(Press-News.org) A new technique that stimulates heart muscle cells with low-energy light raises the possibility of a future light-controlled pacemaker, researchers reported in Circulation: Arrhythmia & Electrophysiology, a journal of the American Heart Association.
"Electronic cardiac pacemakers and defibrillators are well established and successful technologies, but they are not without problems, including the breakage of metal leads, limited battery life and interference from strong magnetic fields," said Emilia Entcheva, Ph.D., senior author of the study and associate professor of biomedical engineering at Stony Brook University in Stony Brook, New York. "Eventually, optical stimulation may overcome some of these problems and offer a new way of controlling heart function."
The research is part of a new field called optogenetics that introduces light-sensitive proteins into "excitable" cells, making it possible to control specific activities within cells. Excitable cells can actively generate electrical signals such as nerve cells and muscle cells.
The main appeal of control by light is the unprecedented ability to remotely, without contact, turn on/off a single cell or a cell type, not possible by electrical or other means of stimulation.
Several years ago, investigators discovered that brain cells could be stimulated using light if they were genetically altered to produce a light-sensitive protein called channelrhodopsin 2 (ChR2).
In the new study, researchers created cells expressing the ChR2 protein and coupled them with heart muscle cells from animals, creating heart tissue stimulated by light. They found light-triggered heart muscle contractions and electrical waves were indistinguishable from electrically-triggered waves.
Rather than directly modifying heart cells, the researchers coupled donor cells optimized for light responsiveness with the heart cells. The new technique uses much lower energy than in prior studies and doesn't require the use of viruses or the introduction of genes from other organisms into heart cells. Instead, cells from a person's bone marrow or skin can be cultured and modified to respond to light, reducing the possibility that the immune system will reject the light-sensitive cells.
"Our method of non-viral cell delivery may overcome some hurdles toward potential clinical use by harvesting cells from the patient, making them light-responsive and using them as donor cells in the same patient," Entcheva said.
The approach may someday improve pacemakers and defibrillators. Instead of metal leads, a light-controlled pacemaker would use biocompatible, flexible plastic optic fibers.
In preliminary calculations, a light-based system might require only one-tenth the energy, meaning that a battery could last 50 years rather than five. The more immediate application of the technique will likely be to aid heart research.
"Optical stimulation is a great tool to selectively probe and control different parts of the electrical circuitry of the heart to better understand where the vulnerable sites are or what gives rise to lethal arrhythmias," Entcheva said.
The technique might also be used to test new drugs for possible cardiac side effects.
###
Co-authors are: Zhiheng Jia, M.S.; Virginijus Valiunas, Ph.D.; Zongju Lu, Ph.D.; Harold Bien, M.D., Ph.D.; Huilin Liu, M.S.; Hong-Zhang Wang, Ph.D.; Barbara Rosati, Ph.D.; Peter R. Brink, Ph.D.; and Ira S. Cohen, M.D., Ph.D. Author disclosures and sources of funding are on the manuscript.
Statements and conclusions of study authors published in American Heart Association scientific journals are solely those of the study authors and do not necessarily reflect the association's policy or position. The association makes no representation or guarantee as to their accuracy or reliability. The association receives funding primarily from individuals; foundations and corporations (including pharmaceutical, device manufacturers and other companies) also make donations and fund specific association programs and events. The association has strict policies to prevent these relationships from influencing the science content. Revenues from pharmaceutical and device corporations are available at www.heart.org/corporatefunding.
NR11 – 1109 (Circ/Entcheva)
Technique to stimulate heart cells may lead to light-controlled pacemakers
2011-08-09
ELSE PRESS RELEASES FROM THIS DATE:
Siblings of those with blood clots in leg have higher risk of same disorder
2011-08-09
Siblings of those who have been hospitalized with potentially lethal blood clots in the legs or pelvis are more likely to also suffer the disorder than those with healthy siblings, according to research published in Circulation: Journal of the American Heart Association.
The Swedish study is the first to show a direct correlation between venous thromboembolism (VTE) and family risk in a nationwide setting, sorted by age and gender.
VTE consists of deep vein thrombosis (DVT), which typically involves blood clots that form in the deep veins of the leg or pelvis, and ...
Light speed hurdle to invisibility cloak overcome by undergraduate
2011-08-09
An undergraduate student has overcome a major hurdle in the development of invisibility cloaks by adding an optical device into their design that not only remains invisible itself, but also has the ability to slow down light.
The optical device, known as an 'invisible sphere', would slow down all of the light that approaches a potential cloak, meaning that the light rays would not need to be accelerated around the cloaked objects at great speeds ― a requirement that has limited invisibility cloaks to work only in a specified region of the visible spectrum.
This ...
Drug development in the blink of an eye
2011-08-09
The development of drugs for brain-related conditions is not an efficient process; only 8% of candidate drugs that enter clinical trials gain FDA approval. A key reason for this low success rate is a lack of preclinical tests that accurately predict drug efficacy and detect unwanted side effects. But now, Jeremy Nathans and colleagues, at Johns Hopkins University School of Medicine, Baltimore, have developed a new preclinical approach that they hope can be used alongside current strategies to guide more efficient drug development for brain-related conditions.
In the study, ...
JCI online early table of contents: August 8, 2011
2011-08-09
EDITOR'S PICK: Drug development in the blink of an eye
The development of drugs for brain-related conditions is not an efficient process; only 8% of candidate drugs that enter clinical trials gain FDA approval. A key reason for this low success rate is a lack of preclinical tests that accurately predict drug efficacy and detect unwanted side effects. But now, Jeremy Nathans and colleagues, at Johns Hopkins University School of Medicine, Baltimore, have developed a new preclinical approach that they hope can be used alongside current strategies to guide more efficient ...
When and how to toilet train children
2011-08-09
Parents often ask their doctors for advice on toilet training young children, and a new article in CMAJ (Canadian Medical Association Journal) (pre-embargo link only) http://www.cmaj.ca/site/embargo/cmaj110830.pdf summarizes current approaches and evidence to help physicians respond to these queries.
"Toilet training is felt to be a natural process that occurs with development, yet very little scientific information is available for physicians who care for children," writes Dr. Darcie Kiddoo, Divisions of Pediatric Surgery and Urology, University of Alberta, Edmonton, ...
Gladstone scientist discovers genetic factor implicated in heartbeat defect
2011-08-09
SAN FRANCISCO, CA—August 8, 2011—A scientist at the Gladstone Institutes has discovered how gene regulation can make hearts beat out of sync, offering new hope for the millions who suffer from a potentially fatal heart condition.
In a paper being published this week in the online Early Edition of the Proceedings of the National Academy of Sciences, Gladstone Investigator Benoit G. Bruneau, PhD announces the identity of the molecular regulator that uses electrical impulses to synchronize each heartbeat.
Abnormalities in heartbeat synchronization, called heart arrhythmias, ...
Study urges caution with lenalidomide dosage
2011-08-09
COLUMBUS, Ohio – An early phase multiple myeloma trial has unexpectedly revealed that the drug lenalidomide interacts with another protein in cells that affect its dose level in the body, say researchers at the Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute (OSUCCC – James) who conducted the study.
Lenalidomide is an anti-inflammatory drug, and more than 390 clinical trials have been initiated to study its activity in a number of cancers and other diseases.
The study found that lenalidomide ...
Buyer beware -- herbal products missing key safety information
2011-08-09
Many people use herbal medicines believing them to be safe simply because they are 'natural'. However many of these products have potentially dangerous interactions with other drugs and can have similar side effects to conventional drugs. New research published in BioMed Central's open access journal BMC Medicine reveals that many over-the-counter herbal products do not contain any of the key information required for safe use.
Despite their wholesome image, many herbal products have adverse effects and a third of users are completely unaware of any risks. Researchers ...
Herbal remedies escape EU law
2011-08-09
Many herbal remedies available over-the-counter in pharmacies and health food shops are still lacking important information needed for safe use, according to University of Leeds researchers.
In April this year, a new EU law came into force regulating the sale of traditional herbal medicines, such as St John's wort and Echinacea. These products must now contain clear information on possible side effects, how they could interact with other prescribed medicines and whether people with existing illnesses should take them or not. They are clearly marked with the THR logo showing ...
Chimpanzees are spontaneously generous after all
2011-08-09
Researchers at the Yerkes National Primate Research Center have shown chimpanzees have a significant bias for prosocial behavior. This, the study authors report, is in contrast to previous studies that positioned chimpanzees as reluctant altruists and led to the widely held belief that human altruism evolved in the last six million years only after humans split from apes. The current study findings are available in the online edition of Proceedings of the National Academy of Sciences.
According to Yerkes researchers Victoria Horner, PhD, Frans de Waal, PhD, and their ...