Young at heart. mouse ventricles of Cross-sections show the visible change in size when old hearts are immersed in the young blood.
Francesco Loffredo
It's time to go back on a ticker aging. Drawing on a bizarre experimental technique invented there more than a century, but rarely now, researchers have found that a protein in the blood makes the old mouse hearts appear young and healthy again. It is not yet known if humans react the same way, but scientists hope that this discovery may help treat one of the most frustrating ailments of the heart.
"This is probably the first round we have about what makes the heart young and making the old," said cardiologist Deepak Srivastava of the Gladstone Institute of Cardiovascular Disease in San Francisco, California who was not involved in the work.
As the heart muscles age, they grow thicker. The thickened heart can still pump blood on normally, but he can not relax enough to fill between the pumps. The condition is called diastolic heart failure, named after the rest of the heart, or diastolic phase. There is currently no treatment to reverse the thickening of the heart and restore normal function.
But researchers continue to seek such a heart fountain of youth. One approach has been to apply a technique of 150 years to infuse young blood in older mice. Parabiosis called heterochronic the method involves surgically connect the systemic circulation of two different ages mouse, opening a flap of skin on the side of each mouse and sewing the two together, so that the pumps of the same blood through the two creatures. (There are more than a century, the technique was developed to study the exchange of nutrients between animals.) Previous studies have found better muscle health and strongest healing in older mice receiving the blood of a younger counterpart. But the heart tissue is not known to be as strong as the skeletal muscles and skin. The effect can work both ways-young mouse stem cells lose power in the old blood.
stem cell biologist Amy Wagers and cardiologist Richard Lee, both of the Harvard Stem Cell Institute, wonders if all the factors that circulate in young blood, such as hormones, may affect the aging hearts. Wagers, Lee and their colleagues used parabiosis yoke together on February 5 years mouse (downright ancient in mouse years) with 2-month-old counterparts. The team also joins 12 pairs aged mice and young mice 10 pairs, as witnesses. The first result was "evidently positive," said Lee, who also practices at Brigham and Women's Hospital in Boston. After 4 weeks of access for young mouse heart tissue of five older mice had thinned and softened, looking as spry and flexible as the 2-month-olds. " Older mice had now young hearts, while young mice hearts remained strong.
But the team has spent years trying to understand why; it was often the subject of Lee and weekly bike in paris. "There had found factors that are proposed for the aging factors," said Lee, "but it was not the identification of a circulating factor that can go the other way, to transform old tissue in the youngest tissue. "the team began to examine the factors in the blood, including 69 amino acids and more than a hundred fat. with the help of SomaLogic, a company-protein analysis Boulder, Colorado, the team has made a breakthrough, narrowing down the suspects likely to only 13 factors.
one of the suspects, growth differentiation factor 11, or GDF-11 appears explain the miraculous rejuvenation heart. GDF-11, which regulates the growth of (smell) receptors and olfactory spinal column is produced in abundance in young mice, but production decreases with age. other experiences team on cultured heart cells confirmed that GDF-11 stops the growth of thickening observed with age.
In addition, the researchers report online today in Cell , old mice injected with this protein for 30 days developed younger, stronger heart tissue. GDF-11, they say, directly counteracts the genes responsible for the thickening of the muscle.
"It is conceivable that this is just a story of interesting mice," says Lee, "but we're hoping to get data that could tell us that respect for man . "GDF-11 also appears in human blood, he said, although his role in the aging of the human heart is still uncertain. Then the team will study how GDF-11 affects other age-sensitive organs such as the tissues of the bone marrow.
Srivastava adds that GDF-11 appears to be effective against heart disease due to age, but he hopes that the protein could one day help patients hearts, stiffened by attacks heart, to relax.
This study is a validation of the parabiosis modern science of the 18th century using the molecular biology of the 21st century, says Gerald Dorn cardiologist at the University of Washington in St. Louis . However, the use of technology gives the research a gothic macabre flavor, he said. "I was looking to see if Tim Burton or Vincent Price were a part of the experimental design."
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