In vivo/ex vivo cellular interactions with titanium and copper

Machined, commercially pure titanium (Ti) disks were coated with approximat ely 400 nm copper (Cu) by physical vapor deposition or left uncoated. The k inetics of inflammatory cell recruitment, distribution and viability was ev aluated around Ti, Cu, and in sham sites after 1, 3, 12, 18, 24, and 48 h i n a rat subcutaneous (s.c.) model. Further analysis of the cells on implant surfaces was performed by ex vivo incubation of the disks. Ti and Cu stimu lated an increased recruitment of inflammatory cells in comparison with sha m sites. A markedly higher amount of cells, predominantly polymorpho-nuclea r granulocytes (PMN), was detected around Cu after 18 h and onwards. More c ells were found at the implant surfaces than in the surrounding exudates af ter 18 h. The total amount of lactate dehydrogenase (LDH), an indicator of plasma membrane injury, was higher in Cu exudates after 18 h in comparison with Ti and sham. In contrast, no differences in the proportion of dead cel ls (trypan blue dye uptake) were detected in the exudates. Further, LDH lev els were higher around Ti than Cu during the initial 18 h of ex vivo incuba tion. The results of this study indicate that the early inflammatory proces s associated with a cytotoxic material in soft tissues is largely attribute d to the induction of a markedly strong and prolonged chemotactic response. In contrast, this process is characterized by a higher amount of inflammat ory cells around a biocompatible material than in sham sites, but with a tr ansient course and total LDH similar to sham sites. (C) 2001 Kluwer Academi c Publishers.