Microstructures of Randall's plaques and their interfaces with calcium oxalate monohydrate kidney stones reflect underlying mineral precipitation mechanisms
Microstructures of Randall's plaques and their interfaces with calcium oxalate monohydrate kidney stones reflect underlying mineral precipitation mechanisms
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DOI：
10.1007/s00240-016-0925-2
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发表时间：
2017-06-01
期刊：
影响因子：
3.1
通讯作者：
Kleebe, Hans-Joachim
中科院分区：
文献类型：
--
作者：
Sethmann, Ingo;Wendt-Nordahl, Gunnar;Kleebe, Hans-Joachim
兰德尔氏斑（RP）是草酸钙一水合物（COM）肾结石形成的首选部位。然而，虽然间质磷酸钙（CaP）斑块形成的过程还没有得到很好的理解，斑块微观结构作为CaP沉淀条件的指标的潜力只得到了有限的关注。我们研究了RP相关的COM结石的钙化组织的结构细节和斑块-结石界面的微结构特征，作为结石形成的初始过程的指标。如果来自肾小管系统的重吸收离子持续扩散到胶原结缔组织中，则可以预期间质液的CaP过饱和度显著增加。密集包装，细粒CaP颗粒被发现在致密的基底膜纹理，而较大的，分层颗粒分散在粗网格间质组织，我们建议是由于差分空间限制和离子扩散的限制。颗粒形态表明初始沉淀为亚稳态无定形磷酸钙（ACP）。第一COM晶体的RP-石头界面处的形态和排列范围从堆叠的自形体血小板到骨架形态，甚至多孔的树枝状结构，这表明，在这个顺序中，增加COM过饱和度的水平。此外，这些第一COM晶体通常被CaP包覆。在此基础上，我们提出，离子从钙磷过饱和间质液可能会扩散通过多孔RP到尿液中，在COM过饱和度的局部增加，从而引发晶体成核，因此，启动结石形成。初始COM层的持久孔隙中的离子贫化流体可以从间隙流体得到补充，导致多孔COM中的CaP沉淀。
Randall's plaques (RP) are preferred sites for the formation of calcium oxalate monohydrate (COM) kidney stones. However, although processes of interstitial calcium phosphate (CaP) plaque formation are not well understood, the potential of plaque microstructures as indicators of CaP precipitation conditions received only limited attention. We investigated RP-associated COM stones for structural details of the calcified tissues and microstructural features of plaque-stone interfaces as indicators of the initial processes of stone formation. Significantly increased CaP supersaturation can be expected for interstitial fluid, if reabsorbed ions from the tubular system continuously diffuse into the collagenous connective tissue. Densely packed, fine-grained CaP particles were found in dense textures of basement membranes while larger, laminated particles were scattered in coarse-meshed interstitial tissue, which we propose to be due to differential spatial confinements and restrictions of ion diffusion. Particle morphologies suggest an initial precipitation as metastable amorphous calcium phosphate (ACP). Morphologies and arrangements of first COM crystals at the RP-stone interface ranged from stacked euhedral platelets to skeletal morphologies and even porous, dendritic structures, indicating, in this order, increasing levels of COM supersaturation. Furthermore, these first COM crystals were often coated with CaP. On this basis, we propose that ions from CaP-supersaturated interstitial fluid may diffuse through porous RP into the urine, where a resulting local increase in COM supersaturation could trigger crystal nucleation and, hence, initiate stone formation. Ion-depleted fluid in persistent pores of initial COM layers may get replenished from interstitial fluid, leading to CaP precipitation in porous COM.