Network architecture strongly influences the fluid flow pattern through the lacunocanalicular network in human osteons
Network architecture strongly influences the fluid flow pattern through the lacunocanalicular network in human osteons
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DOI：
10.1007/s10237-019-01250-1
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发表时间：
2019-11-28
影响因子：
3.5
通讯作者：
Weinkamer, Richard
中科院分区：
文献类型：
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作者：
van Tol, Alexander F.;Roschger, A.;Weinkamer, Richard
一种流行的假说解释了骨骼的机械敏感性是由于骨细胞感知负载引起的间质液挤压通过腔隙小管网络（LCN）而产生的。然而，LCN 的复杂结构影响通过网络的液体流动的方式在很大程度上尚未被探索。因此，我们的目标是结合实验和计算技术来量化通过人体骨的真实 LCN 的流体流量。骨样本用罗丹明染色，通过 3D 共焦显微镜对 LCN 进行成像。然后进行图像分析，将图像堆栈转换为数学网络结构，以便使用液压回路理论估计骨的固有渗透性以及负载引起的流体流动。研究了具有相当均匀的 LCN 的普通骨和骨中常见亚型（所谓的骨中骨）的流体流动，其特征是这些骨的内部和外部之间存在低网络连接的环状区域。我们分析了一名 57 岁女性股骨中轴的 8 块普通骨和 9 块骨中骨，该女性没有任何已知疾病。与普通骨相比，骨中骨的固有渗透性小 2.7 倍，但负载引起的流体速度却高 2.3 倍。骨中骨中流体速度的增加可以用更长的路径长度来解释，从骨水泥线穿过骨到哈弗氏管所需的路径长度更长，包括更多充满液体的腔隙和小管。这一解释得到了观察的证实，即纯结构参数（哈弗运河的平均路径长度）是平均流体流速的极好预测因子。我们得出的结论是，骨中骨可能对皮质骨的机械敏感性有特别重要的贡献，因为这种类型的骨中的流体流量较高。
A popular hypothesis explains the mechanosensitivity of bone due to osteocytes sensing the load-induced flow of interstitial fluid squeezed through the lacunocanalicular network (LCN).However, the way in which the intricate structure of the LCN influences fluid flow through the network is largely unexplored. We therefore aimed to quantify fluid flow through real LCNs from human osteons using a combination of experimental and computational techniques. Bone samples were stained with rhodamine to image the LCN with 3D confocal microscopy. Image analysis was then performed to convert image stacks into mathematical network structures, in order to estimate the intrinsic permeability of the osteons as well as the load-induced fluid flow using hydraulic circuit theory. Fluid flow was studied in both ordinary osteons with a rather homogeneous LCN as well as a frequent subtype of osteons-so-called osteon-in-osteons-which are characterized by a ring-like zone of low network connectivity between the inner and the outer parts of these osteons. We analyzed 8 ordinary osteons and 9 osteon-in-osteons from the femur midshaft of a 57-year-old woman without any known disease. While the intrinsic permeability was 2.7 times smaller in osteon-in-osteons compared to ordinary osteons, the load-induced fluid velocity was 2.3 times higher. This increased fluid velocity in osteon-in-osteons can be explained by the longer path length, needed to cross the osteon from the cement line to the Haversian canal, including more fluid-filled lacunae and canaliculi. This explanation was corroborated by the observation that a purely structural parameter-the mean path length to the Haversian canal-is an excellent predictor for the average fluid flow velocity. We conclude that osteon-in-osteons may be particularly significant contributors to the mechanosensitivity of cortical bone, due to the higher fluid flow in this type of osteons.