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Step to the artificial heart: muscles from the spray can
About one to two percent of the adult population in industrialized nations suffers from severe heart failure (heart failure). A donor heart is transplanted to end-stage patients if possible. However, there is often no suitable organ available. An artificial heart could be the salvation. In order to recreate the complex organ in the laboratory, it would first have to be possible to grow multi-layered, living tissue. Researchers have now come closer to this goal: using a spray process, they produced functioning muscle fibers.
One of the most common fatal diseases
Heart failure (heart failure) is one of the most common fatal diseases. As a result of this disease, the heart is no longer able to provide the body with sufficient blood and oxygen. In recent years there have been repeated reports of new approaches to treating heart failure that can increase resilience and performance. But when the heart becomes weaker and there is a risk of failure, a heart transplant is the only treatment that can save the life of the seriously ill patient. However, a suitable organ is not always available. Swiss researchers from the Swiss Federal Laboratories for Materials Testing and Research (Empa) have now come a little closer to this goal.
Artificial organ for heart failure
Anyone who is dependent on a transplant due to heart failure must hope for a suitable donor organ. An elegant alternative would be an artificial heart, which does not trigger any rejection reactions in the body after implantation.
The “Zurich Heart” project of the Research Association for University Medicine Zurich, whose partner is Empa, is currently developing such an artificial heart.
In order for the pump to be accepted by the body from the laboratory, it should - like a camouflage cap - be encased and lined with human tissue.
So far, growing multi-layer, functional tissues has been a major challenge in the emerging field of tissue engineering.
Empa researchers have now succeeded in growing cells into muscle fibers in a three-dimensional plastic structure.
Muscle fibers ensure the stability and flexibility of the constantly beating heart
"The human heart is naturally made up of several layers of different tissues," explains Lukas Weidenbacher from Empa’s Biomimetic Membranes and Textiles department in St. Gallen in a message.
Muscle fibers in the lining play a crucial role here, as they ensure the stability and flexibility of the constantly beating heart.
However, growing multi-layered muscle fibers is difficult because the cells first have to be introduced into a spatial framework.
"It is indeed possible to create three-dimensional plastic structures that are very similar to human tissue, for example through so-called electrospinning," says Weidenbacher.
Here, liquid polymers are spun as extremely delicate threads in the form of natural fabrics. However, harmful solvents that are necessary for the method are poison for the sensitive cells.
The Empa researchers have therefore packaged the precious cells in protective capsules. A gelatin shell contains one to two cells each. This keeps the cells protected from the solvents.
A special spraying process, electrospraying, enables the capsules to be inserted into the pores of the spun framework. "The cells protected in this way survive spraying very well," explains the materials researcher.
And once the cells have nested at the destination, the gelatin capsule dissolves within minutes.
The scanning electron microscope shows that the cells in their plastic nest like it: as soon as the capsules are dissolved, the immature precursor cells begin to fuse with one another and mature into elongated muscle fibers.
In the end, a structure should be created that is as similar as possible to natural muscle tissue. "Since the artificial heart is constantly flushed by the blood circulation, it is important that the surfaces are designed so that no clots form," says Weidenbacher.
Invisible for body defense
For the series of experiments, the researchers used immature muscle cells from a mouse cell line. The progenitor cells differentiated in the scaffold and produced proteins that are typically found in muscles.
In the future, however, the implantable artificial heart will be populated with cells that come from the patient himself. In this way, a personal heart could be cultivated for those affected that remains “invisible” to the body's defenses. (ad)