Possibility of skin epithelial cell transdifferentiation in tracheal reconstruction.

In tissue engineering, injured tissue is normally reconstructed with cells obtained from that tissue itself. However, it is difficult to obtain cells for reconstruction of the trachea because of its shape and limited accessibility. Therefore, other cell sources having similar form and function or stem cells are used for tracheal reconstruction. In a previous study, we used autologous skin epithelial cells and successfully reconstructed canine tracheas. We found that the tracheal epithelial layer was completely covered with ciliated cells, which is a remarkable finding because skin and tracheal epithelial cells originate from different germinal layers and have very different forms. In this study, to elucidate the origin of the ciliated cells, we identified the stem cell contents of skin epithelial cells on primary culture, marked the skin epithelial cells with PKH26 dye, and transplanted them onto canine tracheas. After 5 months, we identified PKH26 fluorescence on the tracheal epithelial layers, especially over the tracheal cartilages. Consequently, we demonstrated that transplanted autologous skin epithelial stem cells can remain viable on the trachea for a few months and can transdifferentiate into tracheal epithelial cells and chondrocytes.