Automated, high-throughput derivation, characterization and differentiation of induced pluripotent stem cells.

Induced pluripotent stem cells (iPSCs) are an essential tool for modeling how causal genetic variants impact cellular function in disease, as well as an emerging source of tissue for regenerative medicine. The preparation of somatic cells, their reprogramming and the subsequent verification of iPSC pluripotency are laborious, manual processes limiting the scale and reproducibility of this technology. Here we describe a modular, robotic platform for iPSC reprogramming enabling automated, high-throughput conversion of skin biopsies into iPSCs and differentiated cells with minimal manual intervention. We demonstrate that automated reprogramming and the pooled selection of polyclonal pluripotent cells results in high-quality, stable iPSCs. These lines display less line-to-line variation than either manually produced lines or lines produced through automation followed by single-colony subcloning. The robotic platform we describe will enable the application of iPSCs to population-scale biomedical problems including the study of complex genetic diseases and the development of personalized medicines.

Characterization of a subpopulation of developing cortical interneurons from human iPSCs within serum-free embryoid bodies.

Production and isolation of forebrain interneuron progenitors are essential for understanding cortical development and developing cell-based therapies for developmental and neurodegenerative disorders. We demonstrate production of a population of putative calretinin-positive bipolar interneurons that express markers consistent with caudal ganglionic eminence identities. Using serum-free embryoid bodies (SFEBs) generated from human inducible pluripotent stem cells (iPSCs), we demonstrate that these interneuron progenitors exhibit morphological, immunocytochemical, and electrophysiological hallmarks of developing cortical interneurons. Finally, we develop a fluorescence-activated cell-sorting strategy to isolate interneuron progenitors from SFEBs to allow development of a purified population of these cells. Identification of this critical neuronal cell type within iPSC-derived SFEBs is an important and novel step in describing cortical development in this iPSC preparation.

Contributions of bone morphogenetic proteins in cardiac repair cells in three-dimensional in vitro models and angiogenesis.

One of the main efforts in myocardial tissue engineering is towards designing cardiac tissues able to rescue the reduction in heart function once implanted at the site of myocardial infarction. To date, the efficiency of this approach in preclinical applications is limited in part by our incomplete understanding of the inflammatory environment known to be present at the site of myocardial infarct and by poor vascularization. It was recently reported that polarized macrophages known to be present at the site of myocardial infarction secrete bone morphogenetic proteins (BMPs)-2 and -4 causing changes in the expression of cardiac proteins in a 2D in vitro model. Here, these findings were extended towards cardiac tissues composed of human embryonic stem cell derived cardiomyocytes embedded in collagen gel. By preconditioning cardiac tissues with BMPs, constructs were obtained with enhanced expression of cardiac markers. Additionally, after BMP preconditioning, the resulting cardiac-tissues were able to sustain diffusion of the BMPs with the added benefit of supporting human umbilical vein endothelial cell tube formation. Here, a model is proposed of cardiac tissues preconditioned with BMPs that results in stimulation of cardiomyocyte function and diffusion of BMPs able to support angiogenesis. This platform represents a step towards the validation of more complex bioengineered constructs for in vivo applications.

BMP protein-mediated crosstalk between inflammatory cells and human pluripotent stem cell-derived cardiomyocytes.

Following cardiac injury, the ischaemic heart tissue is characterized by the invasion of pro-inflammatory (M1) and pro-healing (M2) macrophages. Any engineered cardiac tissue will inevitably interact with the inflammatory environment found at the site of myocardial infarction at the time of implantation. However, the interactions between the inflammatory and the cardiac repair cells remain poorly understood. Here we recapitulated in vitro some of the important cellular events found at the site of myocardial injury, such as macrophage recruitment and their effect on cardiac differentiation and maturation, by taking into account the involvement of paracrine-mediated signalling. By using a 3D inverted invasion assay, we found that cardiomyocyte (CM) conditioned medium can trigger the recruitment of pro-inflammatory (M1) macrophages, through a mechanism that involves, in part, CM-derived BMP4. Pro-inflammatory (M1) macrophages were also found to affect CM proliferation and differentiation potential, in part due to BMP molecules secreted by macrophages. These effects involved the activation of the canonical outside-in signalling pathways, such as SMAD1,5,8, which are known to be activated during myocardial injury in vivo. In the present study we propose a new role for CM- and macrophage-derived BMP proteins during the recruitment of macrophage subtypes and the maturation of repair cells, representing an important step towards creating a functional cardiac patch with superior therapeutic properties. Copyright © 2015 John Wiley & Sons, Ltd.

Directed Differentiation of Human Pluripotent Stem Cells to Microglia.

Microglia, the immune cells of the brain, are crucial to proper development and maintenance of the CNS, and their involvement in numerous neurological disorders is increasingly being recognized. To improve our understanding of human microglial biology, we devised a chemically defined protocol to generate human microglia from pluripotent stem cells. Myeloid progenitors expressing CD14/CX3CR1 were generated within 30 days of differentiation from both embryonic and induced pluripotent stem cells (iPSCs). Further differentiation of the progenitors resulted in ramified microglia with highly motile processes, expressing typical microglial markers. Analyses of gene expression and cytokine release showed close similarities between iPSC-derived (iPSC-MG) and human primary microglia as well as clear distinctions from macrophages. iPSC-MG were able to phagocytose and responded to ADP by producing intracellular Ca2+ transients, whereas macrophages lacked such response. The differentiation protocol was highly reproducible across several pluripotent stem cell lines.

Economic and Sociological Correlates of Suicides: Multilevel Analysis of the Time Series Data in the United Kingdom.

For the effects of social integration on suicides, there have been different and even contradictive conclusions. In this study, the selected economic and social risks of suicide for different age groups and genders in the United Kingdom were identified and the effects were estimated by the multilevel time series analyses. To our knowledge, there exist no previous studies that estimated a dynamic model of suicides on the time series data together with multilevel analysis and autoregressive distributed lags. The investigation indicated that unemployment rate, inflation rate, and divorce rate are all significantly and positively related to the national suicide rates in the United Kingdom from 1981 to 2011. Furthermore, the suicide rates of almost all groups above 40 years are significantly associated with the risk factors of unemployment and inflation rate, in comparison with the younger groups.

Genetic Drift Can Compromise Mitochondrial Replacement by Nuclear Transfer in Human Oocytes.

Replacement of mitochondria through nuclear transfer between oocytes of two different women has emerged recently as a strategy for preventing inheritance of mtDNA diseases. Although experiments in human oocytes have shown effective replacement, the consequences of small amounts of mtDNA carryover have not been studied sufficiently. Using human mitochondrial replacement stem cell lines, we show that, even though the low levels of heteroplasmy introduced into human oocytes by mitochondrial carryover during nuclear transfer often vanish, they can sometimes instead result in mtDNA genotypic drift and reversion to the original genotype. Comparison of cells with identical oocyte-derived nuclear DNA but different mtDNA shows that either mtDNA genotype is compatible with the nucleus and that drift is independent of mitochondrial function. Thus, although functional replacement of the mitochondrial genome is possible, even low levels of heteroplasmy can affect the stability of the mtDNA genotype and compromise the efficacy of mitochondrial replacement.

Rapid and Efficient Generation of Transgene-Free iPSC from a Small Volume of Cryopreserved Blood.

Human peripheral blood and umbilical cord blood represent attractive sources of cells for reprogramming to induced pluripotent stem cells (iPSCs). However, to date, most of the blood-derived iPSCs were generated using either integrating methods or starting from T-lymphocytes that have genomic rearrangements thus bearing uncertain consequences when using iPSC-derived lineages for disease modeling and cell therapies. Recently, both peripheral blood and cord blood cells have been reprogrammed into transgene-free iPSC using the Sendai viral vector. Here we demonstrate that peripheral blood can be utilized for medium-throughput iPSC production without the need to maintain cell culture prior to reprogramming induction. Cell reprogramming can also be accomplished with as little as 3000 previously cryopreserved cord blood cells under feeder-free and chemically defined Xeno-free conditions that are compliant with standard Good Manufacturing Practice (GMP) regulations. The first iPSC colonies appear 2-3 weeks faster in comparison to previous reports. Notably, these peripheral blood- and cord blood-derived iPSCs are free of detectable immunoglobulin heavy chain (IGH) and T cell receptor (TCR) gene rearrangements, suggesting they did not originate from B- or T- lymphoid cells. The iPSCs are pluripotent as evaluated by the scorecard assay and in vitro multi lineage functional cell differentiation. Our data show that small volumes of cryopreserved peripheral blood or cord blood cells can be reprogrammed efficiently at a convenient, cost effective and scalable way. In summary, our method expands the reprogramming potential of limited or archived samples either stored at blood banks or obtained from pediatric populations that cannot easily provide large quantities of peripheral blood or a skin biopsy.

Frequency and fitness consequences of bacteriophage φ6 host range mutations.

Viruses readily mutate and gain the ability to infect novel hosts, but few data are available regarding the number of possible host range-expanding mutations allowing infection of any given novel host, and the fitness consequences of these mutations on original and novel hosts. To gain insight into the process of host range expansion, we isolated and sequenced 69 independent mutants of the dsRNA bacteriophage Φ6 able to infect the novel host, Pseudomonas pseudoalcaligenes. In total, we found at least 17 unique suites of mutations among these 69 mutants. We assayed fitness for 13 of 17 mutant genotypes on P. pseudoalcaligenes and the standard laboratory host, P. phaseolicola. Mutants exhibited significantly lower fitnesses on P. pseudoalcaligenes compared to P. phaseolicola. Furthermore, 12 of the 13 assayed mutants showed reduced fitness on P. phaseolicola compared to wildtype Φ6, confirming the prevalence of antagonistic pleiotropy during host range expansion. Further experiments revealed that the mechanistic basis of these fitness differences was likely variation in host attachment ability. In addition, using computational protein modeling, we show that host-range expanding mutations occurred in hotspots on the surface of the phage's host attachment protein opposite a putative hydrophobic anchoring domain.