Normal patterns of angiogenesis and extracellular matrix deposition in chick chorioallantoic membranes are disrupted by mainstream and sidestream cigarette smoke.

The adverse effects of cigarette smoke on mature blood vessels are well established, whereas little is known about the influence of smoke on blood vessel development. To determine if cigarette smoke alters angiogenesis, chick chorioallantoic membranes (CAMs) were exposed for 4 days to culture medium (control) or to mainstream (MS) or sidestream (SS) smoke solution, and then blood vessel patterns were compared in blind tests. In contrast to the normal tree-like branching of control blood vessels, smoke-treated CAMs often had vessels that ran parallel to each other without much branching. A significant increase in the number of fibroblasts was observed in histological sections of treated CAMs, and this increase correlated with alterations in extracellular matrix components. Many more matrix fibrils were observed in treated CAMs than in controls using scanning electron microscopy. Immunohistochemistry showed that type III collagen was distributed in a tight band adjacent to the endoderm in controls but was distributed throughout the mesoderm in both treatment groups. Western blots confirmed that both type I and type III collagen were more abundant in treated CAMs than in controls. Fibronectin, which was localized immunohistochemically in the basal laminae and mesodermal matrix of controls, increased in abundance in CAMs treated with SS smoke solutions. Hyaluronic acid, which was present in a dense band subjacent to the capillary plexus of control CAMs, was greatly reduced in MS-treated CAMs and was absent in SS-treated CAMs. These observations demonstrate that both MS and SS cigarette smoke solutions caused abnormal pattern formation of CAM blood vessels and altered the composition of the extracellular matrix in the CAM mesoderm.