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Tag Archives: pluripotent stem cells

Friday Science Review: January 22, 2010

Some really exciting research in this week’s review…

Special (RNAi) Delivery: One of the obstacles for RNAi based therapeutics is the difficulty in getting the RNAi into the cells efficiently to invoke a positive response.  Vancouver based Tekmira Pharmaceuticals (TSX: TKM.TO), in partnership with Alnylam Pharmaceuticals (Nasdaq: ALNY) and researchers at the University of British Columbia, Drs. Pieter Cullis and Marco Ciufolini, developed a new and improved RNAi delivery method that is 10X better than their standard delivery platform.  Using their knowledge of lipid structure and how specific features influences delivery into cells, they used a rational design approach to develop a new cationic lipid, DLin-KC2-DMA (KC2), that is used with their current SNALP system (stable nucleic acid-lipid particles) to achieve the remarkable results.  Details of the study are reported in this week’s issue of Nature Biotechnology.

Resolving Stem Cell Populations: The differentiation of stem cells is a complex multi-step process that is not fully understood.   With each step, the potential of that stem cell becomes more and more restricted.  Researchers performed a series of intricate detailed studies on cell populations to resolve distinct Intermediate Term Reconstituting Hematopoietic Stem Cells or ITRC (versus long- and short-term populations).  The significance of this key finding is that researchers who are interested in harnessing the potential of long-term reconstituting hematopoietic stem cells can more accurately study a pure population of true, self-renewing stem cells with homogeneous characteristics.  Prior to this new “intermediate-term” identification, the majority of “long-term” cells were actually comprised of intermediate-term cells.  Dr. Norman Iscove and his team at the University Health Network describe their work in the latest issue of Cell Stem Cell.

Fishing for New Drugs: A high-throughput behavioural monitoring system to observe the response of Zebrafish to neuroactive chemical compounds should help expedite the discovery of new drugs for neurological disorders.  Researchers setup a video system and applied “behavioural barcodes” that they say can track the effects of 14,000 chemicals on zebrafish behaviour.  The capacity of this large-scale screen is unique and the use of zebrafish is quite informative because they are transparent, genetically tractable, and more similar to humans than you might think.  In this platform, response to two strong light pulses after exposure to chemicals is monitored and the observations are translated into barcodes that make data analysis of this magnitude a lot more manageable.  Drs. Jennifer Bryan and Rick White at UBC collaborated with Harvard researchers and published their study in Nature Chemical Biology.

Intrinsic Stimulator of Muscle Regeneration: A new subpopulation of cells in muscle tissue that contribute to muscle injury repair has been identified.  The surprise is that these cells, called fibro/adipogenic progenitors (FAPs), are derived from a different developmental lineage as muscle cells.  These fat-lineage cells, which are resident in muscle tissue, are ‘activated’ in response to muscle damage but they do not become muscle cells.  Instead, they release factors that promote and enhance muscle progenitors in the myogenesis repair process.  The conundrum, however, is that too much of these FAPs can lead to fibrosis and contribute to muscle disorders.  The study, reported in Nature Cell Biology, was led by Dr. Fabio Rossi at the University of British Columbia.

Pharmacoviral Therapy for Gliomas: Oncolytic viruses (VSVs) are used in the treatment against malignant gliomas but are limited in efficacy due to the viral induced IFN (interferon) response – one of our body’s natural defense mechanism.  Knowledge of the molecular mechanisms involving the mTOR pathway in IFN production led researchers to investigate the use of rapamycin, an mTOR inhibitor, in conjunction with the VSVs.  This “pharmacoviral” combinatorial approach was very successful when tested in rats with malignant gliomas and represents a potentially new therapeutic strategy.  Dr. Nahum Sonenberg and his team at McGill University are experts in the mTOR pathway and describe their work in the Proceedings of the National Academy of Sciences.

Friday Science Review: January 8, 2010

I am starting the new year and decade by recognizing the accomplishments of two distinguished scientists…

Two outstanding Canadian scientists were recognized for their valuable contributions to the global research community.

Dr. Andras Nagy’s innovative technique to reprogram mature body cells into stem cells – called induced pluripotent stem cells or iPS cells – was named Method of the Year by the prestigious journal Nature Methods.  Earlier in the year, Dr. Nagy was selected as one of Scientific American magazine’s top 10 – Guiding Science for Humanity.

Dr. Tony Pawson was honoured as one of ten “Nation Builders of the Decade” by the Globe and Mail.  His breakthrough research over the past decade and beyond has propelled our understanding of the intricate communication that goes on within a cell and between cells.  Dr. Pawson was also awarded the Kyoto Prize this year.

Bypassing PTEN Mutants in Cancer Cells: The discovery of a novel link between the proteins PTEN and PKR may lead to new approaches forncer treatments.  Dr. Antonis Koromilas’ research at McGill University identified that the tumour suppressor function of PTEN requires it to activate the PKR-eIF2alpha pathway, which applies an inhibitory control on protein synthesis.  In a cancer cell where PTEN is mutated, PKR also loses its ability to control protein synthesis and the cell continues growing into a tumour.  The significance of this is that they can now try to bypass the PTEN mutation and find alternate ways to activate PKR and regain control of cell growth.  The research is reported in the journal Science Signaling.

Distinguishing Sister Chromatids: In studying cell division, scientists have long desired to follow the fate of sister chromatids – the identical chromosome copies that is distributed to each cell during the process of cell division.  Researchers used the CO-FISH (chromosome orientation fluorescence in situ hybridization) technique with unidirectional probes.  When they observed the process in different cell types, they found that the chromatids segregated randomly in some cell types but not in others.  The non-randomness may be a mechanism to direct cells to be slightly different from its sister cell and is one of many layers of complexity in developing higher organisms.  The solution to this biological phenomenon by Dr. Peter Lansdorp at the BC Cancer Agency deserves the recognition in the prestigious journal Nature.

Prognostic Marker for Bone Cancer Survival: Genetic deletion mutations in a specific chromosome region called osteo3q13.31 may be predictive of a poor prognosis for osteosarcoma patients.  The copy number alteration (CNA) marker was identified in subsets (80%) of osteosarcoma patients where their bone cancers appeared to be more difficult to treat.  With this genetic marker, patients may be screened to identify candidates who should be treated more aggressively from the onset of diagnosis.  Furthermore, the osteo3q13.31 region contains 3 genes that were not previously associated with the disease and requires further investigation that may lead to additional therapeutic options.  The study was conducted by Dr. David Malkin’s team at The Hospital for Sick Children and is published in Cancer Research.

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Friday Science Review: March 6, 2009

Cool Canadian science stories this week…

Stem Cells: The big Canadian science news this week was the report by Dr. Nagy’s lab at the Lunenfeld that they have found a much safer way to make pluripotent stem cells from adult tissue.  Their publication (co-authored with Keisuke Kaji’s team at the University of Edinburgh) appeared in Nature this week.

Also on the stem cell front, Dr. Kremer, the co-director of the Musculoskeletal Axis of the Research Institute of the McGill University Health Centre, used Interferon gamma to induce the differentiation of mesenchymal stem cells into osteoblasts in vitro, and that IFNγ knockout mice also show reduced bone density and that isolated mesenchymal stem cells from the knockout mice show a differentiation defect.  Long story short: a potential new target for improving bone density.

Clinical Trials: Good news for GSK and for scientists at McMaster University, who showed that GSK’s Mepolizumab (pdf), an anti-IL5 humanized antibody that blocks eosinophil production, helps severe asthmatics improve asthma and reduce their need for prednisone by close to 90 per cent, a result that was seconded by a group in the UK.

Nanotechnology Costs: We noted a few weeks ago that there were changes coming to nanotechnology regulatory environment, and now researchers in BC and Minnessota estimate that testing the toxicity of existing nanomaterials in the United States could cost between $249 million and $1.18 billion and that full-scale testing could take decades to complete. They propose a tiered approach, similar to the EU’s REACH program for testing toxic chemicals, to define priorities.  Hat tip to ScienceInsider.

Hosted Services: Canadians, being hospitable types, are hosting World Diabetes Congress in Montreal in October, as well as a new Occupational Cancer Research Centre – charged with “improving knowledge and evidence to help identify, prevent and ultimately eliminate exposures to cancer-causing substances in the workplace.”

Musical Chairs: A group at Ryerson University’s centre for learning technologies in conjunction with the science of music, auditory research and technology (SMART) lab have developed a chair that allows the hearing-impaired to experience music by using the skin as a hearing membrane. 

Global Issues: An Amazon drought caused a major release of carbon dioxide; but don’t worry, because we’ll find a new planet in no time.  Sound painful? Don’t worry – a spoonful of sugar really does help the medicine go down.

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