Mesenchymal Stem Cell (MSC)-Derived Extracellular Vesicles Protect from Neonatal Stroke by Interacting with Microglial Cells.

Mesenchymal stem cell (MSC)-based therapies are beneficial in models of perinatal stroke and hypoxia-ischemia. Mounting evidence suggests that in adult injury models, including stroke, MSC-derived small extracellular vesicles (MSC-sEV) contribute to the neuroprotective and regenerative effects of MSCs. Herein, we examined if MSC-sEV protect neonatal brain from stroke and if this effect is mediated via communication with microglia. MSC-sEV derived from bone marrow MSCs were characterized by size distribution (NanoSight™) and identity (protein markers). Studies in microglial cells isolated from the injured or contralateral cortex of postnatal day 9 (P9) mice subjected to a 3-h middle cerebral artery occlusion (tMCAO) and cultured (in vitro) revealed that uptake of fluorescently labeled MSC-sEV was significantly greater by microglia from the injured cortex vs. contralateral cortex. The cell-type-specific spatiotemporal distribution of MSC-sEV was also determined in vivo after tMCAO at P9. MSC-sEV administered at reperfusion, either by intracerebroventricular (ICV) or by intranasal (IN) routes, accumulated in the hemisphere ipsilateral to the occlusion, with differing spatial distribution 2 h, 18 h, and 72 h regardless of the administration route. By 72 h, MSC-sEV in the IN group was predominantly observed in Iba1+ cells with retracted processes and in GLUT1+ blood vessels in ischemic-reperfused regions. MSC-sEV presence in Iba1+ cells was sustained. MSC-sEV administration also significantly reduced injury volume 72 h after tMCAO in part via modulatory effects on microglial cells. Together, these data establish feasibility for MSC-sEV delivery to injured neonatal brain via a clinically relevant IN route, which affords protection during sub-acute injury phase.

PLGF, a placental marker of fetal brain defects after in utero alcohol exposure.

Most children with in utero alcohol exposure do not exhibit all features of fetal alcohol syndrome (FAS), and a challenge for clinicians is to make an early diagnosis of fetal alcohol spectrum disorders (FASD) to avoid lost opportunities for care. In brain, correct neurodevelopment requires proper angiogenesis. Since alcohol alters brain angiogenesis and the placenta is a major source of angiogenic factors, we hypothesized that it is involved in alcohol-induced brain vascular defects. In mouse, using in vivo repression and overexpression of PLGF, we investigated the contribution of placenta on fetal brain angiogenesis. In human, we performed a comparative molecular and morphological analysis of brain/placenta angiogenesis in alcohol-exposed fetuses. Results showed that prenatal alcohol exposure impairs placental angiogenesis, reduces PLGF levels and consequently alters fetal brain vasculature. Placental repression of PLGF altered brain VEGF-R1 expression and mimicked alcohol-induced vascular defects in the cortex. Over-expression of placental PGF rescued alcohol effects on fetal brain vessels. In human, alcohol exposure disrupted both placental and brain angiogenesis. PLGF expression was strongly decreased and angiogenesis defects observed in the fetal brain markedly correlated with placental vascular impairments. Placental PGF disruption impairs brain angiogenesis and likely predicts brain disabilities after in utero alcohol exposure. PLGF assay at birth could contribute to the early diagnosis of FASD.

Dysregulation of RasGRP1 in rheumatoid arthritis and modulation of RasGRP3 as a biomarker of TNFα inhibitors.

BACKGROUND: B and T cells play a key role in rheumatoid arthritis (RA) pathophysiology. RasGRP1 and RasGRP3 are involved in T and B cell receptors signaling, and belong to gene combination able to predict infliximab responsiveness, leading to the question of RasGRP1 and RasGRP3 involvement in RA. METHODS: RasGRP1 and RasGRP3 expression levels were measured by qRT-PCR and/or western-blot in peripheral blood mononuclear cells (PBMCs), in T and B cells from untreated RA patients and in RA patients treated by TNFα inhibitors. T and B cells from healthy controls (HC) were cultured with TNFα, and TNFα receptors neutralizing antibodies to highlight the TNFα effects on RasGRP1 and RasGRP3 pathways. MAPK pathways and apoptosis were respectively analyzed using the Proteome Profiler arrays and flow cytometry. RESULTS: In PBMCs from RA patients, gene expression levels of RasGRP1 were invariant while RasGRP3 was downregulated under TNFα inhibitors and upregulated under TNFα. In T cells from RA patients, RasGRP1 was decreased and its gene expression level was correlated with disease activity. In T cells from HC, TNFα stimulation increased RasGRP1 gene expression level while it reduced RasGRP1 protein expression level. Bryostatin-1 experiments have confirmed that the TNFα effect observed on T cells proliferation was due to the decrease of RasGRP1 expression. Besides, RasGRP3 expression level increased in PBMCs from RA patients under TNFα and in B cells from HC leading us to conclude that RasGRP3 in B cells was modulated by TNFα. CONCLUSION: This study demonstrates RasGRP1 dysregulation in RA patients while RasGRP3 is characterized as a biomarker linked to TNFα inhibitors. After binding to TNFR1, TNFα reduced RasGRP1 protein expression resulting in inhibition of T cell activation. TRIAL REGISTRATION: Clinicaltrials.gov NCT00234234 , registered 04 November 2008; NCT00767325 , registered 05 October 2005.