<p>Heart transplantation &ndash; also called cardiac transplantation &ndash; is the treatment of choice for many who suffer severe heart failure. Treatments to prevent infection and suppress the immune system have dramatically increased survival rates, but there simply aren&#8217;t enough hearts available. ;</p>
<p>Nearly 5,000 cardiac transplants occur each year (globally), but there are an estimated 50,000 individuals who qualify for the surgery. ;This means that only patients with the very worst prognoses will receive a transplant. And there&rsquo;s always the risk that a person&rsquo;s body will reject the foreign heart and launch a massive immune attack that can kill the patient. ;To reduce that risk and eliminate the need for donors, <strong>researchers are working to build synthetic hearts from a person&rsquo;s own cells. ;</strong></p>
<p>The image above shows regenerated heart tissue maturing in a bioreactor created by scientists at Harvard Medical School and Massachusetts General Hospital. ;As reported by <em>Popular Science</em> and published in the <em>Circulation Research</em> journal, the team used adult skin cells to grow functional human heart tissue. ;</p>
<p>&#8220;Generating functional cardiac tissue involves meeting several challenges,&#8221; says lead study author Jacques Guyette, PhD, of the MGH Center for Regenerative Medicine (CRM). &#8220;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.&#8221;</p>
<p>In other words, ;organs developed ;in a lab need a sort of ;&lsquo;scaffolding&rsquo; on which to grow &ndash; sort of like constructing a house with the frame already in place. ;</p>
<p>In 2008, research team leader Harald Ott, MD, of the MGH CRM and the Department of Surgery invented a technique in which donor organs are striped with a detergent solution to eliminate certain cells that may incite an immune response from the recipient. The remaining extracellular matrix scaffold is then repopulated with organ-appropriate cells. Ott&#8217;s team ;successfully used the procedure to grow working rat lungs and kidneys before trying it with human hearts.  ;</p>
<p>&ldquo;This report is the first to conduct a detailed analysis of the matrix scaffold remaining after decellularization of whole human hearts, along with recellularization of the cardiac matrix in three-dimensional and whole-heart formats,&rdquo; read the study&rsquo;s press release. ;</p>
<p>Using 73 donor hearts, the scientists washed away as many cells as possible that were deemed unfit for transplant. Next, researchers used a new technique (involving messenger RNA) to transform adult skin cells into pluripotent stem cells (iPSCs) &#8211; cells that ;can evolve into any type of cell found in the human body. ;The new cells were &lsquo;instructed&rsquo; to differentiate into cardiomyocytes (cardiac muscle cells). The cells were then reseeded into the remaining matrix tissue.</p>
<p>Specialized bioreactor chambers bathed the growing hearts in ;nutrient solution and provided an environment similar to that of a human body. After two weeks, ;the hearts contained properly structured tissue that was similar to that of immature human hearts. When given a shock of electricity, <strong>the hearts started beating. ;</strong></p>
<p>This isn&rsquo;t the first time human heart tissue has been grown in a lab, but it is the closest scientists have ever come to growing a full human heart. But the team admits they aren&rsquo;t at that level yet. ;</p>
<p>&#8220;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,&#8221; explains Guyette. &#8220;Among the next steps that we are pursuing are improving methods to generate even more cardiac cells &#8211; recellularizing a whole heart would take tens of billions &#8211; 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&#8217;s heart.&#8221;</p>
<p><strong>Editor&#8217;s note:</strong> This is not strictly speaking a political story, but this under-reported accomplishment is a huge milestone in the advancement of medicine and a celebration of American innovation and ingenuity. Congratulations to these scientists!</p>
<p> ;</p>