The skin is a densely innervated organ. After a traumatic injury, such as an amputation, burn or skin graft, nerve growth and the recovery of sensitivity take a long time and are often incomplete. The roles played by growth factors and the process of neuronal growth are crucial. We developed an in vitro model of human skin explants co-cultured with a rat pheochromocytoma cell line differentiated in neuron in presence of nerve growth factor (NGF). This model allowed the study of the influence of skin explants on nerve cells and nerve fibre growth, probably through mediators produced by the explant, in a simplified manner. The neurite length of differentiated PC12 cells cocultured with skin explants increased after 6 days. These observations demonstrated the influence of trophic factors produced by skin explants on PC12 cells.Key words: neuron -neuronal growth -skin
Accepted for publication 18 January 2013Nerve growth following a traumatic injury, such as an amputation, burns or skin graft, takes a long time and is often incomplete. Neurotrophins and semaphorins have been implicated in the guidance of neuronal growth (1,2) through interactions with each other to regulate the motility of the sensory neuronal growth cone. However, the mechanisms of the interactions between the peripheral neurons and the keratinocytes/epidermis/skin remain unclear. To study these interactions under normal physiological and injured conditions, the development of in vitro co-culture models is important. At present, models enabling the study of neuron-skin interactions are rare (3), with the majority involving either primary sensory neurons or a neuronal cell line co-cultured with keratinocytes (4-6), reconstructed skin (7), a skin explant (8) or lesional skin (9). Furthermore, the neurons used in these models are limited due to ethical problems involved in harvesting primary neurons and by the necessity to select an appropriate cell line. Today, adult stem cells could be small sources of neurons or other cellular types for regenerative medicine and tissue engineering, but they are not co-cultured (10,11).PC12 is a versatile rat pheochromocytoma cell line that can be differentiated into neurons with sensory or autonomic characteristics using NGF (12,13). These differentiated PC12 cells have been used as a model for sensory or autonomic neurons (14-16). We developed an in vitro model of human skin explant, which can be considered as an equivalent of injured skin, co-cultured with PC12 cells differentiated into neurons.PC12 cells were co-cultured with human skin explants (E) until 10 days. Skin explants (three donors, one for each experiment) were cut using a 6-mm diameter biopsy punch and placed in 12-well culture plate with one skin explant per well. The skin explants were co-cultured with PC12 cells for more than 10 days at an airliquid interface, and the medium was changed every 2 days. The PC12 cells, which were obtained from the ATCC (ATCC, CRL-1721), were grown in DMEM-F12 media (Lonza, BE12-719F) supplemented with 10% ca...