Exosomes Derived from Mesenchymal Stromal Cells Promote Axonal Growth of Cortical Neurons

Abstract

Treatment of brain injury with exosomes derived from mesenchymal stromal cells (MSCs) enhances neurite growth. However, the direct effect of exosomes on axonal growth and molecular mechanisms underlying exosome-enhanced neurite growth are not known. Using primary cortical neurons cultured in a microfluidic device, we found that MSC-exosomes promoted axonal growth, whereas attenuation of argonaut 2 protein, one of the primary microRNA (miRNA) machinery proteins, in MSC-exosomes abolished their effect on axonal growth. Both neuronal cell bodies and axons internalized MSC-exosomes, which was blocked by botulinum neurotoxins (BoNTs) that cleave proteins of the soluble N-ethylmaleimide sensitive factor attachment protein receptor (SNARE) complex. Moreover, tailored MSC-exosomes carrying elevated miR-17-92 cluster further enhanced axonal growth compared to native MSC-exosomes. Quantitative RT-PCR and Western blot analysis showed that the tailored MSC-exosomes increased levels of individual members of this cluster and activated the PTEN/mTOR signaling pathway in recipient neurons, respectively. Together, our data demonstrate that native MSC-exosomes promote axonal growth while the tailored MSC-exosomes can further boost this effect and that tailored exosomes can deliver their selective cargo miRNAs into and activate their target signals in recipient neurons. Neuronal internalization of MSC-exosomes is mediated by the SNARE complex. This study reveals molecular mechanisms that contribute to MSC-exosome-promoted axonal growth, which provides a potential therapeutic strategy to enhance axonal growth.

Increased miR‐124‐3p in microglial exosomes following traumatic brain injury inhibits neuronal inflammation and contributes to neurite outgrowthviatheir transfer into neurons

“…From the data, mean values were calculated for each parameter in every learning session. The latency time to reach the submerged platform (d [28][29][30][31][32] and the time spent in the goal quadrant (d 33) were measured as the indicators of learning ability. In addition, rTBI mice in the above treatment groups were euthanized at 35 DPI, and the expression levels of TNF-a, IL-1b, IL-6, and IL-10 in the injured hemisphere were measured with real-time PCR.…”

Mesenchymal Stromal Cells Promote Axonal Outgrowth Alone and Synergistically with Astrocytes via tPA

“…The day of plug detection was considered to be embryonic day 0 (E0). Cortical cells were dissected from day 17–18 (E17-18) mouse embryos according to our established procedure with some modifications [35, 36]. Briefly, embryos were removed under deep Ketamine anesthesia, and the cerebral cortex dissected, stripped of meninges, and dissociated by a combination of Ca 2+ and Mg 2+ free Hanks balance salt solution (HBSS, Thermo Fisher Scientific Inc. Wayne, MI) containing 0.125% trypsin (Thermo Fisher Scientific Inc.) at 37°C for 20 min, then mechanically triturated for ~20 times.…”

Exosomes in stroke pathogenesis and therapy

“…Exosomes transfer their cargo miRNAs to recipient cells (120,121) and MSC-derived exosomes contain more than 700 miRNAs that are bound to argonaute2 (AGO2), a component of the RNAinduced silencing complex (RISC) (122,123). The effect of engineered MSC-derived exosomes that carry elevated miRNAs on brain remodeling after stroke has been investigated in vitro and in vivo (118,119).…”