Transplantation of Exosomes Derived From Human Wharton's Jelly Mesenchymal Stromal Cells Enhances Functional Improvement in Stroke Rats

Cerebral ischemic stroke is a major cerebrovascular disease and the leading cause of adult disability. We and others previously demonstrated that transplantation of human Wharton's jelly mesenchymal stromal cells (WJ-MSCs) attenuated neuronal damage and promoted functional improvement in stroke animals. This study aimed to investigate the protective effects of human WJ-MSC exosome (Exo) transplant in cellular and rat models of cerebral stroke. Administration of Exo significantly antagonized glutamate-mediated neuronal loss and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-X nick end labeling (TUNEL) in rat primary cortical neuronal cultures. Adult male rats underwent a 60-min middle cerebral artery occlusion (MCAo); Exo or vehicle was injected through the tail vein 5-10 min after the MCAo. Two days later, the rats underwent a series of behavioral tests. Stroke rats receiving Exo developed a significant improvement in locomotor function and forelimb strength while reductions in body asymmetry and Bederson's neurological score. After the behavioral test, brain tissues were harvested for histological and quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) analyses. Animals receiving Exo had less infarction volume, measured by 2,3,5-triphenyl tetrazolium chloride (TTC) staining. Transplantation of Exo increased the expression of protective neurotrophic factors (BMP7, GDNF) and anti-apoptotic factors (Bcl2, Bcl-xL) in the ischemic brain. These findings suggest that early post-treatment with WJ-MSC Exo, given non-invasively through the vein, improved functional recovery and reduced brain damage in the stroke brain.