Printed life – possibilities and limits of bioprinting
Printed life – possibilities and limits of bioprinting
Implants, prostheses and various other components made of plastic, metal or ceramics are already being produced by additive manufacturing. But skin, blood vessels or entire organs from the printer – is that possible? For some years now, intensive research has been underway into the production of biologically functional tissue using printing processes. Some things are already possible with bioprinting – others are still dreams of the future.
In the USA, more than 113,000 people are on the waiting list for a donor organ. This number will increase continuously with life expectancy. In addition to the growing demand, there is also a shrinking supply. According to the U.S. Department of Health and Human Services, this means that about twenty people die every day because they have not received a transplant in time.
More organ transplants, fewer animal experiments
There are too few organ donors to meet the demand for donated organs.
The great hope for closing this supply gap lies in bioprinting – that is, printing biological tissue. However, it has not yet been possible to produce completely functional organs with this technology. Tissue models produced in bioprinting processes are mainly used for drug research. "The idea is to create a mini version of different human organs in a microfluidic chip format, in order to for example test safety of different drugs in a high throughput manner," explains Prof. Aleksandr Ovsianikov from the Institute of Materials Science and Technology at the Vienna University of Technology in an interview.
Such organs-on-a-chip contribute to a considerable reduction in animal testing. Every year, more than 115 million animals are killed in animal experiments worldwide. The number of unreported cases is likely to be significantly higher, as many animals are not included in the animal experiment statistics. Among others, mice, rats, guinea pigs, cats, dogs, horses and monkeys are affected. The effectiveness of drugs is being researched on many of them. Bioprinting therefore not only has the potential to save human lives in the future, but can already prevent animals from suffering and dying for experimental purposes today.
More topic-related exciting news from the editors of MEDICA-tradefair.com:
Currently, there are two methods of producing tissue artificially: 3D laser printing and inkjet printing. In the additive process, the cells are combined with biocompatible materials and a laser beam is applied to a substrate under vapor pressure. This creates the tissue drop by drop. In bioprinting using an inkjet printer, two nozzles work alternately. One nozzle emits a hydrogel – a viscous, fast-curing plastic – and the other nozzle emits the living cells. EnvisionTEC offers a 3D bioprinter with its "3D Bioplotter". They also have biocompatible printing materials such as silicone in their range that can be used for biomanufacturing. In contrast to bioprinting, framework structures are produced from biocompatible materials, which are subsequently seeded with living material, i.e. cells.
So far, bioprinting has made it possible to print simple tissues such as muscle, cartilage, skin and parts of the liver or kidney. For the production of complete functional organs, three requirements must be met: First, a framework is needed that defines the shape. Secondly, living cells must be implemented in the right places. And third, the artificial organ must be supplied with blood. Only then is the organ viable.
"Cells are highly sensitive"
Instead of the usual material used for 3D printing – plastic, metal or ceramic – bioprinting uses cells in combination with biocompatible material.
Today, additive manufacturing can easily meet the first requirement. The second requirement is somewhat more complex. Dr. Achim Weber from the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB explains in an interview why printing with living material is so difficult: "Cells are highly sensitive and they love their natural environment." So not only must a certain temperature and physiological pH value be maintained during the printing process, but the shear forces resulting from the high acceleration also play a role. However, if printing is too slow, the composition of the ink can change. "That's why we need a material that can protect the cells from dying once it is added," says Weber, who is conducting research on such bio-inks at Fraunhofer IGB. Gelatine is particularly suitable for this purpose. An algae-based bio-ink was developed at Harvard Medical School.
Bioprinting is currently not yet able to create blood vessels to supply an artificial organ with nutrients. In addition, previous methods are too slow for large organs, so that the cells die during the printing process. Added to this are the difficulties generally encountered with transplants in terms of transport and storage. Scientists at UC Berkeley have therefore developed parallelization – a process in which several printers simultaneously print 2D layers, which are then stacked on top of each other to form a 3D structure. The 2D-printed cells are frozen directly as they are joined to the rest of the 3D structure. All this significantly minimizes cell death during printing, freezing, transport and storage.
Of successes and records
Artificial knee joints, foot prostheses, dental implants – the applications of 3D printing in medicine are numerous. Will it soon include the production of entire organs?
Prof. Ovsianikov and his 3D Printing and Biofabrication research group at the Vienna University of Technology have developed a particularly fast process: "Processing speed relies on the material sensitivity. We have developed specialized bio-inks that can be processed with a laser scanning speed of up to one meter per second in the presence of cells. This is an absolute record." Gelatine was also used as the basis here. "My group began commercializing this technology a couple of years ago in order to make it more accessible to other users. With the NanoOne, our start-up UpNano GmbH has developed the fastest device in the world that is also capable of embedding cells," he reports on the success to date.
Researchers at Tel Aviv University (TAU) recently even succeeded in developing a functional mini heart from the 3D printer. Together with Bayer Pharmaceuticals, they are testing drugs on the artificial heart tissue. Earlier, TAU produced a 3D-printed cardiac patch to regenerate the heart in patients with cardiovascular disease. The patch was made from the patient's own fatty tissue. A novel bio-ink developed at Terasaki Institute in the U.S. enables 3D printing of tissue directly on the body.
Products and exhibitors about bioprinting
Exhibitors and products related to laboratory technology and 3D printing can be found in the database of MEDICA and COMPAMED 2020:
All these examples illustrate the problem of the lack of standardization and reproducibility of the results, since the most diverse approaches are being worked on worldwide. But they also give rise to hope. "We keep learning new things about the interaction between different materials and living cells. It is highly likely that we will be able to print more complex structures and high-resolution constructs in the near future," confirms Dr. Weber.
Researchers predict that 3D printing of entire functioning organs will be possible in about 10 to 20 years. By then, life-saving organ transplants could be printed, patients could be better treated, expensive hospital stays could be reduced and animal testing could be a thing of the past.
The article was written by Elena Blume. MEDICA-tradefair.com