(Press-News.org) DURHAM, N.C. -- Duke University biomedical engineers have grown three-dimensional human heart muscle that acts just like natural tissue. This advancement could be important in treating heart attack patients or in serving as a platform for testing new heart disease medicines.
The "heart patch" grown in the laboratory from human cells overcomes two major obstacles facing cell-based therapies – the patch conducts electricity at about the same speed as natural heart cells and it "squeezes" appropriately. Earlier attempts to create functional heart patches have largely been unable to overcome those obstacles.
The source cells used by the Duke researchers were human embryonic stem cells. These cells are pluripotent, which means that when given the right chemical and physical signals, they can be coaxed by scientists to become any kind of cell – in this case heart muscle cells, known as cardiomyocytes.
"The structural and functional properties of these 3-D tissue patches surpass all previous reports for engineered human heart muscle," said Nenad Bursac, associate professor of biomedical engineering at Duke's Pratt School of Engineering. "This is the closest man-made approximation of native human heart tissue to date."
The results of Bursac's research, which is supported by the National Heart Lung and Blood Institute, were published on-line in the journal Biomaterials.
Bursac said this approach does not involve genetic manipulation of cells.
"In past studies, human stem cell-derived cardiomyocytes were not able to both rapidly conduct electrical activity and strongly contract as well as normal cardiomyocytes," Bursac said. "Through optimization of a three-dimensional environment for cell growth, we were able to 'push' cardiomyocytes to reach unprecedented levels of electrical and mechanical maturation."
The rate of functional maturation is an important element for the patch to become practical. In a developing human embryo, it takes about nine months for a neonatal functioning heart to develop and an additional few years to reach adult levels of function; however, advancing the functional properties of these bioengineered patches took a little more than a month, Bursac said. As technology advances, he said, the time should shorten.
"Currently, it would take us about five to six weeks starting from pluripotent stem cells to grow a highly functional heart patch," Bursac said.
"When someone has a heart attack, a portion of the heart muscle dies," Bursac said. "Our goal would be to implant a patch of new and functional heart tissue at the site of the injury as rapidly after heart attack as possible. Using a patient's own cells to generate pluripotent stem cells would add further advantage in that there would likely be no immune system reaction, since the cells in the patch would be recognized by the body as self."
In addition to a possible therapy for patients with heart disease, Bursac said that engineered heart tissues could also be used to effectively screen new drugs or therapies.
"Tests or trials of new drugs can be expensive and time-consuming," Bursac said. "Instead of, or along with testing drugs on animals, the ability to test on actual, functioning human tissue may be more predictive of the drugs' effects and help determine which drugs should go on to further studies."
Some drug tests are conducted on two-dimensional sheets of heart cells, but according to Bursac, the 3-D culture model provides a superior environment for functional maturation of cells. This is expected to better mimic real-world heart muscle responses to different drugs or toxins. Engineered heart tissues made with cells from patients with a cardiac genetic disease could be used as the model to study that disease and explore potential therapies.
The current experiments were conducted on one human pluripotent stem cell line. Bursac and his colleagues have reproduced their findings on two other cell lines and are testing additional lines. They are also planning to move to larger animal models to learn how the patch would become functionally integrated with its host and how the patch establishes connections with the circulatory system.
###
Other members of the research team were Donghui Zhang and Ilya Shadrin from Duke, and Jason Lam, Hai-Qian Xian and Ralph Snodgrass, from VistaGen Therapeutics, San Francisco, who provided cardiomyocytes for these studies. Bursac's team and VistaGen are collaborating to develop engineered cardiac tissues for more predictive drug screening and development.
Duke scientists build a living patch for damaged hearts
2013-05-06
ELSE PRESS RELEASES FROM THIS DATE:
Breaking the silence of suicide
2013-05-06
This news release is available in French.
Montreal, May 6, 2013 – Just over a month ago, a young high school student from Halifax committed suicide after photos of her being raped were posted on the Internet. Her story wasn't just about bullying. It was also about the complex feelings her friends and family faced with her decision to take her own life.
Such a reaction is common to cultures around the word. New research from Concordia University shows that, no matter where it occurs, a veil of shame and sense of taboo surround suicide. These attitudes often force those ...
New analysis suggests wind, not water, formed mound on Mars
2013-05-06
A roughly 3.5-mile high Martian mound that scientists suspect preserves evidence of a massive lake might actually have formed as a result of the Red Planet's famously dusty atmosphere, an analysis of the mound's features suggests. If correct, the research could dilute expectations that the mound holds evidence of a large body of water, which would have important implications for understanding Mars' past habitability.
Researchers based at Princeton University and the California Institute of Technology suggest that the mound, known as Mount Sharp, most likely emerged as ...
Solid-state controllable light filter may protect preterm infants from disturbing light
2013-05-06
Preterm infants appear to mature better if they are shielded from most wavelengths of visible light, from violet to orange. But it has been a challenge to develop a controllable light filter for preterm incubators that can switch between blocking out all light--for sleeping--and all but red light to allows medical staff and parents to check up on the kids when they're awake. Now, in a paper accepted for publication in Applied Physics Letters, a journal of the American Institute of Physics, researchers describe a proof-of-concept mirror that switches between reflective and ...
Scaling up gyroscopes: From navigation to measuring the Earth's rotation
2013-05-06
Accurately sensing rotation is important to a variety of technologies, from today's smartphones to navigational instruments that help keep submarines, planes, and satellites on course. In a paper accepted for publication in the American Institute of Physics' journal Review of Scientific Instruments, researchers from the Technical University of Munich and New Zealand's University of Canterbury discuss what are called "large ring laser gyroscopes" that are six orders of magnitude more sensitive than gyroscopes commercially available. In part, the increased sensitivity comes ...
Research finds new cause for common lung problem
2013-05-06
New research has found that in cases of lung edema, or fluid in the lungs, not only do the lungs fail to keep water out as previously believed, but they are also allowing water to pump in.
"Usually, our lungs pump fluid out of the air space, and it was previously believed that this pump mechanism just stopped when people had lung edema," said Dr. Wolfgang Kuebler, a scientist at St. Michael's Hospital. "But we've found not only do they stop pumping fluid out as they're supposed to do, they've gotten confused and are actually pumping in the reverse direction, bringing ...
Hospital surgical volume should be considered when judging value of procedures
2013-05-06
SAN DIEGO – The volume of cases performed at an institution each year has a direct effect on the outcome of surgical procedures, and should always be considered when looking at the benefits of a technique, according to a team of researchers at Henry Ford Hospital in Detroit.
Those conclusions will be presented May 5 at the annual meeting of the American Urological Association in San Diego.
The starting point of the study was the rapid increase in the use of surgical robots to assist in radical prostatectomy, in which the entire prostate gland and some surrounding tissue ...
Genome sequencing provides unprecedented insight into causes of pneumococcal disease
2013-05-06
Boston, MA — A new study led by researchers from Harvard School of Public Health (HSPH) and the Wellcome Trust Sanger Institute in the UK has, for the first time, used genome sequencing technology to track the changes in a bacterial population following the introduction of a vaccine. The study follows how the population of pneumococcal bacteria changed following the introduction of the 'Prevnar' conjugate polysaccharide vaccine, which substantially reduced rates of pneumococcal disease across the U.S. The work demonstrates that the technology could be used in the future ...
Media advisory: Brain cell injections may quiet epileptic seizures
2013-05-06
More than two million people in the United States suffer from epilepsies, a group of neurological disorders caused by abnormal nerve cell firing in the brain which often produce debilitating seizures. Although anti-epileptic drugs and other therapies reduce seizures in about two-thirds of patients, the remaining one-third do not respond to any form of therapy and those who take drugs can experience harmful side effects. NIH funded researchers at the University of California at San Francisco used a mouse model of epilepsy to show that transplanting new born inhibitory nerve ...
Divide and define: Clues to understanding how stem cells produce different kinds of cells
2013-05-06
ANN ARBOR—The human body contains trillions of cells, all derived from a single cell, or zygote, made by the fusion of an egg and a sperm. That single cell contains all the genetic information needed to develop into a human, and passes identical copies of that information to each new cell as it divides into the many diverse types of cells that make up a complex organism like a human being.
If each cell is genetically identical, however, how does it grow to be a skin, blood, nerve, bone or other type of cell? How do stem cells read the same genetic code but divide into ...
Scientists alarmed by rapid spread of Brown Streak Disease in cassava
2013-05-06
BELLAGIO, ITALY (6 MAY 2013)— Cassava experts are reporting new outbreaks and the increased spread of Cassava Brown Streak Disease or CBSD, warning that the rapidly proliferating plant virus could cause a 50 percent drop in production of a crop that provides a significant source of food and income for 300 million Africans.
The "pandemic" of CBSD now underway is particularly worrisome because agriculture experts have been looking to the otherwise resilient cassava plant—which is also used to produce starch, flour, biofuel and even beer—as the perfect crop for helping to ...