Insulin-like growth factor-I stimulates the disintegration of Hertwig’s epithelial root sheath and cellular cementogenesis in mouse molars in vitro
Insulin-like growth factor-I stimulates the disintegration of Hertwig’s epithelial root sheath and cellular cementogenesis in mouse molars in vitro
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发表时间：
2019
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通讯作者：
Naoki Fujiwara;Akira Fujimura;Mitsuo Kishi;Hisatomo Kondo;Yoshinori Sahara;Haruki Tamura;Toshimi Chiba;N. Chosa;Mamoru Noda;Kaztmasa Morikawa;Hiroyuki Yamada;Kanako Isobe;K. Kikuchi;Miho Kumagai;A. Kuji;Kazumasa Morikawa
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作者：
Naoki Fujiwara;Akira Fujimura;Mitsuo Kishi;Hisatomo Kondo;Yoshinori Sahara;Haruki Tamura;Toshimi Chiba;N. Chosa;Mamoru Noda;Kaztmasa Morikawa;Hiroyuki Yamada;Kanako Isobe;K. Kikuchi;Miho Kumagai;A. Kuji;Kazumasa Morikawa
在此之前，我们已经阐明了胰岛素样生长因子-I（IGF-I）在5日龄小鼠下颌第一磨牙牙根形成的早期阶段的作用。我们报道了IGF-I刺激Hertwig上皮根鞘（HERS）外釉上皮细胞的有丝分裂活性，导致根的伸长。在本研究中，我们使用20天大小鼠的下颌第一磨牙，以进一步阐明IGF-I在牙根形成后期阶段的作用。对照外植体显示HERS的正常发育，与体内相似。但用100 ng/ml IGF-I处理的外植体显示HERS内层和外层的细胞增殖减少。此外，还观察到根鞘沿着崩解并出现细胞性牙骨质形成。认为IGF-I信号加快了HERS层从细胞增殖维持长度到细胞崩解的变化速率，最终促进成牙骨质细胞分化和细胞性牙骨质形成。这些结果表明，IGF-I是根形成的重要调控因子之一。
Previously, we have elucidated the role of insulin-like growth factor-I (IGF-I) during the early stages of tooth root formation in mandibular first molars of 5-day-old mice. We reported that IGF-I stimulates the mitotic activity in the outer enamel epithelium of the Hertwig's epithelial root sheath (HERS), resulting in the elongation of the root. In the present study, we used mandibular first molars from 20-day-old mice in order to further elucidate the role of IGF-I during the later stages of tooth root formation. The control explants showed normal development of the HERS, similar to that in vivo. But the explants treated with 100 ng/ml of IGF-I showed diminished cell proliferation in the inner and outer layers of the HERS. In addition, obvious disintegration of the root sheath along with the appearance of cellular cementogenesis was noted. It was considered that IGF-I signaling accelerated the changing rate, from the maintenance of the length via cell proliferation to the disintegration of the HERS layer, eventually facilitating the differentiation of cementoblasts and cellular cementogenesis. These findings indicated that IGF-I is one of the important regulatory factors throughout root formation.