Nanoscale surfaces for the long-term maintenance of mesenchymal stem cell phenotype and multipotency

The discovery of stem cells has led to rapid advances in the field of regenerative medicine. Their unique properties, including the ability to self-renew and differentiate make them ideal for the repair/replacement of tissues that have been damaged as a result of disease or injury. Mesenchymal stem cells in particular represent a highly valuable pool of adult stem cells for such regenerative applications due to their accessibility, and potential as an autologous patient derived autologous nature However current methods for the in vitro expansion of high quality autologous mesenchymal stem cells results in spontaneous differentiation of the stem cell population and a loss of differentiation capacity over time. In vivo, it is the stem cell niche that provides stem cells with the appropriate cues required to maintain stem cell self-renewal. It is proposed that by mimicking these cues using biomaterials, that the self-renewal of mesenchymal stem cells can be controlled in vitro. In this study, a novel nanopit topography was investigated for its effects on the maintenance and growth of mesenchymal stem cells in vitro. To investigate this, three main aspects of mesenchymal stem cell state were examined in response to this novel nanotopography: maintenance of the stem cell phenotype over time including expression of stem cell markers and differentiation potential over time, changes in signalling pathways associated with differentiation and lastly, the metabolic profile of stem cells. As a result of this study we have identified a novel nanopit topography, which in the absence of chemical supplements, provides a substrate that is conducive to the maintenance of mesenchymal stem cells. Small RNAs have also been implicated in the regulation of signalling pathways and the metabolic state of stem cells. Furthermore, the ability to produce nanotopographically-patterned substrates using current standard techniques provides an inexpensive, high throughput method for the production of novel tissue culture plastics suitable for the maintenance of mesenchymal stem cells

Chapter Nanopatterned Surfaces for Biomedical Applications

Optical physic

Dietary Protein Deficiency and Mycobacterium Bovis BCG Affect Interleukin-2 Activity in Experimental Pulmonary Tuberculosis

Inbred strain 2 guinea pigs were vaccinated with Mycobacterium bovis BCG or were left unvaccinated. They were maintained for 6 weeks on defined, isocaloric diets containing either 30% (control animals) or 10% (animals receiving low protein) ovalbumin as the sole protein source. Animals were challenged by the respiratory route with a low dose of virulent M. tuberculosis H37Rv and killed 4 weeks later. Protein-malnourished animals were not protected by previous vaccination with BCG. Lymphocytes isolated from various tissues were tested in vitro for proliferative responses to mitogen (concanavalin A) and antigen (purified protein derivative [PPD]), production of interleukin-2 (IL-2), and response to exogenous recombinant IL-2 (rIL-2). Protein-malnourished guinea pigs responded only weakly to PPD skin tests, and their blood and lymph node lymphocytes exhibited impaired proliferation when cultured with PPD in vitro. IL-2 levels were consistently low in cultures of stimulated blood and spleen lymphocytes from protein-deprived animals. BCG vaccination of nutritionally normal guinea pigs, on the other hand, induced significantly more IL-2 production by PPD- and concanavalin A-stimulated lymphocytes. The addition of exogenous mouse rIL-2 (40 and 80 U/ml) in vitro to PPD-stimulated blood and lymph node cells from nonvaccinated, protein-deprived guinea pigs resulted in no improvement of the proliferative response. Previous vaccination of malnourished guinea pigs did not consistently enhance the response of PPD-stimulated lymphocytes to added rIL-2. Dietary protein deficiency and BCG vaccination appear to modulate antigen-driven cellular immunity in animals with tuberculosis by altering the production of, and the response to, IL-2 by PPD-stimulated lymphocytes

A young child with a history of wheeze

The parents of a 3-year old boy are anxious about their son who has recurring episodes of wheezing. They are frustrated that no one seems to be able to give them answers to their questions and would like a referral to a specialist. Does their son have asthma and what is the prognosis; how can the recurrent wheezing be managed and can the risk of asthma be reduced; are there lifestyle changes that could improve the environment and avoid triggers? Communication and support from the family practice team were essential. Listening to the parents' concerns, explaining the diagnostic uncertainty, being realistic about what drug treatments could achieve, and providing practical advice on inhaler use and trigger avoidance reassured the parents that there was a strategy for managing their son's wheeze. The specialist referral was postponed

Septin filaments exhibit a dynamic, paired organization that is conserved from yeast to mammals

© The Author(s), 2011. This article is distributed under the terms of the Creative Commons Attribution 3.0 License. The definitive version was published in Journal of Cell Biology 193 (2011): 1065-1081, doi:10.1083/jcb.201012143.The septins are conserved, GTP-binding proteins important for cytokinesis, membrane compartmentalization, and exocytosis. However, it is unknown how septins are arranged within higher-order structures in cells. To determine the organization of septins in live cells, we developed a polarized fluorescence microscopy system to monitor the orientation of GFP dipole moments with high spatial and temporal resolution. When GFP was fused to septins, the arrangement of GFP dipoles reflected the underlying septin organization. We demonstrated in a filamentous fungus, a budding yeast, and a mammalian epithelial cell line that septin proteins were organized in an identical highly ordered fashion. Fluorescence anisotropy measurements indicated that septin filaments organized into pairs within live cells, just as has been observed in vitro. Additional support for the formation of pairs came from the observation of paired filaments at the cortex of cells using electron microscopy. Furthermore, we found that highly ordered septin structures exchanged subunits and rapidly rearranged. We conclude that septins assemble into dynamic, paired filaments in vivo and that this organization is conserved from yeast to mammals.This work was supported by the National Science Foundation under grant No. MCB-0719126 to A.S. Gladfelter, the National Institute of Biomedical Imaging and Bioengineering under grant No. EB002583 to R. Oldenbourg, a Drexel CURE grant from the State of Pennsylvania Tobacco Settlement Fund, and National Institute of Neurological Disorders and Stroke grant NS48090- 06A to E.T. Spiliotis

Extrapolated longer-term effects of the DAPA-CKD trial: a modelling analysis

Background: The Dapagliflozin and Prevention of Adverse Outcomes in Chronic Kidney Disease (DAPA-CKD) trial assessed dapagliflozin versus placebo, in addition to standard therapy, in patients with chronic kidney disease (CKD) and albuminuria, and was terminated prematurely due to overwhelming efficacy. The study objective was to model the long-term clinical outcomes of DAPA-CKD beyond the trial follow-up. Methods: A Markov model extrapolated event incidence per 1000 patients and CKD progression rates for patients receiving dapagliflozin or placebo over a 10-year time horizon. We derived treatment-specific CKD stage transition matrices using DAPA-CKD trial data. We extrapolated relevant efficacy endpoints using parametric survival equations for all-cause mortality and generalized estimating equations for recurrent events. Results: When extrapolated over a 10-year period, patients randomized to dapagliflozin spent more time in CKD stages 1–3 and less in stages 4–5 than placebo [0.65 (95% CrI 0.41, 0.90) and –0.23 (95% CrI -0.45, 0.00) years per patient, respectively]. Dapagliflozin prevented an estimated 83 deaths and 51 patients initiating kidney replacement therapy per 1000 patients over 10 years. Predicted rates of hospitalized heart failure and abrupt declines in kidney function were reduced (19 and 39 estimated events per 1000 patients, respectively). Conclusions: Adding dapagliflozin to standard therapeutic management of CKD is expected to have long-term cardiorenal benefit beyond what has been demonstrated in the DAPA-CKD trial, with patients predicted to live longer with fewer complications

HMG-coenzyme A reductase inhibition, type 2 diabetes, and bodyweight: evidence from genetic analysis and randomised trials.

BACKGROUND: Statins increase the risk of new-onset type 2 diabetes mellitus. We aimed to assess whether this increase in risk is a consequence of inhibition of 3-hydroxy-3-methylglutaryl-CoA reductase (HMGCR), the intended drug target. METHODS: We used single nucleotide polymorphisms in the HMGCR gene, rs17238484 (for the main analysis) and rs12916 (for a subsidiary analysis) as proxies for HMGCR inhibition by statins. We examined associations of these variants with plasma lipid, glucose, and insulin concentrations; bodyweight; waist circumference; and prevalent and incident type 2 diabetes. Study-specific effect estimates per copy of each LDL-lowering allele were pooled by meta-analysis. These findings were compared with a meta-analysis of new-onset type 2 diabetes and bodyweight change data from randomised trials of statin drugs. The effects of statins in each randomised trial were assessed using meta-analysis. FINDINGS: Data were available for up to 223 463 individuals from 43 genetic studies. Each additional rs17238484-G allele was associated with a mean 0·06 mmol/L (95% CI 0·05-0·07) lower LDL cholesterol and higher body weight (0·30 kg, 0·18-0·43), waist circumference (0·32 cm, 0·16-0·47), plasma insulin concentration (1·62%, 0·53-2·72), and plasma glucose concentration (0·23%, 0·02-0·44). The rs12916 SNP had similar effects on LDL cholesterol, bodyweight, and waist circumference. The rs17238484-G allele seemed to be associated with higher risk of type 2 diabetes (odds ratio [OR] per allele 1·02, 95% CI 1·00-1·05); the rs12916-T allele association was consistent (1·06, 1·03-1·09). In 129 170 individuals in randomised trials, statins lowered LDL cholesterol by 0·92 mmol/L (95% CI 0·18-1·67) at 1-year of follow-up, increased bodyweight by 0·24 kg (95% CI 0·10-0·38 in all trials; 0·33 kg, 95% CI 0·24-0·42 in placebo or standard care controlled trials and -0·15 kg, 95% CI -0·39 to 0·08 in intensive-dose vs moderate-dose trials) at a mean of 4·2 years (range 1·9-6·7) of follow-up, and increased the odds of new-onset type 2 diabetes (OR 1·12, 95% CI 1·06-1·18 in all trials; 1·11, 95% CI 1·03-1·20 in placebo or standard care controlled trials and 1·12, 95% CI 1·04-1·22 in intensive-dose vs moderate dose trials). INTERPRETATION: The increased risk of type 2 diabetes noted with statins is at least partially explained by HMGCR inhibition. FUNDING: The funding sources are cited at the end of the paper

Genome-wide association and Mendelian randomisation analysis provide insights into the pathogenesis of heart failure

Heart failure (HF) is a leading cause of morbidity and mortality worldwide. A small proportion of HF cases are attributable to monogenic cardiomyopathies and existing genome-wide association studies (GWAS) have yielded only limited insights, leaving the observed heritability of HF largely unexplained. We report results from a GWAS meta-analysis of HF comprising 47,309 cases and 930,014 controls. Twelve independent variants at 11 genomic loci are associated with HF, all of which demonstrate one or more associations with coronary artery disease (CAD), atrial fibrillation, or reduced left ventricular function, suggesting shared genetic aetiology. Functional analysis of non-CAD-associated loci implicate genes involved in cardiac development (MYOZ1, SYNPO2L), protein homoeostasis (BAG3), and cellular senescence (CDKN1A). Mendelian randomisation analysis supports causal roles for several HF risk factors, and demonstrates CAD-independent effects for atrial fibrillation, body mass index, and hypertension. These findings extend our knowledge of the pathways underlying HF and may inform new therapeutic strategies

Evaluating the Effects of SARS-CoV-2 Spike Mutation D614G on Transmissibility and Pathogenicity.

Global dispersal and increasing frequency of the SARS-CoV-2 spike protein variant D614G are suggestive of a selective advantage but may also be due to a random founder effect. We investigate the hypothesis for positive selection of spike D614G in the United Kingdom using more than 25,000 whole genome SARS-CoV-2 sequences. Despite the availability of a large dataset, well represented by both spike 614 variants, not all approaches showed a conclusive signal of positive selection. Population genetic analysis indicates that 614G increases in frequency relative to 614D in a manner consistent with a selective advantage. We do not find any indication that patients infected with the spike 614G variant have higher COVID-19 mortality or clinical severity, but 614G is associated with higher viral load and younger age of patients. Significant differences in growth and size of 614G phylogenetic clusters indicate a need for continued study of this variant