Mesenchymal Stem Cells Induce T-Cell Tolerance and Protect the Preterm Brain after Global Hypoxia-Ischemia

Abstract

Hypoxic-ischemic encephalopathy (HIE) in preterm infants is a severe disease for which no curative treatment is available. Cerebral inflammation and invasion of activated peripheral immune cells have been shown to play a pivotal role in the etiology of white matter injury, which is the clinical hallmark of HIE in preterm infants. The objective of this study was to assess the neuroprotective and anti-inflammatory effects of intravenously delivered mesenchymal stem cells (MSC) in an ovine model of HIE. In this translational animal model, global hypoxia-ischemia (HI) was induced in instrumented preterm sheep by transient umbilical cord occlusion, which closely mimics the clinical insult. Intravenous administration of 2 x 106 MSC/kg reduced microglial proliferation, diminished loss of oligodendrocytes and reduced demyelination, as determined by histology and Diffusion Tensor Imaging (DTI), in the preterm brain after global HI. These anti-inflammatory and neuroprotective effects of MSC were paralleled by reduced electrographic seizure activity in the ischemic preterm brain. Furthermore, we showed that MSC induced persistent peripheral T-cell tolerance in vivo and reduced invasion of T-cells into the preterm brain following global HI. These findings show in a preclinical animal model that intravenously administered MSC reduced cerebral inflammation, protected against white matter injury and established functional improvement in the preterm brain following global HI. Moreover, we provide evidence that induction of T-cell tolerance by MSC might play an important role in the neuroprotective effects of MSC in HIE. This is the first study to describe a marked neuroprotective effect of MSC in a translational animal model of HIE.

Comparison of ECG-based physiological markers for hypoxia in a preterm ovine model

“…Five animals were excluded due to incomplete UCOs. The study group was originally set up to investigate processes and treatment of preterm hypoxic-ischemic encephalopathy (23)(24)(25). The original studies were approved by the local Animal Ethics Research Committee (DEC-UM, Maastricht …”

Global Hypoxia-Ischemia Induced Inflammation and Structural Changes in the Preterm Ovine Gut Which Were Not Ameliorated by Mesenchymal Stem Cell Treatment

“…Finally, a catheter was placed in the amniotic cavity for amniotic fluid pressure measurements. The EEG, ECG and amniotic fluid pressure measurements have been previously reported by Jellema et al (32). Each fetal catheter was exteriorized through a trocar hole in the flank of the ewe.…”

“…Human bone marrow-derived MSCs (Merck Millipore) were isolated and prepared as previously described (32). Briefly, MSCs were isolated from a male donor, expanded, frozen and stored in liquid nitrogen.…”

“…Briefly, MSCs were isolated from a male donor, expanded, frozen and stored in liquid nitrogen. The MSCs were characterized by identifying cell surface molecules by flow cytometry analysis as previously described (32). MSCs were suspended in phosphate-buffered saline (PBS) 1 h before administration.…”

“…MSCs were prepared at a dose of 3.5 × 10 6 MSCs ( approximately 2.0 × 10 6 /kg) based on clinical trials of focal ischemia (28) and patients with inflammatory bowel disease (29,30). MSCs were given intravenously and were not associated with any signs of immunological rejection as previously described (32). At 113 d of gestation (7 d after the induction of UCO), both the ewes and fetuses were euthanized by pentobarbital (200 mg/kg).…”