||Characterization of Dental Pulp Myofibroblasts in Rat Molars after Pulpotomy
Edanami, Naoki枝並, 直樹
学位の種類: 博士（歯学）. 報告番号: 甲第4368号. 学位記番号: 新大院博（歯）甲第389号. 学位授与年月日: 平成29年9月20日
Journal of Endodontics. 2017, 43(7), 1116-1121.
Introduction: Myofibroblasts express α-smooth muscle actin (α-SMA) and play a critical role in wound healing. Myofibroblast differentiation is controlled by the joint actions of transforming growth factor (TGF)-β1 and the extradomain A fibronectin splice variant (EDA-FN). Currently, the contribution of myofibroblasts to dental pulp healing is unknown. Therefore, we analyzed expressional characteristics of α-SMA-positive cells and investigated TGF-β1, EDA-FN, and α-SMA expression levels after pulpotomy to better understand dental pulp healing. Methods: The maxillary first molars of 8-week-old Wistar rats were pulpotomized with mineral trioxide aggregate. After 1-14 days, localization and co-localization of α-SMA, RECA-1 (as a marker of endothelial cells), NG2 (as a marker of perivascular cells), prolyl-4-hydroxylase (P4H; as an additional marker of myofibroblasts), and EDA-FN were analyzed using immunohistochemistry and double-immunofluorescence. Time-course changes in the mRNA expression levels of TGF-β1, EDA-FN, and α-SMA were evaluated using quantitative RT-PCR analysis. Results: Spindle-shaped α-SMA-positive cells transiently appeared following pulpotomy. These cells initially emerged in the pulp core at day 3, then accumulated at the wound site by day 5. These cells were isolated from RECA-1-positive cells, and did not express NG2 but did express P4H. The mRNA levels of TGF-β1, EDA-FN, and α-SMA were significantly upregulated following pulpotomy. EDA-FN and α-SMA were co-localized at wound sites at day 5. Conclusions: In association with upregulation of TGF-β1 and EDA-FN expression, α-SMA and P4H double-positive cells accumulated at wound sites following pulpotomy. This suggests that myofibroblasts participate in dental pulp healing.