Abstract 135: MicroRNA 133b Promotes Neural Plasticity Via Exosome Transfer After Treatment Of Stroke With Mesenchymal Stromal Cells In Rats
Introduction: Our previous in vitro study demonstrated that MSCs via exosomes transfer miR-133b to neural cells which promote neurite outgrowth. In the present in vivo study, we altered the miR-133b level in MSC exosomes, and tested neural plasticity and functional recovery after MSC treatment of stroke in rats.
Methods: We generated stable rat MSC cell lines with transfection of pre-miR-133b (miR-133b+MSC) and miR-133b inhibitor (miR-133b-MSC). Adult Wistar rats were subjected to 2h MCAo and intravenously received MSCs (3x106) or PBS at 24h after MCAo. Functional tests (Neurological Severity Score and Foot Fault) were performed. Rats were sacrificed 14 days after MCAo and adjacent frozen coronal sections were used for immunostaining. Western blot and TaqMan miRNA assay were used to detect protein and miR-133b.
Results: The miR-133b levels in MSCs and their corresponding exosomes were increased in miR-133b+MSCs (652.1±54.1% and 367.4±21.6%, respectively), and were decreased in miR-133b-MSCs (33.5±4.4% and 21.0±8.1%, respectively) compared to normal MSCs. At day 14 after MCAo, all MSC treatment groups except miR-133b-MSCs improved (P<0.05) functional recovery compared with PBS treatment, and miR-133b+MSCs improved (P<0.05), while miR-133b-MSCs treatment decreased (P<0.05) functional recovery compared to normal MSCs. Bielshowsky silver, NF-200 and synaptophysin staining showed that neurite remodeling increased along the ischemic boundary zone (P<0.05) after normal MSC treatment and were enhanced by miR-133b+MSC treatment (36.4±4.3%, 12.2±5.2% and 21.6±5.6%, respectively). Compared to MCAo control, normal MSC treatment increased (P<0.05) the miR-133b level in the CSF exosomes, which was further increased by miR-133b+MSCs (101.1±13.2%) and significantly decreased by miR-133b-MSCs (73.9±10.1%). MCAo increased RhoA and CTGF (target proteins of miR-133b, P<0.05, respectively) expression in rat brain and miR-133b+MSC treatment further reversed protein expression at day 14 after MCAo compared to normal MSCs.
Conclusions: In concert with our in vitro data, the present study indicates that MSC treatment promotes neural plasticity and functional recovery after stroke by transferring miRNAs (e.g. miR-133b) to neural cells via exosomes.
- © 2012 by American Heart Association, Inc.