Printed organs – more than just pretty pictures

Since the first organ transplant in 1954, immunosuppressive drugs and advanced surgical techniques have greatly improved the long-term success of organ transplantation. Nevertheless, there are not enough organs to meet the current demand. As people live longer, the need for organs and tissues increases. According to organdonor.gov, 18 people a day die waiting for an organ. To circumvent the current organ bottleneck, researchers around the globe are working on engineering transplantable organs. Implantable organs made from three-dimensional printers are particularly promising because the automated approach allows for reproducible mass production. Although transplantation of engineered printed organs is still years away, currently printed organs can provide great research value. These organs are unique research models to investigate disease progression and drug development and could possibly be used in medical schools.

 

Three-dimensional printing builds three-dimensional objects by layering material. The application of this printing technology to organ engineering is in its infancy, but the potential of this technology is amazing. Organ printing can be broken down into three main steps: preprocessing, processing and postprocessing. During preprocessing, the blueprint of the patient-specific organ is created and converted into a bioprinter-friendly format. In the processing step, a bioprinter prints the organ using self-assembling tissue spheroids (i.e., bioink). The organ is placed in a bioreactor for postproccessing. During this time, the bioreactor encourages accelerated tissue maturation with the end goal of having a functional organ suitable for transplantation.

 

Organs have an intricate branched microvasculature system. The ability to mimic the complex microvasculature system of organs has been a major limiting factor in the development of complete organs. Without the correct microvasculature system, an engineered organ cannot function properly because this system is essential in providing oxygen and nutrients to the organ and removing waste. On this front, organ printing may provide a unique advantage to traditional scaffolding methods of tissue regeneration. Because organ printing assembles layer-by-layer from the bottom up, it can incorporate a built-in branched vasculature system. Although an incorporated vasculature system is feasible with bioprinting, numerous challenges still need to be met before this occurs.   

 

Seemingly straightforward, each step of organ engineering requires an extremely interdisciplinary approach, access to a wide array of biofabrication materials and stable financial backing.  Despite these challenges, the ability to engineer new organs is essential for our ability to meet the growing demand for organs. The ability to engineer donor-specific organs would not only relieve a very taxed organ supply but also provide the opportunity for organs to be made from one’s own cells. Using one’s own cells reduces the chance of immune rejection and the need for immune suppression. While organ printing appears quite promising, researchers are still a ways off from the mass production of three-dimensional transplantable organs. As this technology advances, it is clear that there is also a lucrative incentive behind this breakthrough. From patents on the underlying technology that makes bioprinting possible to companies such as Organova and Tengion, it is clear that the building of organs will be as much about business as it is about science.