In Vitro Biocompatibility of a Novel Cobalt-Chrome-Boron Alloy

Objectives: Ion-release from metallic biomaterials due to wear decreases their long-term stability. A new alternative Co-Cr alloy with boron addition increases the wear resistance of the cast. Moreover, boron is an essential element in the human body which plays an important role in bone growth. We evaluated the cytotoxicity of Co-Cr-B alloy in peripheral blood mononuclear cells (PBMCs) and its effect on gene expression of pro-inflammatory cytokines.
Methods: PBMCs were isolated and cultured in RPMI-1640 medium at 37°C with 5% CO₂. 1×10⁶ cells were co-cultured with Co-Cr-B alloy discs (treatment) or 100ng/mL lipopolysaccharide (LPS) of E. coli O111:B4 or medium (untreated control), then incubated under the same conditions for 16h. At time, cells were collected for total RNA extraction and gene expression of IL-1β, IL-6, IL-8 and TNF-α was evaluated by RT-qPCR. Supernatant was used to determinate the production of lactate dehydrogenase using LDH-Citotoxicity Assay Kit II (Abcam, Cambridge, UK). Experiments were performed in triplicate (three independent). Level of significance was assessed by the Student t test and Dunnett test (P≤0.05).
Results: Our results showed low cytotoxicity on cells cultured with the Co-Cr-B alloy (2.83%±4.6%) while no difference was observed compared to untreated cells. Moreover, no change on mRNA levels of IL-1β, IL-6, IL-8 and TNF-α was observed in cells co-cultured with the alloy compared to untreated control, however cells treated with LPS showed overexpression (P≤0.05).
Conclusions: This novel alloy could be considered as a biocompatible material for the development of medical devices and manufacture of dental implants. However, in vivo studies should be performed to evaluate the immunological response and osteogenic differentiation potential of the Co-Cr alloy with boron.