BackgroundCancer is still the most challenging disease and is responsible for many deaths worldwide. Considerable research now focuses on targeted therapy in cancer using natural components to improve anti-tumor efficacy and reduce unfavorable effects. Lactoferrin is an iron-binding glycoprotein found in body fluids. Increasing evidence suggests that lactoferrin is a safe agent capable of inducing anti-cancer effects. Therefore, we conducted a study to evaluate the effects of the exosomal form of bovine milk lactoferrin on a human MDA-MB-231 breast cancer cell line.MethodsThe exosomes were isolated from cancer cells by ultracentrifugation and incorporated with bovine milk lactoferrin through the incubation method. The average size of the purified exosome was determined using SEM imaging and DLS analysis. The maximum percentage of lactoferrin-loaded exosomes (exoLF) was achieved by incubating 1 mg/ml of lactoferrin with 30 µg/ml of MDA-MB-231 cells-derived exosomes. Following treatment of MDA-MB-231 cancer cells and normal cells with 1 mg/ml exoLF MTT assay applied to evaluate the cytotoxicity, PI/ annexin V analysis was carried out to illustrate the apoptotic phenotype, and the real-time PCR was performed to assess the pro-apoptotic protein, Bid, and anti-apoptotic protein, Bcl-2.ResultsThe average size of the purified exosome was about 100 nm. The maximum lactoferrin loading efficiency of exoLF was 29.72%. MTT assay showed that although the 1 mg/ml exoLF treatment of MDA-MB-231 cancer cells induced 50% cell growth inhibition, normal mesenchymal stem cells remained viable. PI/ annexin V analysis revealed that 34% of cancer cells had late apoptotic phenotype after treatment. The real-time PCR showed an elevated expression of pro-apoptotic protein Bid and diminished anti-apoptotic protein Bcl-2 following exoLF treatment.ConclusionThese results suggested that exoLF could induce selective cytotoxicity against cancer cells compared to normal cells. Incorporating lactoferrin into the exosome seems an effective agent for cancer therapy. However, further studies are required to evaluate anti-tumor efficacy and the underlying mechanism of exoLF in various cancer cell lines and animal models.