The world has been facing the crisis of supplying transplantable organs over the last decade. The most promising solution to rectify this shortage is the use of tissue engineering techniques. One of the developing strategies to overcome this deficit is using “3D bioprinting”.
Ø What is 3D bioprinting?
It is a fabrication technology which is used in constructing living tissues or artificial organs using cellular layers with digital control. The high printing resolution makes the matrix/biomolecules/cells and biomaterials (bioinks containing hydrogels) to be suspended in the bioinks to mimic the nature of the functional tissues.
Ø Types of bioprinting techniques
· Inkjet printing – the first bioprinting technology very much similar to conventional 2D inkjet printing. The cost is low and cell viability is more than 85%
· Laser assisted printing – it consists of a donor layer comprised of energy absorbents where a laser pulse is applied for stimulation. The cost is high and the cell viability is more than 95%
· Extrusion printing – it is a modification of inkjet printing which is used to print the viscous materials with varying densities. The cost is moderate and the cell viability is around 40-80%
· Stereolithography – it uses light to solidify the bioink layers to print complex patterns over the printing plane. It is more advantageous than the traditional methods. The cost is low and the cell viability is more than 85%
Ø Applications
o Tissue assembly for reconstructive surgery (regenerative medicine).
o Used in constructing functional tissues such as muscles, bone, cartilages and vasculature.
o Efficient tool for drug delivery and preclinical testing
o Can restore functional tissues or organs with lifelong immunosuppression after transplantation.
o The bioengineered substances are much stronger than the average body tissues and materials
o Recently has been used in cancer research to examine the pathology, growth and metastasis.
Ø Limitations
· Lack of integrity and mechanical strength of the structures due to the innate properties of hydrogels.
· The structures should withstand the external pressure and the shape after implantation.
· The bioinks should be less viscous to prevent clogging.
· It is a great challenge to print hollow complex structures using the layer methods.
· A sacrificial material should be used to prevent collapse between the layers, but this might increase the complexity of the process too.
· No proper reliable methods are available to print pre-vascularized tissues.
· Self-assembly of vascular tissues is a slow process which can lead to necrosis in partially assembled tissues.
· Materials with cell compatibility and mechanical properties should be carefully selected.
Bioprinting plays a vital role in bio fabrication to create micro and macro scale biomedical systems. In the future, it can be an efficient tool which may use nanoparticles for artificial organ generation. Bioprinting can be used wherever the integration of live cells are needed. DNA assays of stem cells, proteins and biosensors are already designed through bioprinting. It has a huge potential in drug delivery and preclinical testing due to its high speed. The in vivo bioprinting assessments are still in their initial stages. However this 3D bioprinting technique is a promising remedy for increasing organ shortages. In spite of all the challenges, this is a growing technology with massive potential in the long run.