National Clinical Research Center of Stomatology, Department of Endodontics, School of Medicine, Shanghai Key Laboratory of Stomatology & Shanghai Research Institute of Stomatology, Ninth People's Hospital, Shanghai Jiaotong University, Shanghai, China.
Developmental Biology of Hard Tissue, Graduate School of Dental Medicine, Faculty of Dental Medicine, Hokkaido University, Kita 13 Nishi 7 Kita-ku, Sapporo, 060-8586, Japan.
Calcif Tissue Int. 2021 Mar;108(3):391-406. doi: 10.1007/s00223-020-00776-2. Epub 2020 Nov 10.
To verify whether PTH acts on bone-specific blood vessels and on cells surrounding these blood vessels, 6-week-old male mice were subjected to vehicle (control group) or hPTH [1-34] (20 µg/kg/day, PTH group) injections for 2 weeks. Femoral metaphyses were used for histochemical and immunohistochemical studies. In control metaphyses, endomucin-positive blood vessels were abundant, but αSMA-reactive blood vessels were scarce. In the PTH-administered mice, the lumen of endomucin-positive blood vessels was markedly enlarged. Moreover, many αSMA-positive cells were evident near the blood vessels, and seemed to derive from those vessels. These αSMA-positive cells neighboring the blood vessels showed features of mesenchymal stromal cells, such as immunopositivity for c-kit and tissue nonspecific alkaline phosphatase (TNALP). Thus, PTH administration increased the population of perivascular/stromal cells positive for αSMA and c-kit, which were likely committed to the osteoblastic lineage. To understand the cellular events that led to increased numbers and size of bone-specific blood vessels, we performed immunohistochemical studies for PTH/PTHrP receptor and VEGF. After PTH administration, PTH/PTHrP receptor, VEGF and its receptor flk-1 were consistently identified in both osteoblasts and blood vessels (endothelial cells and surrounding perivascular cells). Our findings suggest that exogenous PTH increases the number and size of bone-specific blood vessels while fostering perivascular/stromal cells positive for αSMA/TNALP/c-kit.
为了验证 PTH 是否作用于骨特异性血管及其周围细胞，将 6 周龄雄性小鼠接受 vehicle（对照组）或 hPTH[1-34]（20μg/kg/天，PTH 组）注射 2 周。使用股骨干骺端进行组织化学和免疫组织化学研究。在对照组干骺端，内粘蛋白阳性血管丰富，但αSMA 反应性血管很少。在给予 PTH 的小鼠中，内粘蛋白阳性血管的管腔明显扩大。此外，血管附近有许多 αSMA 阳性细胞，似乎来源于这些血管。这些血管周围的 αSMA 阳性细胞具有间充质基质细胞的特征，如对 c-kit 和组织非特异性碱性磷酸酶（TNALP）的免疫阳性。因此，PTH 给药增加了 αSMA 和 c-kit 阳性的血管周围/基质细胞的数量，这些细胞可能属于成骨细胞系。为了了解导致骨特异性血管数量和大小增加的细胞事件，我们进行了 PTH/PTHrP 受体和 VEGF 的免疫组织化学研究。给予 PTH 后，PTH/PTHrP 受体、VEGF 及其受体 flk-1 均在成骨细胞和血管（内皮细胞和周围血管周围细胞）中一致鉴定。我们的研究结果表明，外源性 PTH 增加了骨特异性血管的数量和大小，同时促进了αSMA/TNALP/c-kit 阳性的血管周围/基质细胞。
