Verkoelen C F, van der Boom B G, Kok D J, Houtsmuller A B, Visser P, Schröder F H, Romijn J C
Department of Urology, Erasmus University, Rotterdam, The Netherlands.
Kidney Int. 1999 Apr;55(4):1426-33. doi: 10.1046/j.1523-1755.1999.00383.x.
Adherence of crystals to the surface of renal tubule epithelial cells is considered an important step in the development of nephrolithiasis. Previously, we demonstrated that functional monolayers formed by the renal tubule cell line, Madin-Darby canine kidney (MDCK), acquire protection against the adherence of calcium oxalate monohydrate crystals. We now examined whether this property is cell type specific. The susceptibility of the cells to crystal binding was further studied under different culture conditions.
Cell-type specificity and the influence of the growth substrate was tested by comparing calcium oxalate monohydrate crystal binding to LLC-PK1 cells and to two MDCK strains cultured on either permeable or impermeable supports. These cell lines are representative for the renal proximal tubule (LLC-PK1) and distal tubule/collecting duct (MDCK) segments of the nephron, in which crystals are expected to be absent and present, respectively.
Whereas relatively large amounts of crystals adhered to subconfluent MDCK cultures, the level of crystal binding to confluent monolayers was reduced for both MDCK strains. On permeable supports, MDCK cells not only obtained a higher level of morphological differentiation, but also acquired a higher degree of protection than on impermeable surfaces. Crystals avidly adhered to LLC-PK1 cells, irrespective of their developmental stage or growth substrate used.
These results show that the prevention of crystal binding is cell type specific and expressed only by differentiated MDCK cells. The anti-adherence properties acquired by MDCK cells may mirror a specific functional characteristic of its in situ equivalent, the renal distal tubule/collecting ducts.
晶体黏附于肾小管上皮细胞表面被认为是肾结石形成过程中的一个重要步骤。此前，我们证明了由肾小管细胞系马-达二氏犬肾（MDCK）形成的功能性单层细胞可获得对一水合草酸钙晶体黏附的保护作用。我们现在研究了这种特性是否具有细胞类型特异性。在不同培养条件下进一步研究了细胞对晶体结合的敏感性。
通过比较一水合草酸钙晶体与LLC-PK1细胞以及在可渗透或不可渗透支持物上培养的两种MDCK菌株的结合情况，测试细胞类型特异性和生长底物的影响。这些细胞系分别代表肾单位的近端小管（LLC-PK1）和远端小管/集合管（MDCK）节段，预计在前者中不存在晶体，而在后者中存在晶体。
尽管相对大量的晶体黏附于亚汇合的MDCK培养物，但两种MDCK菌株中晶体与汇合单层细胞的结合水平均降低。在可渗透支持物上，MDCK细胞不仅获得了更高水平的形态分化，而且比在不可渗透表面上获得了更高程度的保护。晶体 avidly 黏附于LLC-PK1细胞，无论其发育阶段或所用的生长底物如何。
这些结果表明，防止晶体结合具有细胞类型特异性，并且仅由分化的MDCK细胞表达。MDCK细胞获得的抗黏附特性可能反映了其原位等效物肾远端小管/集合管的特定功能特征。
