The unique characteristic of 3D bioprinting is the cellular ink that is used, from which precisely shaped grafts can be produced. This technique differs from traditional tissue engineering in which a scaffold is first created and then filled with cells.
Tissue engineering has been revolutionized since 2004 by the emergence of three-dimensional (3D) bioprinting. In this approach, additive manufacturing techniques (microextrusion, laser-assisted printing, and inkjet printing) are used to create autologous biological tissues. Mesenchymal stem cells or differentiated cells are placed in a fluid hydrogel to form a “bio-ink.”
The computer-assisted design of the numerical 3D model is based on an “.stl” file, which can be produced from the computed tomography scan of a tissue defect.
To date, the tissues (eg, liver tissue, heart tissue, skin, cartilage) produced with in vitro 3D bioprinting have mostly been centimeter scale, and promising results have been obtained. In vitro bioprinting of composite tissues with different cell types has also been performed with a few encouraging results in animal studies. The growing interest in 3D bioprinting is highlighted by the tripling between 2012 and 2015 of research articles published on this topic. Four journals dedicated specifically to bioprinting have recently been launched.
On a macroscopic scale, the main advantage of 3D bioprinting is that it will allow the creation of personalized autologous grafts that perfectly fit the tissue defect and thereby increase the success of the reconstruction.
Autologous grafts produced by computer-assisted manufacturing will be faster to implant and minimize donor site morbidity. The practical limitation in terms of graft size is the ability to create a vascular network. Once this limit is overcome, the production of “ready-to-implant” organs and autologous free flaps with a vascular pedicle will become possible.