How Can You Mend a Broken Heart?

The powers that be love blaming millennials for just about anything and everything. Unsurprisingly, next up on the list of millennial faults is reduced organ donation from motorcycle accidents. Millennials aren’t riding motorcycles to quite the extent that Baby Boomers did. As such, motorcycle deaths are decreasing, dragging down organ donation rates from ill-fated bikers (heaven forbid a statistic relating to millennials should be positive).

Organ transplantation has a colourful and convoluted history. The first autograft-transplantation (movement of tissue from one part of the patient’s body to another) took place in the late 1800s. This was a skin graft from the inner thigh used to repair the patient’s nose, which had been destroyed by syphilis. By the early 1900s, effective skin and cornea allograft-transplantations (movement of tissue from a human donor to human recipient) had been performed. However, it was not until the 1950s that successful transplantation of larger, more complex organs began. The first of these was a kidney transplant. The first heart transplant was performed by South African cardiac surgeon Christiaan Barnard in 1967, and transplant technology has followed an exciting trajectory ever since. Doctors can now transplant a huge variety of tissues and organs including intestines, pancreases, hands, testes, penises, bones, heart valves, and, recently, faces.

The heart is one of the most in-demand organs for transplantation. Unlike liver and kidney donors who can share their organs and then live to fight another day, heart donors must, of course, be deceased to give their recipient a new lease on life.

Thankfully, medical researchers have been working to ensure that the lack of millennials involved in fatal motorcycle accidents doesn’t severely impact the number of patients getting the new hearts they need. In an attempt to make organ donors obsolete, scientists are seeing to it that the wild notion of hearts being grown in labs is becoming increasingly more realistic. As a side benefit, synthetic hearts mitigate an enormous risk that comes with transplantation: the patient’s body rejecting the new organ and mounting a massive immune response against the foreign cells. Scientists have been seeing to this in a number of ways:

 

  • Regenerating old hearts in the lab: Using a detergent, cells from human hearts unfit for transplantation can be striped away, leaving behind only the extracellular scaffold of the heart. This matrix can then be repopulated with the patient’s own skin cells that have been reverse engineered into stem cells. These are then induced to become the cardiac cells that are required to build a beating human heart. In 2016, it took just two weeks for scientists to grow such hearts, but the researchers are clear that although well structured, the hearts resembled immature organs. Consequently, much work remains to be done before we are able to create individualised hearts for patients to order for transplantation.
  • Growing hearts patches: A heart attack can result in up to a billion cardiac cells that can never regrow after being destroyed, but this doesn’t mean the whole heart subsequently becomes completely dysfunctional. Nevertheless, heart attack patients frequently receive heart transplants because a partial transplant (excluding heart valve transplants) isn’t a procedure that can be performed. However, early 2019 saw the announcement of successfully grown swatches of cardiac muscle that are capable of conducting the electrical signals required to make a heart beat. These can literally be used to patch up a broken heart. This has been a work in progress for the past 20 years, and the patches will imminently be tested in clinical trials. Once widely available, these heart patches will reduce the need for entire heart transplants and improve survival outcomes for heart attack patients.
  • 3D printing hearts: The technology is still in its infancy but, earlier this year, researchers at Tel Aviv University 3D printed a tiny vascularised heart using the patient’s own cells. This made the miniature organ an immunological and biochemical match. The heart was printed in the same manner in which all other inanimate objects are 3D printed: layer by layer, additively growing the heart from the bottom up. It will be many years before a 3D printed, human-sized heart is stitched into Ruth Purcell, a patient. However, when this does happen, two huge barriers in organ donation will be overcome: lack of supply from donors, and organ rejection.

 

Although you may not yet be able to hit ‘print’ and receive your new heart ready for transplantation tomorrow, synthetic hearts are well on the way to saving lives. Of the thousands of people currently in need of a heart transplant, many of them won’t survive the waitlist. This tragic lack of supply is an issue I have every hope we will not face for many decades more.