THEORETICAL-ANALYSIS OF IN-VIVO MACROPHAGE ADHESION AND FOREIGN-BODY GIANT-CELL FORMATION ON POLYDIMETHYLSILOXANE, LOW-DENSITY POLYETHYLENE, AND POLYETHERURETHANES

Quantitative description of foreign body giant cell (FBGC) formation o n implanted polymer surfaces as a function of time can conceivably cor relate cell adhesion with polymer properties and possibly predict the behavior of the polymer in vivo. In the present study, the formation o f FBGCs on various biomedical polymers was quantified by two parameter s: the density of adherent macrophages present initially that particip ate in FBGC formation (d(o)) and the rate constant for cell fusion (k) ; both kinetic parameters were used to calculate the time-dependent FB GC density (d(fc)). The materials used were: three Pellethane poly(eth erurethanes) (PEUs) varying in weight percent of hard segment, one pol y(etherurethane urea) (PEUU), and NHLBI-DTB primary reference material s: low density polyethylene (LDPE), silica-free polydimethylsiloxane ( PDMS). The results indicated that up to 5 weeks of implantation, FBGCs were formed from the fusion of one population of adherent macrophages present by 3 days post-implantation. Furthermore, only a small fracti on (<8%) of this initial adherent macrophage population participated i n FBGC formation. Based on the results of previous studies and the cur rent study, it was concluded that increase in PEU hard segment weight percent, surface hardness and hydrophobicity increased total protein a dsorption and effectively increased d(o) and d(fc). No further correla tions between the material properties of all polymers and the cell kin etics can be made at this time. However, this study demonstrated that macrophage adhesion and FBGC formation can be quantified with the cell fusion model, and are modulated by various polymer properties. (C) 19 94 John Wiley and Sons, Inc.