Generation and characterization of mesenchymal stem cells from the affected femoral heads of dogs with Legg Calvé Perthes disease.

Background: Canine Legg Calvé Perthes disease (LCPD) occurs during the growth period, and the cause of ischemic necrosis of the femoral head during growth remains unclear. If LCPD-affected femoral head-derived mesenchymal stem cells (LCPD-MSCs) can be generated, they can be used as a new tool for the pathophysiological analysis of canine LCPD. Aim: To generate affected femoral head-derived mesenchymal stem cells (MSCs) from dogs with LCPD and investigate the mRNA expression levels of angiogenesis-related factors and osteogenic differentiation potency of LCPD-MSCs. Methods: This study was performed using affected femoral heads from dogs diagnosed with LCPD and underwent femoral head and neck ostectomy. The necrotic tissue was harvested from the LCPD-affected femoral head and cultured statically (LCPD group, n = 6). Canine bone marrow-derived MSCs (BM-MSCs) were used as controls (control group, n = 6). First, the morphology of the cultured cells was observed, and the expression of CD29, CD34, CD44, CD45, CD90, and major histocompatibility complex class II was analyzed using flow cytometry. Additionally, the trilineage differentiation potency of the LCPD-affected head-derived adherent cells was examined. Furthermore, the expression levels of HIF1A, VEGFA, VEGFB, and PDGFB mRNAs and the bone differentiation potency of LCPD-affected head-derived adherent cells were investigated. Results: LCPD-affected femoral head-derived adherent cells showed a fibroblast-like morphology, and the expression of cell surface antigens was similar to that of BM-MSCs. In addition, LCPD-affected femoral head-derived adherent cells showed the same trilineage differentiation potency as BM-MSCs and were consistent with MSC characteristics. Furthermore, the mRNA expression levels of angiogenesis-related factors could be objectively measured in LCPD-MSCs and those MSCs had bone differentiation potency. Conclusion: In the present study, canine LCPD-MSCs were successfully generated, suggesting their usefulness as a tool for pathological analysis of LCPD in dogs.

A pilot study of microRNA assessment as a means to identify novel biomarkers of spontaneous osteoarthritis in dogs.

MicroRNAs (miRNAs) are important regulators of intercellular signaling and are promising biomarkers in osteoarthritis (OA). In this study, comprehensive analysis was performed to identify miRNAs involved in the pathogenesis of spontaneous OA in dogs. Dogs diagnosed with OA based on radiography and arthroscopy of the stifle joint were included in the OA group. Dogs without any evidence of orthopedic disease were included in the unaffected group. To investigate miRNA expression levels, RNA sequencing analysis (RNA-seq) was performed in synovial tissue (OA group: n = 3, Unaffected group: n = 3) and RT-qPCR was performed in synovial tissue, synovial fluid and serum (OA group: n = 17, Unaffected group: n = 6), and compared between the two groups. The RNA-seq results showed that 57 miRNAs were significantly upregulated and 42 were significantly downregulated in the OA group. Specifically, miR-542 and miR-543 expression levels in the synovial tissue, synovial fluid, and serum were consistently higher in the OA group than in the unaffected group, suggesting that these miRNAs may be used as biomarkers for detecting canine OA. This is the first report to comprehensively analyze the expression patterns of miRNAs in the synovial tissue of dogs with spontaneous OA.

Treatment of methicillin-resistant Staphylococcus aureus infection following tibial plateau leveling osteotomy in a dog.

BACKGROUND: In recent years, surgical site infections caused by drug-resistant pathogens have emerged as a cause of concern in small animal practice. In this report, methicillin-resistant Staphylococcus aureus (MRSA) infections associated with tibial plateau leveling osteotomy (TPLO) is reported. However, there have been no reports on the treatment of MRSA infection following TPLO in dogs. This case report describes the use of a combination of vancomycin and rifampicin to treat MRSA infection following TPLO in a dog. CASE DESCRIPTION: A 7-year-old spayed female American cocker spaniel was referred for right hind limb lameness that did not improve with conservative treatment. The dog was diagnosed with cranial cruciate ligament rupture, for which TPLO was performed. Once the surgical wound was closed, the dog licked the skin on the surgical site, causing the injury to dehisce. MRSA was detected from the purulent discharge, and chloramphenicol was then administered based on the drug sensitivity test results. Because of the continued drainage, the implants were removed after the bone union of the osteotomy site was observed. Since this did not provide any relief to the existing condition, the antibiotic was changed to vancomycin at 132 days after TPLO surgery, and the infected location was cleaned many times through a drain tube placed into the tibia. However, the infection could not be controlled. Thus, a rifampicin and vancomycin combination was started. As a result, the purulent discharge disappeared and the fistula entirely closed on the 154th day after TPLO surgery. CONCLUSION: A combination of rifampicin and vancomycin may be effective for treating MRSA infection at the surgical site following TPLO surgery that does not heal despite implant removal and administration of vancomycin.