|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1994 : ¥600,000 (Direct Cost : ¥600,000)
Fiscal Year 1993 : ¥1,500,000 (Direct Cost : ¥1,500,000)
A study was conducted to develop epithelialized tracheal prostheses by inoculating tracheal epithelial cells into grafts which had previously been vascularized in the subcutis of nude mice.
High-porosity tracheal grafts made of ultrafine polyester fibers, 7 mm in diameter and 25 mm long, were implanted into the backs of nude mice. Four weeks after implantation, the grafts were partially exposed from the surrounding subcutis so as not to impair graft vascularization. Then, rabbit tracheal epithelial cells harvested by enzyme digestion of tracheal tissue were inoculated into the grafts (ca 6 x 10^5 cells/graft). Four weeks later, the grafts were retrieved and examined histologically, focusing chiefly on formation of graft epithelialization.
Five out of 7 grafts (71.4%) showed infection, with (n=3,42.9%) or without (n=2) graft protrusion from the skin. The other two grafts contained serous fluid in the lymina, and one of them (14.3%) showed formation of pseudostratified columnar and stratified squamous epithelia on one third of the luminal surface. The high incidence of complications was considered to be due to decubitus of the skin.
In order to reduce operative complications, in an additional experiment, tracheal cells were inoculated 3 weeks after implantation and the grafts were removed 3 weeks later (n=7). Four grafts were infected (57.1%), two apparently penetrating the skin (28.6%). The other three grafts (42.9%) were totally (n=2) or partially (about 60%, n=1) epithelialized by stratified squamous epithelium.
In conclusion, the tracheal grafts used in this study appeared to be readily epithelialized (80%, 4 out of 5 grafts) in this culture model, after establishment of appropriate culture conditions to prevent operative complications. Well-developed graft vascularization may be the most important factor for success. Further studies using rabbits as hosts for tracheal replacement are expected.