Objectives:Beside having roles in energy homeostasis and endocrine modulation, adipose tissue (AT) is now considered a promising source of mesenchymal stromal cells (adipose-derived stromal cells or ASCs) for regenerative medicine. Despite numerous studies on cultured ASCs, native human ASCs are rarely investigated. Indeed, the phenotype of ASCs in their native state, their localization within AT and comparison with bone marrow-derived mesenchymal stromal cells (BM-MSCs) has been poorly investigated.Design:To address these issues, the stroma vascular fraction (SVF) of human AT was extracted and native cell subtypes were isolated by immunoselection to study their clonogenic potential in culture. Immunohistology on samples of human AT in combination with reconstruction of confocal sections were performed in order to localize ASCs.Results:Compared with BM-MNCs, all native ASCs were found in the CD34+ cell fraction of the AT-SVF. Native ASCs expressed classical mesenchymal markers described for BM-MSCs. Interestingly, CD34 expression decreased during ASC cell culture and was negatively correlated with cell proliferation rate. Immunohistological analysis revealed that native ASCs exhibited specific morphological features with protrusions. They were found scattered in AT stroma and did not express in vivo pericytic markers such as NG2, CD140b or alpha-smooth muscle actin, which appeared during the culture process. Finally, ASCs spontaneous commitment to adipocytic lineage was enhanced in AT from obese humans.Conclusions:The use of complementary methodological approaches to study native human ASCs revealed their immunophenotype, their specific morphology, their location within AT and their stemness. Furthermore, our data strongly suggest that human ASCs participate in adipogenesis during AT development.

BackgroundFacemasks and respirators have been stockpiled during pandemic preparedness. However, data on their effectiveness for limiting transmission are scarce. We evaluated the effectiveness of facemask use by index cases for limiting influenza transmission by large droplets produced during coughing in households.Methodology and Principal FindingsA cluster randomized intervention trial was conducted in France during the 2008–2009 influenza season. Households were recruited during a medical visit of a household member with a positive rapid influenza A test and symptoms lasting less than 48 hours. Households were randomized either to the mask or control group for 7 days. In the intervention arm, the index case had to wear a surgical mask from the medical visit and for a period of 5 days. The trial was initially intended to include 372 households but was prematurely interrupted after the inclusion of 105 households (306 contacts) following the advice of an independent steering committee. We used generalized estimating equations to test the association between the intervention and the proportion of household contacts who developed an influenza-like illness during the 7 days following the inclusion. Influenza-like illness was reported in 24/148 (16.2%) of the contacts in the intervention arm and in 25/158 (15.8%) of the contacts in the control arm and the difference between arms was 0.40% (95%CI: −10% to 11%, P = 1.00). We observed a good adherence to the intervention. In various sensitivity analyses, we did not identify any trend in the results suggesting effectiveness of facemasks.ConclusionThis study should be interpreted with caution since the lack of statistical power prevents us to draw formal conclusion regarding effectiveness of facemasks in the context of a seasonal epidemic.Trial Registrationclinicaltrials.gov NCT00774774

Mitophagy is a critical cellular process that selectively targets damaged mitochondria for autophagosomal degradation both under baseline conditions and in response to stress preventing oxidative damage and cell death. Recent studies have linked alterations in mitochondria function and reduced autophagy with the development of age-related pathologies. However, the significance of mitochondrial autophagy in vessel wall in response to atherogenic lipid stressors is not known. In the present study, we investigated the role of mitophagy on human vascular smooth muscle cells (VSMC) apoptosis induced by oxidized low-density lipoproteins (LDL). We reported for the first time that the engulfment of defective mitochondria by autophagosomes occurred in human VSMC in response to oxidized LDL. The molecular mechanism mediating mitophagy in human VSMC involved dynamin-related protein 1 (Drp1)-mediated mitochondrial fission, accumulation of PTEN-induced putative kinase 1 (PINK1) and the recruitment of the E3 ubiquitin ligase Parkin to mitochondria. Likewise, we found increased voltage-dependent anion channel 1 (VDAC1) and mitofusin 2 (Mnf2) mitochondrial proteins ubiquitination and LC3 association to mitochondria. Using flow cytometry in the presence of lysosomal inhibitors, we showed that PINK1 and Parkin silencing impaired mitophagy flux and enhanced oxidized LDL-induced VSMC apoptosis. In addition, overexpression of PINK1 and Parkin were protective by limiting cell death. Moreover, reduced Bax levels found in VSMC-overexpressing Parkin indicated cross talk among mitophagy and mitochondrial apoptotic signalling pathways. Altogether these data demonstrate that mitophagy is a safeguard mechanism against human VSMC apoptosis induced by atherogenic stressors and highlight mitophagy as a potential target to stabilize atherosclerotic plaque.