Suswillo Rosemary F L, Javaheri Behzad, Rawlinson Simon C F, Dowthwaite Gary P, Lanyon Lance E, Pitsillides Andrew A
Comparative Biomedical Sciences, Royal Veterinary College, London, UK.
Institute of Dentistry, Barts & The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.
Cell Biochem Funct. 2017 Jan;35(1):56-65. doi: 10.1002/cbf.3245.
Identifying mechanisms by which cells of the osteoblastic lineage communicate in vivo is complicated by the mineralised matrix that encases osteocytes, and thus, vital mechanoadaptive processes used to achieve load-bearing integrity remain unresolved. We have used the coculture of immunomagnetically purified osteocytes and primary osteoblasts from both embryonic chick long bone and calvariae to examine these mechanisms. We exploited the fact that purified osteocytes are postmitotic to examine both their effect on proliferation of primary osteoblasts and the role of gap junctions in such communication. We found that chick long bone osteocytes significantly increased basal proliferation of primary osteoblasts derived from an identical source (tibiotarsi). Using a gap junction inhibitor, 18β-glycyrrhetinic acid, we also demonstrated that this osteocyte-related increase in osteoblast proliferation was not reliant on functional gap junctions. In contrast, osteocytes purified from calvarial bone failed to modify basal proliferation of primary osteoblast, but long bone osteocytes preserved their proproliferative action upon calvarial-derived primary osteoblasts. We also showed that coincubated purified osteocytes exerted a marked inhibitory action on mechanical strain-related increases in proliferation of primary osteoblasts and that this action was abrogated in the presence of a gap junction inhibitor. These data reveal regulatory differences between purified osteocytes derived from functionally distinct bones and provide evidence for 2 mechanisms by which purified osteocytes communicate with primary osteoblasts to coordinate their activity.
识别成骨细胞谱系细胞在体内进行通讯的机制，因包裹骨细胞的矿化基质而变得复杂，因此，用于实现承重完整性的重要机械适应性过程仍未得到解决。我们利用免疫磁珠纯化的来自胚胎期鸡长骨和颅骨的骨细胞与原代成骨细胞共培养来研究这些机制。我们利用纯化的骨细胞已停止有丝分裂这一事实，来研究它们对原代成骨细胞增殖的影响以及缝隙连接在此类通讯中的作用。我们发现，鸡长骨骨细胞显著增加了源自相同来源（胫跗骨）的原代成骨细胞的基础增殖。使用缝隙连接抑制剂18β-甘草次酸，我们还证明，这种与骨细胞相关的成骨细胞增殖增加并不依赖于功能性缝隙连接。相比之下，从颅骨纯化的骨细胞未能改变原代成骨细胞的基础增殖，但长骨骨细胞对源自颅骨的原代成骨细胞保留了其促增殖作用。我们还表明，共孵育的纯化骨细胞对原代成骨细胞机械应变相关的增殖增加具有显著的抑制作用，并且在存在缝隙连接抑制剂的情况下这种作用被消除。这些数据揭示了源自功能不同骨骼的纯化骨细胞之间的调节差异，并为纯化骨细胞与原代成骨细胞通讯以协调其活动的两种机制提供了证据。
