Here are some stem cell stories that caught our eye this past week. Some are groundbreaking science, others are of personal interest to us, and still others are just fun.
Two-week embryos grabbed headlines. I have rarely seen as many online news outlets pick up a basic science story as happened this week with the news that an international team had nearly doubled the time it is possible to keep an embryo alive in a lab dish. While the research has tremendous potential to improve the chances couples can bring a new life into their families, the bulk of the coverage focused on the ethical issues surrounding the research embryo itself.
After countless national and international confabs in the late 1970s and into the 1980s, research organizations around the world adopted the policy that no one would grow an embryo in the lab beyond 14 days. That is the point the “primitive streak” develops marking the first time cells within the embryo adopt individual identities. But the rule required no enforcement because no one knew how to coax an embryo into growing beyond nine days, and few could get them even to grow seven.
That changed this week, when the team led by Ali Brivanlou at Rockefeller University got embryos to grow to 13 days. They followed a procedure developed by a team colleague in Cambridge, UK, in mice reported earlier. They basically made the embryos feel more at home. They tested many different chemicals to add to the lab dish to optimize growth and gave the embryos a rigid structure more like a uterine wall.
They successfully mimicked implantation, the key step when the few-day-old embryo attaches to the uterus. Failure in this critical step is a key cause of infertility, but we have never been able to find out how it happens, and what little we do know suggests the mouse model for that step is not a good one for looking at human fertility.
“This portion of human development was a complete black box,” said Brivanlou in a university press release picked up by many outlets including Bioscience Technology. She later added: “With this work, we can really appreciate the differences between human and mouse, and across all mammals. Because of the variations between species, what we learn in model systems is not necessarily relevant to our own development, and these results provide crucial information we couldn’t learn elsewhere.”
Because of that incredible potential value in this work, the journal Nature that published the research paper also ran a commentary about the current 14-day limit on growing embryos in the lab. It does not call for changing the policy at this time, but it does suggest the conversation–likely to be long–about whether the benefits of this work outweigh the ethical trip wires should begin soon.
The Washington Post wrote one of the most balanced pieces discussing both sides of the issue.
A mightier disease-in-a-dish model. We frequently write about using iPS type stem cells to model diseases. Usually this involves getting a skin sample from a patient with a genetically-linked disease, converting it to stem cells and then growing the nerve or other tissue impacted by the disease. But you can also mimic the disease by genetically modifying normal stem cells to have specific mutations. This allows you to start to sorting out the role of individual genes in diseases linked to multiple genes.
One problem with the latter had been that gene editing techniques, particularly the wildly popular CRISPR-Cas9 method, usually edit both strands of DNA, but many disease mutations can do their damage with only a single incorrect gene, so-called heterozygous mutations. Now, another Rockefeller University team, this one led by the University’s president Marc Tessier-Lavigne, developed a way to make the CRISPR edit much more specific and only impact one strand of DNA.
HealthCanal picked up the university’s press release about the work published in Nature. The specific gene editing in this reports involved mutations linked to Alzheimer’s disease.
A better recipe for bone. Researchers trying to grow new tissue are finding the make-up of the scaffold you use can be more important than the stem cells you put on the structure. A Johns Hopkins team recently reported an improved recipe for making a scaffold for growing bone. Their formula: 30 percent pulverized natural bone and the remainder a special plastic with the mixture extruded using a 3D printer.
“Bone powder contains structural proteins native to the body plus pro-bone growth factors that help immature stem cells mature into bone cells,” said Hopkins’ Warren Grayson. “It also adds roughness to the PCL (plastic), which helps the cells grip and reinforces the message of the growth factors.”
MDTmag posted the university press release about the research published in ACS Biomaterials Science & Engineering.
Licensing moved cancer therapy forward. We at CIRM are always thrilled when one of our projects hurdles a milestone toward becoming a widely available therapy. One such critical move was announced last month and picked up this week by HealthCanal.
Oncternal Therapeutics licensed the antibody drug named for our agency, Cirmtuzumab, for further testing of its ability to fight leukemia, and potentially other cancers. The antibody selectively targets a protein on cancer stem cells, ROR1, which has the unwieldy full name “receptor-tyrosine kinase-like orphan receptor 1.” The license also includes rights to other drugs that might be developed targeting ROR1.
University of California, San Diego, which developed Cirmtuzumab, has begun a clinical trial but has not got to a point where it can report results. We covered it in more detail in our series CIRM Fights Cancer.