Ultrasoft Alginate Hydrogels Support Long-Term Three-Dimensional Functional Neuronal Networks

Area of Science:

• Biomaterials Science
• Neuroscience
• Cell Biology

Background:

• Neuron development and function are highly sensitive to the mechanical properties of the extracellular matrix.
• Existing 3D culture models have limitations including undefined composition, degradation, and poor biocompatibility.
• Three-dimensional (3D) cultures are explored to better mimic native tissue environments.

Purpose of the Study:

• To investigate the potential of ultrasoft hydrogels made from unmodified alginate for promoting neuron development.
• To characterize the mechanical properties of alginate hydrogels and their effect on neuronal cultures.

Main Methods:

• Alginate hydrogels were prepared using ionic cross-linking with varying macromer content and CaCl2 concentration.
• Hydrogel stiffness was mechanically characterized across a range of 10–4000 Pa.
• Dissociated rat embryonic cortical neurons were encapsulated in the hydrogels, and their viability, neuritogenesis, and activity were assessed.

Main Results:

• A wide range of hydrogel stiffness was achieved by tuning alginate concentration and CaCl2 levels.
• Neurons encapsulated in the softest alginate hydrogels (0.1% w/v, 10 mM CaCl2) exhibited high viability.
• Extensive axon and dendrite formation, along with long-term neuronal activity, were observed in the 3D cultures.

Conclusions:

• Unmodified alginate can be used to create ultrasoft hydrogels that potently promote neuritogenesis.
• This 3D culture system provides a stable and functional platform for neuronal networks.
• Alginate hydrogels offer a cost-effective and versatile material for applications in neuropharmacology, toxicology, and regenerative medicine.