Stories about: blood disorders

Stem cell workaround cracks open new leads in Diamond Blackfan anemia

Diamond Blackfan anemia iPS cells hematopoietic progenitor cells
Though not bona-fide stem cells, hematopoietic progenitor cells produce red blood cells when exposed to certain chemicals. Could some of these compounds lead to new drugs for Diamond Blackfan anemia?

Diamond Blackfan anemia (DBA) has long been a disease waiting for a cure. First described in 1938 by Louis K. Diamond, MD, of Boston Children’s Hospital and his mentor, Kenneth Blackfan, MD, the rare, severe blood disorder prevents the bone marrow from making enough red blood cells. It’s been linked to mutations affecting a variety of proteins in ribosomes, the cellular organelles that themselves build proteins. The first mutation was reported in 1999.

But scientists have been unable to connect the dots and turn that knowledge into new treatments for DBA. Steroids are still the mainstay of care, and they help only about half of patients. Some people eventually stop responding, and many are forced onto lifelong blood transfusions.

Researchers have tried for years to isolate and study patients’ blood stem cells, hoping to recapture the disease process and gather new therapeutic leads. Some blood stem cells have been isolated, but they’re very rare and can’t be replicated in enough numbers to be useful for research.

Induced pluripotent stem (iPS) cells, first created in 2006 from donor skin cells, seemed to raise new hope. They can theoretically generate virtually any specialized cell, allowing scientists model a patient’s disease in a dish and test potential drugs.

There’s been just one hitch. “People quickly ran into problems with blood,” says hematology researcher Sergei Doulatov, PhD. “iPS cells have been hard to instruct when it comes to making blood cells.”

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Rare blood disorder sideroblastic anemia slowly reveals its genetic secrets

congenital sideroblastic anemia
Regardless of the gene, all patients with sideroblastic anemia have sideroblasts: red blood cell precursors with abnormal iron deposits in mitochondria, shown here ringing the cell nucleus. (Paulo Henrique Orlandi Mourao/Wikimedia)

A decade ago, Brooks McMurray’s routine check-up was anything but routine. The suburban Boston boy’s spleen was enlarged. His red blood cell count was low and the cells were very small and very pale, which suggested a serious iron deficiency anemia. The family pediatrician referred McMurray, now a 19-year-old college freshman, to Dana-Farber/Boston Children’s Cancer and Blood Disorders Center.

There hematologists discovered the boy had unexpectedly high iron levels. Together with pathologist Mark Fleming, MD, DPhil, they solved the mystery. McMurray has congenital sideroblastic anemia, an inherited blood disorder so rare that fewer than 1,000 cases have been reported worldwide. Iron was getting stuck in the wrong place in the precursor red blood cells developing in his bone marrow.

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Rainbow-hued blood stem cells shed new light on cancer, blood disorders

color-coded blood stem cells
These red blood cells bear color tags made from random combinations of red, green and blue fluorescent proteins. Same-color cells originate from the same blood stem cell (Nature Cell Biology 2016, Henninger et al).

A new color-coding tool is enabling scientists to better track live blood stem cells over time, a key part of understanding how blood disorders and cancers like leukemia arise, report researchers in Boston Children’s Hospital’s Stem Cell Research Program.

In Nature Cell Biology today, they describe the use of their tool in zebrafish to track blood stem cells the fish are born with, the clones (copies) these cells make of themselves and the types of specialized blood cells they give rise to (red cells, white cells and platelets). Leonard Zon, MD, director of the Stem Cell Research Program and a senior author on the paper, believes the tool has many implications for hematology and cancer medicine since zebrafish are surprisingly similar to humans genetically.

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BCL11A-based gene therapy for sickle cell disease passes key preclinical test

sickle cell gene therapy coming
(unsplash/Pixabay)

Research going back to the 1980s has shown that sickle cell disease is milder in people whose red blood cells carry a fetal form of hemoglobin. The healthy fetal hemoglobin compensates for the mutated “adult” hemoglobin that makes red blood cells stiffen and assume the classic “sickle” shape.

Normally, fetal hemoglobin production tails off after birth, shut down by a gene called BCL11A. In 2008, researchers Stuart Orkin, MD, and Vijay Sankaran, MD, PhD, at the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center showed that suppressing BCL11A could restart fetal hemoglobin production; in 2011, using this approach, they corrected sickle cell disease in mice.

Now, the decades-old discovery is finally nearly ready for human testing — in the form of gene therapy. Today in the Journal of Clinical Investigation, Dana-Farber/Boston Children’s researchers report that a precision-engineered gene therapy vector suppressing BCL11A production overcame a key technical hurdle.

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Tool helps interpret subtle DNA variants from genome-wide association studies

Genome-wide association studies are huge undertakings that compare the genomes of large populations. They can turn up thousands to tens of thousands of genetic variants associated with disease. But which GWAS variants really matter?

That question becomes exponentially harder when the variants lie in the vast stretches of DNA that don’t encode proteins, but instead have regulatory functions.

“It’s hard to know which hits are causal hits, and which are just going along for the ride,” says Vijay Sankaran, MD, PhD, a pediatric hematologist/oncologist at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center and an associate member of the Broad Institute.

Reporting in Cell, Sankaran’s team and two other groups at the Broad Institute describe a new tool that can looks at hundreds of thousands of genetic elements at once to pinpoint variants that truly affect gene expression or function. Called the massively parallel reporter assay (MPRA), it could help reveal subtle genetic influences on diseases and traits.

In Sankaran’s case, the MPRA is helping him understand how common variants contribute to blood disorders in children. “Most of the common variation is just tuning genetic function,” he says. “Just slightly, not turning it on or off, but actually just tuning it like a dimmer switch.”

The above video explains how the assay works – via DNA “barcodes.” Read more on the Broad Institute’s blog, Broad Minded.

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Stuart Orkin honored for his lifetime research on blood development

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Presenter Bill Evans, IBM Watson Health and Stuart H. Orkin, MD

When colleagues describe Stuart H. Orkin, MD, associate chief of hematology/oncology at Boston Children’s Hospital and chair of pediatric oncology at Dana-Farber Cancer Institute, the words “immeasurable,” “vanguard” and “mentor” quickly roll off the tongue.

In honor of his 35-year career and commitment to blood cell research, Boston Children’s Hospital presented Orkin with the 2015 Lifetime Impact Award, during Boston Children’s Global Pediatric Innovation Summit held this week. The award recognizes a clinician and/or researcher who has significantly impacted pediatric care through practice-changing innovations or discoveries and made extraordinary and sustained leadership contributions in health care throughout his or her career.

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Hematologist Vijay Sankaran receives Boston Children’s Hospital Rising Star Award

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Before an audience of several hundred luncheon attendees, physician-scientist Vijay G. Sankaran, MD, PhD, received Boston Children’s Hospital’s 2015 Rising Star Award — recognizing the outstanding achievements of an up-and-coming innovator under the age of 45 in pediatric health care.

Sankaran, a board-certified pediatric hematologist/oncologist with Dana-Farber/Boston Children’s Cancer and Blood Disorders Center, conducts innovative research on red blood cell disorders such as Diamond-Blackfan anemia, sickle cell disease and thalassemia.

The Rising Star Award and companion Lifetime Impact Award ceremony were held at the hospital’s Global Pediatric Innovation Summit + Awards on November 10.

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Targeting inflammation in sickle cell disease with fatty acids

sickle cell disease red blood cells
(OpenStax College/Wikimedia Commons)

Painful, tissue-damaging vaso-occlusive crises (a.k.a. pain crises) are one of the key clinical concerns in sickle cell disease (SCD). The characteristic C-shaped red blood cells of SCD become jammed in capillaries, starving tissues of oxygen and triggering searing pain. Over a patient’s life, these repeated rounds of oxygen deprivation (ischemia) can take a heavy toll on multiple organs.

There’s some debate as to why these crises take place—is the sickled cell’s shape and rigidity at fault, or are the blood vessels chronically inflamed and more prone to blockage? Either way, doctors can currently do little to treat vaso-occlusive crises, and nothing to prevent them.

The inflammation view, however, is leading some researchers to ask whether omega-3 fatty acids—which can alleviate inflammation—might be part of the solution. A recent mouse study in the journal Haematologica, led by Mark Puder, MD, PhD, of Boston Children’s Vascular Biology Program, and Carlo Brugnara, MD, of the hospital’s Department of Laboratory Medicine reveals some molecular clues and suggests that human trials of omega-3s might be a good next step.

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A first for CRISPR: Cutting genes in blood stem cells

CRISPR T-cells stem cells HIV gene editing
The CRISPR system (red) at work.

CRISPR—a gene editing technology that lets researchers make precise mutations, deletions and even replacements in genomic DNA—is all the rage among genomic researchers right now. First discovered as a kind of genomic immune memory in bacteria, labs around the world are trying to leverage the technology for diseases ranging from malaria to sickle cell disease to Duchenne muscular dystrophy.

In a paper published yesterday in Cell Stem Cell, a team led by Derrick Rossi, PhD, of Boston Children’s Hospital, and Chad Cowan, PhD, of Massachusetts General Hospital, report a first for CRISPR: efficiently and precisely editing clinically relevant genes out of cells collected directly from people. Specifically, they applied CRISPR to human hematopoietic stem and progenitor cells (HSPCs) and T-cells.

“CRISPR has been used a lot for almost two years, and report after report note high efficacy in various cell lines. Nobody had yet reported on the efficacy or utility of CRISPR in primary blood stem cells,” says Rossi, whose lab is in the hospital’s Program in Cellular and Molecular Medicine. “But most researchers would agree that blood will be the first tissue targeted for gene editing-based therapies. You can take blood or stem cells out of a patient, edit them and transplant them back.”

The study also gave the team an opportunity to see just how accurate CRISPR’s cuts are. Their conclusion: It may be closer to being clinic-ready than we thought.

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The costs of quiescence, for cars and blood cells

Old car aging blood cell hematopoietic stem cell blood disorder Derrick Rossi
Like an old, unused car, our aging blood stem cells can accumulate damage over time that they can't fully repair.

My first car was my grandfather’s 1980 Chevrolet Malibu. For about two years before my family gave it to me, it sat unused in Grandpa’s garage—just enough time for all of the belts and hoses to rot and the battery to trickle down to nothing.

Why am I telling this story? Because it’s much like what happens to the DNA in our blood-forming stem cells as we age.

Hematopoietic stem cells (HSCs) spend very little of their lives in an active, cycling state. Much of the time they’re quiescent or dormant, keeping their molecular and metabolic processes dialed down. These quiet periods allow the cells to conserve resources, but also give time an opportunity to wear away at their genes.

“DNA damage doesn’t just arise from mistakes during replication,” explains Derrick Rossi, PhD, a stem cell biology researcher with Boston Children’s Hospital’s Program in Cellular and Molecular Medicine. “There are many ways for damage to occur during periods of inactivity, such as reactions with byproducts of our oxidative metabolism.”

The canonical view has been that HSCs always keep one eye open for DNA damage and repair it, even when dormant. But in a study recently published in Cell Stem Cell, Rossi and his team found evidence to the contrary­­—which might tell us something about age-related blood cancers and blood disorders.

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