Exosomes Derived from MicroRNA-146a-5p-Enriched Bone Marrow Mesenchymal Stem Cells Alleviate Intracerebral Hemorrhage by Inhibiting Neuronal Apoptosis and Microglial M1 Polarization

Drug Des Devel Ther. 2020 Aug 5:14:3143-3158. doi: 10.2147/DDDT.S255828. eCollection 2020.

Abstract

Introduction: Intracerebral hemorrhage (ICH) is a devastating type of stroke with high mortality, and the effective therapies for ICH remain to be explored. Exosomes (Exos) have been found to play important roles in cell communication by transferring molecules, including microRNAs (miRNAs/miRs). MiRNAs are critical regulators of genes involved in many various biological processes and have been demonstrated to aggravate or alleviate brain damages induced by ICH. The aim of the present study was to investigate the effect of Exos derived from miR-146a-5p-enriched bone marrow mesenchymal stem cells (BMSCs-miR-146a-5p-Exos) on experimental ICH.

Methods: ICH was induced in adult male Sprague-Dawley rats by an intrastriatal injection of collagenase type IV. At 24 h after surgery, Exos were administrated. For detecting apoptotic cells, TUNEL staining was performed using an in situ Cell Death Detection Kit. Fluoro-Jade B staining was performed to detect degenerating neurons. Immunofluorescence assay was performed to detect the expression of myeloperoxidase (MPO) and OX-42. The binding of miR-146a-5p and its target genes was confirmed by luciferase reporter assay.

Results: At 24 h after surgery, BMSCs-miR-146a-5p-Exos administration significantly improved neurological function, reduced apoptotic and degenerative neurons, and inhibited inflammatory response. Furthermore, miR-146a-5p-enriched Exos obviously inhibited the M1 polarization of microglia after ICH in rats, accompanied by the reduced expression of pro-inflammatory mediators releasing by M1 microglia including inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2) and monocyte chemoattractant protein-1 (MCP-1). Finally, we observed that miR-146a-5p directly targeted interleukin-1 receptor-associated kinase1 (IRAK1) and nuclear factor of activated T cells 5 (NFAT5), which contributed to the inflammation response and the polarization of M1 microglia/macrophages.

Conclusion: We demonstrated that miR-146a-5p-riched BMSCs-Exos could offer neuroprotection and functional improvements after ICH through reducing neuronal apoptosis, and inflammation associated with the inhibition of microglial M1 polarization by downregulating the expression of IRAK1 and NFAT5.

Keywords: apoptosis; exosomes; intracerebral hemorrhage; microRNA-146a-5p; microglial M1 polarization.

MeSH terms

  • Animals
  • Apoptosis*
  • Cerebral Hemorrhage / chemically induced
  • Cerebral Hemorrhage / metabolism*
  • Exosomes / metabolism*
  • Injections, Intraventricular
  • Male
  • Matrix Metalloproteinase 9 / administration & dosage
  • Matrix Metalloproteinase 9 / metabolism
  • Mesenchymal Stem Cells / metabolism*
  • MicroRNAs / metabolism*
  • Microglia / metabolism*
  • Neurons / metabolism*
  • Rats
  • Rats, Sprague-Dawley

Substances

  • MIRN146 microRNA, rat
  • MicroRNAs
  • Matrix Metalloproteinase 9

Grants and funding

This study was supported by grants from the National Natural Science Foundation of China (No. 81601063), the Doctoral Foundation of the First Affiliated Hospital of Harbin Medical University (No. 2017B015), the Post-doctoral Science Foundation of China (No. 2016M591550), and the Post-doctoral Science Foundation of Heilongjiang Province (No. LBH-Z16117).