Intranasally Administered Exosomes from Umbilical Cord Stem Cells Have Preventive Neuroprotective Effects and Contribute to Functional Recovery after Perinatal Brain Injury

Thomi Thomi,Surbek Surbek,Muri Muri,Joerger-Messerli Joerger-Messerli,Schoeberlein Schoeberlein,Haesler Haesler

doi:10.3390/cells8080855

Thomi Thomi, Surbek Surbek + Show 4 more

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https://doi.org/10.3390/cells8080855

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Journal: Cells	Publication Date: Aug 8, 2019
Citations: 89	License type: CC BY 4.0

Affiliation: University Hospital of Bern, University of Bern

Abstract

Perinatal brain injury (PBI) in preterm birth is associated with substantial injury and dysmaturation of white and gray matter, and can lead to severe neurodevelopmental deficits. Mesenchymal stromal cells (MSC) have been suggested to have neuroprotective effects in perinatal brain injury, in part through the release of extracellular vesicles like exosomes. We aimed to evaluate the neuroprotective effects of intranasally administered MSC-derived exosomes and their potential to improve neurodevelopmental outcome after PBI. Exosomes were isolated from human Wharton’s jelly MSC supernatant using ultracentrifugation. Two days old Wistar rat pups were subjected to PBI by a combination of inflammation and hypoxia-ischemia. Exosomes were intranasally administered after the induction of inflammation and prior to ischemia, which was followed by hypoxia. Infrared-labeled exosomes were intranasally administered to track their distribution with a LI-COR scanner. Acute oligodendrocyte- and neuron-specific cell death was analyzed 24 h after injury in animals with or without MSC exosome application using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay and immunohistochemical counterstaining. Myelination, mature oligodendroglial and neuronal cell counts were assessed on postnatal day 11 using immunohistochemistry, Western blot or RT-PCR. Morris water maze assay was used to evaluate the effect of MSC exosomes on long-term neurodevelopmental outcome 4 weeks after injury. We found that intranasally administered exosomes reached the frontal part of the brain within 30 min after administration and distributed throughout the whole brain after 3 h. While PBI was not associated with oligodendrocyte-specific cell death, it induced significant neuron-specific cell death which was substantially reduced upon MSC exosome application prior to ischemia. MSC exosomes rescued normal myelination, mature oligodendroglial and neuronal cell counts which were impaired after PBI. Finally, the application of MSC exosomes significantly improved learning ability in animals with PBI. In conclusion, MSC exosomes represent a novel prevention strategy with substantial clinical potential as they can be administered intranasally, prevent gray and white matter alterations and improve long-term neurodevelopmental outcome after PBI.

Highlights

Perinatal brain injury (PBI) is a major complication in infants born prematurely causing substantial mortality and neurodevelopmental impairment
We evaluated the effect of exosome treatment on the number of mature oligodendrocytes by performing double-stainings for developmental stage-specific markers CNPase and Ki67 together with the general nuclear oligodendrocyte marker oligodendrocyte transcription factor 2 (Olig2) (Figure 5E–J)
Evidence from our study indicates that white matter injury in PBI does not result from oligodendrocyte-specific cell death and is more likely to be caused by impaired oligodendrocyte maturation

Summary

Introduction

Perinatal brain injury (PBI) is a major complication in infants born prematurely causing substantial mortality and neurodevelopmental impairment. The pathogenesis of perinatal brain injury is complex but is thought to involve both fetal inflammation and neonatal hypoxia/ischemia causing the activation of brain resident immune cells, excitotoxicity and the generation of free radicals [8]. This subsequently leads to substantial white matter injury, as the preterm white matter is mainly populated by immature oligodendrocytes especially sensitive to hypoxic-ischemic and inflammatory insults [8]. Neuropathological studies of postmortem brains from preterm infants indicate that myelination deficits in PBI are mediated by immature oligodendrocyte-specific cell death, as immature oligodendrocytes seem to be sensitive to hypoxic-ischemic and inflammatory insults [10,11]. Other studies found no evidence of oligodendrocyte loss but identified impaired differentiation of vulnerable immature oligodendrocytes as the underlying cause for alterations in myelination [12,13]

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