The ability to edit genes in patients’ blood
stem cells — which produce red blood cells, platelets, immune cells and more — offers
the potential to cure many genetic blood disorders. If all goes well, the
corrected cells engraft in the bone marrow and produce healthy, properly
functioning blood cells… forever.
But scientists have had difficulty introducing
edits into blood stem cells. The efficiency and specificity of the edits and
their stability once the cells engraft in the bone marrow have been variable.
A new approach, described this week in Nature Medicine and in January in the journal Blood, overcomes prior technical challenges, improving the efficiency, targeting and durability of the edits. Researchers at Dana-Farber/Boston Children’s Cancer and Blood Disorders Center and the University of Massachusetts Medical School successfully applied the technique to two common blood diseases — sickle cell disease and beta thalassemia — involving mutations in the gene for beta globin protein.
But Stegmaier is also interested in epigenetic regulators — proteins that help control the regulation of genes and contribute to many pediatric cancers. They’re a hot subject of research: Child cancers tend to arise in developing tissues, and epigenetic regulators are active during early development. Clinical trials are starting to test drugs that inhibit epigenetic cancer-promoting factors.
There’s a problem, though: Cancers often become resistant to targeted inhibitors, including epigenetic inhibitors. So, again using genome-wide approaches, Stegmaier set out to find ways to overcome this resistance. …
Three-dimensional modeling and CRISPR-Cas9 gene editing technology are giving scientists a new view into Sturge-Weber syndrome, a rare congenital disorder that causes small blood vessels, called capillaries, to be malformed. These capillary malformations can cause port wine birthmarks on the face and neck, and in some cases, abnormal vasculature in the brain that can spark seizures.
A novel screening method using CRISPR-Cas9 genome editing technology has revealed new drug targets that could potentially enhance the effectiveness of PD-1 checkpoint inhibitors, a promising new class of cancer immunotherapy.
Part of the problem may be that, until now, the right tools haven’t been available to exploit GWAS data. But a few recent studies—including two out of Dana-Farber/Boston Children’s Cancer and Blood Disorders Center—have used GWAS data to identify therapeutically promising targets, and then manipulated those targets using the growing arsenal of gene editing methods.
Labs the world over are jumping onto the gene editing bandwagon (and into the inevitable patent arguments). And it’s hard to blame them. As these technologies have evolved over the last two decades starting with the zinc finger nucleases (ZFNs), followed by transcription activator-like effector nucleases (TALENs) and CRISPR—they’ve become ever more powerful and easier to use.
But one question keeps coming up: How precise are these systems? After all, a method that selectively mutates, deletes or swaps specific gene sequences (and now can even turn genes on) is only as good as its accuracy.
Algorithms can predict the likely “off-target” edits based on the target’s DNA sequence, but they’re based on limited data. “The algorithms are getting better,” says Richard Frock, PhD, a fellow in the laboratory of Frederick Alt, PhD, at Boston Children’s Hospital. “But you still worry about the one rare off-target effect that’s not predicted but falls in a coding region and totally debilitates a gene.”
Frock, Alt (who leads Boston Children’s Program in Cellular and Molecular Medicine, or PCMM), fellow Jiazhi Hu, PhD, and their collaborators recently turned a method first developed in Alt’s lab for studying broken chromosomes into a quality assurance tool for genome editing. As a bonus, the method—called high-throughput genome translocation sequencing (HTGTS)—also reveals the “collateral damage” gene editing methods might create in a cell’s genome, information that could help researchers make better choices when designing gene editing experiments. …
You have an immune system. Your cat has an immune system. And bacteria have an immune system, too—one that we’ve tapped to make one of the most powerful tools ever for editing genes.
The tool is called CRISPR (for “clustered regularly interspaced short palindromic repeats”), and it makes use of enzymes that “remember” viral genes and cut them out of bacterial genomes. Applied to bioengineering, CRISPR is launching a revolution. And the Boston Globereported over the weekend that while researchers at the University of California at Berkeley first developed CRISPR, the technique is booming in labs around Boston. …
CRISPR—a gene editing technology that lets researchers make precise mutations, deletions and even replacements in genomic DNA—is all the rage among genomic researchers right now. First discovered as a kind of genomic immune memory in bacteria, labs around the world are trying to leverage the technology for diseases ranging from malaria to sickle cell disease to Duchenne muscular dystrophy.
In a paper published yesterday in Cell Stem Cell, a team led by Derrick Rossi, PhD, of Boston Children’s Hospital, and Chad Cowan, PhD, of Massachusetts General Hospital, report a first for CRISPR: efficiently and precisely editing clinically relevant genes out of cells collected directly from people. Specifically, they applied CRISPR to human hematopoietic stem and progenitor cells (HSPCs) and T-cells.
“CRISPR has been used a lot for almost two years, and report after report note high efficacy in various cell lines. Nobody had yet reported on the efficacy or utility of CRISPR in primary blood stem cells,” says Rossi, whose lab is in the hospital’s Program in Cellular and Molecular Medicine. “But most researchers would agree that blood will be the first tissue targeted for gene editing-based therapies. You can take blood or stem cells out of a patient, edit them and transplant them back.”
The study also gave the team an opportunity to see just how accurate CRISPR’s cuts are. Their conclusion: It may be closer to being clinic-ready than we thought. …
Technology sometimes unfolds at a slow, measured pace and sometimes at lightning speed. Right now, we are witnessing what is arguably one of the fastest moving fields in biomedical science: a form of genome editing aptly known as CRISPR.
CRISPR allows researchers to make very precise—some would say crisp—changes to the genomes of human cells and those of other organisms. You might think of it as a kind of guided missile. Its precision is opening the doors to a wide variety of research and, hopefully, medical applications. Indeed, the possibilities seem to be bound only by scientists’ imaginations.
“For a long time, we have been accumulating new knowledge about which gene mutation causes which disease. But until very recently, we haven’t had the ability to go in and correct those mutations,” explains Feng Zhang, PhD, a core member of the Broad Institute of Harvard and MIT, and one of the method’s pioneers. “CRISPR is one of the tools that is starting to allow us to directly go in and do surgery on the genome and replace the mutations.”
CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeats. While this name is a bit verbose, it points to the technology’s origins: a set of genetic sequences first discovered in bacteria. …