Mesenchymal stromal cell-derived exosomes ameliorate peripheral neuropathy in a mouse model of diabetes
Diabetic peripheral neuropathy (DPN) is one of the major complications of diabetes, which contributes greatly to morbidity and mortality. There is currently no effective treatment for this disease. Exosomes are cell-derived nanovesicles and play an important role in intercellular communications. The present study investigated whether mesenchymal stromal cell (MSC)-derived exosomes improve neurological outcomes of DPN.
Exosomes were isolated from the medium of cultured mouse MSCs by ultracentrifugation. Diabetic mice (BKS.Cg-m+/+Leprdb/J, db/db) at the age of 20 weeks were used as DPN models. Heterozygous mice (db/m) of the same age were used as the control. MSC-exosomes were administered weekly via the tail vein for 8 weeks. Neurological function was evaluated by testing motor and sensory nerve conduction velocities, and thermal and mechanical sensitivity. Morphometric analysis was performed by myelin sheath staining and immunohistochemistry. Macrophage markers and circulating cytokines were measured by western blot and ELISA. MicroRNA (miRNA) array and bioinformatics analyses were performed to examine the exosomal miRNA profile and miRNA putative target genes involved in DPN.
Treatment of DPN with MSC-exosomes markedly decreased the threshold for thermal and mechanical stimuli and increased nerve conduction velocity in diabetic mice. Histopathological analysis showed that MSC-exosomes markedly augmented the density of FITC-dextran perfused blood vessels and increased the number of intraepidermal nerve fibres (IENFs), myelin thickness and axonal diameters of sciatic nerves. Western blot analysis revealed that MSC-exosome treatment decreased and increased M1 and M2 macrophage phenotype markers, respectively. Moreover, MSC-exosomes substantially suppressed proinflammatory cytokines. Bioinformatics analysis revealed that MSC-exosomes contained abundant miRNAs that target the Toll-like receptor (TLR)4/NF-κB signalling pathway.
MSC-derived exosomes alleviate neurovascular dysfunction and improve functional recovery in mice with DPN by suppression of proinflammatory genes.
KeywordsDiabetes Diabetic peripheral neuropathy Exosomes Inflammation Mesenchymal stromal cells miRNA
Diabetic peripheral neuropathy
Glycogen synthase kinase
Intraepidermal nerve fibre
Inducible nitric oxide synthase
Ingenuity Pathway Analysis
Interleukin-1 receptor-associated kinase 1
Myelin basic protein
Motor nerve conduction velocity
Mesenchymal stromal cell
Protein gene product 9.5
Region of interest
Sensory nerve conduction velocity
The authors thank J. Landschoot-Ward and Q.-e. Lu (Department of Neurology, Henry Ford Health System) for immunohistochemistry staining.
XSL and BF designed the study, analysed and interpreted data, and composed the manuscript. BF, CL, AS, LW, WP, RZ, MC and ZGZ conducted the experiments, acquired and analysed data and edited the manuscript. All authors have critically reviewed and approved the manuscript. XSL and ZGZ are the guarantors of this work and, as such, had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
This work was supported by the National Institutes of Health National Institute of Diabetes and Digestive and Kidney Disease grant RO1 RDK102861A (XSL), American Heart Association Grant-in-Aid 14GRNT20460167 (XSL), and RO1 NS075156 (ZGZ).
Duality of interest
The authors declare that there is no duality of interest associated with this manuscript.
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