DiversityNursing Blog

Drug Testing Using 'Heart-On-A-Chip' Steps Closer

Posted by Erica Bettencourt

Wed, Mar 11, 2015 @ 02:43 PM

Catharine Paddock PhD

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Drug development is a costly and lengthy business, not helped by the fact there is a high failure rate in drug testing due to the reliance on animal models. Animal biology is not an ideal substitute for human biology, but until something better comes along, it is all we have. Now, a new study suggests the organ-on-a-chip method may offer a more ideal model.

Study leader Kevin Healy, a bioengineering professor at the University of California-Berkeley, says:

"It takes about $5 billion on average to develop a drug, and 60% of that figure comes from upfront costs in the research and development phase. Using a well-designed model of a human organ could significantly cut the cost and time of bringing a new drug to market."

As around one third of the candidate drugs that are ditched are those that seem to have a bad effect on the heart, Prof. Healy and colleagues decided to design a model based on the human heart.

They conclude that their work is a major step forward in the development of faster, more accurate ways of testing drug safety. Prof. Healy believes that:

"Ultimately, these chips could replace the use of animals to screen drugs for safety and efficacy."

In their study, they describe how they devised the model and tested it with cardiovascular medications.

'Heart-on-a-chip' contains a network of pulsating cardiac muscle cells

The human heart model that Prof. Healy and colleagues devised is a "heart-on-a-chip" comprising an inch-long silicone device with a thin network of pulsating cardiac muscle cells.

In the journal Scientific Reports, the team says their heart-on-a-chip - which they call a "cardiac microphysiological system (MPS)" - is an ideal tool for testing toxic side effects of new drugs on the human heart because it ticks four important boxes:

  1. It uses cells that have human genes
  2. The cells are aligned in a way that reflects the structure of human heart tissue
  3. It mimics the dynamics of blood flow in heart tissue
  4. It can be used for biological, electrophysiological and physiological analysis.

The authors note that using animal models to predict human reactions to drugs often fail because of fundamental differences in biology between species. For example, the ion channels that conduct the electrical pulses that heart cells send out can vary in number and type between animals and humans.

"Many cardiovascular drugs target those channels, so these differences often result in inefficient and costly experiments that do not provide accurate answers about the toxicity of a drug in humans," Prof. Healy explains.

Device is populated with heart cells made from human-induced pluripotent stem cells

The heart-on-a-chip is made of heart cells generated from human-induced pluripotent stem cells - the adult stem cells that can be coaxed to differentiate into various types of tissue.

The heart-on-a-chip has a 3D geometry and spacing that is comparable to that of connective tissue fiber in a human heart. The researchers then populated this with layers of differentiated heart cells, which in the confined geometry were forced to align in one direction.

Microfluidic channels on either side of the cell-populated area perform like blood vessels and mimic the same dynamics of nutrients and drugs diffusing from blood vessels into human tissue.

Such a setup could also serve as a model of how the cells get rid of their waste products, note the authors.

Lead author Dr. Anurag Mathur, a postdoctoral scholar in Healy's lab and a fellow of the California Institute for Regenerative Medicine, explains:

"This system is not a simple cell culture where tissue is being bathed in a static bath of liquid. We designed this system so that it is dynamic; it replicates how tissue in our bodies actually gets exposed to nutrients and drugs."

Heart-on-a-chip tested with four drugs and reacted as expected

The authors explain how within 24 hours of populating the device with heart cells, the engineered heart tissue was beating on its own at the normal rate of 55-80 beats per minute.

The team tested four well-known cardiovascular drugs on the device: isoproterenol, E-4031, verapamil and metoprolol. They used changes in the pulse rate of the tissue to measure the response to the drugs.

The changes in pulse rate were as expected for the drugs. For example, after half an hour of being exposed to isoproterenol - a drug used to treat slow heart rate, or bradycardia - the pulse rate of the heart-on-a-chip increased from 55 to 124 beats per minute.

Multi-organ testing devices could have hundreds of microphysiological cell systems

The engineered tissue remained viable and worked for several weeks. Such a timescale is sufficient for testing several different drugs, Prof. Healy says.

He and his colleagues are now investigating whether the method can be used to model multi-organ interactions. Prof. Healy notes:

"Linking heart and liver tissue would allow us to determine whether a drug that initially works fine in the heart might later be metabolized by the liver in a way that would be toxic."

The team anticipates the "widespread adoption" of organ-on-a-chip for drug screening and disease modeling and foresee devices containing hundreds of microphysiological cell systems. 

The project is funded through the Tissue Chip for Drug Screening Initiative, which is sponsored by the National Institutes of Health.

In October 2014, Medical News Today learned how the University of Kansas is leading the development of a  lab-on-a-chip that promises to detect lung cancer - and possibly other deadly cancers - much earlier. That method, which only uses a small drop of a patient's blood, is also based on microfluid technology. It analyzes the contents of exosomes - tiny bags of molecules that cells release now and again.

Source: www.medicalnewstoday.com

Topics: device, medical technology, heart, health, healthcare, cardiac, drug testing

Younger Women Hesitate To Say They're Having A Heart Attack

Posted by Erica Bettencourt

Wed, Feb 25, 2015 @ 11:41 AM

MAANVI SINGH

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Each year more than 15,000 women under the age of 55 die of heart disease in the United States. And younger women are twice as likely to die after being hospitalized for a heart attack as men in the same age group.

It doesn't help that women tend to delay seeking emergency care for symptoms of a heart attack such as pain and dizziness, says Judith Lichtman, an associate professor of epidemiology at the Yale School of Public Health. "We've known that for a while," she says.

In a small study published Tuesday in Circulation: Cardiovascular Quality and Outcomes, Lichtman and her colleagues looked into why women delay getting help. The researchers conducted in-depth interviews with 30 women, ages 30 to 55, who had been hospitalized after a heart attack.

It turned out that many had trouble recognizing that they were having symptoms of a heart attack. "A lot of them talk about not really experiencing the Hollywood heart attack," Lichtman tells Shots.

A heart attack doesn't necessarily feel like a sudden painful episode that ends in collapse, she notes. And women are more likely than men to experience vague symptoms like nausea or pain down their arms.

"Women may experience a combination of things they don't always associate with a heart attack," Lichtman says. "Maybe we need to do a better job of explaining and describing to the public what a heart attack looks and feels like."

But even when women suspected that they were having a heart attack, many said they were hesitant to bring it up because they didn't want to look like hypochondriacs.

"We need to do a better job of empowering women to share their concerns and symptoms," Lichtman says.

And medical professionals may need to do a better job of listening, she adds. Several women reported that their doctors initially misdiagnosed the pain, assuming that the women were suffering from acid reflux or gas.

Doctors should pay special attention to women who have high blood pressure or cholesterol, as well as those with a family history of heart disease, Lichtman says.

This is just a preliminary study. Lichtman has already started working on a much larger study investigating why women have a higher risk of dying from heart disease than men.

But the findings aren't too surprising, says Dr. Nisha Parikh, a cardiologist at the University of California, San Francisco who wasn't involved in the research.

"I take care of young women who have heart disease, and this story is very common," she says.

Part of the issue is that most of the research on heart disease has focused on men, since the condition is more common among men. As a result, the diagnostic tools that doctors use to identify heart disease aren't always well suited for female patients.

Cardiologists are just beginning to rethink how to best recognize and treat heart attacks in women, Parikh notes.

Heart disease is the third leading cause of death for women ages 35 to 44, and it's the second leading cause of death for women 45 to 54, according to the Centers for Disease Control and Prevention. (Cancer is the No. 1 cause.)

"Historically we thought of heart disease as sort of a man's disease," Parikh says. "But that's not the case."

This study also highlights the importance of empowering women to speak up about their worries, says. Dr. Jennifer Tremmel, a cardiologist at Stanford University.

"It's interesting because the whole idea of female hysteria dates back to ancient times," Tremmel says. "This is an ongoing issue in the medical field, and we all have to empower women patients, so they know that they need to not be so worried about going to the hospital if they're afraid there's something wrong."

Source: www.npr.org

Topics: women, heart attack, emergency, heart disease, heart, health, nurse, nurses, doctors, health care, patients, hospital, young women, heart health

Hospital Live Tweets Heart Transplant Surgery

Posted by Erica Bettencourt

Wed, Feb 18, 2015 @ 12:19 PM

JESSICA FIRGER

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Have you ever wondered what happens during a heart transplant operation? The surgical team at Baylor University Medical Center (@BaylorHealth) in Dallas understands the curiosity. On Monday night, the hospital offered the public an intimate look at the process of one patient's heart transplant journey using the hashtag #HeartTXLive and also #heartTX.

While hospitals have tweeted about organ transplant surgeries before, this is believed to be the first one to be tweeted in real time. The hospital says they chose to tell the story from the patient's point of view, and also documented the surgery with photos and video. 

Dr. Gonzo Gonzalez (@HRTTRNSPLNTMD), chief of cardiac surgery and heart transplant and mechanical circulatory support at Baylor University Medical Center assisted with the live tweets, while Dr. Juan MacHannaford performed the surgery. 

To protect the patient's identity, the hospital used pseudonyms for the patient and her husband, referring to them as Jane and John in the tweets. Jane was born with cardiomyopathy, which causes an enlargement of the heart muscle and structural problems. In Jane's case, she was born with an abnormal left ventricle, and had a bacterial infection at 3 months old that caused her to go into cardiac arrest. 

The live tweets paint a picture of the stress that comes with performing such a high-profile and high-risk surgery -- from waiting for the donor organ's arrival to the complex process of removing the patient's heart, implanting the new one and ensuring it's beating and circulating the patient's blood inside her body. Here are some highlights:

 

 

 

 

 

 

 

Source: www.cbsnews.com

Topics: surgery, heart, nurses, doctors, hospital, medicine, patient, twitter, tweet, transplant

Did An Irregular Heartbeat Help Make Beethoven a Music Legend?

Posted by Erica Bettencourt

Wed, Jan 14, 2015 @ 01:45 PM

By: ActiveBeat Author

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Several researchers believe that a significant heart problem could represent a critical factor in determining Ludwig van Beethoven’s success in music.

Many people are aware that, when he died in 1827, Beethoven was deaf. But he also struggled with a serious heart condition known as arrhythmia, or an irregular heartbeat. (It’s also worth noting that experts suspect Beethoven was suffering from cirrhosis of the liver, lead poisoning, and syphilis when he passed away.)

Joel D. Howell, an internal medicine specialist, says he believes this irregular heartbeat can be detected in Beethoven’s work. “When your heart beats irregularly from heart disease, it does so in some predictable patterns,” Howell says. “We think we hear some of those patterns in his music.”

The researchers also point to Beethoven’s String Quartet No. 13 in B flat major (Opus 130), which they say features “a short paroxysm of atrial tachyarrhythmia.” Beethoven even wrote that the song should be played with a “heavy heart”.

Howell and the other researchers recognize that their findings will encounter skepticism. However, they feel that, “in highly charged passages of certain pieces, the possibility of cardiac arrhythmia can lend a quite physical aspect to one’s interpretation of the music in question. These passages can seem, in an unexpected literal sense, to be heartfelt.”

Source: www.activebeat.com

Topics: music, researchers, deaf, heart disease, Beethoven, heart, heart beat

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