Comparison of small-type nociceptor distributions in vivo and in dorsal root ganglia derived neuron cultures: testing the accuracy of a popular in vitro model
The Dorsal Root Ganglion (DRG) cell culture model is a powerful and frequently used tool in the field of neurobiology. Its use has profoundly impacted the study of peripheral neuropathies and helped make important discoveries about neural sensitization pathways. However, few studies have comprehensively tested how accurately this in vitro model portrays the distribution and spatial patterning of sensory neurons in vivo. As a first step in making such comparisons, we wanted to comparing their relative distributions of small-type nociceptors (peptidergic and non-peptidergic neurons) in vivo and in vitro. Our data suggest that there are significantly fewer peptidergic and more mixed-identity neurons in culture compared to in DRG cell bodies or in sural (sensory) nerves. Additionally, we discovered an interesting pattern of growth between some peptidergic and non-peptidergic neurons in vitro, whereby they often traveled in pairs, appearing as either a single neuron of mixed identity or two neurons in extremely close proximity with identical trajectories. These results stress the importance of making careful and more refined evaluations of the DRG cell culture model depending on the context of a particular scientific question.