Comparative analysis of immunological compatibility of bioactive calcium phosphate coatings on titanium and magnesium alloys

Abstract

Current strategies for developing the biomaterials suggest passive modulation of osteoinductive and osteoconductive properties of the implant surface through a change in their physical and chemical parameters. Also, the osseointegration of implant depends on the reaction of the immune system, the severity of which is determined by physical and chemical properties of the material and the morphological features of the coating. In this paper, the plasma electrolytic oxidation (PEO) method for the formation of biologically active compositional corrosion resistant calcium phosphate coatings on titanium BT1-0 and magnesium alloy MA8, designed for bone bioengineering was used. Bioactive PEO coatings were additionally treated with superdispersed polytetrafluoroethylene (SPTFE) in order to improve anti-corrosion properties. The cellular and molecular aspects of immunological compatibility of bioactive calcium phosphate coatings formed on titanium and magnesium alloys by promising technology of plasma electrolytic oxidation and intended for bone tissue bioengineering were studied. It is shown that PEO coatings formed on titanium and magnesium induce an activation of human peripheral blood leukocytes in vitro, associated with increased expression of activation of molecules of CD69, CD38, CD11b on the cell membranes while shedding L-selectin (CD62L). Influence of coating process technologies on the intensity of the activation processes was established. Contact cells with calcium-phosphate PEO coatings formed on titanium and magnesium alloys induced a less pronounced activation in comparison with the untreated implants. The minimal reaction of the cells of the innate immunity was observed at using a composite of PEO coatings with SPTFE, obtained by electrophoretic deposition. The composite coating on magnesium alloys induces response of the cells of the innate immunity, comparable with the response to the coatings on titanium alloys. On the whole, immunological characteristics of the PEO coatings on titanium BT1-0 and magnesium alloy of MA8 demonstrate possibility of development of materials and wares for implant surgery, including bioresorbable alloys on magnesium base.