Because injury that can start a joint infection might go unnoticed by a horse owner, veterinarians often must deal with a serious joint problem that has had time to become established before he or she is called in for a diagnosis. In addition, bacteria can form biofilms in the joint, which make it harder to successfully reach those bacteria with standard treatments.
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Those standard treatments can be prolonged and expensive, and despite aggressive care, six to 10% of affected horses die or are euthanized as a result of the joint infection or associated complications. For horses that survive, research has shown that more than 50% will suffer from chronic arthritis for the rest of their lives.
Lauren Schnabel, DVM, PhD, DACVS, DACVSMR, is an associate professor at North Carolina State University. Schnabel was working with current postdoctoral research fellow Jessica Gilbertie, DVM, PhD, who had an idea how to treat these difficult infections: a modified platelet-rich plasma (PRP).
Schnabel and Gilbertie had used platelet-rich plasma to treat other orthopedic injuries in horses, and they knew there was evidence that platelets could help combat infections.
The research, “Platelet‐rich plasma lysate displays antibiofilm properties and restores antimicrobial activity against synovial fluid biofilms in vitro,” was authored by Jessica M. Gilbertie, Thomas P. Schaer, Alicia G. Schubert, Megan E. Jacob, Stefano Menegatti, R. Ashton Lavoie, and Lauren V. Schnabel. It was published in January 2020 in the Journal of Orthopaedic Research).
The abstract of the research stated the following, in part: “Using an in vitro equine model, we investigated the ability of platelet‐rich plasma (PRP) formulations to combat synovial fluid biofilm aggregates. Synovial fluid was infected, and biofilm aggregates allowed to form over a two‐hour period. PRP was collected and processed into different formulations by platelet concentration, leukocyte presence, and activation or lysis. Infected synovial fluid was treated with different PRP formulations with or without aminoglycoside cotreatment. Bacterial load (colony‐forming unit/mL) was determined by serial dilutions and plate counting at eight hours post treatment.
“All PRP formulations displayed antimicrobial properties; however, formulations containing higher concentrations of platelets without leukocytes had increased antimicrobial activity. Lysis of PRP and pooling of the PRP lysate (PRP‐L) from multiple horses as compared to individual horses further increased antimicrobial activity. This activity was lost with the removal of the plasma component or inhibition of the proteolytic activity within the plasma. Fractionation of pooled PRP‐L identified the bioactive components to be cationic and low‐molecular weight (<10 kDa).
“Overall, PRP‐L exhibited synergism with amikacin against aminoglycoside-tolerant biofilm aggregates with greater activity against gram‐positive bacteria. In conclusion, the use of PRP‐L has the potential to augment current antimicrobial treatment regimens, which could lead to a decrease in morbidity and mortality associated with infectious arthritis.”
Schnabel added, “A huge thank you to Morris Animal Foundation and all of their generous donors for their continued support of our efforts and allowing us to help horses.”
Listen to Dr. Schnabel discuss her PRP research in this episode of Morris Animal Foundation’s Fresh Scoop podcast.
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