Essay Sample on Bioprinting: The Future of Organ Transplants

With patients requiring a kidney transplant having to wait anywhere from 3-5 years or even longer, a new solution was needed to offset the long wait times. Bioprinting is a groundbreaking technology being researched to solve the problem. Bioprinting is a manufacturing process where cells are printed together to create an imitation of natural tissues found in the human body. At current, there are four main methods of bioprinting: inkjet, extrusion, laser-assisted, and electric field assisted. While all four methods can produce cell structures, each method has its strengths and weaknesses that make no one method better than another at current. For a cell structure to be successfully printed, many sensitive variables must be controlled, as well as a very specific process that must be followed.

Regardless of which bioprinting method is utilized, all of them roughly follow the same standard process. First, a CT or MRI scan must be taken of the patient to get the exact dimensions of the organ. The scan is then taken and replicated as a 3D model in CAD software. 

The finalized model is then run through a slicer, which is another 3D program that analyzes the model and determines the structure of the layers required to successfully print the model. 

Next, the bioink gets prepared. 

This is a very sensitive process due to the substance being patient and function specific. The bioink is a combination of living cells and a compatible base made from a natural or synthetic polymer that the cells can survive on. During the printing process, the bioink is layered into the shape of the 3D model. Finally, once the printing is done, solidification takes place. During the process, the once viscous bioink solidifies into shape. 

As it solidifies, a process called crosslinking is conducted to mesh the layers together. Crosslinking is handled by UV lights and sometimes additional chemicals. Once the part is done crosslinking, it is ready to be used.

Inkjet-based bioprinting is comparative to traditional inkjet printers. As a plate travels through the printer, tiny nozzles deposit droplets of bioink onto it. 

This method allows for high-resolution printing and preciseness of a single cell at a time even. Extrusion-based bioprinting is comparable to a high-tech hobbyist 3D printer. It prints in scaffolded layers to produce a three-dimensional result. Due to the versatility of 3D printing, extrusion-based printing was one of the first modalities developed and is one of the most widely used methods today (Zhang et al., 2021). 

Laser-assisted bioprinting is a recently developed advanced method that utilizes lasers to move cells from a solution onto a surface with both high speed and precision. Due to not being restricted by a nozzle, higher viscosity bioinks can be utilized. However, due to the heat generated from the lasers, there is a chance that the cells could be damaged during the printing process. Electric field-assisted printing utilizes electric fields to print droplets and fibers at nanometer-level precision. Due to the high voltages used to control the cell structures when sprayed, there is a risk that the electrical current will damage the cells in the process of printing.

Even with a multitude of methods and strategies for bioprinting, there are still several hurdles to overcome before they can be fully realized. One of the biggest obstacles is the limited options of biomaterials to be utilized in bioink. While synthetic polymers can be utilized and are highly adaptable, they are non-degradable and lack cell adhesion qualities. In turn, they are unable to support cell growth very well. Even so, the alternative of natural polymers is not a complete solution either. Natural polymers are better suited for cell adhesion and growth but are not as strong and are prone to deterioration. As a result, a blend of the two is required. To achieve this, a balance between printability, biocompatibility, mechanical properties, and sterilization stability is required (Mao et al., 2020). 

When it comes to biocompatibility, the printed scaffolding support must not only be biodegradable but also have several finer requirements. The degradation rate should not only match the cell's production rate to replace implanted materials, but the scaffolding must also be non-toxic and easily metabolized so that it does not jeopardize the integrity of the print. 

Finally, the speed and resolution of prints must be further accelerated to make the use of prints to quickly care for patients realistic.

With the continued research into materials for bioprinting, scientists continue to find more and more optimized blends of bioinks. 

As the number of usable materials expands, bioprinting becomes more accessible. At current bioprinting is developing both as a technology and as a regulated practice. Currently, the FDA does not have an official definition for bioprinting or any regulations under an existing or new framework (Tibbetts, 2021). This makes applying bioprinting in actual practice difficult due to the lack of regulations or definitions for the work. Even so, bioprinting continues to develop further in labs. 

With the currently developing technologies in the field, it can be expected that researchers will meet their goals of increasing both the printing speed and resolution of the prints. 

Ideally, within the next few decades, scientists will be able to revolutionize bioprinting to the point of being able to print organs, tissues, and other biological parts. With this development, bioprinting will ideally be available to all on demand, resolving the long wait lists for organ transplants.