Custom Printed Organs

By David W. Niesel and Norbert K Herzog

Arguably, among the most exclusive waiting lists are those for organ transplantation. This is an expensive "do or die" medical procedure with limited availability. In the US, kidney transplant waiting list time wait varies from 5-189 months with only four having times of under twelve months. Consider that every 10 minutes someone is added to an organ waiting list and twenty-one people a day die waiting. Remember one donor can save up to eight lives through multiple organ use. As of 2016, there are 121,527 people on an organ transplant waiting list and in 2015, but only about 15,000 donors. Despite advances in transplantation technology and national efforts to stimulate organ donation, the difference between need and supply remains wide. This gap in the supply and demand for transplantable organs has led to desperate measures to obtain organs. In the Far East, there is a thriving organ black market where some prey on the less fortunate or some reported kidnappings and even murder to obtain them.

There are some alternatives. Researchers have developed ways to use organs from animals for transplantation, called xenotransplantation to reduce the gap in transplantable organs. Several countries including Russia and New Zealand have already approved clinical trials using pig derived cells for treating Type 1 diabetes. However xenotransplantation is controversial. One major concern is the fear that animal viruses could be introduced into humans. Finally and significantly, there are a host of religious, social and ethical issues that will be a challenge to large scale xenotransplantation.

You have likely heard about 3D printing's impact with some calling it the start of a new industrial revolution. 3D printing is a modification of the office inkjet technology but the nozzle moves both back and forth and up and down to deposit plastic or other melted material to form a 3D object. In medicine, 3D printing is important for prosthetics for children where replacement parts can be produced as the child grows. Surgeons have been using this technology to produce working models for reconstructive surgeries. Orthopedists produce working models of fractured bones to optimize the placement of screws and plates before surgery and dentists' offices produce crowns and dentures.

New advances in 3D printing are beginning to produce tissues that could one day be transplanted. Such bioprinting uses the technology to add layers of biocompatible material to make a scaffolding then adds tissue specific cells to grow in and on it. This scaffolding provides the tissue shape and structure based on anatomical location and need. For example, a bioprinted trachea would be printed to the precise dimensions needed. Eventually the biocompatible materials degrade leaving a new tissue. A new bioprinting technology also provides spaces for blood vessels insuring that once implanted, the tissue will receive nutrients and oxygen from blood. Researchers used this technique to print cartilage in the shape of a human ear, muscle and jawbone. Implanted into mice, these engineered tissues remained viable and began to develop a blood supply. While these are first steps, we may look back and characterize these as the "proof of principle" for printing organs for human transplantation. Eventually, this will mean saving lives and creating a limitless supply of life saving organs for transplantation.

Medical Discovery News is hosted by professors Norbert Herzog at Quinnipiac University, and David Niesel of the University of Texas Medical Branch. Learn more at www.medicaldiscoverynews.com.