Everyday, millions of messages are passed around the world in complex networks of information. If the information flow is disrupted, however, these messages can become lost. The human body is one such network where this can occur. Irreversible damage to nerve tissue, for example as a result of sports injuries, requires medical intervention to help regenerate the injured tissue.
In their publication in Small, Abdolrahman Omidinia-Anarkoli, Laura De Laporte, and co-workers from the Leibniz Institute for Interactive Materials in Aachen, Germany, describe a promising, injectable hybrid hydrogel with the ability to induce oriented cell growth.
To combine these two important properties—injectability and unidirectional guidance—the authors develop a simple and effective procedure to fabricate a tunable, biomimetic anisotropic hydrogel comprised of magneto-responsive, short polymeric fibers: Anisogel.
In the first preparation step, they blend poly(lactide-co-glycolide) with superparamagnetic iron oxide nanoparticles and then electrospin aligned fibers on a parallel plate. After embedding the fibers in an optimum cutting temperature gel for subsequent cryosectioning, the fibers are purified. The short fibers are mixed within a hydrogel precursor solution. To obtain fiber orientation after injection, a low magnetic field of ≤300 mT is applied before hydrogel crosslinking. After polymer crosslinking, the magnetic field can be removed and the unidirectional structure can prompt linear cell growth.
To analyze the ability of the Anisogel to enable unidirectional nerve growth, a dorsal root ganglion (DRG) or single nerve cells are mixed into the hydrogel and cultured for 7 days. Using a hydrogel without fibers or with randomly oriented fibers, the neurites grow with radial extensions, while the Anisogel supports the unidirectional growth of the neurites along the fiber direction.
The functionality of the growing neurons inside the gels is investigated by measuring the calcium transient through a fluorescent indicator (Fluo-4). While hydrogels with randomly oriented fibers show signals in multiple directions, calcium signals along neurons inside the Anisogel induce signal propagation in the direction of the short, aligned fibers.
To find out more about this novel, low-invasive anisotropic hydrogel, please visit the Small homepage.