Regulation of leukocyte adhesion molecules by leukocyte/biomaterial-conditioned media: A study with calcium-phosphate-coated and non-coated NiTi-shape memory alloys

To evaluate the role of soluble mediators released after interaction of leukocytes with biomaterials on cells of the implant microenvironment, the surface expression of adhesion molecules (CD11b, CD62L, CD66b, ICAM-1) on freshly isolated whole blood leukocytes (WBL) was analyzed by flow cytometry after incubation in leukocyte/nickel-titanium shape-memory alloy (NiTi-SMA)-conditioned media. NiTi-SMA samples were either coated with calcium phosphate by dipping in oversaturated calcium phosphate solution (CaP-coating) or were non-coated. Peripheral blood mononuclear cells (PBMC) and polymorphonuclear neutrophil leukocytes (PMN) were isolated and seeded on both samples to generate respective conditioned media. In comparison with conditioned media obtained by non-coated NiTi-SMA, the expression of CD11b, CD66b, and ICAM-1 on WBL was upregulated by conditioned media obtained from CaP-coated samples. In contrast, the expression of CD62L on WBL was decreased after incubation in conditioned medium obtained from CaP-coated NiTi-samples compared to non-coated NiTi. These data demonstrate the possible influence of released mediators elicited by leukocyte-biomaterial interactions on cells of the implant microenvironment.