From prosthetics to regenerated organism

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Even in ancient times, a person who had lost a big toe might have been provided with a prosthetic replacement. It is clear from mummified skeletons that they were made out of wood, leather or papier mâché. Nowadays, researchers are developing prostheses and implants that are designed not only to replace limbs but actually to regenerate the organism. This can take the form of a thin "synthetic plaster" covered in pigment cells that restores retinal function, or a heart valve that grows with the recipient and will ideally last a lifetime. While the retinal implant is currently being tested in a clinical study in London, the heart valves are already in routine use. Professor Axel Haverich (only in German) has been performing this surgery for ten years now at Hannover Medical School. After the cells have been washed out of donor heart valves, the collagen scaffold that remains is populated with the patient’s cells in the lab ready for transplanting.

Tissue and cells can be regenerated

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"In principle, regenerative medicine is about regenerating all kinds of tissue and cells", explains Professor Frank Emmrich, director of the Fraunhofer Institute for Cell Therapy and Immunology IZI in Leipzig. Thus regenerative medicine is also concerned with the cells of the immune system, their specific improvement being the goal. In CAR-T cell therapy (chimeric antigen receptor T cells) for example, immune cells are removed from patients and "trained" in the lab to recognise cancer cells. To this end, they are equipped with genetically optimised receptors. These receptors identify molecules that occur in the mutated cells of patients with leukaemia and other types of cancer. The Fraunhofer IZI is currently testing the effectiveness and safety of CAR-T cell therapy. In collaboration with the University Hospital of Würzburg and the Max Delbrück Center for Molecular Medicine (MDC) in Berlin, IZI is preparing the first patient study. Professor Emmrich, a doctor and immunologist, is optimistic: "What makes this therapy so elegant is that the genetically modified T cells multiply in the patient's body and protect the healthy tissue." As he points out, however, this cell therapy is so far suitable only for leukaemia and not for cancers involving solid tumours such as breast or lung cancer.

Automatic production of replacement tissue

Another area of research in biomedical engineering involves cultivating tissue and organs from the patient’s own cells in the laboratory. Known as tissue engineering, this technique aims to address the shortage of donor organs for transplants. With the aid of bioprinting, the idea is to automate and accelerate the production of artificial replacement tissue.

So that such procedures can be put into clinical practice as quickly as possible, researchers at the Department of Plastic and Hand Surgery at the Medical Center – University of Freiburg (only in German) have teamed up with the Department of Microsystems Engineering at the University of Freiburg and a number of companies to form the 3D-Bio-Net consortium (only in German). Their goal is to create and trial a platform for bioprinting. Besides a special bioprinter, this would also require software that is capable among other things of translating the three-dimensional structures of artificial tissue into a language that the printer can "understand".

Scientists at the Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB in Stuttgart have developed what are known as bio-inks that they hope will allow tissue to be printed out as if on an inkjet printer. Gelatine and cells form the basis of the transparent liquids. The biomolecules can be modified so as to give them different levels of strength and different swelling properties. Natural tissue – from hard cartilage to soft fatty tissue – can be replicated and printed in this way.

A complex challenge: breathing life into printed tissue

Comparing this process to an inkjet or 3D printer for plastic components only makes sense at first glance. As Emmrich explains, actually breathing life into printed tissue is complicated: "It has to be supplied with blood via a vascular system, which requires different cell types and structures to be combined. The bigger the tissue, the harder this becomes." Clearly, biomedical engineering still faces considerable challenges, yet there can be no doubt that it will play a key role in shaping the medicine of tomorrow.

 

Fraunhofer Group for Life Sciences

Europe's largest application-oriented research organisation, Fraunhofer, pools its expertise in biology, chemistry, biochemistry, biotechnology, medicine, pharmacology, ecology and nutrition science in its Group for Life Sciences. Besides the Fraunhofer Institute for Cell Therapy and Immunology IZI, five other research institutions belong to the group. Its scientists also contribute expertise in IT, engineering science and legal regulations. The Fraunhofer Group for Life Sciences covers the entire process from development to application – not only in its biomedical technology business unit, but also in the area of food safety and when it comes to biotechnology processes for the bioeconomy and screening methods for environmental and consumer protection.

www.lifesciences.fraunhofer.de