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.
Generating real heart muscle for repair. There was some good news last week on stem cells for heart disease despite the much-covered analysis from the British Medical Journal that highlighted some of the flaws in early studies in humans. Those studies often showed modest improvements in heart function, but generally not enough to make a clinical difference for patients. The cells used in most those studies, a type of stem cell found in bone marrow and fat called mesenchymal stem cells, can secrete factors that can reduce inflammation and foster some growth of new blood vessels, but they can not make new heart muscle.
Now, a team at the University of Washington has started with human embryonic stem cells and found a way to produce large quantities of heart muscle cells. When they injected a billion of those cells into the damaged hearts of monkeys they saw the cells infiltrate the site of damage, mature, assemble into muscle fibers and integrate into the normal beating of the monkey heart. While this has been done in small animals, the UW team was the first to generate the cells in sufficient quantities to repair a heart similar in size to ours. The team published the work in Nature April 30 and the writers at Genetic Engineering and Biotechnology News wrote it up. You can read about work CIRM supports in this area on our heart disease fact sheet.
Human muscle grown on pig scaffold. Our own muscle stem cells can repair small areas of damage but get overwhelmed when someone has an injury that removes a large section of muscle, as often happens to our soldiers in combat. So the Defense Department funded a team at the University of Pittsburg to develop ways to give our stem cells a boost. The team used pig tissue that had all the cells removed leaving a scaffold that is called the extracellular matrix. With the cells removed the patient’s immune systems won’t reject the pig tissue, but it does provide a structure to direct the growth of muscle from stem cells. In three veterans and two civilians who had lost 60 to 90 percent of one leg muscle they saw, on average, a 20 percent gain in strength after the implants. The team published their work in Science Translational Medicine on April 30 and the Associated Press ran a story that got picked up widely including by the ABC NEWS website.
Recent adult cell cloning put in perspective. Two teams in the past couple of weeks have replicated the feat of a group in Oregon that exactly a year ago published the first verifiable cloning of human cells. As with all of science, these acts of replication validate the original heralded breakthrough. Also in keeping with good science, the recent teams pushed the field forward tweaking the successful technique. The first replication reported by a team from Korea and the U.S. succeeded with cells from older adults, in one case a 75 year-old, where as the Oregon group had used more malleable fetal or baby cells. Then this week, scientists at the New York Stem Cell Foundation reported not only cloning adult cells, one from a 32-year-old, but also maturing the resulting stem cells into insulin producing cells, taking us another step toward the goal of such therapeutic cloning: creating stem cell lines and mature tissues that match the genetics of the donor. Monya Baker wrote a nice review of the three teams’ work in the “News and Comment” section of Nature last week.
This type of cloning, technically called somatic cell nuclear transfer (SCNT) has worked for years in lesser mammals but has evaded success in humans until last year. CIRM held a workshop on nuclear transfer in 2010 to discuss reasons for the failure to create these cells in humans and reasons for why the science could still be important to the stem cell field as a whole.
Stress impairs stem cells ability to heal wounds. The stress hormone epinephrine inhibits stem cells from migrating to the site of skin wounds and may be part of the reason so many patients, particularly diabetics, have skin ulcers that just won’t heal. The source of the stress hormone in these patients could be two-fold, the stress of living with the disease, and the release of the hormone caused by bacteria at the site of the wound. A team from the University of California at Davis, reported on the impact of epinephrine on stem cells in the journal CIRM helped to found, Stem Cells Translational Medicine, and the journal’s press release was widely picked up including this take at SFGate.
Italian researcher accused of criminal acts. For folks who follow the ups and downs of clinics offering questionable therapies, there was a bit of celebration last week, particularly among my science writer friends in Italy. A prosecutor in Turin issued a statement that the Stamina Foundation had committed criminal acts defrauding a thousand patients of substantial sums of money while subjecting them to substantial risks. A judge will now determine whether charges should be brought against the head of the foundation and 19 others accused along with him. ScienceInsider reported on the latest chapter in this saga.