Efficient Recombinase-Mediated Cassette Exchange in hPSCs to Study the Hepatocyte Lineage Reveals AAVS1 Locus-Mediated Transgene Inhibition

Tools for rapid and efficient transgenesis in "safe harbor" loci in an isogenic context remain important to exploit the possibilities of human pluripotent stem cells (hPSCs). We created hPSC master cell lines suitable for FLPe recombinase-mediated cassette exchange (RMCE) in the AAVS1 locus that allow generation of transgenic lines within 15 days with 100% efficiency and without random integrations. Using RMCE, we successfully incorporated several transgenes useful for lineage identification, cell toxicity studies, and gene overexpression to study the hepatocyte lineage. However, we observed unexpected and variable transgene expression inhibition in vitro, due to DNA methylation and other unknown mechanisms, both in undifferentiated hESC and differentiating hepatocytes. Therefore, the AAVS1 locus cannot be considered a universally safe harbor locus for reliable transgene expression in vitro, and using it for transgenesis in hPSC will require careful assessment of the function of individual transgenes

Adventage of mesenchymal stem cells (MSC) expansion directly from purified bone marrow CD105^+ and CD271^+ cells

Mesenchymal Stem Cells (MSC) are employed in gene and cellular therapies. Routinely MSC are isolated from bone marrow mononuclear cells (MNC) by plastic adherence. Here we compared new isolation strategies of bone marrow MSC including immunodepletion of hematopoietic cells and immunomagnetic isolation of CD105+ and CD271+ populations. Four fractions were obtained: MNC MSC, RosetteSep-isolated MSC, CD105+ and CD271+ sorted MSC. We evaluated i) number of CFU-F colonies, ii) cell phenotype, iii) in vitro differentiation of expanded cells and iv) expression of osteo/adipogenesis related genes. Results: Average number of day 9 CFU-F colonies was the highest for CD271 positive fraction. Real-Time PCR analysis revealed expression of RUNX2, PPARgamma and N-cadherin in isolated cells, particularly high in CD271+ cells. Expression of CD105, CD166, CD44, CD73 antigens was comparable for all expanded populations (over 90%). We observed various levels of hematopoietic contamination with the highest numbers of CD45+ cells in MNC-MSC fraction and the lowest in CD105+ and CD271+ fractions. Cells of all the fractions were CD34 antigen negative. Expanded CD105 and CD271 populations showed higher level of RUNX2, osteocalcin, PTHR, leptin, PPARgamma2 and aggrecan1 genes except for alpha1 collagen. After osteogenic differentiation CD105+ and CD271+ populations showed lower expression of RUNX, PPARgamma2 and also lower expression of osteocalcin and PTHR than MNC, with comparable alpha1-collagen expression. Chondrogenic and adipogenic gene expression was higher in MNC. More clonogenic CD105+ and particularly CD271+ cells, which seem to be the most homogenous fractions based on Real-Time PCR and immunostaining data, are better suited for MSC expansion

Registro español de nutrición enteral domiciliaria del año 2009; Grupo NADYA-SENPE

Objetivo: Describir las características de la Nutrición Enteral Domiciliaria (NED) en España, registrada por el grupo NADYA-SENPE durante el año 2009. Material y métodos: Recopilación y análisis descriptivo de los datos del registro de NED del grupo NADYASENPE desde el 1 de enero al 31 de diciembre de 2009. Resultados: Se registraron 6.540 pacientes, 5,11% más que en el año anterior y 6.649 episodios de NED (3.135 en mujeres, 47,93%) pertenecientes a 32 centros hospitalarios. Siendo 6.238 (95,38%) mayores de 14 años. La edad media en los menores de 14 años fue de 3,67 ± 2,86 y de 72,10 ± 16,89 en los mayores de 14 años. La enfermedad de base que se registró con más frecuencia fue la neurológica en 2.732 (41,77%) ocasiones, seguida de la neoplasia en 1838; 28,10%. La vía de acceso se registró en 1.123 (17,17%) de los episodios, siendo más frecuente la administración por sonda nasogástrica 562 (50,04%). El tiempo medio de tratamiento nutricional fue de 323 días (10,77 meses). Finalizaron 606 episodios de NED, siendo el motivo más frecuentes el fallecimiento del enfermo, lo que aconteció en 295 (48,68%) ocasiones y el paso a alimentación oral en 219 (36,14%). Los pacientes mantenían una actividad normal en 2162 episodios de NED (32,55%) y en 2468 (37,13%) hacían vida “cama-sillón”. El grado de dependencia fue “total” en 2598 (39,07%) de los episodios registrado. El suministro de la fórmula nutricional se realizó desde el hospital en 4.183 (62,91%) casos y por la farmacia de referencia en 2.262 (el 34,02%) y el material fungible se suministró desde el hospital en 3.531 (53,11%) de los casos. Conclusiones: El número de pacientes con NED registrados es superior al del año 2008, continuando con el incremento progresivo desde el inicio del registro. Las características de los mismos mantiene el mismo perfil que en años anteriores con pequeñas variaciones.Objective: To describe the Home Enteral Nutrition Characteristics (HEN) recorded by the group NADYASENPE during 2009. Material and methods: collection and analysis of the data voluntary recorded in the HEN registry from the NADYASENPE group from January 1st to December 31st. Results: 6.540 HEN patients were registered, 5.11% more than the previous year and 6,649 episodes (3,135 in women, 47,93%) from 32 different hospitals. 6,238 of them (95,38%) were over 14 years. The mean age of the patients under 14 yr was 3,67 ± 2,86 and it was 72,10 ± 16,89 in those over 14 yr group. The base illness registered more frequently was the neurological disorders in 2,732 (41,77%) patients, followed by cancer patients in 1,838; 28,10%. The enteral access route was registered in 1,123 (17,17%) of the episodes, being more frequent the administration by nasogastric tube 562 (50,04%). The mean length of nutritional treatment by episode was 323 days (10,77 months). 606 episodes of HEN ended, being the principal reasons for discontinuing treatment the patient death in 295 (48,68%) occasions. The transition to oral feeding occurred in 219 (36,14%) cases. Patients maintained normal activity in 2162 (32,55%) HEN episodes and 2,468 (37,13%) cases were living “bedcouch”. The level of dependence was “total” in 2,598 (39,07%) of the episodes recorded. The nutritional formula was provided by the hospital in 4,183 (62,91%) cases and by the reference pharmacy in 2,262 (el 34,02%). Consumables were provided by the hospital in 3,531 (53,11%) cases. Conclusions: The number of HEN patients recorded increased from the year 2008, continuing the gradual growth increase since the start of registration. The characteristics of the patients remain in the same profile as in previous years

Protein Phosphatase 2A Interacts with the Na+,K+-ATPase and Modulates Its Trafficking by Inhibition of Its Association with Arrestin

Background: The P-type ATPase family constitutes a collection of ion pumps that form phosphorylated intermediates during ion transport. One of the best known members of this family is the Na +,K +-ATPase. The catalytic subunit of the Na +,K +-ATPase includes several functional domains that determine its enzymatic and trafficking properties. Methodology/Principal Findings: Using the yeast two-hybrid system we found that protein phosphatase 2A (PP2A) catalytic C-subunit is a specific Na +,K +-ATPase interacting protein. PP-2A C-subunit interacted with the Na +,K +-ATPase, but not with the homologous sequences of the H +,K +-ATPase. We confirmed that the Na +,K +-ATPase interacts with a complex of A- and C-subunits in native rat kidney. Arrestins and G-protein coupled receptor kinases (GRKs) are important regulators of G-protein coupled receptor (GPCR) signaling, and they also regulate Na +,K +-ATPase trafficking through direct association. PP2A inhibits association between the Na +,K +-ATPase and arrestin, and diminishes the effect of arrestin on Na +,K +-ATPase trafficking. GRK phosphorylates the Na +,K +-ATPase and PP2A can at least partially reverse this phosphorylation. Conclusions/Significance: Taken together, these data demonstrate that the sodium pump belongs to a growing list of io

Ubiquitous [Na+]i/[K+]i-Sensitive Transcriptome in Mammalian Cells: Evidence for Ca2+i-Independent Excitation-Transcription Coupling

Stimulus-dependent elevation of intracellular Ca2+ ([Ca2+]i) affects the expression of numerous genes – a phenomenon known as excitation-transcription coupling. Recently, we found that increases in [Na+]i trigger c-Fos expression via a novel Ca2+i-independent pathway. In the present study, we identified ubiquitous and tissue-specific [Na+]i/[K+]i-sensitive transcriptomes by comparative analysis of differentially expressed genes in vascular smooth muscle cells from rat aorta (RVSMC), the human adenocarcinoma cell line HeLa, and human umbilical vein endothelial cells (HUVEC). To augment [Na+]i and reduce [K+]i, cells were treated for 3 hrs with the Na+,K+-ATPase inhibitor ouabain or placed for the same time in the K+-free medium. Employing Affymetrix-based technology, we detected changes in expression levels of 684, 737 and 1839 transcripts in HeLa, HUVEC and RVSMC, respectively, that were highly correlated between two treatments (p<0.0001; R2>0.62). Among these Na+i/K+i-sensitive genes, 80 transcripts were common for all three types of cells. To establish if changes in gene expression are dependent on increases in [Ca2+]i, we performed identical experiments in Ca2+-free media supplemented with extracellular and intracellular Ca2+ chelators. Surprisingly, this procedure elevated rather than decreased the number of ubiquitous and cell-type specific Na+i/K+i-sensitive genes. Among the ubiquitous Na+i/K+i-sensitive genes whose expression was regulated independently of the presence of Ca2+ chelators by more than 3-fold, we discovered several transcription factors (Fos, Jun, Hes1, Nfkbia), interleukin-6, protein phosphatase 1 regulatory subunit, dual specificity phosphatase (Dusp8), prostaglandin-endoperoxide synthase 2, cyclin L1, whereas expression of metallopeptidase Adamts1, adrenomedulin, Dups1, Dusp10 and Dusp16 was detected exclusively in Ca2+-depleted cells. Overall, our findings indicate that Ca2+i-independent mechanisms of excitation-transcription coupling are involved in transcriptomic alterations triggered by elevation of the [Na+]i/[K+]i ratio. There results likely have profound implications for normal and pathological regulation of mammalian cells, including sustained excitation of neuronal cells, intensive exercise and ischemia-triggered disorders

Minimal information for studies of extracellular vesicles 2018 (MISEV2018):a position statement of the International Society for Extracellular Vesicles and update of the MISEV2014 guidelines

The last decade has seen a sharp increase in the number of scientific publications describing physiological and pathological functions of extracellular vesicles (EVs), a collective term covering various subtypes of cell-released, membranous structures, called exosomes, microvesicles, microparticles, ectosomes, oncosomes, apoptotic bodies, and many other names. However, specific issues arise when working with these entities, whose size and amount often make them difficult to obtain as relatively pure preparations, and to characterize properly. The International Society for Extracellular Vesicles (ISEV) proposed Minimal Information for Studies of Extracellular Vesicles (“MISEV”) guidelines for the field in 2014. We now update these “MISEV2014” guidelines based on evolution of the collective knowledge in the last four years. An important point to consider is that ascribing a specific function to EVs in general, or to subtypes of EVs, requires reporting of specific information beyond mere description of function in a crude, potentially contaminated, and heterogeneous preparation. For example, claims that exosomes are endowed with exquisite and specific activities remain difficult to support experimentally, given our still limited knowledge of their specific molecular machineries of biogenesis and release, as compared with other biophysically similar EVs. The MISEV2018 guidelines include tables and outlines of suggested protocols and steps to follow to document specific EV-associated functional activities. Finally, a checklist is provided with summaries of key points

Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches

Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its 'Minimal Information for Studies of Extracellular Vesicles', which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly