Following up on previous studies, Hopkins cardiologists used a thin tube to extract samples of heart tissue no bigger than a grain of rice within hours of the animals' heart attacks, then grew large numbers of cardiac stem cells in the lab from tissue obtained through biopsy, and within a month implanted the cells into the pigs' hearts. With help from a blue-dye tracking system, the scientists have shown that within two months the cells had developed into mature heart cells and vessel-forming endothelial cells.
"This is a relatively simple method of stem cell extraction that can be used in any community-based clinic, and if further studies show the same kind of organ repair that we see in pigs, it could be performed on an outpatient basis," says Eduardo Marbán, M.D., Ph.D., senior study author and professor and chief of cardiology at The Johns Hopkins University School of Medicine and its Heart Institute. "Starting with just a small amount of tissue, we demonstrated that it was possible, very soon after a heart attack, to use the healthy parts of the heart to regenerate some of the damaged parts."
Marbán cautions that no overall improvements in heart function have yet been shown in these studies, which were not designed to establish such changes and used relatively low numbers of infused cells (10 million or less). "But we have proof of principle, and we are planning to use larger numbers of cells implanted in different sites of the heart to test whether we can restore function as well," he says. "If the answer is yes, we could see the first phase of studies in people in late 2007."
The latest Hopkins findings are scheduled to be presented Nov. 13 at the American Heart Association's annual Scientific Sessions in Chicago. They are believed to be the first results in animal studies to show that so-called cardiac stem cell therapy can be successfully applied with minimally invasive methods to circumstances closely resembling those in humans. Scientists say the results build on earlier studies with cardiac stem cells in mice and humans that demonstrated success in regenerating infarcted heart muscle and restoring heart cell function post-infarct.
For the study, cardiac stem cells were extracted by tissue biopsy from eight pigs whose main arterial blood supply was tightened for more than two hours, duplicating the effects and damage caused by heart attack.
Using techniques developed in Marbán's lab, researchers extracted about a million cardiac stem cells from undamaged heart tissue, growing them without the use of potentially dangerous chemical stimulators.
After three weeks, the stem cells turned into spherical balls of cells that mimicked the electrical properties of heart muscle cells. The so-called cardiospheres yielded on average more than 14 million cells.
Within a month after the initial heart attack, a catheter tube was inserted into an artery in the pig leg for infusing the cardiospheres. Previous research had shown that they would on their own migrate to the damaged zones of the heart. Marbán's team was able to confirm this because they had labeled the stem cells with a gene that codes for an enzyme producing a blue dye, which could be seen under a microscope.
Months later, when researchers examined the hearts to see if any damaged tissue had been repaired, they found blue spots indicating where the stem cells had taken root. Closer examination of results revealed that stem cells had matured and grown in the border zones of the damaged area, where researchers suspect both dead and living tissue mingle and some blood supply remains.
"The goal is to repair heart muscle weakened not only by heart attack but by heart failure, perhaps averting the need for heart transplants," says Peter Johnston, M.D., study author and a Reynolds Foundation postdoctoral cardiology research fellow at Hopkins' Heart Institute. "By using a patient's own adult stem cells rather than a donor's, there would be no risk of triggering an immune response that could cause rejection."
David March | EurekAlert!
Fine organic particles in the atmosphere are more often solid glass beads than liquid oil droplets
21.04.2017 | Max-Planck-Institut für Chemie
Study overturns seminal research about the developing nervous system
21.04.2017 | University of California - Los Angeles Health Sciences
The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.
Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...
The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...
Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.
Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...
Two researchers at Heidelberg University have developed a model system that enables a better understanding of the processes in a quantum-physical experiment...
Glaciers might seem rather inhospitable environments. However, they are home to a diverse and vibrant microbial community. It’s becoming increasingly clear that they play a bigger role in the carbon cycle than previously thought.
A new study, now published in the journal Nature Geoscience, shows how microbial communities in melting glaciers contribute to the Earth’s carbon cycle, a...
20.04.2017 | Event News
18.04.2017 | Event News
03.04.2017 | Event News
21.04.2017 | Physics and Astronomy
21.04.2017 | Health and Medicine
21.04.2017 | Physics and Astronomy