Mesenchymal stem cells release antimicrobial factors that enhance the activity of traditional antibiotics. Could systemic delivery of mesenchymal stem cells be the way to treat chronic drug-resistant infections in the future?

Rise of the superbugs

Antimicrobial resistance describes a situation where bacteria and viruses have adapted and evolved to resist the drugs that are designed to kill them. According to a study commissioned by the Public Health Agency of Canada these superbugs will likely kill 400, 000 Canadians and cost the economy over $400 billion over the next 30 years.

Now that we are no longer in the “golden years” of antibiotics, when antimicrobial drugs were the main method used to combat infections, how can we get a handle on the rise of the superbugs?

How about using stem cells as an alternative? This is what the researchers in this current study investigated – the potential of using stem cells to battle chronic infections.

Antimicrobial properties of stem cells

Previous studies have shown that stem cells, mesenchymal stem cells (MSCs) in particular, have immunological properties. For example, they release signalling molecules that recruit cells in the immune system responsible for killing foreign pathogens to specific areas of the body. MSCs also make antimicrobial peptides. These peptides are used by the body as a first line of defense to kill microbes like bacteria, viruses and yeast.

Other studies involving mice show that MSCs can lower the death rate associated with infections and what is more enhance the activity of antibiotics used to treat certain diseases. This group of researchers have previously shown that systematic delivery of MSCs was even more effective when combined with traditional antibiotics.

Their current study builds on these previous findings to by looking at one specific superbug, MRSA (Methicillin-resistant Staphylococcus aureus), responsible for many chronic infections and deaths around the world.

MSCs enhance the activity of antibiotics

Antibacterial effects of MSCs

Researchers found that MSCs from bone marrow had bactericidal properties and were able to enhance the effects of antibiotics. Bacterial cells exposed to MSCs grew much slower compared to those that were not.  When used together, MSCs and antibacterial drugs like vanomycin were much more effective at killing bacterial cells than antibacterials alone.

The next set of experiments looked at if stem cells released peptides useful for immunity. Indeed, MSCs released peptides used by the body as a first line of defense to activate the immune system, which ultimately resulted in the rapid death of bacterial cells.

Finally, they highlighted using a mouse model that MSCs can be used to decease bacterial burden and to promote faster wound healing.

Stem cells as an alternative

In the wake of the superbug report and the fact that antibiotic resistance is considered a global crisis, findings from this study offer new hope for the future. The idea is patients with chronic infections will be treated with antibiotics and MSC infusions to tackle superbugs more effectively. Could it be that stem cells may offer an alternative way to combat superbugs that are resistant to antibiotics in the future?

Reference

Antibacterial activity of human mesenchymal stem cells mediated directly by constitutively secreted factors and indirectly by activation of innate immune effector cells