Researchers have developed 3D printed artificial heart valves designed to allow a patient's own cells to form new tissue. To form these scaffolds using melt electrowriting – an advanced additive manufacturing technique – the team has created a new fabrication platform that enables them to combine different precise, customized patterns and hence to fine-tune the scaffold’s mechanical properties.
Their long-term goal is to create implants for children that develop into new tissue and therefore last a lifetime.
A close-up of a printed scaffold for a heart valve. The different structures that ensure the appropriate biomechanics are clearly visible.
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In the human body, four heart valves ensure that blood flows in the correct direction. It is essential that heart valves open and close properly. To fulfil this function, heart valve tissue is heterogeneous, meaning that heart valves display different biomechanical properties within the same tissue.
A team of researchers working with Petra Mela, Professor of Medical Materials and Implants at the Technical University of Munich (TUM), and Prof. Elena De-Juan Pardo from The University of Western Australia, have now, for the first time, imitated this heterogeneous structure using a 3D printing process called melt electrowriting. To do this, they have developed a platform that facilitates printing precise customized patterns and their combination, which enabled them to fine-tune different mechanical properties within the same scaffold.
Melt electrowriting is a comparatively new additive manufacturing technology that uses high voltage to create accurate patterns of very thin polymer fibers. A polymer is heated, melted and pushed out of a printing head as a liquid jet to form the fibers.
During this process, a high-voltage electric field is applied, which considerably narrows the diameter of the polymer jet by accelerating it and pulling it towards a collector. This results in a thin fiber with a diameter typically in the range of five to fifty micrometers. Moreover, the electric field stabilizes the polymer jet, which is important for creating defined, precise patterns.
The team used medical grade polycaprolactone (PCL) for 3D printing, which is compatible with cells and biodegradable. The idea is that once the PCL-heart valves are implanted, the patient's own cells will grow on the porous scaffold, as has been the case in first cell culture studies. The cells might then potentially form new tissue, before the PCL-scaffold degrades.
"Our goal is to engineer bioinspired heart valves that support the formation of new functional tissue in patients. Children would especially benefit from such a solution, as current heart valves do not grow with the patient and therefore have to be replaced over the years in multiple surgeries. Our heart valves, in contrast, mimic the complexity of native heart valves and are designed to let a patient’s own cells infiltrate the scaffold", says Petra Mela.
The next step on the way to the clinic will be pre-clinical studies in animal models. The team also works on further improving the technology and developing new biomaterials.
MEDICA-tradefair.com; Source: Technical University of Munich