MiR-133b promotes neural plasticity and functional recovery after treatment of stroke with multipotent mesenchymal stromal cells in rats via transfer of exosome-enriched extracellular particles

Abstract

To test, in vivo, the hypothesis that exosomes from multipotent mesenchymal stromal cells (MSCs) mediate microRNA 133b (miR-133b) transfer which promotes neurological recovery from stroke, we used knockin and knockdown technologies to upregulate or downregulate the miR-133b level in MSCs (miR-133b1MSCs or miR- 133b2MSCs) and their corresponding exosomes, respectively. Rats were subjected to middle cerebral artery occlusion (MCAo) and were treated with naiv̈e MSCs, miR-133b1MSCs, or miR-133b2MSC at 1 day after MCAo. Compared with controls, rats receiving naiv̈e MSC treatment significantly improved functional recovery and exhibited increased axonal plasticity and neurite remodeling in the ischemic boundary zone (IBZ) at day 14 after MCAo. The outcomes were significantly enhanced with miR-133b1MSC treatment, and were significantly decreased with miR-133b2MSC treatment, compared to naiv̈e MSC treatment. The miR-133b level in exosomes collected from the cerebral spinal fluid was significantly increased after miR-133b1MSC treatment, and was significantly decreased after miR-133b2MSC treatment at day 14 after MCAo, compared to naiv̈e MSC treatment. Tagging exosomes with green fluorescent protein demonstrated that exosomes-enriched extracellular particles were released from MSCs and transferred to adjacent astrocytes and neurons. The expression of selective targets for miR-133b, connective tissue growth factor and ras homolog gene family member A, was significantly decreased in the IBZ after miR-133b1MSC treatment, while their expression remained at similar elevated levels after miR- 133b2MSC treatment, compared to naiv̈e MSC treatment. Collectively, our data suggest that exosomes from MSCs mediate the miR-133b transfer to astrocytes and neurons, which regulate gene expression, subsequently benefit neurite remodeling and functional recovery after stroke. © AlphaMed Press.