The lab of Leonard Zon, MD, has long been interested in making blood stem cells in quantity for therapeutic purposes. To test for their presence in zebrafish, their go-to research model, they turned to the MYB gene, a marker of blood stem cells. To spot the cells, Joseph Mandelbaum, a PhD candidate in the lab, attached a fluorescent green tag to MYB that made it easily visible in transparent zebrafish embryos.
“It was a real workhorse line for us,” says Zon, who directs the Stem Cell Research Program at Boston Children’s Hospital.
In addition to being a marker of blood stem cells, MYB is an oncogene. About five years ago, Zon was having lunch at a cancer meeting and, serendipitously, sat next to Jeff Kaufman, who was also interested in MYB. Kaufman was excited to hear about Zon’s fluorescing MYB zebrafish, which can be studied at scale and are surprisingly similar to humans genetically.
“Have you ever heard of adenoid cystic carcinoma?” he asked Zon. …
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?
Your hospital just received a #1 ranking from U.S. News & World Report. What does this mean relative to your role there?
I’ve been at Boston Children’s Hospital for 25 years, and it’s really satisfying to be at the premier institution for clinical care. And we’re very lucky to have one of the premier stem cell programs in the world. I have a strong sense that my impact on society is as a physician-scientist, bringing basic discoveries to the clinic. We’re able to have a huge impact on finding new diagnoses and new therapies for our children.
What inspires you to do your job every day?
As a hematologist I take care of patients who have devastating diseases – a variety of blood diseases and cancer. When I see these children, I’m always wondering, could there be ways to treating them that haven’t been thought of before? Successfully treating a child gives them an entire lifetime of health. …
A quick look at recent research Vector finds noteworthy.
Tracking infants’ microbiomes
Microbiome studies are blooming as rapidly as bacteria in an immunocompromised host. But few studies have been done in children, whose microbiomes are actively forming and vulnerable to outside influences. Two studies in Science Translational Medicine on June 15 tracked infants’ gut microbiomes prospectively over time. The first, led by researchers at the Broad Institute and Massachusetts General Hospital, analyzed DNA from monthly stool samples from 39 Finnish infants, starting at 2 months of age. Over the next three years, 20 of the children received at least one course of antibiotics. Those who were repeatedly dosed had fewer “good” bacteria, including microbes important in training the immune system. Overall, their microbiomes were less diverse and less stable, and their gut microbes had more antibiotic resistance genes, some of which lingered even after antibiotic treatment. Delivery mode (cesarean vs. vaginal) also affected microbial diversity. A second study at NYU Langone Medical Center tracked 43 U.S. infants for two years and similarly found disturbances in microbiome development associated with antibiotic treatment, delivery by cesarean section and formula feeding versus breastfeeding. …
It’s long been a mystery why some of our cells can have mutations associated with cancer, yet are not truly cancerous. Now researchers have, for the first time, watched a cancer spread from a single cell in a live animal, and found a critical step that turns a merely cancer-prone cell into a malignant one.
Their work, published today in Science, offers up a new set of therapeutic targets and could even help revive a theory first floated in the 1950s known as “field cancerization.”
“We found that the beginning of cancer occurs after activation of an oncogene or loss of a tumor suppressor, and involves a change that takes a single cell back to a stem cell state,” says Charles Kaufman, MD, PhD, a postdoctoral fellow in the Zon Laboratory at Boston Children’s Hospital and the paper’s first author. …
Bone marrow transplantation, a.k.a. stem cell transplantation, can offer a cure for certain cancers, blood disorders, immune deficiencies and even metabolic disorders. But it’s a highly toxic procedure, especially when a closely matched marrow donor can’t be found. Using stem cells from umbilical cord blood banked after childbirth could open up many more matching possibilities, making transplantation safer.
But what if the blood stem cells in those units could be supercharged to engraft more efficiently in the bone marrow and grow their numbers faster? That’s been the quest of the Zon lab for the past seven years, in partnership with a see-through zebrafish called Casper. …
The care and feeding of more than 250,000 zebrafish just got better, thanks to a $4 million grant from the Massachusetts Life Sciences Center to upgrade Boston Children’s Hospital’s Karp Aquatics Facility. Aside from the fish, patients with cancer, blood diseases and more stand to benefit.
From a new crop of Boston-Children’s-patented spawning tanks to a robotic feeding system, the upgrade will help raise the large numbers of the striped tropical fish needed to rapidly identify and screen potential new therapeutics. It’s all part of the Children’s Center for Cell Therapy, established in 2013. We put on shoe covers and took a look behind the scenes. (Photos: Katherine Cohen) …
At TEDx Longwood this spring, Leonard Zon, MD, founder and director of the Stem Cell Program at Boston Children’s Hospital, took the stage. In his enthusiastic yet humble style, he took the audience on a journey that included time-lapse video of zebrafish embryos developing, a riff by Jay Leno and a comparison of stem cell “engraftment” to a college kid coming home after finals: “You sleep for three days, and on day 4, you wake up and you’re in your own bed.” Three takeaways:
1) Stem cells made from our own skin cells can help find new therapeutics. With the right handling, they themselves can be therapeutics, producing healthy muscle, insulin-secreting cells, pretty much anything we need. (So far, this has just been done in mice.)
2) Zebrafish, especially when they’re see-through, can teach us how stem cells work and can be used for mass screening of potential drugs. The Zon Lab boasts 300,000 of these aquarium fish, and can mount robust “clinical trials” with 100 fish per group.
One of the hot trends in drug discovery could be called drug re-discovery: finding new uses for drugs that have already received FDA approval for a different indication.
It’s an approach that allows researchers and clinicians to rapidly test potential treatments for rare or difficult-to-treat conditions. Because the drug’s safety profile is already known, much of the preclinical and early clinical work that goes into developing a drug can be bypassed.
Scientists have had little success in growing skeletal muscle for patients with muscular dystrophy and other disorders that degrade and weaken muscle. Undertaking experiments in zebrafish, mouse and human cells, researchers have identified a way to do that, creating cells that Leonard Zon, MD, hopes to see tested in patients in the next several years.
But what really excites Zon, director of the Stem Cell research program at Boston Children’s Hospital, is the power of the chemical screening platform he and his colleagues used. Described last week in the journal Cell, it found a cocktail of three compounds that induced human muscle cells to grow—in just a matter of weeks. Zon believes it could fast-track drug discovery for multiple disorders. …