Glass W F, Teng P R, Haney L B
Department of Pathology, University of Virginia Health Sciences Center, Charlottesville 22908, USA.
J Am Soc Nephrol. 1996 Oct;7(10):2230-43. doi: 10.1681/ASN.V7102230.
Smooth muscle cell and mesangial cell hillock formation have been proposed as in vitro models of vascular sclerosis and glomerular sclerosis. This growth pattern is characterized by multilayered ridges and nodules, termed hills or hillocks, separated by less populated areas termed valleys. In this study, it was discovered that an extracellular matrix rich in pericellular fibronectin-fibrils was key to hillock formation. Human mesangial cells were plated onto serum-coated or noncoated substrata in serum-free medium. Subconfluent cells on serum-coated substrata migrated together, forming aggregates, but cells on noncoated substrata remained evenly dispersed. When plated at confluent densities, cells in serum-coated dishes formed hillocks, but cells in noncoated dishes did not. In serum-coated dishes, the substratum underlying subconfluent cells was vitronectin-rich but fibronectin-poor, whereas the pericellular matrix contained abundant fibronectin fibrils. In contrast, the substratum of subconfluent cells plated in noncoated dishes lacked vitronectin but was fibronectin-rich, whereas the pericellular matrix contained few fibronectin fibrils. The distributions of integrin receptors for fibronectin (rabbit anti-alpha 5 beta 1) and vitronectin (rabbit anti-alpha V, beta 3, and beta 5) followed the distributions of their ligands, fibronectin and vitronectin, respectively. Antibodies to fibronectin blocked hillock formation by cells on serum-coated substrata and prevented spreading of cells on noncoated substrata. In summary, key steps in hillock formation are: (1) migration, (2) secretion of fibronectin and assembly of pericellular fibrils, (3) fibronectin fibril-mediated cell-cell adhesion, and (4) aggregation of cells with further migration to form multiple layers. A similar mechanism may play a role in vascular and glomerular sclerosis.
平滑肌细胞和系膜细胞小丘形成已被提出作为血管硬化和肾小球硬化的体外模型。这种生长模式的特征是多层嵴和结节，称为小丘，由人口较少的区域（称为山谷）分隔。在本研究中，发现富含细胞周围纤连蛋白原纤维的细胞外基质是小丘形成的关键。将人系膜细胞接种到无血清培养基中包被血清或未包被的基质上。包被血清基质上的亚汇合细胞一起迁移，形成聚集体，但未包被基质上的细胞保持均匀分散。以汇合密度接种时，包被血清培养皿中的细胞形成小丘，但未包被培养皿中的细胞不形成。在包被血清的培养皿中，亚汇合细胞下方的基质富含玻连蛋白但纤连蛋白含量低，而细胞周围基质含有丰富的纤连蛋白原纤维。相比之下，接种在未包被培养皿中的亚汇合细胞的基质缺乏玻连蛋白但富含纤连蛋白，而细胞周围基质含有很少的纤连蛋白原纤维。纤连蛋白（兔抗α5β1）和玻连蛋白（兔抗αV、β3和β5）的整合素受体分布分别遵循其配体纤连蛋白和玻连蛋白的分布。抗纤连蛋白抗体可阻断包被血清基质上细胞的小丘形成，并阻止细胞在未包被基质上的铺展。总之，小丘形成的关键步骤是：（1）迁移，（2）纤连蛋白的分泌和细胞周围原纤维的组装，（3）纤连蛋白原纤维介导的细胞间粘附，以及（4）细胞聚集并进一步迁移形成多层。类似的机制可能在血管和肾小球硬化中起作用。
