Chemiluminescent responses of macrophages exposed to biomaterials: a biocompatibility screening test

Chemiluminescence (CL) response of alveolar macrophages (AM) exposed to either phagocytosable or nonphagocytosable particles of polymethylmethacrylate (PMMA) or titanium in vitro was monitored. The results were correlated to known in vivo bone tissue compatibility of the materials. Moreover, the quantity and morphology of adherent AM on titanium and PMMA disks were assessed using scanning electron microscopy (SEM). Our results with PMMA indicated that a high CL response to phagocytosable as well as nonphagocytosable particles of the biomaterial in question, correlated with poor bone tissue compatibility. By contrast, a low CL response to phagocytosable particles and no response to nonphagocytosable particles correlated with a satisfactory bone tissue compatibility, as in the case of titanium. SEM showed 48% more AM adherent to PMMA than titanium per unit area. Also, the percentage of cells with membrane damage was three times higher on PMMA than on titanium. It appears that the CL response of AM exposed to biomaterials in vitro thus can be used as an easy to do screening test for potential orthopaedic implant materials before in vivo tests are considered.