Abstract-Versican is an extracellular matrix (ECM) proteoglycan that is synthesized as multiple splice variants. In a recent study, we demonstrated that retroviral-mediated overexpression of the variant V3, which lacks chondroitin sulfate (CS) chains, altered arterial smooth muscle cell (ASMC) phenotype in short-term cell culture. We now report that V3-overexpressing ASMCs exhibit significantly increased expression of tropoelastin and increased formation of elastic fibers in long-term cell cultures. In addition, V3-overexpressing ASMCs seeded into ballooned rat carotid arteries continued to overexpress V3 and, at 4 weeks after seeding, produced a highly structured neointima significantly enriched in elastic fiber lamellae. In contrast to the hydrated, myxoid neointima produced by rounded or stellate vector-alonetransduced cells, V3-expressing cells produced a compact and highly ordered neointima, which contained elongated ASMCs that were arranged in parallel arrays and separated by densely packed collagen bundles and elastic fibers. These results indicate that a variant of versican is involved in elastic fiber assembly and may represent a novel therapeutic approach to facilitate the formation of elastic fibers. T he extracellular matrix (ECM) proteoglycan versican, the major chondroitin sulfate proteoglycan of vessel wall, 1 is distinguished by a central extended region with attached glycosaminoglycan (GAG) chains by an amino-terminal globular domain (G1) that binds hyaluronan (HA) and by a carboxy-terminal selectin-like domain (G3) that binds to other matrix components including tenascin-R and fibulin-1. [2][3][4][5][6] The mRNA that codes the GAG attachment region, which in the full-length form has 2 domains, can undergo differential splicing to produce 4 variants: V0, with 2 (␣ and ) GAG binding regions; V1 (with the  GAG exon); V2 (with the ␣ GAG exon); and V3 with neither GAG exon and formed from the G1 and G3 domains only. 7-9 V3 is thus predicted to be a glycoprotein and not a proteoglycan. V3 mRNA has been demonstrated in aortic tissue as well as cultures of ASMCs by Northern blot 10 and has been detected, by polymerase chain reaction (PCR), from cDNA libraries for various tissues including brain, stomach, and liver. 9 Recently, we reported that retroviral insertion and overexpression of the gene for V3 into cultured Fischer rat ASMCs induces a number of phenotypic changes. 11 Compared with vector-alone-transduced cells, V3 ASMCs are more flattened and spread, show a large increase in area of close contacts and in the size of peripheral focal contacts, increased resistance to trypsin detachment, reduced pericellular coats, and decreased rates of growth and migration. The mechanism by which V3 effects these changes is not clear, although the morphological features, the reduced growth and migration, and the reduced cell coat, raise the possibility that V3 may affect the accumulation of components of the extracellular matrix. For example, Evanko et al 12 showed recently that the V1 isoform of versican in ...