Cobald chromium molybdenum surface modifications alter the osteogenic differentiation potential of human mesenchymal stem cells

Objectives Surface roughness on orthopedic implant materials has been shown to be highly influential on the behaviour of osteogenic cells. Soon after implantation, mesenchmal stem and progenitor cells (MSPCs) migrate to the bone-implant interface and participate in the matrix remodeling.

Methods In this study, five surface topographies on cobald chromium molybdenum (CoCrMo) were engineered to examine the influence on human primary MSPCs. Elemental analysis of CoCrMo discs coated with titanium nitride (TiN), polished and porous coated surfaces, and pure titanum (cpTi) surfaces was performed using EDX. The modified morphology of the surfaces was determined using SEM. Human primary MSPCs were expanded from tissue samples of spongiosa bone and characterized according the criteria for defining multipotent mesenchymal stromal cells of the International Society for Cellular Therapy using flow cytometry and multilineage differentiation analysis. Osteogenic differentiation potential was analysed using qRT-PCR and Luminex^® technology.

Results and Conclusion The SEM microscopic images revealed significant differences in morphology of the uncoated CoCrMo discs and their modifications. TiN and cpTi coatings fundamentally changed the composition of the chemical elements. Flow cytometry and differentiation into the osteogenic, adipogenic, and chondrogenic lineage confirmed the phenotype of MSPCs. ALP and osteopontin expression increased significantly in all groups about 5-fold respectively 10-fold compared to the undifferentiated controls. Compared to the uncoated CoCrMo surface 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 4-7fold. In the dynamic process of bone metabolism, 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.

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Publication History

Article published online:
15 October 2020