PolyKARD- Artificial Cardiac Tissue...

In the future, novel polymers should make it possible to individually manufacture artificial elastic tissue replacements for pericardium, heart valves or blood vessels. In the PolyKARD project, biomimetic polymers are being developed that can mimic the mechanical properties of the pericardial tissue. Using 3D printing and electrospinning, tailor-made implants are to be produced from it. In addition, a 3D printer is to be developed for the first time that can produce class III medical products. The PolyKARD partners - AdjuCor GmbH, the Fraunhofer Institute for Applied Polymer Research IAP, the NMI Natural Science and Medical Institute, Young Optics Europe GmbH and pro3dure medical GmbH - want to manufacture the implants up to the first clinical studies, probably in 2022. advance.

Heart disease is one of the most common causes of death. Around 23 million people worldwide suffer from cardiac insufficiency – and the trend is rising. In contrast, the number of heart transplants is stagnating at around 3000 transplants per year worldwide. Artificially produced implants could help many people who are waiting for a donor organ. The 3D printing of precisely fitting implants has become indispensable in medicine, for example in orthopedics or dental surgery. For implants that are intended to replace elastic tissue, however, the need for research is much greater, because the demands on the materials are high: they must retain their mechanical properties for many years, be 100% durable and biocompatible and must not cause any rejection reactions from the immune system. The latter is particularly important for materials that are in permanent contact with the body.

New polymers for modern printing technologies and individual medical technology

As part of the PolyKARD project, biomimetic polymers are being developed that are intended to mimic the biological and mechanical material properties of the heart sac, also known as the pericardium. The pericardium is a collagenous and mechanically extremely stable structure that surrounds the heart. The pericardium of cattle or pigs is already being used clinically as a replacement for human heart valves or for the reconstruction of blood vessels. However, the processing of animal tissue is expensive and mechanically does not guarantee long-term stability. The unreliable quality due to the great variability between the donor animals as well as ethical and religious aspects are also problematic.

»In the project, we are developing biomimetic pericardium replacement materials that can be used, for example, for artificial heart sacs, heart valves, blood vessels, stents, tendons or septum closures. The special thing about it is that the implants are made of photopolymers and can be produced individually in a 3D printer or by means of electrospinning. The monomers are developed as inks or resins. They only polymerize when they are irradiated with UV light," explains Dr. Wolfdietrich Meyer, who heads the project at the Fraunhofer IAP in Potsdam. The research team at the Fraunhofer IAP is synthesizing a photo-crosslinkable material that consists of different polyurethane segments and collagen components.

Elastic, biocompatible and durable

The newly synthesized polymers are tested for in vitro cytotoxicity at the NMI in Reutlingen according to DIN EN ISO 10993-5. When processing the polymers, various 3D printing manufacturing processes are used on the one hand, and so-called electrospinning on the other. At the NMI, this spinning process is used to create porous structures that can grow together with the patient's own tissue.The carrier substrates produced are characterized with regard to their mechanical and biological properties. A special focus is placed on the simulation of the mechanical properties of the pericardium and on the growth behavior of cells.

The first application of the biomimetic polymer is to print a novel surface for an extravascular heart support system. The system from Munich-based AdjuCor GmbH is based on a patient-specific, mechanical implant, which is positioned completely outside the bloodstream (extravascular) in the pericardial cavity around the epicardial surface of both heart chambers. »A biomimetic pericardium replacement material would only cause minor immune reactions and would therefore lead to a gentle healing phase. This can further shorten intensive care and hospital stays«, explains cardiac surgeon and CEO of AdjuCor Prof. Stephen Wildhirt.

On the way to market maturity

In order to be approved on the market for clinical applications in the future, both the new photopolymers and the processing methods must meet extensive requirements. For the large-scale production of photopolymers, the GMP guidelines (English Good Manufacturing Practice, GMP for short) must be observed. They ensure the quality of the production processes and environment. The company pro3dure medical GmbH Iserlohn will establish the upscaling process of the photopolymers as well as the resin synthesis taking into account these GMP.

Young Optics Europe GmbH in Jena uses the 3D printers they have developed to process previously biocompatible photopolymers for products in medical classes I - IIa. As part of the PolyKARD project, a 3D printing system for the manufacture of class III medical devices is to be established for the first time, which will also enable complete traceability of the raw materials used for manufacture.

New materials with holistic chemistry The three-year PolyKARD project started in April 2019 and is supported by the VDI Verein Deutscher Ingenieure e.V. 13XP5087D). On February 4, 2020, the partners will meet again to present the first milestones. "We have already been able to successfully synthesize and print the first elastic photourethane resins from non-toxic starting materials," explains Wolfdietrich Meyer.

»In the future we would like to realize the medical concept of a holistic approach even more in our chemistry. We want to develop more materials based on renewable raw materials for 3D printing and electrospinning that are biocompatible and can be processed with the highest precision. We also keep an eye on the life cycle of the component and, if necessary, on environmentally friendly disposal,” says Meyer.

The first application of the pericardium replacement material is to produce a novel surface for an extravascular heart support system using 3D printing. © AdjuCor GmbH

Project	»Synthesis of a biomimetic pericardium polymer for cardiac applications« (PolyKARD)
Promotion	BMBF | Material innovations for a healthy life: ProMatLeben – polymers
Project sponsor	VDI Association of German Engineers e.V. Duration: 03.2019 - 02.2022
funding code	12XP5087D
Partner	AdjuCor GmbH | Garching Fraunhofer Institute for Applied Polymer Research IAP | Potsdam NMI Natural Science and Medical Institute | Reutlingen Young Optics Europe GmbH (subsidiary of BURMS)| Jena pro3dure medical GmbH | Iserlohn

Source : https://wwwpro3dure.com/de/news-events/polykard-artificial-pericardium-tissue-from-the-3d-printer