Nickel-Titanium-Shape-Memory-Alloys (NiTi-SMA) are of biomedical interest due to an unusual range of pure elastic deformability (superelasticity) and the shape memory effect which allows this material to return to a predictable previously memorized shape after external changes in temperature. HMSCs (human multipotent mesenchymal stromal cells) are currently the most promising cell type for regenerative medicine and tissue engineering, due to the ability to differentiate into several tissues such as bone, tendon, cartilage or muscle. For tissue engineering newly developed porous NiTi-SMA materials are evaluated preloaded with hMSCs. For biocompatibility testing the high nickel content (50 %at) of NiTi-SMA plays a critical role. To analyse the influence of Ni-ions on hMSCs viability and activation, cells were cultured with or without NiCl 2 for 24h and 7days. Cells were either seeded in media containing NiCl 2 or the NiCl 2 was later added to already adherent cells. Cell metabolism, proliferation and viability were analysed by alamarBlue TM assay or fluorescence microscopy. Cytokine 8,11) release from hMSCs was determined by ELISA. NiCl 2 concentrations below 25 lg/ ml were well tolerated by the cells. A significant decrease in cell proliferation occurred at threshold values of 200 lg/ ml (24 h) and 25 lg/ ml (7 d). There was a significant, dose dependent increase in the release of IL-8 from hMSCs cultured in the presence of sub toxic NiCl 2 concentrations. The present study demonstrates for the first time that high but non-toxic concentrations of Ni 2+ are capable to activate hMSCs. Thus high Ni 2+ concentrations apart from allergen-or particle-induced inflammation, may lead to tissue inflammation in the vicinity of a NiTi-SMA implant in vivo and subsequently to implant failure e.g. due to implant loosening.