Multivariate analysis reveals topography dependent relationships amongst neurite morphological features from dorsal root ganglia neurons

Objective. Nerve guidance scaffolds containing anisotropic architectures provide topographical cues to direct regenerating axons through an injury site to reconnect the proximal and distal end of an injured nerve or spinal cord. Previous in vitro cultures of individual neurons revealed that fiber characteristics such as fiber diameter and inter-fiber spacing alter neurite morphological features, such as total neurite length, the longest single neurite, branching density, and the number of primary neurites. However, the relationships amongst these four neurite morphological features have never been studied on fibrous topographies using multivariate analysis. Approach. In this study, we cultured dissociated dorsal root ganglia on aligned, fibrous scaffolds and flat, isotropic films and evaluated the univariate and multivariate differences amongst these four neurite morphological features. Main results. Univariate analysis showed that fibrous scaffolds increase the length of the longest neurite and decrease branching density compared to film controls. Further, multivariate analysis revealed that, regardless of scaffold type, overall neurite length increases due to a compromise between the longest extending neurite, branching density, and the number of primary neurites. Additionally, multivariate analysis indicated that neurite branching is more independent of the other neurite features when neurons were cultured on films but that branching is strongly related to the other neurite features when cultured on fibers. Significance. These findings are significant as they are the first evidence that aligned topographies affect the relationships between neurite morphological features. This study provides a foundation for analyzing how individual neurite morphology may relate to neural regeneration on a macroscopic scale and provide information that may be used to optimize nerve guidance scaffolds.