Histological and functional analysis of vascular smooth muscle cells in a novel culture system with honeycomb-like structure

Vascular smooth muscle cells (SMCs) undergo phenotype change with the devel opment of atherosclerosis. The phenotype changes of SMCs have been observed in various culture conditions, such as collagen-coated dishes. Here, we re port the morphological and functional features of SMCs in a novel culture s ystem using type I-collagen in a characteristic three-dimensional structure designated as honeycombs. The number of ribosome and mitochondria in SMCs cultured in honeycombs was one half or third of those cultured on collagen- coated plastic plates. DNA and protein synthesis of SMCs cultured in honeyc ombs were less than 1 and 30-40%, respectively, of those cultured on plasti c plates. In addition, PDGF-BB did not increase the amount of DNA synthesis in SMCs in honeycombs. SMCs in honeycombs were shown to express several pr oteins, which are known to express in SMCs in medial layers of arteries. Pa rticularly, caldesmon heavy chain was expressed in SMCs cultured in honeyco mbs, whereas not in those on plastic plates. Although focal adhesion kinase (FAK) was clearly detected in SMCs in honeycomb, the phosphotyrosine conte nt of focal adhesion kin ase decreased in the process of culture. Immunoblo t analysis showed dear different expression of ERK1 and ERK2 of mitogen-act ivated protein kinase in SMCs. SMCs in honeycombs expressed ERK2, more abun dantly compared to ERK1, whereas SMCs in plates show the same levels of exp ressions for both proteins. Thus, the histological and functional feature o f SMCs in the novel culture system is different from SMCs in plastic plates . The three-dimensional culture system described here may be indicating tha t cultured SMCs are able to express different proteins responding to the su rrounding structures. (C) 2001 Elsevier Science Ireland Ltd. All rights res erved.