A Patch for the Heart

Following a heart attack, blood flow to the heart is interrupted and the resulting lack of oxygen can cause heart damage. The heart wall can rupture in severe cases, requiring immediate surgical intervention. Today, bovine pericardial patches are used to repair such heart defects owing to their stability, permeability and ease of implantation.

An interdisciplinary research team from ETH Zurich and the University Hospital of Zurich, led by Professor Robert Katzschmann and Professor Omer Dzemali, have developed a novel three-dimensional heart patch for intraventricular implantation. The team has just presented it in the scientific journal Advanced Materials.

Not only to seal but also to heal

The bovine pericardial patches currently used, BPPs for short, have significant disadvantages. Not only are they biologically inert, meaning they remain foreign bodies in the heart and cannot be broken down, but they can also cause unwanted reactions such as calcification, thrombosis, or inflammation. ¡°Traditional heart patches do not integrate into the heart tissue and remain permanently in the body. We wanted to solve this problem with our patch, which integrates into the existing heart tissue,¡± explains Lewis Jones, lead author of the study.

The ¡°RCPatch¡± (Reinforced Cardiac Patch) could become a long-term alternative to conventional patches made from bovine pericardium: ¡°Our goal was to develop a patch that not only closes a defect but also helps to repair it completely,¡± explains Katzschmann.

One patch, three components

The new RCPatch has significant advantages over bovine pericardium because it consists of three parts: a fine mesh that seals the damage, a 3D-printed scaffold for stability and a hydrogel populated with heart muscle cells. The scaffold has a lattice structure composed of a degradable polymer, which the researchers produce in a 3D printer. ¡°The scaffold is stable enough and can be filled with a hydrogel containing living cells,¡± explains Jones.

The ETH researchers combined the lattice structure with a thin mesh so that it could be easily attached to the heart. Katzschmann and his team enriched this mesh with the same hydrogel. This allows the RCPatch to integrate into the surrounding tissue and grow together with the heart muscle cells. ¡°The big advantage is that the scaffold is completely degraded after the cells have combined with the tissue. This means that no foreign body remains,¡± explains Jones. The combination of the three components results in a dense, easy-to-use heart patch that is partly made of living cells.

Initial tests on the heart

An initial animal experiment demonstrated the ability of the patch to be successfully implanted and withstand the high pressure in the heart. The researchers succeeded in preventing bleeding and restoring cardiac function. In preclinical tests on pig models, the RCPatch was used to close an artificial defect in the left ventricle. ¡°We were able to show that the patch retains its structural integrity even under real blood pressure,¡± says Katzschmann.

The research group has thus created a promising foundation for the development of a mechanically reinforced and tissue-engineered heart patch suitable for implantation in humans. In the long term, the RCPatch is intended not to only repair but also to regenerate myocardial damage, ultimately healing the heart. In the next step, the researchers aim to develop the material further and investigate its stability in long-term animal studies.