Potential of Wharton’s Jelly Mesenchymal Stem Cell Exosomes for the Treatment of Hypoxic-Ischemic Encephalopathy of Prematurity

INTRODUCTION: Hypoxic-ischemic encephalopathy (HIE) of prematurity is often accompanied by infection and inflammation. In animal models of HIE, Wharton’s jelly mesenchymal stem cells (WJ-MSC) have the capacity to induce neuroregeneration and reduce inflammation, mainly due to their paracrine effects involving the release of exosomes. Our aim was to evaluate the feasibility of an intranasal administration of WJ-MSC-derived exosomes in vivo and their anti-inflammatory potential in vitro. METHODS: We isolated the exosomes from WJ-MSC supernatants by serial centrifugations. We evaluated the feasibility of an intranasal exosome administration using an in vivo model of HIE. Brain damage was introduced in 3-day old rat pups by lipopolysaccharides (LPS, i.p.) and unilateral carotid artery cautherization followed by hypoxia (8% O2). Exosomes were labeled with an infrared dye, delivered intranasally and traced in the bodies 30 min, 3 h and 24 h later. Microglial activation was studied using the cell line BV-2. To study anti-inflammatory effects, BV-cells were stimulated with LPS in presence or absence of exosomes. Toll like receptor 4 (TLR-4) signaling pathways activation and pro-inflammatory gene expression were evaluated after 15 min, 30 min, 60 min and 6 h. RESULTS: Intranasally administered exosomes rapidly translocated to the brain and diffused locally within 30 min. No exosomes were found in the spleen, likely excluding systemic absorption. Exosomes suppressed TLR-4 signaling activation in LPS-stimulated BV-2 cells by preventing the suppression of NF-κB inhibitor alpha (IκBα) and the phosphorylation of extracellular signal-regulated kinases (ERK) (P<0.005). This led to a dampened upregulation of the pro-inflammatory genes tumor necrosis factor (TNF)-α and interleukin (IL)-6 and suppressed the TLR-4 responsive gene IκBα (P