The
foreign body reaction (FBR), which leads to the encapsulation of implanted
biomaterials, has been implicated in the failure of many medical devices. The
protein layer that is nonspecifically adsorbed onto the implant surface immediately after implantation is thought to dictate this reaction. It is hypothesized that
biomaterial surfaces having specific
proteins with precisely controlled orientations will decrease the FBR. Previously, we have reported that
osteopontin (OPN) adsorbed on positively charged surfaces has a preferable orientation for in vitro cell adhesion and spreading as compared to negatively charged surfaces. It is expected that coating a layer of OPN in its preferred orientation on an implant surface will decrease the FBR. In this work, in vivo studies were performed to test this hypothesis. A positively charged
polymer (p(
HEMA-co-AEMA)) and a negatively charged
polymer (p(
HEMA-co-CEA)) coated with OPN were implanted subcutaneously in wild-type mice for 7 or 28 days. Uncoated
polymers were used as control. For the 7-day implants, cells on OPN-coated p(
HEMA-co-AEMA) spread more than cells on the other three materials. Following 28 days of implantation the implants were explanted and the
capsule thickness and vascularity around the implants were characterized. Additionally, the macrophage and foreign body giant cells (FBGCs) around the implants were quantified. It was found in this study that the modification of the positively charged
polymer surface with OPN in a controlled orientation led to a reduction in the
foreign body reaction as determined by
capsule thickness. Our finding provides valuable information for designing better biocompatible
biomaterials with improved in vivo performance.