An in vitro evaluation of inflammation response of titanium functionalized with heparin/fibronectin complex

Immobilization of biomolecules with a variety of biological functions has been a promising method to improve the biocompatibility of biomaterials. However, little is known about their inflammatory property and cytotoxicity, which are both key aspects to most biomaterials designed for tissue engineering applications and in vivo implantation. In this in vitro study, heparin/fibronectin complex (Hep/Fn) was coimmobilized onto titanium surface (HF-Ti), which had been proven to have the properties of both anticoagulation and endothelialization in our previous study. Fourier transform infrared (FTIR) spectroscopy and water contact angle measurement were utilized to determine the surface chemical compositions and physical properties. Toluidine Blue O (TBO) and immunochemistry methods were performed to quantify the surface-immobilized heparin and fibronectin. The early inflammatory responses elicited by pristine Ti and HF-Ti were investigated by proinflammatory cytokine secretion of tumor necrosis factor-alpha (TNF-α) released by attached peritoneal macrophages, monocyte chemoattractant protein-1 (MCP-1) and interleukin-1β (IL-1β) released by attached human umbilical vein endothelial cells (ECs), respectively. Scanning electronic microscopy (SEM) and immunofluorescence were employed to investigate the changes in macrophages and ECs morphologies. The incubation period for both cells was 24h and the results showed that HF-Ti revealed a weaker inflammatory response than pristine Ti, which provoked a stronger inflammatory response and higher activation of macrophages. Our data suggest that Hep/Fn coimmobilized biomaterials surface may develop to be a new generation of biomaterials with both biocompatibility and anti-inflammatory properties, especially for used as cardiovascular implants and in tissue engineering applications.