It’s a promising new stem cell treatment against infection by the superbug MRSA (methicillin-resistant Staphylococcus aureus) that a team at Cornell University’s Baker Institute for Animal Health describes in a new study. With a very specific practical clinical objective, the team treated infected wounds by using mesenchymal stromal cells (MSC). This work, which uses the cellular secretome (secretions of the cells), but without the cells themselves, to treat models of infected wounds, provides in vivo evidence of the ability of this new therapy to significantly reduce the viability of MRSA, but also to help surrounding cells better protect themselves against the bacteria.
Staphylococcus aureus, especially its resistant form, has become a major healthcare problem, as it can be deadly when it occurs in immunocompromised patients or in settings with infected wounds. Some of these bacteria become resistant to many antibiotics, especially by forming biofilms, so there is a considerable need for new therapies to eliminate them.
A new approach to treating MRSA-infected wounds
Although many people carry this resistant microbe without serious consequences, for those whose health is compromised, with conditions such as diabetes it can be deadly.
MSCs are stem cells that can be isolated from bone marrow, adipose (fat) tissue, blood, and other tissue sources and have the ability to differentiate into different tissue types.
“In theory, injected MSCs should colonize the wound site, differentiate into the appropriate tissue type, and regenerate the damaged tissue,” explains lead author Gerlinde R. Van de Walle, Ph.D., associate professor of microbiology and immunology at Cornell University. “However, studies reveal that in practice only a small portion of MSCs actually integrate into injured tissue. For this reason, much of the benefit in tissue regeneration is indirect and is related to ‘paracrine’ communication (depends on what these MSC cells secrete).
A new secretome therapy: the understanding of the biological mechanisms underlying this type of cell therapy obviously opens up new prospects for cell-free regenerative therapies using what these stem cells secrete, which includes both soluble factors and factors released through extracellular vesicles.
These cell-free therapies may prove to be safer alternatives to the use of the cells themselves. Although numerous studies have suggested the ability of MSCs to reduce inflammation, no study had yet evaluated the effects of the MSC secretome on the antimicrobial defense mechanisms of skin cells or on bacterial biofilms.
In vivo study in large animal models of infected wounds confirms that wounds treated for 24 hours with the secretions of these stem cells (MSC) have a much reduced MRSA bacterial load compared to wounds treated with antibiotics:
- MSC-secreted factors significantly reduce MRSA viability.
- MSC-secreted factors stimulate the immune responses of surrounding skin cells which increases their antimicrobial activities.
This work reveals the full antimicrobial properties of the MSC secretome and provides evidence for the efficacy of MSC secretome-based treatments for infected wounds.
the goal is to better exploit the antimicrobial properties of proteins secreted by stem cells as a potential treatment to reduce skin wound infection.
Wounds caused by resistant bacteria have become a nightmare to treat as the arsenal of antibiotics available to doctors is becoming impotent against this scourge. So better exploiting the antimicrobial properties of proteins secreted by stem cells as a potential treatment to reduce skin wound infection is such a promising new avenue and is welcome news.