A tiny mouse has a heart that beats 5-14 times per second, in contrast to the human heart at once per second. And yet mice, and scores of other animals are used extensively in cardiovascular research, despite the fact they do not experience heart attacks and strokes as humans do.

In attempts to simulate human cardiac disorders, researchers carry out painful procedures on mice and rats, such as inserting a clamp into the aorta to force the heart to work harder. This causes increased muscle mass and eventual heart attack due to vascular constriction. 

This artificial state differ significantly from the progressive development of human cardiovascular disease that arises from multiple lifestyle and genetic factors, delaying progress in treatments for human cardiovascular disease, while causing immense animal suffering.

Better and human relevant methods are available to replace animals. Heart-on-a-chips have been around for over a decade, composed of human heart cells to model cardiac function. Now, a team of scientists has created a systematic approach to developing the chips, that will lead to greater standardization. Other research is using human heart tissue obtained from surgeries to study heart disease, deriving new findings for treating heart failure, atherosclerosis and strokes.

Heart-on-a-chip: A microfluidic marvel shaping the future of cardiovascular research

In an effort to replace animal testing and improve the success rate of vital heart treatments, scientists at the National Institute of Standards and Technology (NIST) have developed a tool that will help construct heart-on-a-chip devices.

A heart-on-a-chip is a small intricate device designed to replicate a human heart. Derived from human stem cells and with microchannels that effectively mimic blood vessels, it allows researchers to safely test drugs and observe their efficacy far more accurately and without the harm caused when testing on animals. This major step forward in drug development addresses the limitations of current methods and has even greater potential; while this specific chip is focused on the heart, the same technology can also be used to create chips that replicate other organs too.

The goal, says NIST researcher Dr. Darwin Reyes, is to “be able to skip the animal testing altogether. This would also shorten the time it takes to test drugs, hopefully making the medications cost less.”

Living heart muscle slices drive RNA research into heart failure

Researchers at Hannover Medical School (MHH) in Germany have derived new insights into heart disease and potential treatments without experimenting on animals. In a novel study led by Professor Thomas Thum, MD, PhD, the researchers obtained diseased human hearts that were removed during transplant, and cultured them in the laboratory to form living myocardial slices (LMS). They then added a blocker to the tissue slices to see the effects of switching off the harmful function of a noncoding RNA snippet called miR-21, which plays a role in cardiac fibrosis, or stiffening of the heart muscle. The remarkable result was that the heart tissue began to heal; the diseased portion became more elastic as the heart muscle cells relaxed and began to beat with increased viability. 

Commenting on the study, Professor Thum said: "To our knowledge, this is the first study in which the effects of miR-21 have been investigated directly on living human heart tissue. The LMS model has proven its worth in providing preclinical proof of efficacy and should also contribute to a significant reduction in animal testing in the future. The tests in the cultivation chambers have shown that the miR-21 blocker is a potential drug candidate for stopping and even reversing fibrosis development in heart failure."

In our cellular 'glue,' scientists find answers about heart attacks, strokes, more

Scientists at the University of Virginia conducted animal-free research that may lead to better treatments for cardiovascular disease - the leading cause of death worldwide. The researchers set out to learn more about the atherosclerotic plaques that lead to strokes and heart attacks by studying extracellular matrix, a glue-like material secreted by human blood vessels.

Extracting smooth muscle cells from 123 heart transplant donors, they analyzed the protein composition, and were able to identify 20 locations on human chromosomes that contain genes that are connected to the production of these proteins. They also found gene variations that put people at a greater risk of heart condition. The findings shed light on important knowledge that will be beneficial during the development of new drugs and treatments.