Mesenchymal stem cells transmigrate over the endothelial barrier

Mesenchymal stem cells (MSCs) seem to be a useful tool for cellular therapy in injured tissues, e.g. myocardial infarction or cardiomyopathies resulting in heart failure. For therapeutic approaches it is crucial that MSCs cross the endothelial barrier especially in intravascular or rather intracoronary application. Until today little is known about MSCs transmigrating across the endothelium. We performed co-culture experiments of MSCs on an endothelial monolayer to analyse direct interactions. An increasing flattened morphology of the MSCs was followed by a total integration into the monolayer after 2h. We repeated these experiments in isolated heart perfusions with gold-labelled MSCs. Using electron microscopy we detected MSCs exhibited direct cell-cell contacts. Tight junctions between the endothelial cells became abolished resulting in a distinct split between the cells. MSCs developed tight cell-cell contacts and became integrated into the endothelial wall of the capillary vessel. Finally, using confocal laser scanning microscopy, we assessed the ability of the MSCs to fully pass the endothelial barrier. Within the first 30 min, 30+/-8% of MSCs transmigrated, increasing to about half at 60 min (50+/-8%), whereas after 120 min the rate remained nearly unchanged (53+/-10%). This work demonstrates the capability of MSCs for transendothelial migration. Moreover we showed that the vast majority of MSCs migrated within 30 min, an important finding for the exposure times in clinical settings.     

Detection of Puumala Hantavirus Antigen in Human Intestine during Acute Hantavirus Infection

Background

Puumala virus (PUUV) is the most important hantavirus species in Central Europe. Nephropathia epidemica (NE), caused by PUUV, is characterized by acute renal injury (AKI) with thrombocytopenia and frequently gastrointestinal symptoms.

Methods

456 patients with serologically and clinically confirmed NE were investigated at time of follow-up in a single clinic. The course of the NE was investigated using medical reports. We identified patients who had endoscopy with intestinal biopsy during acute phase of NE. Histopathological, immunohistochemical and molecular analyses of the biopsies were performed.

Results

Thirteen patients underwent colonoscopy or gastroscopy for abdominal pain, diarrhea, nausea and vomiting during acute phase of NE. Immunohistochemistry (IHC) revealed PUUV nucleocapsid antigen in 11 biopsies from 8 patients; 14 biopsies from 5 patients were negative for PUUV nucleocapsid antigen. IHC localized PUUV nucleocapsid antigen in endothelial cells of capillaries or larger vessels in the lamina propria. Rate of AKI was not higher and severity of AKI was not different in the PUUV-positive compared to the PUUV-negative group. All IHC positive biopsies were positive for PUUV RNA using RT-PCR. Phylogenetic reconstruction revealed clustering of all PUUV strains from this study with viruses previously detected from the South-West of Germany. Long-term outcome was favorable in both groups.

Conclusions

In patients with NE, PUUV nucleocapsid antigen and PUUV RNA was detected frequently in the intestine. This finding could explain frequent GI-symptoms in NE patients, thus demonstration of a more generalized PUUV infection. The RT-PCR was an effective and sensitive method to detect PUUV RNA in FFPE tissues. Therefore, it can be used as a diagnostic and phylogenetic approach also for archival materials. AKI was not more often present in patients with PUUV-positive IHC. This last finding should be investigated in larger numbers of patients with PUUV infection.     

Parasitic Nematodes in the Chimpanzee Population on Rubondo Island, Tanzania

We identified 3 nematodes not previously reported in chimpanzees (Pan troglodytes) introduced on Rubondo Island, Tanzania: Protospirura muricola, Subulura sp., and Anatrichosoma sp. Vervet monkeys (Cercopithecus aethiops pygerythrus), rodents, and intermediate insect hosts might maintain Protospirura muricola and Subulura sp., and indigenous monkeys on the island might also maintain Anatrichosoma sp. Low prevalence of Subulura sp. and Anatrichosoma sp. suggests that chimpanzees acquired them from ingestion of contaminated food.     

Beta3-adrenergic eNOS stimulation in left ventricular murine myocardium

This study investigates mechanisms underlying beta3-adrenergic activation of the endothelial nitric oxide synthase (eNOS) in myocardial tissue of wild-type (WT) and beta3-adrenoceptor knockout (beta3-KNO) mice, in the absence and presence of BRL 37344 (BRL), the preferential beta3-adrenoceptor selective agonist. Nitric oxide (NO)-liberation was measured after the application of BRL (10 micromol/L), using fluorescence dye diaminofluorescein (DAF), in left ventricular cardiac preparations. Phosphorylation of eNOSSer1177, eNOSThr495, eNOSSer114, and eNOS translocation, and alterations of 8-isoprostaglandin F2alpha (a parameter for reactive oxygen radical generation), after application of BRL (10 micromol/L), were studied using immunohistochemical stainings in isolated, electrically stimulated (1 Hz) right atrial (RA) and left ventricular (LV) myocardium. An increased NO release after BRL application (10 micromol/L) was observed in the RA and LV myocardial tissue of WT mice, but not in beta3-KNO mice. This NO liberation in WT mice was paralleled by an increased eNOSSer1177, but not eNOSThr495, phosphorylation. A cytosolic eNOS translocation was observed after the application of BRL (10 micromol/L) only in the RA myocardial tissue of WT mice. A BRL (10 micromol/L)-dependent increase in eNOSSer114 phosphorylation was observed only in the LV myocardial tissue of WT mice; this was paralleled by an increase in 8-isoprostaglandin F2alpha. In murine myocardium, 3 beta3-adrenoceptor-dependent activation pathways for eNOS exist (i.e., a translocation and phosphorylation of eNOSSer1177 and eNOSSer114). These pathways are used in a regional-dependent manner. beta3-adrenergic oxygen-derived free radical production might be important in situations of enhanced beta3-adrenoceptor activation, as has been described in human heart failure.     

Effect of solar particle event radiation on gastrointestinal tract bacterial translocation and immune activation

Space flight conditions within the protection of Earth's gravitational field have been shown to alter immune responses, which could lead to potentially detrimental pathology. An additional risk of extended space travel outside the Earth's gravitational field is the effect of solar particle event (SPE) radiation exposure on the immune system. Organisms that could lead to infection include endogenous, latent viruses, colonizing pathogenics, and commensals, as well as exogenous microbes present in the spacecraft or other astronauts. In this report, the effect of SPE-like radiation on containment of commensal bacteria and the innate immune response induced by its breakdown was investigated at the radiation energies, doses and dose rates expected during an extravehicular excursion outside the Earth's gravitational field. A transient increase in serum lipopolysaccharide was observed 1 day after irradiation and was accompanied by an increase in acute-phase reactants and circulating proinflammatory cytokines, indicating immune activation. Baseline levels were reestablished by 5 days postirradiation. These findings suggest that astronauts exposed to SPE radiation could have impaired containment of colonizing bacteria and associated immune activation.