Bioprinting: A Modern Solution to the Organ Shortage Crisis

Have you ever wondered how many people are on the organ waiting list, just waiting for someone to donate an organ to them so they can have another chance at life? Nearly 107,000 people in the United States are currently waiting for an organ donation, and 3,467 of them are waiting for a life-changing heart transplant. Our body is full of organs; we are one of the most advanced organisms in the world. The human body is known as the most complex machinery, running purely on biological matter and nothing else.

An organ transplant is one of the most complicated surgical procedures in the world (due to the fact that there is a high risk of death in procedures like this.), but it can only be done if there is an organ to be transplanted. Today, thousands of people are dying because they don’t have an organ to be transplanted. Having the organ is one thing, but the organ actually matching the host’s body is extremely important. Blood groups, tissue groups, and antibody groups need to match almost perfectly for the body to be able to adapt to the foreign organism that it has been placed inside of.

If the organ doesn’t match the host’s body, it can potentially harm the host, even killing them on certain occasions. This is because if the body doesn’t adapt to the foreign specimen, its immune system will start attacking the transplanted organ, believing it to be a harmful virus, causing it to stop functioning properly. This element makes it extremely difficult to find a match for an organ transplant. It is almost impossible for an organ to match perfectly with the host’s body as every human being has a different DNA and tissue matter.

But, modern problems call for modern solutions and scientists and researchers have found a solution to this daunting problem. The discovery of bioprinting organs can potentially save millions of lives and even aid in the invention of *hybrid specimens. Bioprinting in simple words - is printing organs, sounds freaky doesn’t it? It works on the same concept and principle as 3 dimensional printing but the ink that is used is simply different. While in 3D printing, you use molten plastic that eventually hardens, in bioprinting, you’re using a biological solution consisting of living tissues and cells that react to the body's needs. Bioprinting is simply biomedical engineering that uses biomaterial in 3D printing. You can call it biological engineering as they are using biological matter to make a structure that fulfills the job of an organ and sustains and holds up an organ system. This structure that imitates an organ and does everything an organ does, is essentially a substitute.

Like 3D engineering, bioprinting uses bioinks and stacks them in a layered fashion to create other 3D structures like tissue and organs. Scientists first need to create a microarchitectural plan that is suitable for the printing process as well as its placement in the human body. Then, cells and living bits of tissue are layered to make the biological architecture to make the organ or tissue suitable. Bioprinting is much more complicated and complex than 3D printing because the cells that are being implemented into the bioink are extremely sensitive and can easily die, they are also susceptible to diseases causing them to be infected.

Even though bioprinting comes with its own flaws and problems it is much more efficient than finding a suitable organ because you can take a specimen of cells from the host and customize the printed organ to perfectly match the host’s bodily conditions and attributes. You can take a supplement from the host that is in need of an organ and you can implement it into the bioink, allowing it to have customizable properties, allowing the printed organ to be a 100% match as it comes from the host themselves.

While bioprinting obviously doesn’t work like traditional 3-Dimensional printing, it works similarly with a similar kind of printer in place. The four different types of bioprinters include, inkjet-based, extrusion-based, laser-assisted and stereolithography-based. Now for a brief overview on each of these printer types.

Inkjet-based printers

●      They work like traditional inkjet printers, but instead of inks, they use bioink droplets, which are placed precisely layer by layer onto a surface.

●      The mechanism involves a thermal inkjet and a piezoelectric inkjet.

●      Thermal inkjets heat the bioink to form bubbles, which push the bubbles out.

●      Piezoelectric inkjets utilize electric pulses to force the bioink droplets out and onto a surface. The piezoelectric inkjets are much safer for the cells because they avoid using any heat in the process of forcing the ink droplets out, instead using electric pulses.

●      Pros: Fast, inexpensive, good for high cell viability, suitable for small-scale structures.

●      Cons: Limited to low **viscosity bioinks are not ideal for large or complex tissue structures.

Extrusion-based printers

●      Extrusion-based bioprinting is the most common type of bioprinting today.

●      Bioink is continuously extruded through a nozzle using a mechanical pressure that creates strands of layers that can stack to form the desired outcome of a 3D structure.

●      The bioink is dispensed through a syringe.

●      Cells and biomaterial contained within the bioink, are extruded in a controlled pattern to make biological structures with tissue-like shapes.

●      Pros: Can print with higher viscosity or thicker inks, useful to print more complex tissue structures, and are compatible with many times of ***hydrogels and cell types.

●      Cons: Lower resolution and cells may experience pressure and stress during extrusion.

Laser-Assisted Bioprinting

●      Used to create precise pressure waves that propel droplets of bioink onto the printing surface.

●      Laser pulse hits an absorbing layer, creating a tiny bubble.

●      The bubble pushes the droplet of bioink onto the printing surface.

●      Pros: Extremely precise and accurate, can handle high cell density, low mechanical stress on the cells.

●      Cons: Expensive and complex to operate as well as much slower, especially for large-scale printing.

Stereolithography-Based Bioprinting

●      Uses a light, that is usually ultraviolet, to solidify the bioink in a layered fashion through a process called photopolymerization.

●      The bioink solution is engineered to contain special light-sensitive polymers within it which are able to react to the ultraviolet light and solidify.

●      A focused light beam or projector cures the bioink into a precise shape. The build platform moves according to the biological structure.

●      Pros: Very high resolution, smooth surface finishes, great for printing microstructures.

●      Cons: Bioink must be photopolymerized, and the UV exposure can potentially harm the cells within the bioink solution.

By permitting the manufacturing of fully operational, patient-specific tissues and organs, bioprinting has an opportunity to completely alter medicine. As technology develops, researchers aim to tackle issues like lowering transplant waiting lists, enhancing long-term cell survival, and creating complex structures with blood vessels. Bioprinting could one day allow for tissue production in space, customized drug testing, quicker wound healing, and on-demand organ replacement. Bioprinting has the potential to change healthcare and prolong human life, but it is still in its infancy.

Imagine for yourself, there are so many people around you. Family, friends, colleagues, acquaintances and much more. Anyone could get an organ failure. Over 54,512 people have died of kidney failure in the United States in 2023. The people you know could have been one of these 54,512 people and they could be in the near future. Have you realized that all these people have been on the organ waiting list at one point but never found their match? Yes, sadly many people die waiting on the long list of organ transplants, but thanks to bioprinting, we can lower those numbers and maybe one day, hopefully in the near future, we can save every life that needs an organ transplant.

*Hybrid specimen invention: Hybrid specimen invention is when scientists or farmers create a new living organism by combining two different species or types to produce improved or useful traits, like better growth, strength, or resistance to disease. This is done in farming, animal breeding, and research to solve problems, boost productivity, or study genetics. Hybrid specimens are often stronger or more useful than their parents but sometimes can't reproduce.

**Viscosity means the density of the ink.

***Hydrogel: A hydrogel is a soft, water-rich substance used in bioprinting that consists of a network of polymers and has a high retention of water, frequently more than 90% of its weight.

Because hydrogels may imitate the soft, jelly-like environment found in natural human tissues, they are used as biological inks or as support structures during the printing process. After printing, this offers a secure, nutritious environment for living cells to live, increase, and organize.