Exosomes from marrow stromal cells expressing miR-146b inhibit glioma growth

Exosomes are 30–150 nm vesicles secreted by a wide range of mammalian cells that can contain microRNA (miRNA). To test if marrow stromal cell (MSC) exosomes could be used as a vehicle for delivery of anti-tumor miRNAs, we transfected MSCs with a miR-146b expression plasmid, and harvested exosomes released by the MSCs. Intra-tumor injection of exosomes derived from miR-146-expressing MSCs significantly reduced glioma xenograft growth in a rat model of primary brain tumor.

► Here, we engineered MSCs to shed exosomes that contain miR-146b, a known anti-glioma miRNA.
► Glioma bearing rats were treated with miR-146b exosomes.
► Rats treated with miR-146b exosomes had significantly smaller tumor volumes.
► In vitro, miR-146b exosomes slowed glioma growth and inhibited putative miR-146b targets.