Mesenchymal Dental Pulp Cells Attenuate Dentin Resorption in Homeostasis
Mesenchymal Dental Pulp Cells Attenuate Dentin Resorption in Homeostasis
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DOI：
10.1177/0022034515575347
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发表时间：
2015-06-01
影响因子：
7.6
通讯作者：
Mao, J. J.
中科院分区：
文献类型：
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作者：
Zheng, Y.;Chen, M.;Mao, J. J.
恒牙中的牙本质在发育、动态平衡或衰老过程中很少发生吸收，而骨骼则经历周期性的吸收/重塑。作者假设牙髓间充质间室中的细胞减弱了破骨细胞的形成。从供体匹配的大鼠牙髓(DPCS)和牙槽骨(ABCs)分离出单核细胞和贴壁细胞，分别与原代大鼠脾细胞共培养。原代脾细胞在含有20 ng/m L巨噬细胞集落刺激因子(M-CSF)和50 ng/m L核因子B受体激活剂(RANKL)的化学成分的破骨细胞新生液中容易聚集并形成破骨细胞样细胞。值得注意的是，当DPC与原代脾细胞共同培养时，DPC减弱了破骨细胞的生成，而ABCs轻微但显著地促进了破骨细胞的生成。与供者匹配的ABCs相比，DPC的RANKL表达降低了20倍，但骨保护素(OPG)的表达增加了2倍，RANKL/OPG比率为41：1(ABCs：DPC)。维生素D3显著促进ABCs和DPC中RANKL的表达。在活体中，大鼠上颌切牙被无损伤地拔除(没有任何牙齿断裂)，然后逆行牙髓切除以移除DPC并立即重新植入拔牙窝内，以允许手术治疗的根管内重新填充牙周和牙槽骨来源的细胞。8wk后，根牙本质中出现多个牙本质/牙根吸收陷窝，RANKL和OPG表达较强。在观察的8wk内，牙本质表面可见牙本质退变区和成骨区交替出现。这些发现表明，间充质间隔区的DPC具有抑制破骨细胞生成的先天能力，这种先天能力可能是导致牙本质在动态平衡中缺乏吸收的原因。牙本质吸收的间质衰减可能与正畸牙齿移动中的根管内吸收、牙髓/牙本质再生和牙根吸收有关。
Dentin in permanent teeth rarely undergoes resorption in development, homeostasis, or aging, in contrast to bone that undergoes periodic resorption/remodeling. The authors hypothesized that cells in the mesenchymal compartment of dental pulp attenuate osteoclastogenesis. Mononucleated and adherent cells from donor-matched rat dental pulp (dental pulp cells [DPCs]) and alveolar bone (alveolar bone cells [ABCs]) were isolated and separately cocultured with primary rat splenocytes. Primary splenocytes readily aggregated and formed osteoclast-like cells in chemically defined osteoclastogenesis medium with 20 ng/mL of macrophage colony-stimulating factor (M-CSF) and 50 ng/mL of receptor activator of nuclear factor B ligand (RANKL). Strikingly, DPCs attenuated osteoclastogenesis when cocultured with primary splenocytes, whereas ABCs slightly but significantly promoted osteoclastogenesis. DPCs yielded similar to 20-fold lower RANKL expression but >2-fold higher osteoprotegerin (OPG) expression than donor-matched ABCs, yielding a RANKL/OPG ratio of 41:1 (ABCs:DPCs). Vitamin D3 significantly promoted RANKL expression in ABCs and OPG in DPCs. In vivo, rat maxillary incisors were atraumatically extracted (without any tooth fractures), followed by retrograde pulpectomy to remove DPCs and immediate replantation into the extraction sockets to allow repopulation of the surgically treated root canal with periodontal and alveolar bone-derived cells. After 8 wk, multiple dentin/root resorption lacunae were present in root dentin with robust RANKL and OPG expression. There were areas of dentin resoprtion alternating with areas of osteodentin formation in root dentin surface in the observed 8 wk. These findings suggest that DPCs of the mesenchymal compartment have an innate ability to attenuate osteoclastogenesis and that this innate ability may be responsible for the absence of dentin resorption in homeostasis. Mesenchymal attenuation of dentin resorption may have implications in internal resorption in the root canal, pulp/dentin regeneration, and root resorption in orthodontic tooth movement.