Evaluation of the Cytotoxicity of BMP-2 in the Coating of Dental Implants: an In Vitro Study

BACKGROUND: Bone morphogenetic protein 2 (BMP-2) is increasingly incorporated into bone graft materials due to its positive effects on osseointegration and de novo bone formation. While its efficacy in bone regeneration is well established, concerns have been raised about adverse effects, including inflammation, ectopic bone formation, soft tissue swelling, and even oncogenesis. Understanding the basis of these effects requires investigation of BMP-2 impact on various cell types.

AIM: The study aimed to evaluate the biological effects of BMP-2–containing implant coatings on the human monocytic leukemia cell line THP-1.

METHODS: THP-1 cells were seeded in 12-well plates at 2 mL/well and a concentration of 250 × 10³ cells per well, with PMA (phorbol 12-myristate 13-acetate) added to a final concentration of 150 nM. The cells were incubated at 37 °C with 5% CO₂ for 4–6 h until fully adhered to the culture plastic. Experimental implants (one per well) were then added and incubated for 48 h. To detect apoptotic cells after 48-hour incubation with implants, they were stained with propidium iodide (Lumiprobe, Russia). For each sample, 1 × 10⁵ cells were analyzed. Immunophenotyping was performed using anti-CD45 monoclonal antibodies (130-113-681, clone 5B; Miltenyi Biotec, Germany). Samples were analyzed using a NovoCyte Advanteon flow cytometer (Agilent, USA), and data were processed with Flowing Software 2.

RESULTS: No significant differences in cytostatic effects were observed between implants with and without BMP-2 coating. However, culture medium alone differed significantly from the implant-containing groups, suggesting that the mere presence of an implant affects THP-1 cell behavior. After incubation with the test implant samples, the percentage of apoptotic THP-1 cells, detected by flow cytometry following propidium iodide staining (PI test), did not significantly change between groups, despite a slight increase in this parameter among coated samples. Notably, a significantly higher proportion of CD45⁺ cells was detected after incubation with coated implants.

CONCLUSION: The study showed that implants with and without coating do not differ in their cytostatic properties when incubated with THP-1 cells. When assessing the percentage of apoptotic THP-1 cells, no significant difference was observed between groups of implants with and without coating. However, the group of coated implants exhibited a significantly higher percentage of CD45⁺ cells.