Analysis of the inflammatory response to titanium and PTFE implants in soft tissue by macrophage phenotype quantification

Implants of commercially pure titanium and polytetrafluoroethylene (PTFE) were inserted in the rat abdominal wall for 1, 6 or 12 wk. The foreign body reaction was evaluated by immunohistochemical quantification of monocytes/macrophages and by the thickness of the foreign-body capsule. At all time intervals, the majority of interfacial cells were ED1-positive while ED2-positive cells were localized deeper in the tissue. Neither titanium nor PTFE displayed a significant change in capsule thickness over time. The total cell numbers decreased overtime for both types of material. At 12 wk the PTFE implants, compared to titanium, were surrounded by a significantly thicker reactive capsule with larger total cell numbers. No significant differences were seen in the macrophage subset response between the two types of implants. Thus, the present study showed differences between titanium and PTFE at 12 wk but not at earlier time points.