Inhibition of PMN apoptosis after adherence to dip-coated calcium phosphate surfaces on a NiTi shape memory alloy

Nickel–titanium shape-memory alloys (NiTi-SMA) were coated with calcium phosphate by dipping in oversaturated calcium phosphate solution (CaP-coating). Polymorphonuclear neutrophil granulocytes (PMN) belong to the first cells which will adhere to implant materials. We analyzed the apoptosis of isolated human PMN after cell culture on non-coated and CaP-coated NiTi-SMA by light and scanning electron microscopy (cell morphology) and by flow cytometry (DNA-fragmentation). In contrast to PMN adherent to non-coated NiTi-SMA, the apoptosis of PMN adherent CaP-coated samples was inhibited. Cell culture media obtained from cultured leukocytes with CaP-coatings (conditioned media, CM) were able to transfer the apoptosis inhibiting activities to freshly isolated PMN. There was a significant (p<0.01) increase in GM-CSF, IL-8, IL-6, and TNF-α within CM obtained from coated versus non-coated NiTi-SMA as was determined by ELISA.