Stories about: blood disorders

Restoring ‘youthful’ hemoglobin in sickle cell disease: First patient is symptom-free

Manny Johnson of Boston, 21, previously required monthly blood transfusions to keep his severe sickle cell disease under control. After receiving a new gene therapy treatment, he’s been symptom-free for six months.

Researchers at the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center reported Manny’s case Saturday at the American Society of Hematology meeting in San Diego. Manny is their first patient, and an ongoing clinical trial will treat additional patients between ages 3 and 40.

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Why blood stem cells are in our bones: Evolutionary observation may inform better bone marrow transplants

blood stem cells melanocytes hematopoietic stem cells
In normal zebrafish, blood stem cells in the kidney are protected from sunlight by melanocytes. When this layer is stripped away, stem cell numbers go down. (Image and video below courtesy of the Zon Laboratory and the Howard Hughes Medical Institute.)

Since the late 1970s, biologists have known that blood develops in a specific body location. But they’ve wondered why different creatures house their blood stem cells in different places. In humans and other mammals, they’re in the bone. In fish, they’re in the kidney. Why?

Strange as it seems, the two stem cell “niches” share something in common, say researchers led by Leonard Zon, MD, of Boston Children’s Stem Cell Program, the Harvard Department of Stem Cell and Regenerative Biology (HSCRB) and the Harvard Stem Cell Institute. Both protect blood stem cells from sunlight’s harmful ultraviolet rays. The findings, published today in Nature, may contain lessons for improving blood stem cell transplants for cancer, blood disorders and other conditions.

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Zeroing in on the fetal-to-adult hemoglobin switch and a new way to combat sickle cell disease

Normal red blood cell vs. sickle-shaped blood cell, which is found in sickle cell disease
Normal red blood cell vs. sickle-shaped blood cell.

It’s been known for more than 40 years that in rare individuals, lingering production of the fetal form of hemoglobin — the oxygen-transporting protein found in red blood cells — can reduce the severity of certain inherited blood disorders, most notably sickle cell disease and thalassemia. Typically, however, a protein called BCL11A switches off fetal hemoglobin production past infancy, but exactly how this happens has not been well understood until now.

In a new paper in Cell, researchers at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center have revealed how BCL11A controls the switch in the body’s production of fetal hemoglobin to adult hemoglobin. It does so by binding to a DNA sequence — made up of the bases T-G-A-C-C-A — that lies just in front of the fetal hemoglobin genes.

Another approach to curing sickle cell disease is already being evaluated in a new clinical trial at Dana-Farber/Boston Children’s. The novel gene therapy restores fetal hemoglobin production by genetically suppressing BCL11A, which prevents it from blocking fetal hemoglobin production. Learn more.

“Genetically modifying this TGACCA segment could be another possible strategy to cure sickle cell disease by blocking BCL11A’s ability to bind to this DNA site and switch off fetal hemoglobin production,” says Stuart Orkin, MD, senior author on the study.

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A breakthrough in our understanding of how red blood cells develop

Artist's rendering of red blood cells
Red blood cells.

By taking a deep dive into the molecular underpinnings of Diamond-Blackfan anemia, scientists have made a new discovery about what drives the development of mature red blood cells from the earliest form of blood cells, called hematopoietic (blood-forming) stem cells.

For the first time, cellular machines called ribosomes — which create proteins in every cell of the body — have been linked to blood stem cell differentiation. The findings, published today in Cell, have revealed a potential new therapeutic pathway to treat Diamond-Blackfan anemia. They also cap off a research effort at Boston Children’s Hospital spanning nearly 80 years and several generations of scientists.

Diamond-Blackfan anemia — a severe, rare, congenital blood disorder — was first described in 1938 by Louis Diamond, MD, and Kenneth Blackfan, MD, of Boston Children’s. The disorder impairs red blood cell production, impacting delivery of oxygen throughout the body and causing anemia. Forty years ago, David Nathan, MD, of Boston Children’s determined that the disorder specifically affects the way blood stem cells become mature red blood cells.

Then, nearly 30 years ago, Stuart Orkin, MD, also of Boston Children’s, identified a protein called GATA1 as being a key factor in the production of hemoglobin, the essential protein in red blood cells that is responsible for transporting oxygen. Interestingly, in more recent years, genetic analysis has revealed that some patients with Diamond-Blackfan have mutations that block normal GATA1 production.

Now, the final pieces of the puzzle — what causes Diamond-Blackfan anemia on a molecular level and how exactly ribosomes and GATA1 are involved — have finally been solved by another member of the Boston Children’s scientific community, Vijay Sankaran, MD, PhD, senior author of the new Cell paper.

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Sickle cell gene therapy to boost fetal hemoglobin: A 70-year timeline of discovery

sickled cells occluding a blood vessel
Sickled cells occluding a blood vessel. (Image: Elena Hartley)

Boston Children’s Hospital is now enrolling patients age 3 to 35 in a clinical trial of gene therapy for sickle cell disease. Based on technology developed in its own labs, it differs from other gene therapy approaches by having a two-pronged action. It represses production of the mutated beta hemoglobin that causes red blood cells to form the stiff “sickle” shapes that block up blood vessels. It also increases production of the fetal form of hemoglobin, which people normally stop making after birth.

Fetal hemoglobin doesn’t sickle and works fine for oxygen transport. The gene therapy being tested now restores fetal hemoglobin production by turning “off” a silencing gene called BCH11A.

BCL11A represses fetal hemoglobin and also activates beta hemoglobin, which is affected by the sickle-cell mutation,” David Williams, MD, the trial’s principal investigator, told Vector last year. Williams is also president of the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center. “So when you knock BCL11A down, you simultaneously increase fetal hemoglobin and repress sickling hemoglobin, which is why we think this is the best approach to gene therapy in this disease.”

The therapy is the product of multiple discoveries, the first dating back 70 years. Click selected images below to enlarge.

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Teaching an old drug a new trick to treat an ultra-rare red-blood-cell disease

Failed sickle-cell drug learns a new trick: hereditary xerocytosis

The National Institutes of Health maintains a library of drugs, the Clinical Collection, that are safe for humans but failed in clinical trials or didn’t make it to the market for other reasons. These compounds, numbering 450 to date, are just sitting on the shelf, waiting for a researcher to identify a disease process they might treat.

Repurposing such drugs could potentially save the pharmaceutical industry time and money. Getting a new drug from R&D to market currently takes $2 to 3 billion and 13 to 15 years. In contrast, some estimate that repurposing a safe drug could cost just $300 million and take just 6.5 years.

Pfizer, one of the biggest pharma companies in the world, saw the appeal. It just launched SpringWorks Therapeutics, a mission-driven company dedicated to reviving shelved drugs to treat underserved diseases. In its pipeline are experimental therapies to treat four diseases that currently have no cure.

One of the earliest-stage candidates is senicapoc.

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“Vampires” may have been real people with this blood disorder

Mural of Vlad the Impaler, who was accused of being a vampire. Perhaps, instead, he suffered from a blood disorder called porphyria.Porphyrias, a group of eight known blood disorders, affect the body’s molecular machinery for making heme, which is a component of the oxygen-transporting protein, hemoglobin. When heme binds with iron, it gives blood its hallmark red color.

The different genetic variations that affect heme production give rise to different clinical presentations of porphyria — including one form that may be responsible for vampire folklore.

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Medical milestone: Making blood stem cells in the lab

blood stem cells
The gradation of pink-to-blue cells illustrates the transition from hemogenic endothelial cells to blood progenitor cells during normal embryonic blood development. Daley, Sugimura and colleagues recreated this process in the lab, then added genetic factors to produce a mix of blood stem and progenitor cells. (O’Reilly Science Art)

Pluripotent stem cells can make virtually every cell type in the body.  But until now, one type has remained elusive: blood stem cells, the source of our entire complement of blood cells.

Since human embryonic stem cells (ES cells) were isolated in 1998, scientists have tried to get them to make blood stem cells. In 2007, the first induced pluripotent stem (iPS) cells were made from human skin cells, and have since been used to generate multiple cell types, such as neurons and heart cells.

But no one has been able to make blood stem cells. A few have have been isolated, but they’re rare and can’t be made in enough numbers to be useful.

Now, the lab of George Daley, MD, PhD, part of Boston Children’s Stem Cell Research program as finally hit upon a way to create blood stem cells in quantity, reported today in Nature.

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Naturally-occurring molecule in tree leaves could treat anemia, other iron disorders

Hinoki cypress

“Without iron, life itself wouldn’t be feasible,” says Barry Paw, MD, PhD. “Iron transport is very important because of the role it plays in oxygen transport in blood, in key metabolic processes and in DNA replication.”

Although iron is crucial to many aspects of health, it needs the help of the body’s iron-transporting proteins. Which is why new findings reported in Science could impact a whole slew of iron disorders, ranging from iron-deficiency anemia to iron-overload liver disease. The team has discovered that a small molecule found naturally in Japanese cypress tree leaves, hinokitiol, can transport iron to overcome iron disorders in animals.

The multi-institutional research team is from the University of Illinois, Dana-Farber/Boston Children’s Cancer and Blood Disorders Center, Brigham and Women’s Hospital and Northeastern University. Paw, co-senior author on the new paper and a physician at Dana-Farber/Boston Children’s, and members of his lab demonstrated that hinokitiol can successfully reverse iron deficiency and iron overload in zebrafish disease models.

“Amazingly, we observed in zebrafish that hinokitiol can bind and transport iron inside or out of cell membranes to where it is needed most,” says Paw.

This gives hinokitiol big therapeutic potential.

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Discovering a rare anemia in time to save an infant’s life

Illustration of the erythropoietin hormone. A newly-discovered genetic mutation, which switches one amino acid in EPO's structure, resulted in two cases of rare anemia.
An illustration showing the structure of a cell-signaling cytokine called erythropoietin (EPO). It has long been thought that when EPO binds with its receptor, EPOR, it functions like an on/off switch, triggering red blood cell production. New findings suggest that this process is more nuanced than previously thought; even slight variations to cytokines like EPO can cause disease.

While researching a rare blood disorder called Diamond-Blackfan anemia, scientists stumbled upon an even rarer anemia caused by a previously-unknown genetic mutation. During their investigation, the team of scientists — from the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center, the Broad Institute of Harvard and MIT and Yale University — had the relatively unusual opportunity to develop an “on-the-fly” therapy.

As they analyzed the genes of one boy who had died from the newly-discovered blood disorder, the team’s findings allowed them to help save the life of his infant sister, who was also born with the same genetic mutation. The results were recently reported in Cell.

“We had a unique opportunity here to do research, and turn it back to a patient right away,” says Vijay Sankaran, MD, PhD, the paper’s co-corresponding author and a principal investigator at the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center. “It’s incredibly rewarding to be able to bring research full circle to impact a patient’s life.”

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