Stories about: Therapeutics

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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News Note: Modeling sepsis better to find a cure faster

In this SEM image, E. coli (green) bacteria, a common instigator of sepsis, is captured by bioengineered magnetic beads.
New assessment criteria for monitoring sepsis in pig models could help clinical researchers more accurately evaluate potential sepsis treatments in preclinical experiments. In this SEM image, E. coli (green) bacteria, a common instigator of sepsis, is captured by bioengineered magnetic beads. Credit: Wyss Institute at Harvard University

Sepsis, or blood poisoning, occurs when the body’s response to infection damages its own tissues, leading to organ failure. It is the most common cause of death in people who have been hospitalized, yet no new therapies have been developed in the last 30 years. Many treatments that have prevented death in animal experiments have failed in clinical trials, indicating that a more clinically-relevant sepsis model is needed for therapeutic development.

To bridge this gap, a team of scientists from the Wyss Institute at Harvard University and Boston Children’s Hospital think a better experimental model of sepsis in pigs could help weed out the therapies most likely to succeed in humans. Their method, a scoring criteria to evaluate sepsis in pigs that closely mirrors standard human clinical assessment, is reported in Advances in Critical Care Medicine.

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A new tactic for eczema? A newly identified brake on the allergic attack

baby with eczema
(Arkady Chubykin/Adobe Stock)

Eczema affects about 17 percent of children in developed countries. Often, it’s a gateway to food allergy and asthma, initiating an “atopic march” toward broader allergic sensitization. There are treatments – steroid creams and a recently approved biologic – but they are expensive or have side effects. A new study in Science Immunology suggests a different approach to eczema, one that stimulates a natural brake on the allergic attack.

The skin inflammation of eczema is known to be driven by “type 2” immune responses. These are led by activated T helper 2 (TH2) cells and type 2 innate lymphoid cells (ILC2s), together known as effector cells. Another group of T cells, known as regulatory T cells or Tregs, are known to temper type 2 responses, thereby suppressing the allergic response.

Yet, if you examine an eczema lesion, the numbers of Tregs are unchanged. Interestingly, Tregs comprise only about 5 percent of the body’s T cells, but up to 50 percent of T cells in the skin.

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Snaps from the lab: From gene discovery to gene therapy for one rare disease

Will Ward’s birthday falls on Rare Disease Day (Feb. 28). That’s an interesting coincidence because he has a rare disease: X-linked myotubular myopathy (MTM), a rare, muscle-weakening disease that affects only boys. Originally on Snapchat, this video captures the Ward family’s recent visit to the lab of Alan Beggs, PhD to learn more about MTM research.

Beggs, director of the Manton Center for Orphan Disease Research at Boston Children’s Hospital, has known Will since he was a newborn in intensive care. In this lab walk-though you’ll see a freezer filled with muscle samples, stored in liquid nitrogen; muscle tissue under a microscope; gene sequencing to identify mutations causing MTM and other congenital myopathies and a testing station to measure muscle function in samples taken from animal models.

Beggs’s work, which began more than 20 years ago, led to pivotal studies in male Labrador retrievers who happen to have the same mutation and are born with a canine form of MTM. By adding back a healthy copy of the gene, Beggs’s collaborators got the dogs back on their feet running around again. (Read about Nibs, a female MTM carrier whose descendants took part in these studies.)

Based on the canine results, a clinical trial is now testing gene therapy in boys under the age of 5 with MTM. The phase I/II trial aims to enroll 12 boys and measure their respiratory and motor function and muscle structure after being dosed with a vector carrying a corrected MTM gene. In the meantime, observational and retrospective studies are characterizing the natural history of boys with MTM.

Learn more about the Manton Center for Orphan Disease Research.

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Maintaining mitochondria in neurons: A new lens for neurodegenerative disorders

cartoon of mitochondria being transported in neurons - part of mitostasis
In some neurons, mitochondria must travel several feet along an axon. (Elena Hartley illustration)

Tom Schwarz, PhD, is a neuroscientist at Boston Children’s Hospital’s F.M. Kirby Neurobiology Center, focusing on the cell biology of neurons. Tess Joosse is a biology major at Oberlin College. This article is condensed from a recent review article by Schwarz and Thomas Misgeld (Technical University of Munich).

Like all cells, the neurons of our nervous system depend on mitochondria to generate energy. Mitochondria need constant rejuvenation and turnover, and that’s especially true in neurons because of their high energy needs for signaling and “firing.” Mitochondria are especially abundant at presynaptic sites — the tips of axons that form synapses or junctions with other neurons and release neurotransmitters.

But the process of maintaining mitochondrial number and quality, known as mitostasis, also poses particular challenges in neurons. Increasingly, mitostasis is providing a helpful lens for understanding neurodegenerative disorders. Problems with mitostasis are implicated in Parkinson’s disease, Alzheimer’s disease, ALS, autism, stroke, multiple sclerosis, hypoxia and more.

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News Note: Why is this eye cancer making headlines?

This illustrations shows a catheter is used during intra-arterial chemotherapy for retinoblastoma.
During intra-arterial chemotherapy for retinoblastoma, a catheter is placed into the common femoral artery and threaded through a child’s vasculature to access the blood vessel of the affected eye and deliver a concentrated dose of chemotherapy. Illustration: Dana-Farber/Boston Children’s.

Retinoblastoma is a rare cancer that originates in the retina, the tissue in the back of the eye that converts light into visual information that is interpreted by the brain.

One retinoblastoma symptom in particular is finding itself in the spotlight. With a rise in social media use in recent years, retinoblastoma has attracted media attention for being a type of cancer that can sometimes be detected through photographs. Across the internet, news stories like this one abound in which friends or relatives have alerted parents to the potential risk of eye cancer after noticing that a child’s pupil appears white instead of red — a symptom called leukocoria — on photos posted to social media.

Fortunately, with proper diagnosis and treatment, 95 percent of children diagnosed with retinoblastoma can be cured. What’s more, a catheter-based treatment approach is now sparing patients from some of the side effects that can be expected from more traditional therapies.

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Lab-grown human cerebellar cells yield clues to autism

This Purkinje cell, made from a patient with tuberous sclerosis, will enable study of autism disorders. (Credit: Maria Sundberg)

Autism spectrum disorder (ASD) is increasingly linked with dysfunction of the cerebellum, but the details, to date, have been murky. Now, a rare genetic syndrome known as tuberous sclerosis complex (TSC) is providing a glimpse.

TSC includes features of ASD in about half of all cases. Previous brain autopsies have shown that patients with TSC, as well as patients with ASD in general, have reduced numbers of Purkinje cells, the main type of neuron that communicates out of the cerebellum.

In a 2012 mouse study, team led by Mustafa Sahin, MD, at Boston Children’s Hospital, knocked out a TSC gene (Tsc1) in Purkinje cells. They found social deficits and repetitive behaviors in the mice, together with abnormalities in the cells.

The new study, published last week in Molecular Psychiatry, takes the research into human cells, for the first time creating cerebellar cells known as Purkinje cells from patients with TSC.

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Building a better bubble: Engineering tweaks bring safe IV oxygen delivery closer to reality

thin-shelled engineered oxygen bubbles
(Courtesy Yifeng Peng, Boston Children’s Hospital)

Everything from food aspiration to an asthma attack to heart failure can cause a patient to die from asphyxia, or lack of oxygen. For more than a decade, the Translational Research Laboratory (TRL) of Boston Children’s Hospital’s Heart Center has been pursuing a dream: tiny, oxygen-filled bubbles that can be safely injected directly into the blood, resuscitating patients who can’t breathe.

The lab’s first generation of bubbles were made with a fatty acid, but the lipid shells weren’t stable enough for long-term storage or clinical use. The bubbles popped open too easily.

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Single-shot protection? Building a better hepatitis B vaccine for newborns

newborn vaccines
(Illustrations: Elena Hartley)

The hepatitis B vaccine is one of only three vaccines that are routinely given to newborns in the first days of life. But the current hepatitis B vaccine has limitations: multiple “booster” doses are needed, and it can’t be given to premature babies weighing less than 2 kg.

Annette Scheid, MD, a neonatologist at Brigham and Women’s Hospital, is interested in leveraging infant immune differences to create a better hepatitis B vaccine for newborns. “The reality is that we have to vaccinate several times,” she says. “But we all dream of a vaccine that you give only once.”

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Deconstructing neuropathic pain: Could it give clues to better drugs?

neuropathic pain

Neuropathic pain is chronic pain originating through some malfunction of the nervous system, often triggered by an injury. It causes hypersensitivity to innocuous stimuli and is often extremely debilitating. It doesn’t respond to existing painkillers — even opioids can’t reach it well.

New research in a mouse model, described last week in Cell Reports, deconstructed neuropathic pain and could offer new leads for treating it. The carefully done study showed that two major neuropathic pain symptoms in patients — extreme touch sensitivity and extreme cold sensitivity — operate through separate pathways.

“We think this separation will allow targeted drug-based therapies in the future,” says Michael Costigan, PhD, of the F.M. Kirby Neurobiology Center at Boston Children’s Hospital, who was the study’s senior investigator. “If our results stand experimental scrutiny by others, this will be profoundly important in our overall understanding of neuropathic pain.”

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