Outside fibroblasts play a key role in the development of inner neointima after the implantation of polytetrafluoroethylene grafts.

The neointima formation inside of polytetrafluoroethylene (PTFE) grafts may be associated with the migration of outside fibroblasts to the luminal surfaces. This study aimed to verify whether blockade of fibroblast migration can prevent neointima formation by testing two types of prosthetic vessels, the porous PTFE graft and the impermeable Grasil graft, respectively. After implantation of the PTFE graft in dogs, a time-dependent migration of outside fibroblasts to the luminal side occurred. Compared with the PTFE grafts, the total neointima formation in the Grasil grafts was significantly less. Although the neointima formation at the arterial or venous anastomotic regions did not significantly differ between the two grafts, the neointima at the middle region of the PTFE grafts was significantly evident than the Grasil grafts. The components of the renin–angiotensin system (RAS), such as angiotensin II and its receptor AT1, as well as the forming enzymes of the RAS (angiotensin-converting enzyme and chymase), were all detectable in the grafts' surrounding tissues. Neointima formation at the middle region of the prosthetic vessels could be suppressed almost completely by the blockade of outside fibroblast migration, indicating that outside fibroblasts play a key role in the formation of neointima in this region.