Genetic labels, or “barcodes,” are shedding new light on the natural process of blood development and immune-cell production, finds a study published in Nature this week. It was led by Fernando Camargo, PhD, and first author Alejo Rodriguez Fraticelli, PhD, at Boston Children’s Hospital’s Stem Cell Research Program, the Harvard Department of Stem Cell and Regenerative Biology and the Harvard Stem Cell Institute.
Most of what we know about blood production is through observing what happens when blood stem and progenitor cells are transplanted into an animal. To observe what happens “in the wild,” researchers went in and tagged the blood stem and progenitor cells of mice, using genetic elements called transposons. This allowed them to track how the cells differentiated into five kinds of blood cells (above: megakaryocytes, erythroid cells, granulocytes, monocytes and B-cell progenitors). …
New tools and technologies fueled biomedicine to great heights in 2017. Here are just a few of our top picks. All are great examples of research informing better care for children (and adults).
1. Gene therapy arrives
In 2017, gene therapy solidly shed the stigma of Jesse Gelsinger’s 1999 death with the development of safer protocols and delivery vectors. Though each disease must navigate its own technical and regulatory path to gene therapy, the number of clinical trials is mounting worldwide, with seven gene therapy trials now recruiting at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center. In August, the first gene therapy won FDA approval: CAR T-cell therapy for pediatric acute lymphoblastic leukemia. …
A therapeutic technique to transplant blood-forming (hematopoietic) stem cells directly into the brain could herald a revolution in our approach to treating central nervous system diseases and neurodegenerative disorders.
The technique, which could be used to transplant donor-matched hematopoietic stem cells (HSCs) or a patient’s own genetically-engineered HSCs into the brain, was reported in Science Advances today by researchers from the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center and the San Raffaele Telethon Institute for Gene Therapy.
In their study, the team tested the technique in a mouse model to treat lysosomal storage disorders, a group of severe metabolic disorders that affect the central nervous system.
The team’s findings are groundbreaking because, until now, it was thought that HSCs — from a healthy, matched donor or a patient’s own genetically-corrected cells — needed to be transplanted indirectly …
Type 1 diabetes is caused by an immune attack on the pancreatic beta cells that produce insulin. To curb the attack, some researchers have tried rebooting patients’ immune systems with an autologous bone-marrow transplant, infusing them with their own blood stem cells. But this method has had only partial success.
“We found that in diabetes, blood stem cells are defective, promoting inflammation and possibly leading to the onset of disease,” says Paolo Fiorina, MD, PhD, of Boston Children’s Hospital, senior investigator on the study.
But they also found that the defect can be fixed — by pre-treating the blood stem cells with small molecules or with gene therapy, to get them to make more of a protein called PD-L1.
In experiments, the treated stem cells homed to the pancreas and reversed hyperglycemia in diabetic mice, curing almost all of them of diabetes in the short term. One third maintained normal blood sugar levels for the duration of their lives. …
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.
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. …
For years, the lab of Leonard Zon, MD, director of the Stem Cell Research Program at Boston Children’s Hospital, has sought ways to enhance bone marrow transplants for patients with cancer, serious immune deficiencies and blood disorders. Using zebrafish as a drug-screening platform, the lab has found a number of promising compounds, including one called ProHema that is now in clinical trials.
But truthfully, until now, Zon and his colleagues have largely been flying blind.
“Stem cell and bone marrow transplants are still very much a black box: cells are introduced into a patient and later on we can measure recovery of their blood system, but what happens in between can’t be seen,” says Owen Tamplin, PhD, in the Zon Lab. “Now we have a system where we can actually watch that middle step.” …
Since 2009, Boston Children’s Hospital has committed $6.2 million to support 58 hospital innovations ranging from therapeutics, diagnostics, medical devices and vaccines to regenerative medicine and healthcare IT projects. What a difference six years makes.
The Technology Development Fund (TDF) was proposed to Boston Children’s senior leadership in 2008 after months of research. As a catalyst fund, the TDF is designed to transform seed-stage academic technologies at the hospital into independently validated, later-stage, high-impact opportunities sought by licensees and investors. In addition to funds, investigators get access to mentors, product development experts and technical support through a network of contract research organizations and development partners. TDF also provides assistance with strategic planning, intellectual property protection, regulatory requirements and business models.
Seeking some “metrics of success” beyond licensing numbers and royalties (which can come a decade or so after a license), I asked recipients of past TDF awards to report back any successes that owed at least in part to data generated with TDF funds. While we expected some of the results, we would have never anticipated such a large impact. …
Think, for a moment, of a cell as a computer, with its genome as its software, working to give cells particular functions. One set of genetic programs turns a cell into a heart cell, another set creates a neuron, still another a lymphocyte and so on.
The job of controlling which programs get booted up, and when, falls in part to transcription factors—genes that act like molecular switches to turn other genes on and off.
“There are about 50,000 HSC transplants every year,” Rossi explains, noting that the success of a transplant is highly dependent on the number of cells a patient receives from her donor. “But HSCs only comprise about one in every 20,000 cells in the bone marrow.
“If we could generate autologous HSCs from a patient’s other cells,” he continues, “it could be transformative for transplant medicine and for our ability to model diseases of blood development.”
As they reported April 24 in Cell, Rossi and his collaborators have taken a significant step toward that goal: Using a cocktail of eight transcription factors, they reprogrammed mature mouse blood cells into what they have dubbed induced HSCs (iHSCs). …