Some day, diseases might be cured by printing new tissue or even entire organs from scratch. A new review article explains what is required to realise this future scenario.
At some point, doctors may be able to cure people with various diseases by bioprinting the tissues or organs that are diseased or damaged or have deteriorated over time.
For example, imagine a person being injured and losing a large piece of a muscle and doctors being able to exactly shape and replicate the functions of the lost tissue.
Another person might have various diseased organs, such as the liver, kidneys or lungs. The doctors could print a new organ and transplant it.
This may all sound like amazing fiction, but researchers have taken many of the first steps towards making this possible.
A new review article identifies the steps required to turn the vision into reality.
“This involves the possibility of being able to cure many diseases using cell therapy: giving the body the cells and tissue it lacks. This could include osteoporosis, cardiovascular diseases or repairing muscle damage. Today we have some technologies that enable us to print cells and thereby construct tissue, but we still lack some tools before achieving this in clinical practice,” explains a researcher behind the review article, Alireza Dolatshahi-Pirouz, Group Leader and Associate Professor, Department of Health Technology, Technical University of Denmark, Kongens Lyngby, Denmark.
The review article has been published in Science.
Several bumps on the road ahead
Only the human imagination sets the limits of the potential applications of such technology. The health technology of the future will clearly change many of treatments people receive.
Right now, however, researchers are trying to solve practical problems in implementing health technologies, including the possibility of bioprinting tissues or organs, and the review article addresses these problems.
The first obstacle is how to deliver the cells to the body so that they stay where they need to be. Implanting liver cells into a person with liver disease is not useful if the cells then disseminate to the whole body.
Currently, various biomaterials are used to try to get the cells to stay in the right place in the body. However, encapsulating the cells in the biomaterials limits the cells’ growth and can very quickly result in insufficient cells to repair any damage.
“The human body contains billions of cells, and many cells are needed to make a difference. In addition, attempting to make enough cells can end up making structures that are too thick, which limits the amount of blood and oxygen reaching the cells. Our review article addresses the issue that using cell therapy with many cells in tissues or even organs requires that we can do this without the constraints associated with using biomaterials,” says Alireza Dolatshahi-Pirouz.
Small organ structures grow too slowly
One way to address this problem is to print tissues and organs very accurately so that they have the exact structure, shape and function required.
Cells and even cell layers can already be printed, but achieving the correct three-dimensional structure is difficult.
The researchers explored the progress so far, showing that three-dimensional tissue structures can be printed with a biomaterial and that these can be implanted in the body – subject to the constraints mentioned.
Another possibility being extensively researched is using bioprinted organoids, a kind of mini-organ that can be grown in the laboratory and printed. The problem with both solutions, however, is time.
Growing an organoid takes many weeks, and the existing printers are also hopelessly slow. The doctors cannot use these solutions if a patient is already lying on the operating table.
“The cell structure and structuring of organs and tissues are special, and we must be able to reproduce this rapidly in a bioprinted material so that the tissues already have the required function and structure when we insert organ tissue or muscle tissue into the body. This requires understanding the special architecture of each tissue and being able to recreate it around a scaffold with a bioprinter. Otherwise, for example, a heart muscle would not have the strength required by the heart,” explains Alireza Dolatshahi-Pirouz.
Stem cells could have a role
Alireza Dolatshahi-Pirouz says that stem cells could also have an important role in future tissue replacement therapy because they can divide and become any cell in the body.
Stem cells are already being used in various ways, and experience from this shows that they secrete growth factors that make tissue heal faster and thus can help to ensure that new and old tissue integrate better.
Specifically, Alireza Dolatshahi-Pirouz envisions people having stem cells taken from the umbilical cord at birth and using them to create new organs and tissues if they are injured or become ill.
The same cells could also be used to create all the necessary cells and layers in a given tissue.
“We would like to be able to print cells in the relevant three-dimensional structures with the right architecture – without using biomaterials. We are not there yet. Organoids also have potential, but we do not know whether they can grow uninhibited once inside the body, and this could be problematic. For now, organoids are therefore best suited for research. Some interesting steps in the right direction have been taken, but some issues need to be addressed and will probably be solved in the future,” concludes Alireza Dolatshahi-Pirouz.
