Abstract
Purpose:
Interplay between corneal epithelial cells and trigeminal (TG) neurons profoundly influence the wound healing response after corneal injury. The main aim of our present investigation is to find the molecular cues regulating the interactions between corneal epithelial cells and TG neurons during wound healing using a murine cell culture model system.
Methods:
Corneal epithelial cells from the mouse cornea were cultured by an explant culture method. TG neurons were isolated from two months old mice by standard protocols and cultured. The purity of the TG neurons and corneal epithelial cells were confirmed by immune staining with beta-III-tubulin and cytokeratin 12 antibodies, respectively. Neurite outgrowth assay and RT-PCR analysis were performed to study the effect of conditioned epithelial medium (CEM) on neuron cultures. Scratch assay was used to visualize epithelial-to-mesenchymal transition (EMT) during corneal wound healing and RT-PCR analysis on wounded corneal epithelial cells were performed to study the effect of conditioned neuron medium (CNM) on corneal epithelial cells during wound healing.
Results:
We observed an increase in the neurite outgrowth of TG neurons in the presence of CEM and also in co-culture with corneal epithelial cells. Increase in the expression of substance P (SP) mRNA also was observed with CEM. Existence of EMT during wound healing was documented. RT-PCR analysis revealed a decrease in the expression of Pax6 and bone morphogenetic protein 7 (BMP7) mRNA in epithelial cells during wound healing in the presence of CNM.
Conclusions:
Our data display an existence of communication and on-going interactions between neurons and corneal epithelial cells. Decrease in the expression of BMP7 during wound healing in the presence of CNM may have an essential role in EMT of corneal epithelial cells during wound healing. Studying the molecular signs underlying the interactions of neuronal and epithelial cells would increase our knowledge about corneal wound healing to further develop future therapeutic targets.
Keywords: 482 cornea: epithelium •
614 neuropeptides •
512 EMT (epithelial mesenchymal transition)