Stem Cell-Derived Exosomes as Therapeutic Vectors for Cardiac Repair in Dogs with Dilated Cardiomyopathy in South West Nigeria

Dilated cardiomyopathy is a progressive and frequently fatal cardiac disease in large-breed dogs, characterised by ventricular dilation, myocardial dysfunction, and arrhythmia. Conventional pharmacological management with pimobendan, furosemide, and ACE inhibitors extends survival but does not achieve myocardial repair. Mesenchymal stem cell-derived exosomes, nano-scale extracellular vesicles carrying pro-survival, anti-inflammatory, and regenerative cargo, have emerged as promising cell-free cardiac therapy vectors in rodent models. Their translation to canine clinical models in Nigeria represents a frontier for veterinary regenerative pharmacology. This study investigated the feasibility, pharmacological distribution, and cardiac functional effects of intravenously administered mesenchymal stem cell-derived exosomes in dogs with echocardiographically confirmed dilated cardiomyopathy at veterinary hospitals in Lagos and Ibadan, South West Nigeria. Canine adipose mesenchymal stem cells were isolated from omentum biopsies of healthy donor dogs, expanded in culture, and exosomes harvested by differential ultracentrifugation. Exosomes were characterised by nanoparticle tracking analysis, transmission electron microscopy, and tetraspanin surface marker profiling. Twenty-four dogs with dilated cardiomyopathy were enrolled in a randomised controlled trial receiving three weekly intravenous infusions of exosomes or vehicle. Cardiac outcomes including left ventricular fractional shortening, end-diastolic dimension, and N-terminal pro-brain natriuretic peptide were assessed monthly for six months. Exosome-treated dogs showed statistically significant improvement in fractional shortening from a baseline mean of 16.4 to 22.1 percent by month three. NT-proBNP declined significantly and quality of life scores improved. These findings represent the first clinical evidence of exosome-mediated cardiac benefit in canine dilated cardiomyopathy in an African setting, opening a novel veterinary therapeutics pathway. Keywords: exosomes, dilated cardiomyopathy, cardiac regeneration, mesenchymal stem cells, dogs.