3D printing and additive manufacturing use a variety of materials to print out three-dimensional objects that suit many different manufacturing purposes, such as replacing a single broken part in an otherwise fine system. The 3D printing of human organs and other spatial cellular patterns and biological tissues, also called bioprinting, has the potential to replace a broken or unusable part of the human body.
The end product of 3D bioprinted cellular material differs from a cluster of cells cultured in a petri dish, since it actually recreates the multiple layers of cellular tissue. However, this is a great challenge for the creation of different complex organs in the human body. So far, the only organs and bodily structures that have been successfully 3D bioprinted are those that have particularly flat three-dimensional structures such as skin, tubular structures such as urine tubes and blood vessels, and hollow structures like the bladder.
The first patent for a 3D bioprinter was approved in 2006 for the “Ink-jet printing of viable cells”, in which 25 percent of the cells would remain viable after incubation for 24 hours. Traditional inkjet printers heavily inspired early 3D bioprinters, many of which held cells used for the printing process within the walls of inkjet cartridges. Today, bioprinters that follow this same model are able to print out human skin from an ink cartridge directly on a wound.
The company Organovo invented the first commercially produced bioprinter, called the NovoGen MMX Bioprinter. Organovo’s bioprinter uses “bio-ink”, or biological cellular blocks generated from the cells that are taken from the target tissue to represent key architectural and compositional elements. The printer distributes the bio-ink through a traditional layer-by-layer additive manufacturing approach, with an additional robot print head that can print out bio-inert hydrogel components to utilize as supports for structure.
This multilayered tissue derived from complex organs currently has uses in testing the impact of drugs and other pharmaceuticals without harming any humans or animals. In addition, there is much research being conducted to see how these tissues could potentially be used in the future as a source of therapy to treat patients with diseased or damaged tissue. Organovo currently does printing work relating to the liver and its cells, and, since 2013, the organization has been able to create liver tissue with up to 20 cell layers for testing that can last longer than 40 days.
The term bioprinting is not just limited to the printing of biological material. It also applies to the 3D printing and additive manufacturing of different medical devices, such as prosthetics or titanium and ceramic surgical implants. Different replacement appendages designed and manufactured through 3D printing technology have been successfully grafted to the bodies of living things, such as a four-year old boy’s prosthetic ear and a replacement leg for a dog that lost its leg in an accident.
An issue common with all kinds of surgical implants and other foreign materials that is shared with bioprinted materials is that the body can reject them. This can be incredibly worrisome with the replacement of cells and organs, since they could be necessary for keeping the patient alive. Creating bioprinted materials that exactly match the tissues and organs from which they derive will be essential for the possibility of using them for transplantation.
Other issues will arise with bioprinting when it eventually leaves its experimental stage. For example, it will need to be decided whether it will be used simply for testing drugs and for education, or if complete printed organs will actually be transplanted into patients. Transplanting manufactured organs can save the lives of the masses that today require new organs from donors, including the 122,000 people in the United States Organ Transplant Waiting List. However, ethical issues related to printing human tissue are predicted to come up very soon, such as the possibility of enhancing these organs with “nonhuman” capabilities.