Cardiovascular diseases represent the leading cause of mortality globally, claiming nearly 18 million lives each year, which constitutes almost a third of all deaths worldwide. Alarming statistics reveal that this is a pandemic of the modern era, with estimates indicating that more than 640 million people live with some form of heart and circulatory system disease. The problem is further exacerbated by the fact that damaged heart muscle tissue does not have the ability to regenerate, making treatment extremely complex and placing patients in the final stages of heart failure on long waiting lists for transplantation. Unfortunately, the number of available donor hearts is nowhere near sufficient to meet the growing needs, leaving millions of people without an adequate treatment option. In this context, the scientific community is investing enormous efforts in developing new therapeutic approaches, and one of the most promising directions is regenerative medicine.

A revolution in heart treatment is on the horizon

At the center of research into regenerative therapies are induced pluripotent stem cells (iPSCs). These are cells that can be taken from skin or blood samples of an adult and reprogrammed back to an embryonic, pluripotent state. From this state, scientists can direct them to develop into any type of cell in the body, including cardiomyocytes – heart muscle cells. Theoretically, these laboratory-grown heart cells could be transplanted into a patient's damaged heart, rebuild the destroyed tissue, and restore its lost function. However, the path from theory to clinical application is fraught with challenges. One of the biggest problems scientists face is the low survival rate of transplanted cells. When new cells are injected into damaged, inflamed, and scarred heart tissue, a large proportion of them fail to survive and integrate. Another key challenge is the production of a sufficient number of high-quality heart cells in an efficient and rapid manner to make the therapy available to a large number of patients.

The space station as a unique laboratory

In the search for solutions to these problems, scientists have turned to the most unusual laboratory possible – the International Space Station (ISS). The microgravity environment, the state of weightlessness that prevails in Earth's orbit, offers unique conditions for studying biological processes in ways that are not possible on Earth. Gravity affects almost all aspects of cellular behavior, from shape and structure to growth and communication. By removing this force, scientists can uncover the fundamental mechanisms that govern cellular life. A team of researchers from Emory University, led by Professor Chunhui Xu, hypothesized that microgravity could induce cellular changes that would make heart cells more resilient and better able to survive after transplantation. The inspiration came partly from earlier research showing that some types of cancer cells proliferate faster in space, which was a sign that other cells might also exhibit unusual behavior.

A scientific breakthrough in orbit

The research team from Emory University conducted a sophisticated experiment, sending human heart cells, derived from iPSCs, to the International Space Station. To mimic the structure and function of the human heart as closely as possible, the cells were organized into microscopic three-dimensional spheroids. These cell cultures were frozen for safe transport and thawed just before launch. In parallel, identical control groups of cells remained on Earth to allow for a precise comparison. During their time in space, astronauts monitored the growth and behavior of the cells using a microscope and sent videos back to Earth. After the return of the live cultures, a detailed molecular analysis followed.

Incredible results from space

The results, published in several peer-reviewed articles, including two in the prestigious scientific journal Biomaterials, exceeded expectations. The analyses showed that exposure to microgravity caused profound changes at the genetic and protein levels. First, the cells proliferated significantly faster than their terrestrial counterparts. This discovery has a direct impact on one of the key challenges – mass production. The ability to generate a large number of heart cells more quickly could significantly reduce the cost and speed up the development of future therapies. Second, and perhaps more importantly, genetic analysis revealed an increased expression of a whole range of genes crucial for cell survival. Increased activity was noted in pathways related to cell development, stress response, survival, and cellular metabolism. This practically means that the space environment "trained" the cells to become more resilient, adaptable, and ready to survive in the hostile environment of a damaged heart.

The researchers observed that the cells that had been in space produced more proteins involved in survival and showed signs of greater maturity. Immature heart cells can pose a risk because they can divide uncontrollably, but the cells from space showed characteristics that make them safer and more functional. As explained by Professor Chunhui Xu, whose laboratory leads this research, the space environment provides an incredible opportunity to study cells in new ways. The knowledge gained from this research could enable the development of a completely new strategy for generating heart cells with improved survival, which would bring enormous benefits to patients on Earth. This research not only pushes the boundaries of regenerative medicine but also opens the door to transforming the entire landscape of heart disease treatment, offering hope to the millions of people who need it most.