Introduction: Magnetosomes are natural nanoparticles with a nucleus of iron oxide or iron sulfide derived from magnetotactic bacteria. This structure causes the ability of bacteria to move in the direction of the magnetic field Since they are between 20 and 100 nanometers in size; and due to the membrane, that exists around this iron nucleus, it creates a property for them to bind drugs and therapeutic agents, therefore by attaching the markers to their surface, the ability to precisely identify the target cell can be created in them; So, their use will be very effective in treating diseases such as cancer. This treatment can be by hyperthermia, drug delivery, gene therapy, or antibody delivery. Here is a summary of magnetosomes and a brief overview of hyperthermia using them as a method to treat cancer.
Methods: PubMed, Google Scholar and scopus were used for a comperhansive search for articles published up to 2020. Keywords were included magnetotactic bacteria, magnetosomes, nanoparticles, cancer and hyperthermia. We chose the articles based on their keywords and abstract. Finally, we have found 64 Articles with our study criteria of selection.
Results: Loaded magnetosomes have a long-lasting release property that enhances the drug's effect to form a targeted magnetic therapy. Using doxorubicin (DOX), it has been shown that magnetosomes can provide gene therapy drugs.[56]
About sixty years ago, Gilchrist et Al. recommended the use of hematite, 20 to 100 nm in diameter, using a magnetic field variable at 1.2 MHz to induce heat in the lymph nodes for treatment. The use of hyperthermia in the treatment of cancer is very attractive because it has no toxic side effects and therefore has fewer limitations than chemotherapy and radiotherapy, and even increases the efficiency of treatment, in which either the tumor disappears or its size may be reduced. It does not completely disappear, but inside the tumor, the temperature remains in the range of 37 to 45 degrees Celsius. [53]
As mentioned earlier, due to the presence of a fat membrane around the magnetosome, the protein can attach to it, by which it detects specific cells and tissues. So, in any treatment that uses the magnetosome, damaged or cancerous tissue can form. And are an excellent alternative to SION therapy (Superparamagnetic Iron Oxide Nanoparticle synthetic particles used for hyperthermia) in hyperthermia. The use of an alternating magnetic field also allows the release of the drug to be controlled. [53], [60]
Recently, poly-lysine-coated magnetosomes (PLLs) are more stable, non-pyrogenic, and have a higher potential for heat generation, resulting in significant improvement and antitumor properties in intracranial tumors in mice. In this case, the temperature reaches 42 degrees Celsius in the tumor. [52] In one study, researchers compared the effect of using poly-lysine-coated magnetosomes (M-PLLs) and IONPs (compounds of an iron oxide core coated with hydroxymethyl starch) in hyperthermia to treat cancer. In this study, tumor volume change was measured as a function of time after administration of glucose (M-PLL) and IONPs to mice in different groups. [50]
In another study, an experiment was designed to determine the location of M. gryphiswaldense (MSR-1) cells in vitro and the effect of hyperthermia treatment on lung cancer cells. Fluorescent staining can also be used to detect the correct placement of these magnetosomes on cancer cells. In one study, human A549 lung cancer cells were incubated for 4 hours in the presence of MSR-1 incubated using fluorescence. [61]
Conclusion: The only problem with using magnetosomes is that they are limited compared to synthetic nanomagnets because synthetic nanomagnets can be made as much as needed, but magnetosomes are natural and depend on bacteria and their growth.[53] Resolving this problem can be a turning point in the treatment of many diseases, especially cancer. Given that the growth of magnetotactic bacteria is long-term and grows better in low oxygen conditions, the use of appropriate antibiotics to prevent the growth of infectious microorganisms, as well as methods to accelerate the growth of bacteria, can be the first step to address these problems; Therefore, the use of artificial bacterial primary ecosystem can be a good option for a large-scale pure culture of these bacteria and increase growth efficiency.
It is suggested that magnetosome technology be used to deliver high-dose drugs, such as antibiotics; as we see today that many antibiotics are ineffective due to uncontrolled use, then we can hope that the effective antibiotics will be able to neutralize the function of bacteria for a more extended period of time and be effective in specific diseases.
It is worth mentioning that the use of magnetosomes to deliver drugs with severe side effects such as chemotherapy drugs and iodine therapy in various cancers, can reduce their negative effects rather, by not releasing it into the bloodstream, not destroying the drug, and maintain a reliable dosage of it for a long time, it can reduce the chance of recurrence of the disease and the numerous injections that make the condition difficult for the patient, both financially and in terms of health.