Inoue Satoshi, Otsuka Hirotada, Takito Jiro, Nakamura Masanori
Department of Oral Anatomy and Developmental Biology, Showa University School of Dentistry, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo 142-8555, Japan.
Bone Rep. 2017 Nov 24;8:1-8. doi: 10.1016/j.bonr.2017.11.003. eCollection 2018 Jun.
Fractures are common traumatic injuries that mainly occur in the metaphyses of long bones such as the proximal humerus, distal radius, and proximal femur. However, most studies of fracture repair processes have focused on the diaphyseal region. In this study, we compared the bone repair processes of the metaphysis and the diaphysis of the mouse tibia. Bone apertures were formed in the tibial metaphysis and diaphysis. At indicated times after surgery, samples were collected, and the healing process was investigated using micro-computed tomography, as well as histological, immunohistochemical, and mRNA expression analyses. In the metaphysis, cartilage formation was not detected on the periosteal side. The bone aperture was filled with newly formed bone produced from bone marrow at day 7. In the case of the diaphysis, cartilage was formed around the aperture at day 4 and sequentially replaced by bone on the periosteal side. The bone aperture was filled with newly formed bone at day 14. In the bone marrow, expression of the osteogenic markers such as alkaline phosphatase, osteocalcin, and type I collagen, appeared earlier with metaphyseal injury than with diaphyseal injury. The mRNA expression of chondrogenesis markers was markedly upregulated in the diaphysis compared with that in the metaphysis on the periosteal side. These results indicate differences in the bone repair processes of the two regions, suggesting functional heterogeneity of the periosteum and bone marrow mesenchymal cells in response to bone fractures.
骨折是常见的创伤性损伤，主要发生在长骨的干骺端，如肱骨近端、桡骨远端和股骨近端。然而，大多数关于骨折修复过程的研究都集中在骨干区域。在本研究中，我们比较了小鼠胫骨干骺端和骨干的骨修复过程。在胫骨干骺端和骨干形成骨缺损。在手术后的指定时间收集样本，并使用微计算机断层扫描以及组织学、免疫组织化学和mRNA表达分析来研究愈合过程。在干骺端，骨膜侧未检测到软骨形成。在第7天，骨缺损被骨髓产生的新形成的骨填充。在骨干的情况下，在第4天在缺损周围形成软骨，并在骨膜侧依次被骨替代。在第14天，骨缺损被新形成的骨填充。在骨髓中，与骨干损伤相比，干骺端损伤时成骨标志物如碱性磷酸酶、骨钙素和I型胶原的表达出现得更早。与干骺端骨膜侧相比，骨干中软骨形成标志物的mRNA表达明显上调。这些结果表明两个区域的骨修复过程存在差异，提示骨膜和骨髓间充质细胞在应对骨折时的功能异质性。
