While miraculous promises of bioprinting are being lauded in headlines around the world, one recent report predicts stiff ethical and possibly even legal resistance to the practice.

Researchers at Cardiovascular Innovation Institute (CII) are working on a 3D printer capable of creating a human heart, while biotech company Organovo says it could create a working human liver by the end of the year.

Many other similar breakthroughs appear on the horizon as well, but a report by market research firm Gartner says this research will spark fierce ethical debates by 2016 which could lead to strict legal bans.

"3D bioprinting facilities with the ability to print human organs and tissue will advance far faster than general understanding and acceptance of the ramifications of this technology," Gartner Research Director Pete Basiliere said.

However, Dr. Stuart Williams, who is leading the effort to bioprint a human heart at CII, doesn't foresee any sort of extended ban on the horizon.

"It reminds me of the 50s when people had concerns about the polio vaccine," he said. "You know, people had concerns about the polio vaccine, but it worked. As long as this product works as well as expected, the patients will demand it."

Williams believes that the public probably needs to learn more about bioprinting. "We bio-printers, in terms of communications and explaining things to public, we have to get better and better and better all the time," Williams said. "Sometimes, a lack of understanding can build fear into people."

Williams figures the medical industry is still about five years away from bioprinting pieces of organs that can remain viable indefinitely, but the Gartner report seems more optimistic. It points to a small kidney researchers printed at Hangzhou Dianzi University in China in 2013 that worked for four months before failing.

"These initiatives are well-intentioned, but raise a number of questions that remain unanswered," Basiliere said. "What happens when complex 'enhanced' organs involving nonhuman cells are made? Who will control the ability to produce them? Who will ensure the quality of the resulting organs?"

Williams is a strong advocate of hammering out medical and ethical concerns, but just not at the price of halting work.

For instance, should the design of the human body be improved upon with bioprinting?

"Suppose someone wants to be a better (baseball) pitcher, do we just print improved muscle tissue?" Williams asks.

While that might be a simple question for some, here's a trickier one: The left main artery, which supplies blood to the heart, is called the "widow maker" because it tends to fail. That often results in death, but what about bioprinting a heart with two left main arteries? That way, if one fails, the second one will keep the person alive.

"Why can't we build a heart that never has a heart attack?" Williams asked. "I think we can get there."

But should we get there?

Another concern Williams raises is, when does it simply become too expensive to keep printing parts? Is it proper to spend hundreds of millions of dollars to keep printing parts when that money can be used in other ways?

"We can't just do it no matter what the cost," he said.

This could become a formidable issue very quickly, considering the Gartner report predicts the demand for bioprinting to be particularly strong in economically weak and war-torn regions. It also predicts increasing familiarity within the material sciences and CAD services sectors, and integration with healthcare and hospitals will further increase demand from 2015 onwards.

"The overall success rates of 3D printing use cases in emerging regions will escalate for three main reasons: the increasing ease of access and commoditization of the technology;  (return on investment); and because it simplifies supply chain issues with getting medical devices to these regions," said Mr. Basiliere. "Other primary drivers are a large population base with inadequate access to healthcare in regions often marred by internal conflicts, wars or terrorism."

Williams stresses it is important to not overstate the capabilities of bioprinting. He figures researchers are still a good five years away from bioprinting even a piece of an organ that can be sustained indefinitely.

He predicts it will start by 3D printing false pieces of skeleton, which will be used to replace irreparably damaged bone. Then a few living cells will be bioprinted and attached so we can figure out how to create cells that will continue to grow inside the body. Finally, that will lead to replacing whole organs.

"We are in the same place heart transplants were in the first few years," Williams said. "They did not work that well (at first). It took some very brave patients' experiences so people today can lead normal lives."