Though I love the Steemit platform, one gripe I have with it is that good articles get buried just as fast as bad ones. @SteemSTEM has done some amazing efforts in getting quality science posts recognized, but even with their efforts the best posts will fall into obscurity after a week. I’ve mostly ignored this issue, but while I was doing some background research into this article’s topic (Magnetotactic bacteria!), I found a few articles on the subject had already been posted. Both articles were well written and relatively recent. I thought it would be a shame to either ignore or just passively cite them so I thought I’d try to springboard my post off of them. Rather than give a lengthy introduction on the topic, I’m going to give a brief overview and highlight the quality work done by past Steemians. This will give me more time to focus on exciting developments in the field and might encourage you dear readers to give a second look to some forgotten Steemit posts.

Magnetotactic Bacteria

This post is inspired by a fascinating type of microbe that moves along magnetic fields. These organisms are called magnetotactic bacteria and use the earth’s magnetic field to facilitate navigation (1). A March 2018 post titled Microbial World #8 Bacteria Synthesizes Nano-Sized Compasses to Navigate using Earth's Geometric Field from @vinamra gives a great overview of just how and why these unusual creatures function.

In brief, magnetotactic bacteria gather environmental iron and use it to create small magnetic particles called magnetosomes. These magnetosomes function as tiny compasses, orienting along magnetic fields, and allow bacteria to orient themselves as well. The formation of the magnetosome has been the subject of intense study.

@micro24 has covered some of this work and comprehensively shows that they form within internal compartments in his article Compartmentalization gives the property of sensing Magnetic Field in Bacterial Cell (helps in movement). Please give that a read if you want more info.

I’m always interested in the benefits basic research can give us, so after reading the articles from @vinamra and @micro24, I was curious as to whether investigations into these unusual organisms have yielded useful applications. @micro24 mentioned some water purity applications in his post, but the references he cited were a bit outdated so I looked through the modern work in the field. It didn’t take long for papers describing magnetosome-based medicine to catch my eye.

Treating disease with magnetosomes

It turns out that magnetosomes have a lot of applications for human health. A few of the most prominent are specialized MRI imaging, delivering drugs to a specific location, and Magnetic Hyperthermia (using magnets to apply intense heat) (2):

MRI Imaging:

Magnetic resonance imaging, more commonly known as MRI, is a common technique doctors use to look inside the body (3). In brief, organs and tissue are subject to high magnetic fields and hydrogen atoms within the body absorb and emit tiny amounts energy from these fields that can be visualized as an image.

Magnetosomes, being actual magnets, show up very strongly on an MRI image. They’re also non-toxic because they’re made through an entirely natural process without using harsh chemicals. For these reasons, magnetosomes are very effective at tracking specialized cells within the body. In one recent study, scientists were injecting cardiomycetes, heart repairing cells, into mice with heart disease.

They wanted to track the cells they were injecting into the body so they added magnetosomes to the cardiomycetes prior to injection (4). When they viewed the mice under an MRI, they werw able to see the magnetosomes had clustered around the heart indicating that the cardiomycetes were functioning as expected. This application is already quite far along as companies offering magnetosome labeling products have already popped up (5).

Drug Delivery:

The idea behind magnetosome-based drug delivery is to focus treatment at a specific site in the body to maximize effectiveness and eliminate side effects. This is especially useful for cancers where the disease might be localized to a specific organ, but simply injecting an anti-tumor drug will spread that drug throughout the whole body. Magnetosomes have proven to be a useful way to solve this problem. Anti-tumor Drugs are attached to magentosomes and injected into the body. Strong magnets are then placed near the tumor and the majority of injected magnetosomes will aggregate near the magnet.

The image on the left gives a succinct overview of this process. It’s an attractive method of treatment because it is both non-invasive and doesn’t require any specialized equipment beyond some powerful magnets. Creating sufficient quantities of magnetosome-linked drugs efficiently is probably the biggest obstacle in fully implementing this.

Although multiple studies have shown promise on developing this into an actual treatment for patients (6, 7), I haven’t seen many clinical trials suggesting that this kind of treatment is still a few years off at best.

Magnetic Hyperthermia:

This is by far my favorite use of magnetosomes as medicine because it’s the perfect trifecta of being really cool, fairly easy to explain, and super fucking cool. This type of treatment is based on the idea that cancerous cells can often be killed with heat, which is referred to as hyperthermia therapy (9. Different types of this therapy have been around for some time, but its always been limited by the fact that heat will kill non-cancerous cells too. Researchers have been looking for an effective way to localize the heat to minimize side effects and magnetosomes might just be the answer. Not only can magnetosomes be concentrated on a tumor with magnets, but they can also be heated by applying an alternating magnetic current. The alternating current switches at a very high frequency which vibrates the magnetic particles fast enough to generate heat. Not only does this technique ensure that only the tumor is heated, but it also allows for exquisite control over how hot the region can get. Many studies focus on maintaining the temperature at 42 oC which isn’t strong enough to directly damage cells, but often generates a heat shock response that results in apoptosis of cancer cells. The diagram below explains how this can work in a mouse model.

Using magnetic hyperthermia to treat cancer in mice (2).

Magnetic hyperthermia is particularly attractive for treating glioblastoma, an aggressive and common form of brain cancer with no known cure (10). Preliminary studies show it to be quite effective in mouse models, and clinical trials are underway.

One thing to point out with these applications is that magnetosomes are simply used as a small magnet. In theory, researchers should be able to use any magnetic nanoparticle for this function. However, magnetosomes show clear advantages in practice because they are 100% naturally created. They don’t require toxic organic chemicals for synthesis and can be easily accumulated by growing magnetotactic bacteria. Many studies are devoted to finding the best way to cultivate these types of bacteria to maximize magnetosome production (11). I wouldn’t be too surprised if we start seeing magnetosome-based treatment sometime in the next decade, but I expect some strong pushback from overzealous Insane Clown Posse fans.

Moving magnetosomes forward

The above applications cover the major uses for magnetosomes in medicine, but they have plenty of applications in other fields. If anyone is particularly interested in this topic, feel free to continue this work. You could talk about using them for bioremediation, making really tiny compasses, or proving flat earthers wrong. You’d definitely get an upvote and a resteem from me for the effort. Again I’d like to give a big thanks for the introductory posts on this topic by @vinamra and @micro24. They’ve been very helpful in allowing me to focus on modern magnetosome medicine rather than rehash work that’s already on the platform.

References

(1) https://en.wikipedia.org/wiki/Magnetosome
(2) https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4126476/
(3) https://en.wikipedia.org/wiki/Magnetic_resonance_imaging
(4) https://www.nature.com/articles/srep26960
(5) http://www.bellbiosystems.com/Products/Magnelle-Powering-
(6) https://www.cancerletters.info/article/S0304-3835(07)00407-7/abstract)
(7) http://www.mdpi.com/1996-1944/6/9/3755/htm
(8) https://link.springer.com/article/10.1007/s13204-013-0216-y
(9) https://en.wikipedia.org/wiki/Hyperthermia_therapy
(10) https://www.tandfonline.com/doi/abs/10.1080/02656736.2018.1430867
(11) https://www.sciencedirect.com/science/article/pii/S0928493115304926

Images

All images were taken either directly from the publication referenced or labeled for reuse on Google Images. If any image owner has an issue with this article, please contact me and I will address the issue.