble antioxidant and vital for maintaining cell membrane integrity against lipid peroxidation.5 Besides the antioxidant capacity, vitamin E was shown to have anti-inflammatory properties,6 the ability to reduce tumor development,7,8 and to increase growth factor release from fibroblasts.9 It was also demonstrated that vitamin E accelerated gingival wound healing10 and had a significant protective effect against alveolar bone loss in vivo.11 Selenium is the essential cofactor of glutathione peroxidase, which detoxifies hydrogen peroxide and other organic peroxides. It is effective against oxidative stress, but, when combined with vitamin E, it has a synergistic effect.8,12 It was also demonstrated on a rat model that the combination of vitamin E and selenium was protective against ROS-induced collagen breakdown.13 Basic fibroblast growth factor (bFGF), an endogenous polypeptide growth factor, has numerous biologic activities, such as cell growth, angiogenesis, migration, differentiation, morphogenesis, wound healing, and tissue repair.14,15 Moreover, bFGF stimulates the proliferation of cells, including fibroblasts,16 osteoblasts,17 cementoblasts,18 and endothelial cells,19 which are essential cells for periodontal wound healing and regeneration. Collagen type I is one of the major extracellular protein components of periodontal tissues and is produced by many cells, including periodontal ligament fibroblasts (PDLFs) and gingival fibroblasts (GFs). Remodeling of collagen type I in periodontal ligament (PDL) and other connective tissues is regulated at one level by bFGF,20 and synthesis of the collagen after injury seems to be essential for the wound-healing process.21 Beyond the antioxidant properties of a-tocopherol and selenium, other effects attributable to specific interactions of vitamin E with proteins such as enzymes or transcription factors are possible.22 Vitamin E and the combination of selenium may affect the function of PDLF and GF cells and may increase growth factor release, proliferation rate, and extracellular matrix (ECM) component production; hence, periodontal wound healing and regeneration may be accelerated. Still, little is known about the mechanism and the biologic effects of vitamin E and selenium on oral tissues other than their antioxidative characteristics.

    Therefore, the aim of the present study is to evaluate whether a-tocopherol and the combination with selenium affect bFGF release and collagen type I synthesis from PDLFs and GFs and whether these antioxidants increase the proliferation rate of the cells and accelerate wound healing in vitro.