Unusual inflammatory responses around a collagen-impregnated vascular prosthesis

A collagen-impregnated graft, called Hemashield, has been used clinically; however, some complications such as pyrexia, fluid accumulation, and unusual scar formation around the graft have been reported. To understand the cause of these problems, the graft was examined both in vivo and in vitro. Endotoxin and (1-3)beta-D-glucan were detected in the extract from Hemashield by special quantitative methods called Toxicolor and Endospecy. In an animal study, the grafts were implanted in the thoracic descending aorta of 9 dogs and were designed to explant at 2 weeks. Macroscopic evaluation of the explants showed that the graft had no infection, but fluid accumulation was found in the pleural cavity and around the graft-like seroma. Microscopical observations revealed that neither fibroblasts nor capillary blood vessels had infiltrated in the adventitial side of the graft, but numerous plasma cells, lymphocytes, and macrophages were noticed. The impregnated collagen was partially absorbed. These results indicate that the graft had some contaminants which contained a certain amount of endotoxin and (1-3)beta-D-glucan, resulting in noninfective inflammatory responses around the graft.