Aims
The creation of spinal cord injury (SCI) models in vivo is highly invasive and time‐consuming. In addition, the complexity of the central nervous system (CNS) makes it challenging to understand the impact of mechanical injuries on the response of CNS cells. On the other hand, current in vitro SCI models are over simple and can neither mimic the cellular and physiological characteristics of the native spinal cord tissue nor truly resemble injury conditions often observed in the accident. The current research aimed to investigate how CNS cells within a bioprinted 3D GelMA hydrogel respond to contusion injury models in a controlled environment.
Methods
C6 astrocyte-like and NG 108-15 neuronal cells were embedded in GelMA hydrogel (5%) and bioprinted to simulate the spinal cord environment. An Electroforce machine (BioDynamic 5110) was used to model a contusion injury at high velocities (1000 and 3000 mm.s-1) with compressive displacements of 30%, 60%, and 80% of the initial height of the hydrogel sample. The cellular responses to the compressive displacements and velocities were investigated using immunocytochemistry analysis.
Results
Astrocytic expression of glial fibrillary acidic protein (GFAP) of C6 astrocyte-like cells increased with increasing displacement and velocity over 10 days post-injury. The metabolic activity of all injured groups was significantly increased compared to the non-injured group from the third day onwards. However, NG 108-15 neuronal cells showed the opposite behaviour, where the use of βIII-tubulin (a neuronal marker) highlighted more significant neurite outgrowth in a non-injured group than in the injured group over 10 days. A significant reduction in NG 108-15 neuronal cell viability was observed for injured groups compared with the non-injured group.
Conclusions
The novel SCI platform developed in this study was successfully used to model a contusion injury and enabled interrogation of the response of individual cell types to injury mechanics, which is difficult to achieve using animal models. The proposed model offers a reproducible, clinically relevant and reliable universal 3D in vitro platform to perform different relevant mechanobiological studies.