Woltjen Lab

Stem Cells and Genome Engineering

Research

Lab Research Interests
Our Research in “Plain” English
Human iPS Cells
Reprogramming Mechanisms
Genome Engineering



 

Lab Research Interests

Recombination: Recombineering, Gene Targeting, Transgenics
Reprogramming: iPS Cells, Cellular Plasticity, Epigenetic Memory
Patient-Specific iPS Cells: Disease Modelling, Drug Screening, Gene Correction

Our research aims to develop and adapt cutting edge technologies to promote studies in cellular reprogramming and differentiation. To achieve this, we are employing techniques including: inducible transgene expression, transposition, site-specific recombination, and nuclease-mediated gene targeting.

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Our Research in “Plain” English

To get the job done, it helps to have the right tools.

       Our lab designs and uses tools based on natural processes – for example: enzyme reactions (proteins that can repair or alter DNA), mobile DNA (DNA elements that can move!), bioluminescence (like that from glowing jellyfish or fireflies) or even stem cell specialization (embryo development).

     Induced pluripotent stem (iPS) cells are a new type of tool that we can use to help answer questions about human genetics, health and disease. iPS cells are created from skin or blood cells, and given the power to become any of the ~200 cell types that do special jobs in your body. Thus, we can study cells in the lab which we could not gain access to in patients, such as brain neurons. Combined with our other tools we can study the consequences of genetic disease, screen for drugs which may help a patient, or even try to make positive changes to the DNA to repair the cause of genetic disease.

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Human Induced Pluripotent Stem (iPS) Cells

      In 2007, Kyoto University researchers Drs. Takahashi and Yamanaka demonstrated that human skin cells could be reprogrammed back to a pluripotent embryonic state. As induced pluripotent stem (iPS) cells may be derived from any donor, this technology makes the promise of patient-tailored diagnostics and therapeutics a tangible prospect; revolutionizing the way we perceive regenerative medicine.

      Through iPS cell reprogramming, we may capture a particular genotype, and even engineer it (if need be) to correct mutations leading to genetic disease. Using methods learned from developmental biology to coax the cells into specialized derivatives, we may model diseases or screen for drug effects in vitro. Before iPS cell-based clinical therapies are achieved, these pre-clinical tests will provide a deeper understanding of human health.

human iPS cells

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Somatic Cell Reprogramming Mechanisms

        Reprogramming somatic cells to induced pluripotent stem (iPS) cells through ectopic expression of four transcription factors is a profound technology of which little is known mechanistically. Elucidating the key requirements in the process will improve iPS cell quality and consistency, providing biological insight into cellular plasticity. Using a drug-inducible reprogramming system, we are dissecting the kinetics of early reprogramming. Our goal is to reveal changes that can be applied to augment current reprogramming standards.

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Genome Engineering

    While in Dr. Nagy’s laboratory in Toronto, Dr. Woltjen helped develop a novel non-viral approach to iPS cell production, taking advantage of the piggybac (PB) transposon from Trichoplusia ni. Transposase enzyme expression can be used to re-mobilize the transposon elements, with >95% mutation-free excision from the iPS cell genome.

     Transposition presents itself as a unique method of transgenesis, as transposons integrate broadly throughout the genome, yet may be removed seamlessly. Exploiting these characteristics, we are developing mutagenesis and genetic engineering approaches for the human genome that retain minimal transgene modifications. We promote transposition as a method to create reporter lines, derive accurate disease models from normal iPSCs, and achieve gene correction in those bearing disease alleles.

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