It’s true that surgical cardiology procedures have advanced significantly in recent years, but still, the long wait for the donation of a compatible heart is something that seems far from ending. Or at least, that’s what we thought up until now. A group of American researchers managed to regenerate functional heart tissue in a laboratory from stem cells created from skin cells.
[Image Source: Bernhard Jank, MD, Ott Lab, Center for Regenerative Medicine, Massachusetts General Hospital]
The study was recently published in the journal Circulation Research, detailing the research done at Massachusetts General Hospital. According to the paper, the technique should allow considerable repairs to be made in the cardiac tissue using the patient’s own genetic material. In addition to possibly eliminating the need for a full heart transplant, the discovery also drastically reduces the chances of rejection.
“Generating functional cardiac tissue involves meeting several challenges,” says Jacques Guyette, PhD, of the MGH Center for Regenerative Medicine (CRM), lead author of the report. “These include providing a structural scaffold that is able to support cardiac function, a supply of specialized cardiac cells, and a supportive environment in which cells can repopulate the scaffold to form mature tissue capable of handling complex cardiac functions.”
As noted by Guyette, this is still a process that takes time, especially for such a complex purpose as to restore cardiac functions. Thus, a shortcut to the research was to use 73 donor hearts from the New England Organ Bank, deemed unsuitable for transplantation. Each of these hearts had undergone a thorough cleaning, which got rid of all living cells leaving behind a neutral scaffold ready to receive the new cellular material. Scientists then used an improved method to revert the skin cells to stem cells with messenger RNA, which enabled the growth of new cardiac muscle tissue over the extracellular matrix . From there, it took only a few days for them to grow into contracting muscle tissue.
To speed up this stage, the team placed the growing heart in a bioreactor with a nutrient solution and some elements that reproduce conditions similar to those in a healthy living heart. In about two weeks, the results were small fully functional muscle regions, which similar to the original tissue, responded to electrical stimulation. Despite the improvement, Guyette and his team know that there is still a lote of work ahead.
“Regenerating a whole heart is most certainly a long-term goal that is several years away, so we are currently working on engineering a functional myocardial patch that could replace cardiac tissue damaged due a heart attack or heart failure,” says Guyette. “Among the next steps that we are pursuing are improving methods to generate even more cardiac cells – recellularizing a whole heart would take tens of billions—optimizing bioreactor-based culture techniques to improve the maturation and function of engineered cardiac tissue, and electronically integrating regenerated tissue to function within the recipient’s heart.”