Bioprinted Microchannel Scaffolds Modulate Neuronal Differentiation of Encapsulated Human Spinal Cord Progenitor Cells

A potential approach for treating spinal cord injuries is the implantation of human induced pluripotent stem cells-derived spinal cord progenitor cells (SCPCs) encapsulated in hydrogels. Digital light processing (DLP) enables the fabrication of scaffolds with high microchannel packing density, which are essential for neurofilament infiltration. In this study, SCPCs were encapsulated in gelatin methacrylate (GelMA)-based bioinks for single-layer printing via DLP bioprinting to incorporate human SCPCs within microchannel scaffolds at a reduced printing time. Mechanical properties were evaluated through degradation studies and compression testing, revealing that while the presence of poly(ethylene glycol) diacrylate improved printability and scaffold stability, it adversely affected cell survival. Scaffolds with higher GelMA concentration (10%) induced greater extent of motor neuronal differentiation as compared to those with 7.5% GelMA concentration (9.4 ± 5.1% vs 3.70 ± 2.6%, <i>p</i> < 0.001). In contrast, the scaffolds with lower GelMA concentration increased interneuron differentiation compared to those with higher GelMA concentration (7.3 ± 1.7% vs 1.6 ± 1.8%, <i>p</i> < 0.01), indicating that stiffness and GelMA content may modulate SCPC differentiation to specific neural subtypes. Overall, the encapsulation of SCPCs within the GelMA microchannel scaffold highlights the significance of material composition and stiffness in 3D printability and neuronal differentiation for spinal cord injury treatment.