The world is faced with a vast array of diseases, injuries, and other health conditions that can cause significant pain, suffering, and even death. Many of these conditions are difficult to treat and often require complex surgeries or long-term medical interventions. To help overcome these problems, scientists and medical researchers around the world have been exploring new ways to address these challenges. One of the promising fields that have the potential to revolutionize the way we treat diseases and injuries is tissue engineering.
Tissue engineering is a rapidly advancing field that seeks to create replacement tissues and organs using a combination of cells, biomaterials, and engineering techniques. It is a multidisciplinary approach combining biology, chemistry, physics, and engineering principles to create functional tissue constructs that can replace or repair damaged or diseased tissues. The ultimate goal of tissue engineering is to develop effective treatments for a wide range of illnesses and injuries, from simple skin wounds to complex organ failures. By creating functional tissues and organs in the lab, scientists can better understand how diseases progress and how to develop more effective treatments (Fig. 1) .
Fig.1 Examples of tissue engineering 
One of the key challenges in tissue engineering is creating complex structures that are found in living tissues. Traditional manufacturing techniques, such as injection molding, are not well-suited to creating these complex structures. However, as the field of tissue engineering is constantly evolving, new technologies and techniques are constantly being developed. This is where 3D printing, also known as additive manufacturing, comes in. 3D printing is a process of creating three-dimensional objects by building up layers of material . The most popular methods are:
- Fused Deposition Modeling (FDM): This is the most common type of 3D printing. It works by heating and extruding thermoplastic material through a nozzle to build the object layer by layer. FDM is a relatively simple and inexpensive method of 3D printing, making it accessible to individuals and small businesses.
- 3D bioprinting: This method uses bioink, a mixture of living cells and a supporting material, to print living structures. The printed structure is then incubated in a controlled environment to promote cell growth and tissue development.
- Melt Electrowriting (MEW): This method utilizes a process of extruding a melted material, such as a polymer, through a fine nozzle while applying an electric field to control the shape and structure of the printed material. MEW is capable of creating highly complex, precise, and customizable structures with high resolution.
As each technique has its unique advantages and disadvantages, the choice of method will depend on the project and desired properties of the final application. 3D printing is used to create custom-made implants and in vitro organ and tissue models. The in vitro models can be used to study the behavior of cells and tissues in a controlled environment, providing valuable information for developing new drugs and therapies. 3D printing also enables the production of scaffolds for tissue growth that can mimic the natural architecture of living tissues. These scaffolds can be used to provide a framework for cells to grow and differentiate into the desired tissue types .
Examples of the use of FDM, 3D bioprinting, and MEW for in vitro models, organs, and tissues, as well as for drug development, are numerous and constantly evolving. In one of the examples, researchers used FDM to create 3D-printed bone models to study bone remodeling and bone growth. The study showed that FDM-created models closely mimicked the mechanical properties of natural bone . In another study, 3D bioprinting was employed to create in vitro cardiac tissue model. The developed tissue model had a similar structure and biomechanical functions to native cardiac tissue and could be used as a powerful tool for studying the effects of various diseases and treatments on heart tissue . The 3D bioprinting approach was also used to print the vascularized liver model. The printed structure demonstrated a resemblance to the native tissue with enhanced urea synthesis. In addition, the model was used to test the toxicity of various drugs and showed dose-dependent hepatotoxicity, revealing its potential as a platform for efficient drug screening . Neural regeneration was studied on scaffolds fabricated with MEW. The results showed that the 3D structures were effective in promoting nerve regeneration, suggesting that they may be a useful tool in treating nerve injuries . Another interesting application where MEW was used is the regeneration of the tympanic membrane which separates the outer ear from the middle ear. The researchers used MEW to produce a membrane that has matching mechanical and acoustic properties of native tissue and has the potential to support the healing process .
Another exciting area where 3D printing is making an impact is personalized medical devices, such as prosthetics, implants, and surgical tools. For example, 3D printing has enabled the creation of customized prosthetics with intricate designs and shapes that closely match the individual patient’s anatomy, leading to improved comfort, functionality, and aesthetic outcomes. In addition, 3D printing can also be used to fabricate surgical tools, such as patient-specific guides and templates, that can improve the accuracy and precision of procedures, leading to better outcomes for patients . These are just a few examples of the many ways that 3D printing technologies are being used in medical research and development. With continued advances in these fields, the potential for breakthroughs in the treatment of disease and injury is immense.In conclusion, 3D printing is a rapidly advancing technology that has the potential to further revolutionize the field of tissue engineering. Its ability to create complex and customized structures, and its cost-effectiveness, make it a promising technology for medical research and the treatment of various diseases. The ability of 3D printing to create implantable devices such as scaffolds, and in vitro models, has opened new possibilities in tissue engineering and drug development. Overall, 3D printing has the potential to transform the way we approach medical research and improve patient outcomes. However, there are still many challenges to be addressed, such as improving the accuracy and resolution of printed models and scaling up production to meet the demand for large quantities of functional tissue. Despite these challenges, the future of 3D printing in medical research is bright, and we will likely see continued progress and development in this field in the coming years.
- O’Brien, F.J., Biomaterials & scaffolds for tissue engineering. Materials Today, 2011. 14(3): p. 88-95. https://doi.org/10.1016/S1369-7021(11)70058-X
- Chung, J.J., et al., Toward Biomimetic Scaffolds for Tissue Engineering: 3D Printing Techniques in Regenerative Medicine. Frontiers in Bioengineering and Biotechnology, 2020. 8. https://doi.org/10.3389/fbioe.2020.586406
- Zieliński, P.S., et al., 3D printing of bio-instructive materials: Toward directing the cell. Bioactive Materials, 2023. 19: p. 292-327. https://doi.org/10.1016/j.bioactmat.2022.04.008
- Sudheesh Kumar, P.T., et al., Additively manufactured biphasic construct loaded with BMP-2 for vertical bone regeneration: A pilot study in rabbit. Materials Science and Engineering: C, 2018. 92: p. 554-564. https://doi.org/10.1016/j.msec.2018.06.071
- Wang, Z., et al., 3D bioprinted functional and contractile cardiac tissue constructs. Acta Biomaterialia, 2018. 70: p. 48-56. https://doi.org/10.1016/j.actbio.2018.02.007
- Janani, G., et al., Mimicking Native Liver Lobule Microarchitecture In Vitro with Parenchymal and Non-parenchymal Cells Using 3D Bioprinting for Drug Toxicity and Drug Screening Applications. ACS Applied Materials & Interfaces, 2022. 14(8): p. 10167-10186. https://doi.org/10.1021/acsami.2c00312
- Zhang, Z., et al., 3D anisotropic photocatalytic architectures as bioactive nerve guidance conduits for peripheral neural regeneration. Biomaterials, 2020. 253: p. 120108. https://doi.org/10.1016/j.biomaterials.2020.120108
- von Witzleben, M., et al., Biomimetic Tympanic Membrane Replacement Made by Melt Electrowriting. Advanced Healthcare Materials, 2021. 10(10): p. 2002089. https://doi.org/10.1002/adhm.202002089
- Aimar, A., A. Palermo, and B. Innocenti, The Role of 3D Printing in Medical Applications: A State of the Art. Journal of Healthcare Engineering, 2019. 2019: p. 5340616. https://doi.org/10.1155/2019/5340616