Creative Minds: Interrogating a Master of Disguise

Monica Mugnier

Monica Mugnier

When I volunteered several years ago as a physician in a small hospital in West Africa, one of the most frustrating and frightening diseases I saw was sleeping sickness. Now, an investigator supported by the NIH Common Fund aims to figure out how this disease pathogen manages to evade the human immune system.

Monica Mugnier’s fascination with parasites started in college when she picked up the book Parasite Rex, a riveting, firsthand account of how “sneaky” parasites can be. The next year, while studying abroad in England, Mugnier met a researcher who had studied one of the most devious of parasites—a protozoan, spread by blood-sucking tsetse flies, that causes sleeping sickness in humans and livestock across sub-Saharan Africa.

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Cool Videos: Looking Inside Living Cells

celldancevideoCell biologists now possess an unprecedented set of laboratory tools to look inside living cells and study their inner workings. Many of these tools have only recently appeared, while others have deeper historical roots. Combining the best of the old with the best of the new, researchers now have the power to explore the biological underpinnings of life in ways never seen before.

That’s the story of this video from the lab of Roberto Weigert, an intramural researcher with NIH’s National Cancer Institute and National Institute of Dental and Craniofacial Research. Weigert is a cell biologist who specializes in intravital microscopy (IVM), an extremely high-resolution imaging tool that traces its origins to the 19th century. What’s unique about IVM is its phenomenal resolution can be used in living animals, allowing researchers to watch biological processes unfold in organs under real physiological conditions and in real time.

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Find and Replace: DNA Editing Tool Shows Gene Therapy Promise

Neutrophil being edited with CRISPR/Cas9

Caption: This image represents an infection-fighting cell called a neutrophil. In this artist’s rendering,  the cell’s DNA is being “edited” to help restore its ability to fight bacterial invaders.
Credit: NIAID, NIH

For gene therapy research, the perennial challenge has been devising a reliable way to insert safely a working copy of a gene into relevant cells that can take over for a faulty one. But with the recent discovery of powerful gene editing tools, the landscape of opportunity is starting to change. Instead of threading the needle through the cell membrane with a bulky gene, researchers are starting to design ways to apply these tools in the nucleus—to edit out the disease-causing error in a gene and allow it to work correctly.

While the research is just getting under way, progress is already being made for a rare inherited immunodeficiency called chronic granulomatous disease (CGD). As published recently in Science Translational Medicine, a team of NIH researchers has shown with the help of the latest CRISPR/Cas9 gene-editing tools, they can correct a mutation in human blood-forming adult stem cells that triggers a common form of CGD. What’s more, they can do it without introducing any new and potentially disease-causing errors to the surrounding DNA sequence [1].

When those edited human cells were transplanted into mice, the cells correctly took up residence in the bone marrow and began producing fully functional white blood cells. The corrected cells persisted in the animal’s bone marrow and bloodstream for up to five months, providing proof of principle that this lifelong genetic condition and others like it could one day be cured without the risks and limitations of our current treatments.

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Creative Minds: Modeling Neurobiological Disorders in Stem Cells

Feng Zhang

Feng Zhang

Most neurological and psychiatric disorders are profoundly complex, involving a variety of environmental and genetic factors. Researchers around the world have worked with patients and their families to identify hundreds of possible genetic leads to learn what goes wrong in autism spectrum disorder, schizophrenia, and other conditions. The great challenge now is to begin examining this growing cache of information more systematically to understand the mechanism by which these gene variants contribute to disease risk—potentially providing important information that will someday lead to methods for diagnosis and treatment.

Meeting this profoundly difficult challenge will require a special set of laboratory tools. That’s where Feng Zhang comes into the picture. Zhang, a bioengineer at the Broad Institute of MIT and Harvard, Cambridge, MA, has made significant contributions to a number of groundbreaking research technologies over the past decade, including optogenetics (using light to control brain cells), and CRISPR/Cas9, which researchers now routinely use to edit genomes in the lab [1,2].

Zhang has received a 2015 NIH Director’s Transformative Research Award to develop new tools to study multiple gene variants that might be involved in a neurological or psychiatric disorder. Zhang draws his inspiration from nature, and the microscopic molecules that various organisms have developed through the millennia to survive. CRISPR/Cas9, for instance, is a naturally occurring bacterial defense system that Zhang and others have adapted into a gene-editing tool.

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Sickle Cell Disease: Gene-Editing Tools Point to Possible Ultimate Cure

Sickled red blood cell

Caption: An electron micrograph showing two red blood cells deformed by crystalline hemoglobin into different “sickle” shapes characteristic of people with sickle cell disease.
Credit: Frans Kuypers: RBClab.com, UCSF Benioff Children’s Hospital Oakland

Scientists first described the sickle-shaped red blood cells that give sickle cell disease its name more than a century ago. By the 1950s, the precise molecular and genetic underpinnings of this painful and debilitating condition had become clear, making sickle cell the first “molecular disease” ever characterized. The cause is a single letter “typo” in the gene encoding oxygen-carrying hemoglobin. Red blood cells containing the defective hemoglobin become stiff, deformed, and prone to clumping. Individuals carrying one copy of the sickle mutation have sickle trait, and are generally fine. Those with two copies have sickle cell disease and face major medical challenges. Yet, despite all this progress in scientific understanding, nearly 70 years later, we still have no safe and reliable means for a cure.

Recent advances in CRISPR/Cas9 gene-editing tools, which the blog has highlighted in the past, have renewed hope that it might be possible to cure sickle cell disease by correcting DNA typos in just the right set of cells. Now, in a study published in Science Translational Medicine, an NIH-funded research team has taken an encouraging step toward this goal [1]. For the first time, the scientists showed that it’s possible to correct the hemoglobin mutation in blood-forming human stem cells, taken directly from donors, at a frequency that might be sufficient to help patients. In addition, their gene-edited human stem cells persisted for 16 weeks when transplanted into mice, suggesting that the treatment might also be long lasting or possibly even curative.

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