March of Dimes, a national leader in maternal and infant health research, today announced leading hematologist and stem cell scientist Dr. Leonard Zon as the winner of the 2026 March of Dimes Richard B Johnston Jr, MD Prize for his work in developmental biology. Dr. Zon's pioneering work has illuminated how blood develops in embryos, leading to a deeper understanding of rare blood diseases, including in pregnancy, and breakthrough treatments for genetic blood disorders affecting babies and children.
Dr. Zon, Director of the Stem Cell Research Program at Boston Children’s Hospital and the Grousbeck Professor of Pediatric Medicine at Harvard Medical School, is an acclaimed physician-scientist who has pioneered the use of the zebrafish as a model to study human disease with a focus on blood diseases and cancers affecting newborns and kids.
In 1993, spurred by his desire to understand how blood develops and to mitigate rare yet devastating genetic blood diseases, Dr. Zon turned to the zebrafish, a 1.5-inch tropical fish with horizontal stripes, transparent embryos, and the ability to lay 300 embryos a week. The unique sea creature has helped him make remarkable findings about human biology and disease treatment. Among them, he and his team have illuminated the pathways of blood development in embryos, leading to a deeper understanding of rare blood diseases, including in pregnancy; discovered ferroportin, the iron transporter gene that delivers the crucial micronutrient from mother to baby; and identified a growth factor that exponentially grows stem cell populations for use in gene therapies for children with blood disorders, including sickle cell anemia.
The March of Dimes Richard B Johnston Jr, MD Prize recognizes scientists whose work in developmental biology has transformed our understanding of human health. Dr. Zon's use of developmental biology to illuminate how blood forms in embryos exemplifies this mission, with direct applications to pregnancy complications and childhood diseases.
“Dr. Zon’s groundbreaking work using the zebrafish to study human disease has resulted in truly amazing insights about the most devastating genetic disorders and cancers affecting the smallest patients,” said March of Dimes Chief Scientific Advisor Dr. Emre Seli. “Incredibly, Dr. Zon has balanced seeing sick kids in the clinic with groundbreaking laboratory discoveries about pediatric disorders that have repeatedly stumped scientists. His zebrafish work at the intersection of blood, cancer, genetics and induced pluripotent stem cells has transformed the way we understand and treat human disease.”
One of the first scientists to study zebrafish for the purposes of human disease, Dr. Zon led a team in the late 1990s that discovered five human genes never before implicated in blood diseases. The breakthrough electrified the field of hematology and crystallized zebrafish as not only a reliable — but an outstanding — model for human disease.
Of the five novel genes Dr. Zon’s team discovered, the most significant was the discovery of ferroportin, the iron transporter gene, in 2000. The gene ensures iron, and thereby oxygen-carrying hemoglobin, is delivered from mother to baby through the placenta. This discovery transformed understanding of iron deficiency and anemia of pregnancy, a common condition worldwide which can lead to preterm birth and low birth weight. The finding opened new avenues for preventing and treating maternal anemia and its effects on fetal development.
Dr. Zon, who founded the International Society for Stem Cell Research in 2002, is also behind a transformative discovery around stem cells to treat blood disorders affecting children and babies. In 2007, his lab revealed that prostaglandin E2 could dramatically grow zebrafish stem cell populations. Human clinical trials in 2013 confirmed the lipid’s power: adding it to donor umbilical cord blood increased the recipient’s stem cell populations by 400%, vastly improving transplant success for leukemia patients. Today, the prostaglandin discovery is routinely used in stem cell gene therapy to treat genetic blood diseases in children, including sickle cell anemia, thalassemia, and primary immunodeficiencies, and has enabled advances in gene therapy techniques used by research teams worldwide.
Dr. Zon’s discoveries continue to yield new treatments. His zebrafish research has led to a novel therapeutic for Diamond-Blackfan anemia now approaching human clinical trials, and a treatment to treat a pediatric disease called spinal muscular atrophy, developed by a company he founded, is currently under Food and Drug Administration review.
“Ever since my first experience working with leukemia patients early in my research career, I’ve been trying to uncover the mysteries of blood to help those affected by blood and other diseases,” said Dr. Zon. “So, to be instrumental in the discovery of new pathways that underscore blood development in embryos and to have a real impact on diseases affecting kids and babies, that’s priceless. And to do it with the fascinating zebrafish and be honored for it is icing on the cake.”
This release originally appeared on the March of Dimes website .