Project description:In order to investigate the effects of shear stress on trophoblasts in the intervillous space, we cultured the cytotrophoblast stem cells derived from naïve PSC (nCT) under shear stress.
Project description:Human cytotrophoblast organoid cultures were established from the villous trophoblast of first trimester placentas. We analyzed the global expression profile of the cytotrophoblast organoids (CTB-ORG) and compared to the profile of the tissue of origin i.e. villous cytotrophoblast (vCTB) as well as to differentiated syncytiotrophoblast (STB) and placental fibroblasts (FIB).
Project description:Human naïve pluripotent stem cells (PSC) share features with pre-implantation epiblast. They thus provide an unmatched opportunity for characterising the developmental programme of pluripotency in Homo sapiens. Here we confirm that naïve PSC do not respond directly to germ layer induction, but must first acquire competence. Capacitation for multi-lineage differentiation occurs without exogenous growth factor stimulation and is facilitated by inhibition of Wnt signalling. Whole transcriptome profiling during this formative transition highlights dynamic changes in gene expression, affecting many cellular properties, including metabolism and epithelialisation. Notably, naïve pluripotency factors are exchanged for post-implantation factors, but competent cells remain devoid of lineage primed transcription. The gradual pace of transition for human naïve PSC is consistent with the timespan of primate development from blastocyst to gastrulation. Transcriptome trajectory during in vitro capacitation of human naïve cells tracks the progression of epiblast during embryogenesis in Macaca fascicularis, but shows greater divergence from mouse development. Thus the formative transition of naïve PSC in a simple culture system may recapitulate essential and specific features of pluripotency dynamics during an inaccessible period of human embryogenesis.
Project description:The opportunistic pathogen, Staphylococcus aureus, encounters a wide variety of fluid shear levels within the human host, which may play a key role in dictating whether this organism adopts a commensal interaction with the host or transitions to cause disease. Using rotating-wall vessel bioreactors to create a physiologically-relevant, low fluid shear environment, S. aureus was evaluated for cellular responses that could impact its colonization and virulence. S. aureus cells grown in a low fluid shear environment initiated a novel attachment-independent biofilm phenotype and were completely encased in extracellular polymeric substances. Compared to controls, low-shear cultured cells displayed slower growth and repressed virulence characteristics, including decreased carotenoid production, increased susceptibility to oxidative stress, and reduced survival in whole blood. Transcriptional whole genome microarray profiling suggested alterations in metabolic pathways. Further genetic expression analysis revealed the down-regulation of the RNA chaperone Hfq, which parallels low fluid shear responses of certain Gram negative organisms. This is the first study to report an Hfq association to fluid shear in a Gram positive organism, suggesting an evolutionarily conserved response to fluid shear among structurally diverse prokaryotes. Collectively, our results suggest S. aureus responds to a low fluid shear environment by initiating a biofilm/colonization phenotype with diminished virulence characteristics, which could lead to insight into key factors influencing the divergence between infection and colonization during initial host pathogen interaction. Genetic expression profiles of Staphylococcus aureus cultured under low fluid shear conditions was compared to control cultures of S. aureus which was cultured in identical hardware in an orientation disrupting the low fluid shear effect. Samples from the same date of culture were compared (control 21:low 21 and control 30: low 30). S. aureus was cultured for 20 hours in either the low fluid shear or control orientated rotating wall vessel (RWV) bioreactor at which point the cells were removed and RNA extracted. At 20 hours, both cultures were in the same stage of growth (stationary phase) and at this point phenotypic differences between control and low fluid shear cultures were noted.
Project description:Bronchopulmonary dysplasia (BPD) represents one of the most important sequelae of preterm birth affecting more than 20% of infants born below 32 weeks. Mechanical ventilation exerting shear stress (cyclic mechanical stress, CMS) and oxygen toxicity (hyperoxia, Hox) mainly contribute to the pathogenesis of BPD. The study proposal aims to separate the impact of CMS and Hox on pulmonary mesenchymal stem cells (MSC) isolated from preterm infants participating in the DZL PROTECT-AIRR cohort study in a world-wide unique in vitro setting. The impact of rhythmic 2D and 3D stretch to MSC cell cultures alone and in combination with different fractions of oxygen is evaluated with respect to MSC phenotype, transcriptional regulation, protein alterations and paracrine secretion.
Project description:The opportunistic pathogen, Staphylococcus aureus, encounters a wide variety of fluid shear levels within the human host, which may play a key role in dictating whether this organism adopts a commensal interaction with the host or transitions to cause disease. Using rotating-wall vessel bioreactors to create a physiologically-relevant, low fluid shear environment, S. aureus was evaluated for cellular responses that could impact its colonization and virulence. S. aureus cells grown in a low fluid shear environment initiated a novel attachment-independent biofilm phenotype and were completely encased in extracellular polymeric substances. Compared to controls, low-shear cultured cells displayed slower growth and repressed virulence characteristics, including decreased carotenoid production, increased susceptibility to oxidative stress, and reduced survival in whole blood. Transcriptional whole genome microarray profiling suggested alterations in metabolic pathways. Further genetic expression analysis revealed the down-regulation of the RNA chaperone Hfq, which parallels low fluid shear responses of certain Gram negative organisms. This is the first study to report an Hfq association to fluid shear in a Gram positive organism, suggesting an evolutionarily conserved response to fluid shear among structurally diverse prokaryotes. Collectively, our results suggest S. aureus responds to a low fluid shear environment by initiating a biofilm/colonization phenotype with diminished virulence characteristics, which could lead to insight into key factors influencing the divergence between infection and colonization during initial host pathogen interaction.