Uptake and persistence of bacterial magnetite magnetosomes in a mammalian cell line: Implications for medical and biotechnological applications

Abstract

Magnetotactic bacteria biomineralize intracellular magnetic nanocrystals surrounded by a lipid bilayer called magnetosomes. Due to their unique characteristics, magnetite magnetosomes are promising tools in Biomedicine. However, the uptake, persistence, and accumulation of magnetosomes within mammalian cells have not been well studied. Here, the endocytic pathway of magnetite magnetosomes and their effects on human cervix epithelial (HeLa) cells were studied by electron microscopy and high spatial resolution nano-analysis techniques. Transmission electron microscopy of HeLa cells after incubation with purified magnetosomes showed the presence of magnetic nanoparticles inside or outside endosomes within the cell, which suggests different modes of internalization, and that these structures persisted beyond 120 h after internalization. High-resolution transmission electron microscopy and electron energy loss spectra of internalized magnetosome crystals showed no structural or chemical changes in these structures. Although crystal morphology was preserved, iron oxide crystalline particles of approximately 5 nm near internalized magnetosomes suggests that minor degradation of the original mineral structures might occur. Cytotoxicity and microscopy analysis showed that magnetosomes did not result in any apparent effect on HeLa cells viability or morphology. Based on our results, magnetosomes have significant biocompatibility with mammalian cells and thus have great potential in medical, biotechnological applications.

Isolation of Cancer-Derived Exosomes Using a Variety of Magnetic Nanostructures: From Fe3O4 Nanoparticles to Ni Nanowires

“…Although some surface degradation cannot be discarded, it seems that the MGs are more resilient toward degradation than the MNWs. The stability of MGs inside cancer cells has been reported before [ 30 , 35 ]. It is also notable from these TEM images that inside the endosomes, MGs could form chains and similar arrangements, as we had seen before in Figure 1 b, instead of being agglomerated in a dense cluster.…”

“…Therefore, if our magnetic nanostructures are compartmentalized inside endosomes, there is chance that they are also incorporated into the exosomes being released outside the cell. The incorporation of nanostructures inside endosomes has been frequently reported in the literature [ 29 , 30 , 31 ].…”

LINC81507 act as a competing endogenous RNA of miR-199b-5p to facilitate NSCLC proliferation and metastasis via regulating the CAV1/STAT3 pathway

“…We first preform migration assay in miR-199b-5p and CAV1, which proved that CAV1 had the ability to decrease migration. With respect to membrane localization of CAV1, we used TEM 52–54 (transmission electron microscopy) to examine the membrane integrity after overexpression of LINC81507 in A549 cells. Compared with A549 control cell lines, A549 LINC81507-OE cell lines revealed less cell membrane damage and less alteration of cell wall structure by TEM (additional file.…”

Transformation Cycle of Magnetosomes in Human Stem Cells: From Degradation to Biosynthesis of Magnetic Nanoparticles Anew

“…21,22 They are now considered amongst the best agents for magnetic hyperthermia, 23 photothermia 24,25 , and magnetic resonance imaging. 21,26,27 Besides, it was reported that magnetosomes display low toxicity, which has been due to their relatively insoluble magnetite core, [28][29][30] and furthermore, magnetosomes can have peroxidase-like properties that scavenge cytotoxic reactive oxygen species (ROS). 31,32 The question of the magnetosomes degradability however remains controversial, as a few studies also reported their progressive degradation over time, in protozoans, or in mice, 19,33,34 but not yet in human cells.…”