Tamura Shogo, Mukaide Masato, Katsuragi Yumi, Fujii Wataru, Odaira Koya, Suzuki Nobuaki, Tsukiji Nagaharu, Okamoto Shuichi, Suzuki Atsuo, Kanematsu Takeshi, Katsumi Akira, Takagi Akira, Ikeda Katsuhide, Ueyama Jun, Hirayama Masaaki, Suzuki-Inoue Katsue, Matsushita Tadashi, Kojima Tetsuhito, Hayakawa Fumihiko
Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan.
Department of Integrated Health Sciences, Nagoya University Graduate School of Medicine, Nagoya, Japan.
J Biol Chem. 2022 May;298(5):101833. doi: 10.1016/j.jbc.2022.101833. Epub 2022 Mar 15.
Bone marrow development and endochondral bone formation occur simultaneously. During endochondral ossification, periosteal vasculatures and stromal progenitors invade the primary avascular cartilaginous anlage, which induces primitive marrow development. We previously determined that bone marrow podoplanin (PDPN)-expressing stromal cells exist in the perivascular microenvironment and promote megakaryopoiesis and erythropoiesis. In this study, we aimed to examine the involvement of PDPN-expressing stromal cells in postnatal bone marrow generation. Using histological analysis, we observed that periosteum-derived PDPN-expressing stromal cells infiltrated the cartilaginous anlage of the postnatal epiphysis and populated on the primitive vasculature of secondary ossification center. Furthermore, immunophenotyping and cellular characteristic analyses indicated that the PDPN-expressing stromal cells constituted a subpopulation of the skeletal stem cell lineage. In vitro xenovascular model cocultured with human umbilical vein endothelial cells and PDPN-expressing skeletal stem cell progenies showed that PDPN-expressing stromal cells maintained vascular integrity via the release of angiogenic factors and vascular basement membrane-related extracellular matrices. We show that in this process, Notch signal activation committed the PDPN-expressing stromal cells into a dominant state with basement membrane-related extracellular matrices, especially type IV collagens. Our findings suggest that the PDPN-expressing stromal cells regulate the integrity of the primitive vasculatures in the epiphyseal nascent marrow. To the best of our knowledge, this is the first study to comprehensively examine how PDPN-expressing stromal cells contribute to marrow development and homeostasis.
骨髓发育和软骨内成骨同时发生。在软骨内骨化过程中，骨膜血管和基质祖细胞侵入初级无血管软骨原基，从而诱导原始骨髓发育。我们之前确定，表达骨髓血小板内皮细胞黏附分子（PDPN）的基质细胞存在于血管周围微环境中，并促进巨核细胞生成和红细胞生成。在本研究中，我们旨在研究表达PDPN的基质细胞在出生后骨髓生成中的作用。通过组织学分析，我们观察到源自骨膜的表达PDPN的基质细胞浸润出生后骨骺的软骨原基，并聚集在次级骨化中心的原始血管上。此外，免疫表型分析和细胞特征分析表明，表达PDPN的基质细胞构成了骨骼干细胞谱系的一个亚群。与人类脐静脉内皮细胞和表达PDPN的骨骼干细胞后代共培养的体外异种血管模型表明，表达PDPN的基质细胞通过释放血管生成因子和血管基底膜相关的细胞外基质来维持血管完整性。我们发现，在此过程中，Notch信号激活使表达PDPN的基质细胞进入与基底膜相关的细胞外基质（尤其是IV型胶原）占主导的状态。我们的研究结果表明，表达PDPN的基质细胞调节骨骺新生骨髓中原始血管的完整性。据我们所知，这是第一项全面研究表达PDPN的基质细胞如何促进骨髓发育和稳态的研究。
