Equine stem cells valuable in fighting bacteria in skin wounds, scientists find

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Rebecca Harman at work in the laboratory of Gerlinde Van de Walle. Photo: Supplied
Rebecca Harman at work in the laboratory of Gerlinde Van de Walle. Photo: Supplied

Researchers are exploring the use of stem cells to treat skin wounds in horses with techniques that may eventually translate to treatment of human patients.

Rebecca Harman and a team of researchers in the laboratory of equine health professor Gerlinde Van de Walle at New York’s Cornell University are finding that factors secreted by adult stem cells, also known as mesenchymal stromal cells (MSC), are able to fight bacteria commonly found in skin wounds.

Bacteria often complicate the treatment of chronic skin wounds in humans, driving a need for new therapies that reduce bacteria in wounds.

Although previous research has explored the therapeutic value of these cells in healing, few studies examined their potential to inhibit bacterial growth. Harman and the Van de Walle lab are examining the antibacterial properties of equine MSC-secreted substances, known as factors, such as antimicrobial peptides, to develop therapies for horses and to serve as a model for human studies.

“This equine skin-wound healing model offers a readily translatable example for MSC therapies in humans,” said Harman, a research support specialist at the Baker Institute for Animal Health. “Although mice are smaller and less expensive model organisms, the horse is more physiologically relevant when it comes to human skin-wound healing.”

Stem cells are already commonly used as a biologic therapy for equine joint and tendon injuries. Practitioners isolate them from bone marrow and inject them at injury sites. Bone marrow extraction is invasive, however, and injection-site complications – such as immune responses against the cells – may reduce the efficacy of the therapy.

Harman’s work sidesteps these issues by isolating the stem cells from blood rather than bone marrow, making their collection less invasive. In addition, she is applying the factors secreted by them, rather than the cells themselves, to the wounds, which reduces the chance of a host immune response against the therapy.

Stems cells provide a range of benefits that extend beyond those of conventional antibiotics. Their secreted antimicrobial peptides can directly inhibit the growth of bacteria in skin wounds, and other secreted factors fight bacteria indirectly by attracting resident immune cells that are primed to clear pathogens.

By further experimenting with different delivery methods, the lab’s research may make things easier for practitioners as well. The antimicrobial peptide molecules secreted by the stems cells have proven to be fairly stable and can maintain their activity through a variety of conditions, such as extended freezing or being dried into a powder. This enables long-term storage options that are more efficient than having to isolate the cells and collect secreted factors every time a wound needs to be treated.

The research team will soon partner with Bettina Wagner, chair of Population Medicine and Diagnostic Sciences at the veterinary college, to begin testing on her equine herd. Every summer, Wagner’s Icelandic horses naturally develop skin wounds as part of an allergic reaction. The wounds will be directly treated with the secreted factors  and the lab will monitor bacteria levels over time to see if there are differences between treated and untreated wounds.

“What we learn from the Icelandic herd about the wound-healing properties of MSC-secreted factors could reasonably be tested in human medicine,” Harman says.

Reporting: Melanie Greaver Cordova
Published courtesy of the Cornell Chronicle.

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