Immunohistochemical characterization of the rabbit tracheal cartilages

The objective of this study was to immunohistochemically elucidate the major extracellular matrix constituents of rabbit tracheal cartilage. The impetus for this project is the need for crucial design and validation criteria for tissue engineering juxtaposed with the conspicuous lack of trachea extracellular matrix data in the literature. Tracheal tissue specimens were harvested from New Zealand White rabbits, and were immunostained for collagen I, collagen II, aggrecan and decorin; and a Verhoeff-Van Gieson stain was performed to visualize elastin. The most striking result was the highly organized relationship between distinct fibrous (containing collagen I, decorin and elastin) and hyaline-like (containing collagen II and aggrecan) regions of the tracheal wall. The tracheal cartilage stained strongly with collagen II throughout, with periodic bands of aggrecan in the tracheal arches, meaning that there were areas void of aggrecan immunostaining alternating with areas with strong aggrecan immunostaining. In contrast, the periphery of the cartilage and the perichondrium itself exhibited strong collagen I staining and no collagen II staining. Elastin fibers and decorin were also detected along the periphery of the cartilage in the perichondrium and corresponded highly with the distribution of collagen I staining. The body of the rabbit trachea is therefore composed of a hyaline-cartilage structure primarily made of collagen II and bands of aggrecan, surrounded by a fibrous region composed of elastin and collagen I, indicative of a flexible tissue with distinct regions of compressive integrity. This information will be a valuable reference to future tissue engineering efforts in the creation of a biosynthetic substitute for laryngotracheal reconstruction.