Combined effects of red light and direct-current electric fields on neurite growth in 3D neural cell cultures.

Both red-light (RL) illumination and direct-current electric fields (dcEFs) have independently been shown to promote neurite outgrowth in two-dimensional (2D) neural cell cultures. However, their combined effects in a three-dimensional (3D) culture environment remain unexplored. In this study, we examined the combined effects of RL and dcEFs on neurite extension in human neuroblastoma (SH-SY5Y) and mouse neuroblastoma (N2a) cells embedded within a 3D collagen gel matrix. Our results demonstrated that optimized dcEF stimulation and RL exposure significantly enhanced neurite elongation and directional alignment. RNA sequencing further identified Neuropeptide Y (NPY) and its receptors as key mediators of these effects. Moreover, electrophysiological assessments revealed that neurons subjected to the combined stimulation exhibited enhanced functional maturation. These findings provide compelling evidence supporting the potential applications of RL and dcEFs in neural regeneration and repair.