There are a lot of people waiting for organ transplants and not many organs to give them. This has led to a lot of interest in creating organs in a laboratory. One of the most promising of these routes is 3D printing organs.

Traditional 3D printing of organs works like regular 3D printing. First, scientists prepare the material they are printing with. In organ printing this is often a mix of stem cells. The 3D printer then puts tiny dots of this mixture out onto a sheet layer by layer, slowly building up the organ. The stem cells then grow together to create a solid organ.

This approach had a problem however: it was really difficult to create blood vessels in these organs. Without blood vessels the organs couldn’t get blood and they wouldn’t work. Recently, researchers at Harvard have developed a method that has the potential to solve this.

In their printing method (called SWIFT), a bunch of stem cells are mixed together into a gel that has a similar texture to mayonnaise. They then put this gel into a mold in the shape of the organ. They use a 3D printer to inject trails of ink into the gel. These gel trails are inserted in a blood vessel pattern. After the stem cells harden together into a solid organ this ink is removed. It leaves behind empty space in the shape of blood vessels, allowing blood to flow through the organ and keep it alive.

While there is a lot of work left to do before this method can be used to print full-sized organs, it is a huge step forward in 3D organ printing technology. Maybe you can be one of the scientists who helps perfect it!

Scientists are exploring many different techniques for 3D printing organs and tissues. Sometimes, 3D printing is used to create a scaffold (like the scaffolding used when building a house) for cells to grow on. When creating this “cell scaffold” structure, it is important to pick a material that is biocompatible, meaning it will not cause damage inside the body, and the immune system will not attack it. Sometimes, cells are added to a structural material before printing, and the mixture is called a “bio-ink.” This bio-ink is usually printed in layers to create 3D structures.

For a complicated organ, there will be many different types of cells, and it is a challenge to make sure they are properly organized. An important advantage of this method:
A 3D printed organ could use cells taken from the same person who will receive the transplant. This will lower the risk that the body’s immune system will attack the transplanted organ.

At this time, 3D printed organs are not yet advanced enough to be used in real transplants. A major challenge is that it is difficult to create working blood vessels, as they are very small and their structures are very complicated. However, the field of 3D printing organs is very active, with exciting new breakthroughs happening very often. Just recently scientists have used 3D printing to make artificial skin with working blood vessels ( here). They believe this will soon be used to treat people with severe burns.

From this article:
organ printing

"Modified inkjet printers have been used to produce three-dimensional biological tissue. Printer cartridges are filled with a suspension of living cells and a smart gel, the latter used for providing structure. Alternating patterns of the smart gel and living cells are printed using a standard printing nozzle, with cells eventually fusing together to form tissue. When completed, the gel is cooled and washed away, leaving behind only living cells."