Researchers with the Cornell University College of Veterinary Medicine are exploring the use of stem cells to treat skin wounds in horses with techniques that may eventually translate into the treatment of human patients, according to the university's Cornell Chronicle.
Rebecca Harman and a team of researchers in the lab of Gerlinde Van de Walle -- the Harry M. Zweig assistant professor in equine health in the Cornell College of Veterinary Medicine -- are finding that factors secreted by adult stem cells, also known as mesenchymal stomal cells (MSCs), are able to fight bacteria commonly found in skin wounds.
Bacteria often complicate the treatment of chronic skin wounds in people, driving a need for new therapies that reduce bacteria in wounds. Although previous research has explored the therapeutic value of MSCs in healing, few studies have examined the potential for MSCs to inhibit bacterial growth, Cornell said.
Harman and the Van de Walle lab are examining the antibacterial properties of equine MSC-secreted factors like 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.”
MSCs are already commonly used as a biologic therapy for equine joint and tendon injuries. Practitioners isolate MSCs 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 explained.
Her work sidesteps these issues by isolating MSCs from blood rather than bone marrow, making the collection of these cells less invasive. In addition, Harman is applying the factors secreted by MSCs -- rather than the cells themselves -- to the wounds, which reduces the chance of a host immune response against the therapy, the university said.
MSCs 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, Harmon explained.
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 MSCs have proved 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 MSCs 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 in vivo 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 of MSCs, 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 said.