In situ measurement of solute transport in the bone lacunar-canalicular system
In situ measurement of solute transport in the bone lacunar-canalicular system
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DOI：
10.1073/pnas.0505193102
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发表时间：
2005-08-16
影响因子：
11.1
通讯作者：
Schaffler, MB
中科院分区：
文献类型：
--
作者：
Wang, LY;Wang, YL;Schaffler, MB
通过骨腔隙-小管系统的溶质运输被认为是骨细胞存活和功能所必需的，但已证明难以测量。我们报告的方法，允许直接测量的实时溶质运动在完整的骨骼。通过使用光漂白后的荧光恢复，一个充满活力的注射荧光染料（荧光素钠）的运动在个别骨细胞陷窝可视化在小鼠皮质骨的骨膜表面下的深度高达50 μ m的激光扫描共聚焦显微镜原位。运输进行了分析，通过使用一个两室的溶质扩散的数学模型，占特征的腔隙-小管系统的解剖特征。荧光素（376 Da）的扩散系数测定为3.3 +/- 0.6 × 10（-6）cm 2/sec，这是其在水中扩散系数的62%，与软骨中微尺寸分子的扩散系数相似。荧光素在骨中的扩散也与骨细胞细胞周基质的存在一致，所述骨细胞细胞周基质的结构类似于为内皮糖萼提出的结构[Squire，J.M.，Chew，M.，Nneji，G.，尼尔，C.，巴里，J.&米歇尔，C.等（2001）J.Struct.Biol.136，239-255]。据我们所知，这是第一次直接在骨腔隙-小管系统中测量分子运动的动力学。这种原位成像方法也有助于分析活体动物骨骼中基于对流的运输机制。
Solute transport through the bone lacunar-canalicular system is believed to be essential for osteocyte survival and function but has proved difficult to measure. We report an approach that permits direct measurement of real-time solute movement in intact bones. By using fluorescence recovery after photobleaching, the movement of a vitally injected fluorescent dye (sodium fluorescein) among individual osteocytic lacunae was visualized in situ beneath the periosteal surface of mouse cortical bone at depths up to 50 mu m with laser scanning confocal microscopy. Transport was analyzed by using a two-compartment mathematical model of solute diffusion that accounted for the characteristic anatomical features of the lacunar-canalicular system. The diffusion coefficient of fluorescein (376 Da) was determined to be 3.3 +/- 0.6 x 10(-6) CM2 /sec, which is 62% of its diffusion coefficient in water and is similar to diffusion coefficients measured for comparably sized molecules in cartilage. The diffusion of fluorescein in bone is also consistent with the presence of an osteocyte pericellular matrix whose structure resembles that proposed for the endothelial glycocalyx [Squire, J. M., Chew, M., Nneji, G., Neal, C., Barry, J. & Michel, C. (2001) J. Struct. Biol. 136, 239-255]. To our knowledge, this is the first instance where the dynamics of molecular movement has been measured directly in the bone lacunar-canalicular system. This in situ imaging approach should also facilitate the analysis of convection-based transport mechanisms in bones of living animals.