A network of muscle fibers grows on spun plastic scaffold. Under a confocal laser scanning microscope the muscle fibers appear in red, and the cell nuclei in blue. Image: Lukas Weidenbacher
Researchers at the Swiss Federal Laboratories for Materials Science and Technology (EMPA) have developed an electrospraying technique that can incorporate living cells into a 3D synthetic polymer scaffold. The cells can then grow to form elongated fibers, mimicking natural muscular tissue, and the technique brings the possibility of lab-developed organs for transplant patients, such as artificial hearts, closer to reality.
Tissue engineering research is focused on developing a range of tissues and organs in the lab, often using living cells and synthetic or naturally-derived materials. One of the challenges in achieving this is creating complex, multi-layered structures. This involves manipulating materials while keeping sensitive cells alive during the process.
“The human heart is naturally composed of several layers of different tissues,” explains Lukas Weidenbacher, a researcher involved in the study. However, artificially creating multi-layered muscle fibers is difficult, as it means incorporating living muscle cells deep within a 3D matrix, while keeping them alive and happy.
It is possible to create three-dimensional polymer structures that closely resemble human tissue using a process called electrospinning. Electrospinning involves weaving tiny threads of polymer together, to form a tissue-like matrix, using electricity to manipulate the material.
However, electrospinning typically requires harsh solvents that could kill any cells present in the polymer. To overcome this, the research team developed a new way to protect cells during the process. First, they passed the cells through a microfluidic device that encased them in gelatin sheaths, with one or two cells per sheath. Then, they repeatedly sprayed the sheaths into the electrospun polymer matrix, and added additional layers of polymer on top, to build a multi-layered structure that incorporated the sheaths deep within it.
The sheaths kept the cells away from harmful solvents during electrospinning, and broke down after the electrospinning process, allowing the cells deep within the polymer matrix to grow and form networks of muscle fibers.
So far, the researchers have developed the technique using mouse cells, but eventually hope to use patients’ own cells to create personalized implants, with a view to developing artificial hearts in the future.
As early as 7 days later, the cells join up in the scaffold (white) and form elongated muscle fibers (yellow), as shown in this stained electron microscope image.
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