3D printing, is driving major innovations in many areas, such as engineering, manufacturing, art, education and medicine. Recent advances have enabled 3D printing of biocompatible materials, cells and supporting components into complex 3D functional living tissues. 3D bioprinting is being applied to regenerative medicine to address the need for tissues and organs suitable for transplantation. 3D bioprinting involves additional complexities, such as the choice of materials, cell types, growth and differentiation factors, and technical challenges related to the construction of tissues.

Addressing these complexities requires the integration of technologies from the fields of engineering, biomaterials science, cell biology, physics and medicine. 3D bioprinting has already been used for the generation and transplantation of several tissues, including multilayered skin, bone, vascular grafts, tracheal splints, heart tissue and cartilaginous structures. Other applications include developing high-throughput 3D-bioprinted tissue models for research, drug discovery and toxicology.

3D printing was first described in 1986 by Charles W. Hull. In his method, which he named ‘sterolithography’, thin layers of a material that can be cured with ultraviolet light were sequentially printed in layers to form a solid 3D structure.

Development of solvent-free, aqueous based systems enabled the direct printing of biological materials into 3D scaffolds that could be used for transplantation. A related development was the application of 3D printing to produce medical devices such as stents and splints for use in the clinic.

In a typical process for bioprinting 3D tissues imaging of the damaged tissue and its environment can be used to guide the design of bioprinted tissues. The choice of materials and cell source is essential and specific to the tissue form and function. These components have to integrate with bioprinting systems such as inkjet, microextrusion or laser-assisted printers.

Uses of 3D Bioprinting

Transplants

Terumo, a Japanese conglomerate, has commercialized the Heart Sheet for treatment of heart failure in Japan.

To develop Heart Sheet, muscle tissue is harvested from the patient’s leg and cultured in vitro. Cardiac tissue engineering techniques such as this one can be used to create functional constructs capable of re-establishing the structure and function of damaged myocardium following myocardial infarction. The engineered cardiac tissue, which often comes in the form of a “patch”, is implanted directly onto scar tissue.

The intention is to compensate for the heart’s reduced function by strengthening its structure and boosting its ability to pump blood.

This way, researchers hope to reduce the need for transplants, improve recovery and prevent subsequent events. 3D bioprinting has the potential to provide a heart or blood vessels to patients in need of transplants. The tissue would be made from their own cells, thereby considerably reducing the risk of rejection.

Researchers from Tel Aviv University unveiled the first 3D bioprinted heart with human tissue including chambers, ventricles and blood vessels. To accomplish this, a biopsy of fatty tissue from patients was taken to produce the cells required. Patient-specific cardiac patches were produced first, after which the entire heart was made.

Proposed process for the generation of 3D heart valves through bioprinting to arrive at functional tissue engineered heart valves

(a)slice of CT images

(b)3D CAD model generation

(c)3D bioprinting through bio-ink/ 3D printing through polymer scaffold

(d)3D printed scaffold

(e)scaffold ready

(f)Development of tissue through combining cells, growth factors and developed scaffold

(g)Development and initial tissue remodeling in bioreactor