No abstract

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.

The recent Zika virus (ZIKV) epidemic has highlighted the poor knowledge on its physiopathology. Recent studies showed that ZIKV of the Asian lineage, responsible for this international outbreak, causes neuropathology in vitro and in vivo. However, two African lineages exist and the virus is currently found circulating in Africa. The original African strain was also suggested to be neurovirulent but its laboratory usage has been criticized due to its multiple passages. In this study, we compared the French Polynesian (Asian) ZIKV strain to an African strain isolated in Central African Republic and show a difference in infectivity and cellular response between both strains in human neural stem cells and astrocytes. Consistently, this African strain led to a higher infection rate and viral production, as well as stronger cell death and anti-viral response. Our results highlight the need to better characterize the physiopathology and predict neurological impairment associated with African ZIKV.