Introduction: Declining physical or mental health in older dogs can lead to changes in the dog's cognitive and musculoskeletal function. Regrettably, these degenerative changes cannot be remedied. In the present study, geriatric small dogs exhibiting cognitive and behavioral changes were treated with human embryonic stem cell-derived mesenchymal stemcells (ES-MSCs, n = 21) and mesenchymal stem cell-derived extracellular vesicles (ES-MSC-EVs, n = 21).Methods: Before and 2 weeks after treatment, the cognitive and mobility status of the dogs were assessed using theCanine Cognitive Dysfunction Rating (CCDR) and the Liverpool Osteoarthritis in Dogs (LOAD) scale. Additionally, safety assessments were conducted through blood tests such as complete blood count and serum chemistry.Results: Following an assessment of clinical symptoms and blood tests in both the groups receiving ES-MSC and ES-MSC-EVs treatments, no notable side effects were detected. Moreover, the questionnaire survey revealed that both groups showed alleviation in CCDR and LOAD scores following administration.Discussion: These findings suggest that ES-MSC and ES-MSC-EV treatments have the potential to be used as a therapeutic option for improving clinical symptoms of degenerative diseases such as canine cognitive dysfunction and degenerativemusculoskeletal diseases in elderly dogs.

Acute lung injury is an acute inflammation disorder that disrupts the lung endothelial and epithelial barriers. In this study, we investigated the extracellular vesicles (EVs) obtained via priming inflammatory cytokines such as tumor necrosis factor (TNF)-α and interferon (IFN)-γ on canine adipose mesenchymal stem cells in improving their anti-inflammatory and/or immunosuppressive potential, and/or their ability to alleviate lipopolysaccharide-induced lung injury in vitro. We also explored the correlation between epithelial-to-mesenchymal transition and the inflammatory repressive effect of primed EVs. Using small RNA-Seq, we confirmed that miR-16 and miR-502 significantly increased in EVs from TNF-α and IFN-γ-primed canine adipose mesenchymal stem cells. The pro and anti-inflammatory cytokines were analyzed in a lipopolysaccharide-induced lung injury model and we found that the EV anti-inflammatory effect improved on priming with inflammatory cytokines. EVs obtained from primed stem cells effectively suppress endothelial-to-mesenchymal transition in a lung injury model. Our results suggest a potential therapeutic approach utilizing EVs obtained from adipose mesenchymal stem cells primed with TNF-α and IFN-γ against lung inflammation and endothelial to mesenchymal transition.

Ensuring the safety of mesenchymal stem cell (MSC) therapy is a fundamental requirement in clinical practice. This study aimed to assess the safety of using gonadal tissue-derived MSCs (n = 10) compared to the commonly utilized adipose tissue-derived MSCs (n = 9) in geriatric dogs with chronic diseases. All participants received allogeneic MSC therapy, and no allergic reactions due to allogeneic cell immunogenicity were noted. Both groups showed no adverse changes in physical exams or hematological parameters before and after therapy. Importantly, there were no instances of tumor formation or growth post-treatment in either group. The findings demonstrated that dogs treated with gonadal tissue-derived MSCs experienced no clinical adverse effects. However, clinical adverse effects were reported in one case of adipose tissue-derived MSC therapy. Despite limitations in monitoring beyond one year and constraints due to a small and diverse patient group, this pioneering study validates the safe use of gonadal tissue-derived MSCs in aged companion animals. It underscores the potential of utilizing tissues from neutering procedures to advance regenerative medicine and expand cell banks and therapy options for companion animals.

Background/Aim: Acute lung injury (ALI) is an important pathological process in acute respiratory distress syndrome; however, feasible and effective treatment strategies for ALI are limited. Recent studies have suggested that stem cell-derived exosomes can ameliorate ALI; however, there remains no consensus on the protocols used, including the route of administration. This study aimed to identify the appropriate route of administration of canine stem cell-derived exosomes (cSC-Exos) in ALI. Lipopolysaccharides were used to induce ALI. Materials and Methods: Mice with ALI were treated with cSC-Exos by intratracheal instillation or intravenous injection. The efficacy of the route of administration was confirmed by determining the total cell count in the bronchoalveolar lavage fluid and histopathological changes. The treatment mechanism was confirmed by measuring cytokine levels and immune cell changes in M2 macrophages (CD206+ cells) and regulatory T cells (FOXP+ cells). Results: When cSC-Exos were injected, inflammation was alleviated, pro-inflammatory cytokine levels were reduced, and FOXP3+ and CD206+ cells were activated. Following intratracheal instillation, an enhanced inflammation-relieving response was observed. Conclusion: This study compared the effects of stem cell-derived exosomes on alleviating lung inflammation according to injection routes in an ALI mouse model. It was confirmed that direct injection of exosomes into the airway had a greater ability to alleviate lung inflammation than intravenous injection by polarizing M2 macrophages and increasing regulatory T cells.

Circulating microRNAs (miRNAs) regulate inflammatory responses and have emerged as potential minimally invasive biomarkers of disease. However, comprehensive profiling of circulating miRNAs in naturally occurring inflammatory conditions in dogs remains limited. This study aimed to characterize circulating miRNA expression profiles using small RNA sequencing in plasma samples from dogs with pyometra, non-reproductive inflammatory diseases, and healthy controls to identify shared and disease-related miRNA alterations. Global expression patterns, including heatmap and principal component analysis (PCA), demonstrated separation between healthy controls and diseased dogs. Based on DESeq2 analysis (adjusted p-value < 0.05), 39 circulating miRNAs were commonly altered in both pyometra and non-reproductive inflammatory diseases compared with healthy controls. A total of 83 miRNAs were differentially expressed in the pyometra group, whereas 4 miRNAs were differentially expressed in the non-reproductive inflammatory disease group. Direct comparison between the two disease groups further identified three circulating miRNAs—cfa-miR-885, cfa-miR-599, and cfa-miR-122—as significantly differentially expressed. These findings suggest that circulating miRNA profiles in dogs with pyometra reflect both systemic inflammation and condition-related molecular variation. Further studies with larger cohorts are warranted to validate the clinical relevance of these candidate circulating miRNAs.

Hepatic abscesses are an uncommon but potentially life-threatening condition in dogs. Various predisposing factors have been reported, including biliary tr