When scientists discovered, in the early 2000s, that it was possible to spray living cells through ink jet printers without damaging them, a whole new field of development in biotechnology opened up: bioprinting. Thanks to this, engineers, biologists, doctors and, of course, businessmen, have launched a race to produce organs in 3D, something that has the potential to better meet the demand for transplants—120,000 organs, especially kidneys, are transplanted each year in the world, according to data from the World Health Organization (WHO).
To print an organ from scratch, you have to use multiple print heads to eject different types of cells along with polymers that help maintain the shape of the structure. The printer deposits layer upon layer of cells that unite and become living and functional tissue. This is what a team at the Wake Forest Baptist Medical Center in the United States did when, in 2016, they printed parts of the human body, such as ears.
This technology is still too experimental to achieve that final goal, but researchers from various locations are already manipulating kidney and liver tissues, skin, bones and cartilage, as well as the blood vessels needed to keep those structures alive. Some of them have implanted printed ears, bones and muscles into animals, and observed how well they were integrated within each organism.
Prosthetic ovaries that can conceive
The most promising development in this field occurred last year, when a group of scientists from Northwestern University in Chicago, managed to print prosthetic ovaries for mice, which could conceive and give birth with the help of these artificial organs.
In Chengdu (China) the biotechnology company Sichuan Revotek successfully implanted a printed section of an artery into a monkey, an achievement considered as the first step in the trials of a technique intended for use in humans. On the other side of the world, a San Diego based company, Organovo, announced last year that it had transplanted printed tissue from a human liver into mice, and that the tissue had survived and functioned “normally.” “We hope that, within five years, we can develop this technique to treat problems such as chronic liver failure, for example,” says Benjamin Shepherd, head of preclinical trials at the company. Organovo already offers bioprinted kidney and liver tissues to the pharmaceutical industry to more accurately assess the efficacy and safety of some medications.
According to Roots Analysis, a medical technology consultancy firm, 3D printed kidneys could reach the health industry in about six years. “Livers, which have a natural tendency to regenerate, should also arrive reasonably soon. Hearts, with their complex internal geometries, will take more time,” adds Kavya Verma, an expert researcher in bioprinting at the consultancy.
The companies L’Oréal, Procter & Gamble and BASF have come together to work on the printing of human skin. Their goal is to use this skin to test their products for adverse reactions. In the same vein, Johnson & Johnson has joined forces with Tissue Regeneration Systems, a firm in Michigan, to create 3D implants to heal defects in broken bones. The US firm has also partnered with Aspect, a Canadian biotech company, to try to print meniscus from the human knee (the crescent-shaped cartilage pads that separate the femur from the tibia and act as buffers between these two bones). The considerable wear on this structure sometimes requires surgical intervention.
The potential of bioprinting is already generating ethical debates about its application, from fears about the quality and effectiveness of artificial skin and implants to the accusation that it will allow humans to “play God.” Scientists from the Department of Science, Technology and Innovation at the University of Edinburgh (United Kingdom) have conducted extensive research on the subject and consider this argument unfounded: “There are already many technologies that allow human beings to play God, like genetics. People make small parts of the body and they are used for medical applications,” says Gill Haddow, one of the team’s researchers.
Haddow believes that the main ethical obstacle to 3D organ printing is its cost. The most enthusiastic proponents of the technology affirm that the printed tissues would mean that those who are waiting for a transplant could stop depending on the altruism of the neighbours and the death of a stranger to have an organ, but Haddow considers this discourse quite utopian. “We are talking about an extremely expensive technology that, if it actually reaches the medical industry, only a few people will be able to afford.”