Heart Smart
Heart disease: the biggest killer in the Western world. Modern science: responsible for myriad medical breakthroughs helping people live longer, better lives – and the heart is a keen focal point of this.
In a world-first treatment of damaged hearts, scientists in Japan have successfully transplanted lab-grown heart cells into a human patient. The procedure is part of a radical clinical trial that scientists hope will open new doors in regenerative medicine. The clinical trial harnesses the potential of an incredible, Nobel Prize-winning technology developed at Kyoto University in 2006, called Induced Pluripotent Stem Cells (IPSCS). These are created by harvesting cells from donor tissues and then returning them to their immature state by exposing them to a virus, after which they can develop into any cell type in the body.
Professor Yoshiki Sawa, a cardiac surgeon at Japan’s Osaka University, has been developing a technique to turn IPSCS into sheets of 100 million heart muscle cells, which can be grafted onto a heart to promote regeneration of damaged muscles. The sheets are biodegradable and, once implanted on the surface of the heart, are designed to release growth factors that encourage the formation of new and healthy vessels, as well as boost cardiac function. Professor Sawa says: “I hope that [the transplant] will become a medical technology that will save as many people as possible, as I’ve seen many lives that I couldn’t save.”
With the world’s population of elderly people projected to increase significantly in coming years – largely because people are living longer – so, too, will the rates of heart disease increase. And with it, a rise in the demand for cardiac devices. The design and testing of such devices is, however, a major challenge for engineers. This is because the extensive testing of many of these involves bench-top simulators, as well as animal and human trials. It is time-consuming and costly.
With this in mind, science is stepping up, and engineers at MIT have designed a bionic
“heart”. Made of heart tissues and a robotic pumping system, it beats like a real heart, and ultimately, the researchers hope to use it as a realistic environment to help designers test cardiac devices such as prosthetic heart valves under realistic conditions.
The device is a real biological heart, the tough muscle tissue of which has been replaced with a soft robotic matrix of artificial heart muscles, the orientation of which imitates the pattern of the heart’s natural muscle fibres and allows the heart to beat and pump blood like the real organ would. With this innovative design, which the MIT team calls a “biorobotic hybrid heart,” the researchers envision that device designers and engineers could tweak designs faster and more efficiently – as well as more costeffectively – by testing on the biohybrid heart.
Ellen Roche, assistant professor of mechanical engineering at MIT, explaining the need for a biological heart, says: “Regulatory testing of cardiac devices requires many fatigue tests and animal tests. “[The new device] could realistically represent what happens in a real heart, to reduce the amount of animal testing or iterate the design more quickly.”
When it comes to heart attacks, if a person survives such an event, damage to the heart muscle causes thick scar tissue to form – scar tissue that can increase the chance of heart failure. Researchers have, however, found a way to improve the quality of the scar tissue, meaning improved heart function after a heart attack. The focus is on a protein therapy called recombinant human platelet-derived growth factor-ab (RHPDGF-AB), previously shown to improve heart function in mice that had suffered heart attacks. In a new study intended to bring the treatment closer to human trials, a team tried to produce similar results in pigs.
Researchers from the Westmead Institute for Medical Research (WIMR) and the University of Sydney found that when pigs that had suffered heart attacks received an infusion of RHPDGF, the formation of new blood vessels in the heart was promoted, leading to a reduction of potentially fatal heart arrhythmia.
Associate Professor James Chong, who led the research, says: "This is an entirely new approach with no current treatments able to change scar in this way. By improving cardiac function and scar formation following heart attack, treatment with RHPDGF-AB led to an overall increase in survival rate in our study."
While the treatment did not affect the overall size of the scar, it did improve heart function after the heart attack by triggering an increase in the alignment and strength of scar collagen fibre. The team hopes to start human trials very soon. Chong says: "This project has been developed over more than 10 years and we now have compelling data in two species for the effectiveness of this treatment. We now hope to further investigate the treatment, including whether it could be used in other organ systems impacted by scar tissue, such as the kidneys."
A frequent cause of heart attacks and strokes are the atherosclerotic plaquedeposits on the inner walls of arteries. Now, a newly developed nanoparticle, a collaboration between scientists at Michigan State University and Stanford University, could see such deposits minimised by prompting the body's own cells to "eat" them.
The nanoparticles will be introduced to a patient intravenously by way of a solution flowing straight into the bloodstream. Once the nanoparticles encounter a plaque deposit, they will act upon immune cells inside of it, called macrophages – a type of white blood cell that specialises in destroying pathogens like viruses and bacteria.
Unlike some experimental plaquereduction treatments which harm healthy tissue, the nanoparticles only clear out dead cell material, meaning there should be minimal – if any – negative side effects. Michigan State's Associate Professor Bryan Smith says: "We demonstrated the nanomaterials were able to selectively seek out and deliver a message to the very cells needed. It gives a particular energy to our future work."