Matsuda Saeka, Shoumura Masahito, Osuga Naoto, Tsujigiwa Hidetsugu, Nakano Keisuke, Okafuji Norimasa, Ochiai Takanaga, Hasegawa Hiromasa, Kawakami Toshiyuki
1. Department of Hard Tissue Research, Matsumoto Dental University Graduate School of Oral Medicine, Shiojiri, Japan; 2. Department of Pediatric Dentistry, Matsumoto Dental University School of Dentistry, Shiojiri, Japan.
2. Department of Pediatric Dentistry, Matsumoto Dental University School of Dentistry, Shiojiri, Japan.
Int J Med Sci. 2016 Jun 29;13(7):500-6. doi: 10.7150/ijms.15671. eCollection 2016.
Perforation of floor of the dental pulp is often encountered during root canal treatment in routine clinical practice of dental caries. If perforation were large, granulation tissue would grow to form periodontal polyp. Granulation tissue consists of proliferating cells however their origin is not clear. It was shown that the cells in granulation tissue are mainly from migration of undifferentiated mesenchymal cells of the bone marrow. Hence, this study utilized GFP bone marrow transplantation mouse model. The floor of the pulp chamber in maxillary first molar was perforated using ½ dental round bur. Morphological assessment was carried out by micro CT and microscopy and GFP cell mechanism was further assessed by immunohistochemistry using double fluorescent staining with GFP-S100A4; GFP-Runx2 and GFP-CD31. Results of micro CT revealed alveolar bone resorption and widening of periodontal ligament. Histopathological examination showed proliferation of fibroblasts with some round cells and blood vessels in the granulation tissue. At 2 weeks, the outermost layer of the granulation tissue was lined by squamous cells with distinct intercellular bridges. At 4 weeks, the granulation tissue became larger than the perforation and the outermost layer was lined by relatively typical stratified squamous epithelium. Double immunofluorescent staining of GFP and Runx2 revealed that both proteins were expressed in spindle-shaped cells. Double immunofluorescent staining of GFP and CD31 revealed that both proteins were expressed in vascular endothelial cells in morphologically distinct vessels. The results suggest that fibroblasts, periodontal ligament fibroblasts and blood vessels in granulation tissue were derived from transplanted-bone marrow cells. Thus, essential growth of granulation tissue in periodontal polyp was caused by the migration of undifferentiated mesenchymal cells derived from bone marrow, which differentiated into fibroblasts and later on differentiated into other cells in response to injury.
在龋齿的常规临床根管治疗过程中，牙髓腔底穿孔是常遇到的情况。如果穿孔较大，肉芽组织会生长形成牙周息肉。肉芽组织由增殖细胞组成，但其来源尚不清楚。研究表明，肉芽组织中的细胞主要来自骨髓未分化间充质细胞的迁移。因此，本研究利用绿色荧光蛋白（GFP）骨髓移植小鼠模型。使用1/2号牙科圆钻在上颌第一磨牙的牙髓腔底穿孔。通过显微CT和显微镜进行形态学评估，并使用GFP-S100A4、GFP-Runx2和GFP-CD31双荧光染色的免疫组织化学方法进一步评估GFP细胞机制。显微CT结果显示牙槽骨吸收和牙周膜增宽。组织病理学检查显示肉芽组织中有成纤维细胞、一些圆形细胞和血管增殖。2周时，肉芽组织的最外层由具有明显细胞间桥的鳞状细胞排列。4周时，肉芽组织变得比穿孔大，最外层由相对典型的复层鳞状上皮排列。GFP和Runx2的双重免疫荧光染色显示，两种蛋白均在梭形细胞中表达。GFP和CD31的双重免疫荧光染色显示，两种蛋白均在形态上不同的血管中的血管内皮细胞中表达。结果表明，肉芽组织中的成纤维细胞、牙周膜成纤维细胞和血管均来源于移植的骨髓细胞。因此，牙周息肉中肉芽组织的重要生长是由骨髓来源的未分化间充质细胞迁移引起的，这些细胞分化为成纤维细胞，随后在损伤反应中分化为其他细胞。
