gms | German Medical Science

Objectives: Surface roughness on orthopedic implant materials has been shown to be highly influential on the behavior of osteogenic cells. Mesenchymal stem and progenitor cells (MSPCs) migrate to the interface, adhere, proliferate, and differentiate into osteoblasts, which subsequently form bone matrix. Modifications of the implant surfaces should accelerate this process and improve biocompatibility. The aim of this study is to improve our knowledge of osteoinductive performance on different CoCrMo surfaces and the associated osteogenic and inflammatory mechanisms. We investigated the effect of titanium nitride (TiN) coating, a porous coated surface, a polished surface, and a coating with pure titanium (cpTi) on a CoCrMo alloy regarding the osteogenesis of primary human MSPCs, the expression of 13 osteogenic and inflammatory markers, and the changes of the integrin alpha5beta1 state.

Methods: The surface structure was analysed using scanning electron microscopy (SEM) and their corresponding elemental analysis was performed using energy-dispersive x-ray spectroscopy (EDX). Human primary MSPCs were expanded from tissue samples of spongiosa bone and characterized according to the criteria of the International Society for Cellular Therapy. The characteristic phenotype of MSPC was confirmed by flow cytometry and multilineage differentiation.

Results and Conclusion: Alcaline phosphatase and osteopontin expression increased significantly in all groups about 5-fold and 10-fold, respectively, in comparison to the undifferentiated controls. The porous coated surface showed a reduced expression of osteogenic markers. Due to the osteogenic differentiation, the expression of integrin alpha5beta1, which is particularly important for cell-material contact, increased 4 to 7-fold. In the dynamic process of bone biology, MSPCs cultured and differentiated on cpTi, showed significant upregulation of IL6 and leptin.

With regard to the osteogenic differentiation potential, the coating with pure titanium (cpTi) in particular had a positive effect, whereas the porous coated surface showed poor results. The expression of integrin alpha5beta1, which is particularly important for cell-material contact, also reflected this process. In the dynamic process of bone biology, MSPCs cultured and differentiated on cpTi showed significant upregulation of IL6 and leptin.