In Vivo Inhibition of miR-155 Promotes Recovery after Experimental Mouse Stroke.
A multifunctional microRNA, miR-155, has been recently recognized as an important modulator of numerous biological processes. In our previous in vitro studies, miR-155 was identified as a potential regulator of the endothelial morphogenesis. The present study demonstrates that in vivo inhibition of miR-155 supports cerebral vasculature after experimental stroke. Intravenous injections of a specific miR-155 inhibitor were initiated at 48 h after mouse distal middle cerebral artery occlusion (dMCAO). Microvasculature in peri-infarct area, infarct size, and animal functional recovery were assessed at 1, 2, and 3 weeks after dMCAO. Using in vivo two-photon microscopy, we detected improved blood flow and microvascular integrity in the peri-infarct area of miR-155 inhibitor-injected mice. Electron microscopy revealed that, in contrast to the control group, these animals demonstrated well preserved capillary tight junctions (TJs). Western blot analysis data indicate that improved TJ integrity in the inhibitor-injected animals could be associated with stabilization of the TJ protein ZO-1 and mediated by the miR-155 target protein Rheb. MRI analysis showed significant (34%) reduction of infarct size in miR-155 inhibitor-injected animals at 21 d after dMCAO. Reduced brain injury was confirmed by electron microscopy demonstrating decreased neuronal damage in the peri-infarct area of stroke. Preservation of brain tissue was reflected in efficient functional recovery of inhibitor-injected animals. Based on our findings, we propose that in vivo miR-155 inhibition after ischemia supports brain microvasculature, reduces brain tissue damage, and improves the animal functional recovery. Significance statement: In the present study, we investigated an effect of the in vivo inhibition of a microRNA, miR-155, on brain recovery after experimental cerebral ischemia. To our knowledge, this is the first report describing the efficiency of intravenous anti-miRNA injections in a mouse model of ischemic stroke. The role of miRNAs in poststroke revascularization has been unexplored and in vivo regulation of miRNAs during the subacute phase of stroke has not yet been proposed. Our investigation introduces a new and unexplored approach to cerebral regeneration: regulation of poststroke angiogenesis and recovery through direct modulation of specific miRNA activity. We expect that our findings will lead to the development of novel strategies for regulating neurorestorative processes in the postischemic brain.
Department of Neurosurgery, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131.
Ernesto
E
Caballero-Garrido
Department of Neurosurgery, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131.
Juan Carlos
JC
Pena-Philippides
Ilia State University, 0162 Tbilisi, Georgia, and.
Tamar
http://orcid.org/0000-0002-5567-2678
T
Lordkipanidze
Department of Neurosurgery, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131.
Denis
D
Bragin
BRaIN Imaging Center and College of Pharmacy and.
Yirong
Y
Yang
Department of Mathematics and Statistics, University of New Mexico, Albuquerque, New Mexico 87131.
Erik Barry
EB
Erhardt
Department of Neurosurgery, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131, troitbak@salud.unm.edu.
Tamara
http://orcid.org/0000-0003-1599-6819
T
Roitbak
D000818:Animals; D020244:Infarction, Middle Cerebral Artery / Q000628:therapy*; D007275:Injections, Intravenous; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000235:genetics*; D055806:Microvessels / Q000378:metabolism / Q000473:pathology; D016376:Oligonucleotides, Antisense / Q000008:administration & dosage / Q000627:therapeutic use; D000067492:RNAi Therapeutics; D062725:Tight Junction Proteins / Q000378:metabolism; D019108:Tight Junctions / Q000378:metabolism / Q000648:ultrastructure
D035683:MicroRNAs; C532623:Mirn155 microRNA, mouse; D016376:Oligonucleotides, Antisense; D062725:Tight Junction Proteins
ischemia; microRNA; microvasculature; neuroprotection; regeneration; stroke