In vitro formation of organized structure between keratinocytes and dorsal-root-ganglion cells

We recently found that the morphology in a co-culture system of keratinocytes and dorsal-root ganglion-derived cells depended on the timing of seeding of the two cell types. In skin, epidermis is formed first, followed by construction of peripheral nerve structure. Therefore, we hypothesized that formation of peripheral nerve structure in the epidermis might be driven by interaction between keratinocytes and nerve cells. In the present study, we tested this idea by incubating keratinocytes and dorsal-root ganglion cells in a spatially separated manner and observing the morphological changes in the co-culture system. Extension of nerve fibre-like structures from the ganglion cells was observed, and within 3 days after seeding, many nerve fibre-like extensions penetrated into the keratinocyte cluster, subsequently forming a network that appeared to resemble the cutaneous peripheral nervous system. Our present model may be useful for studying the formation of peripheral nerve structure in the skin.