Few patients with heart failure are fortunate enough to receive a donor’s heart. Ventricular assist devices (or heart pumps) have been around for several years and are designed to buy time as patients wait for a transplant. Unfortunately, the body doesn’t always tolerate these devices. Researchers at Empa now use a new procedure to produce a coating made of cells designed to line the pumps in the future and increase their lifespan.

Mr. Weidenbacher, how did you manage to create muscle fibers that grow in multiple layers?

Lukas Weidenbacher: We basically used a combination of two well-known scientific methods. We combined electrospinning, which allows you to create fine synthetic fibers and cell electrospraying. This enabled us to create multilayered constructs made of cells and synthetic fibers. Alternately, layers of synthetic fibers are first created via the electrospinning process and subsequently, muscle fibers are “sprayed” into the pores of the spun scaffold to obtain a hybrid, multilayered construct.

How does electrospraying work exactly?

Weidenbacher: During this process, we encase the cells with a type of protective capsule made of gelatin. We then use an electric field with positive and negative charge, as we did before during the electrospinning process. With the help of a spraying device, a dispersion with the coated cells is transported into the electric field. The individual liquid particles are subsequently sprayed via the positive charge in the direction of the negative charge. In doing so, they are transported to their destination in the pores of the polymer scaffold. Once there, the gelatin capsule dissolves within minutes. The cells begin to interlace and form elongated muscle fibers, so-called myotubes.

Weidenbacher: One benefit is that thanks to the microfluidic coating, our process prevents cell damage, which can be caused by certain solvents used in the spinning process. The combination of both techniques also gives us spatial control over the cellular distribution in the polymer scaffold. Until now, it was very difficult for tissue engineering to create a mechanically stable 3D construct that contains living cells to use for tissue production. We have now managed to do this with our approach.