Injuries to the central nervous system do not heal as the cavities become scarred. The researchers hope to solve this problem by filling the cavities in such a way that the stem cells feel comfortable in them.

The researchers studied neural stem cells from mouse embryonic brains, which they cultivated on positively charged hydrogels. “Our goal was to create an artificial environment for the cells that mimics the natural cell environment in the brain,” says Kirsten Glotzbach. “Cells have a negatively charged coating, also known as a pericellular matrix. This means they adhere particularly well to positively charged substrates.” The trick with the hydrogels used in the experiments was that the strength of their positive charge could be precisely adjusted.

As the experiments showed, the positively charged hydrogels facilitated the survival of the cells and influenced their future fate. If the stem cells adhere to the hydrogels with a more positive charge, the cells develop into nerve cells. On gels with a low positive charge, on the other hand, stem cells develop primarily into glial cells, which perform important supporting functions for neural cells.

The ability to influence whether stem cells differentiate into neural or glial cells would be a huge advantage. “Depending on the injury, different types of cells need to be replaced,” explains Kristin Glotzbach. It is not just the regeneration of nerve cells that is important. “In some diseases, glial cells are also attacked and need to be replaced. In multiple sclerosis, for example, the nerve cell insulation, which is made up of oligodendrocytes, is destroyed.”

Growth factor supplementation improves survival rates.

When the researchers added the growth factor FGF2 to the positively charged hydrogels, they successfully increased the rate of cell survival and division. But the differentiation into nerve and glial cells again took place at a slower rate.

“In future studies, we plan to incorporate peptides or components of extracellular matrix molecules into the positively charged gels to mimic the cells’ natural environment even more effectively,” says Kristin Glotzbach. The researchers also plan to experiment with three-dimensional gels that could fill cavities after brain injuries.