Cytological evaluation of the tissue–implant reaction associated with subcutaneous implantation of polymers coated with titaniumcarboxonitride in vivo

The aim of the present study was to evaluate the influence of titanium-coated polymers on the inflammatory response and remodeling of connective tissue during wound-healing processes. Discs of polyethyleneterephthalate (PET) and silicone as well as high-weight meshes of polypropylene (PP) were coated with a titaniumcarboxonitride (Ti(C,N,O)) layer by a plasma-assisted chemical vapor deposition process (PACVD) and implanted subcutaneously in the dorsal lumbar region of Wistar rats. Light microscopic and histological evaluation of capsule thickness, capsule quality, implant–tissue interface and collagen composition was performed 7, 14, 21 and 28 days post-operatively. All implants were surrounded by a fibrous capsule with decreasing thickness after 2–4 weeks post-implantation. Titaniumcarboxonitride-coated polymers showed no significant differences in capsule thickness and inflammatory cellular response. An increased collagen type III/I ratio, especially for titaniumcarboxonitride-coated materials, was found in week one after implantation remaining elevated up to week 4. This might be associated with disordered collagen metabolism and immature scar reaction. In contrast to previous in vitro experiments, Ti-coating of polymers did not improve biocompatibility after subcutaneous implantation in rats. Material reduction to low-weight meshes and enlargement of pore size may demonstrate a benefit of Ti-coated meshes with an increased biocompatibility.