Micro-RNAs Shuttled by Extracellular Vesicles Secreted from Mesenchymal Stem Cells Dampen Astrocyte Pathological Activation and Support Neuroprotection in In-Vitro Models of ALS

Abstract

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease with no effective cure. Astrocytes display a toxic phenotype in ALS and contribute to motoneuron (MN) degeneration. Modulating astrocytes’ neurotoxicity can reduce MN death. Our previous studies showed the beneficial effect of mesenchymal stem cell (MSC) administration in SOD1G93A ALS mice, but the mechanisms are still unclear. We postulated that the effects could be mediated by extracellular vesicles (EVs) secreted by MSCs. We investigated, by immunohistochemical, molecular, and in vitro functional analyses, the activity of MSC-derived EVs on the pathological phenotype and neurotoxicity of astrocytes isolated from the spinal cord of symptomatic SOD1G93A mice and human astrocytes (iAstrocytes) differentiated from inducible neural progenitor cells (iNPCs) of ALS patients. In vitro EV exposure rescued mouse and human ALS astrocytes’ neurotoxicity towards MNs. EVs significantly dampened the pathological phenotype and neuroinflammation in SOD1G93A astrocytes. In iAstrocytes, exposure to EVs increased the antioxidant factor Nrf2 and reduced reactive oxygen species. We previously found nine miRNAs upregulated in MSC-derived EVs. Here, the transfection of SOD1G93A astrocytes with single miRNA mimics reduced astrocytes’ activation and the expression of neuroinflammatory factors. Moreover, miR-466q and miR-467f mimics downregulate Mapk11, while miR-466m-5p and miR-466i-3p mimics promote the nuclear translocation of Nrf2. In iAstrocytes, transfection with miR-29b-3p mimic upregulated NQO1 antioxidant activity and reduced neurotoxicity towards MNs. MSC-derived EVs modulate astrocytes’ reactive phenotype and neurotoxicity through anti-inflammatory and antioxidant-shuttled miRNAs, thus representing a therapeutic strategy in ALS.

Attenuation of amyotrophic lateral sclerosis via stem cell and extracellular vesicle therapy: An updated review

“…41 Recently, miRNAs in the setting of ALS revealed evidence that astrocytes assume a phenotype toxic to motor neurons. 42 EVs derived from MSCs protected motor neurons upon exposure in vitro to astrocytes isolated from the spinal cord of SOD1 G93A mice or human astrocytes differentiated from inducible neural progenitor cells collected from patients with ALS. SOD1 G93A astrocytes' pathological phenotype and neuroinflammation were ameliorated with EV therapy, and human astrocytes increased nuclear factor-erythroid 2-related factor-2 (Nrf2) and reduced reactive oxygen species (ROS) expression.…”

“…In human astrocytes, miRNA-29b-3p mimic was found to upregulate the antioxidant activity of NAD(P)H quinone dehydrogenase 1 (NQO1). 42 Bonafede et al 36 demonstrated that EVs derived from murine adipose-derived stromal cells conferred protection from oxidative damage to motor neurons expressing ALS mutations. One of the major systems responsible for responding to oxidative stress in cells is the Kelch-like ECH-associated protein 1 (KEAP1)-Nrf2 system, which consists of the antioxidant Nrf2 and its regulator KEAP1.…”

“…In vivo administration decreased neuroinflammatory markers within the mouse spinal cord but did not affect the course of the disease 41 . Recently, miRNAs in the setting of ALS revealed evidence that astrocytes assume a phenotype toxic to motor neurons 42 . EVs derived from MSCs protected motor neurons upon exposure in vitro to astrocytes isolated from the spinal cord of SOD1 G93A mice or human astrocytes differentiated from inducible neural progenitor cells collected from patients with ALS.…”

“…EVs derived from MSCs protected motor neurons upon exposure in vitro to astrocytes isolated from the spinal cord of SOD1 G93A mice or human astrocytes differentiated from inducible neural progenitor cells collected from patients with ALS. SOD1 G93A astrocytes' pathological phenotype and neuroinflammation were ameliorated with EV therapy, and human astrocytes increased nuclear factor‐erythroid 2‐related factor‐2 (Nrf2) and reduced reactive oxygen species (ROS) expression 42 . Nrf2 is an important driver of a battery of antioxidant genes, also relevant in cerebral ischemia 43 .…”

The microRNAs (miRs) overexpressing mesenchymal stem cells (MSCs) therapy in neurological disorders; hope or hype

“…Additionally, astrocyte activation and the expression of neuroinflammatory markers were decreased after the transfection of SOD1G93A astrocytes with a single miRNA mimic. Furthermore, mimics of miR‐466q and miR‐467f downregulated the Mapk11, while miR‐466m‐5p and miR‐466i‐3p mimics enhanced Nrf2's nuclear translocation 194 . In another study, Sanooghi et al 195 demonstrated the miRNA profiles of cord blood MSCs during differentiation into motor neuron‐like cells.…”