Hirotaka Uchimizu

Middle ear mucosa regeneration by grafting of artificial mucosa

Conclusion. Artificial middle ear mucosa (AMEM), a sheet of mucosal cells grown on collagen gel populated with fibroblasts, is useful as graft material that is able to promote mucosal regeneration after middle ear surgery. Objectives. Regeneration of the middle ear mucosa and pneumatization of the mastoid cavity is critical for good prognosis. We examined whether implantation of AMEM into damaged middle ear cavity would promote mucosal regeneration. Materials and methods. AMEM was prepared as described previously using epithelial cells and fibroblasts isolated from the rabbit middle ear. We implanted AMEM into rabbit middle ear from which mucosa had been surgically removed and evaluated its histological and functional recovery 8 weeks later. Three other groups were used for comparison: a normal control group, a mucosa-eliminated group, and a collagen-implanted group. Results. AMEM grew to be morphologically similar to the native middle ear mucosa. Electron microscope studies showed that implanted AMEM has basal lamina and cilia. AMEM implantation suppressed bone hyperplasia and granulation, leading to better mucosal regeneration. Mucosal gas exchange was also significantly improved after implantation.

The effect of transplantation of nasal mucosal epithelial cell sheets after middle ear surgery in a rabbit model.

Postoperative regeneration of the middle ear mucosa and pneumatization of the middle ear cavity are of great importance after middle ear surgery. This study developed a new method to transplant autologous nasal mucosal epithelial cell sheets into the damaged middle ear cavity. The aim of this study was to evaluate postoperative healing after the transplantation of the cell sheets. Rabbit nasal mucosal epithelial cell sheets were fabricated on a temperature-responsive culture dish, and transplanted into the damaged middle ear of rabbit, which was surgically created. The healing of middle ears was evaluated by histology and X-ray computed tomography after transplantation. Functional evaluation was performed by measuring the maximum middle ear total pressure reflecting a trans-mucosal gas exchange function. Two control groups were used: the normal control group and the mucosa-eliminated control group. Transplantation of cell sheets suppressed the bone hyperplasia and the narrowing of pneumatic space in the middle ear cavity compared with the mucosa-eliminated control group. The mucosal gas exchange function was also better in the cell sheet-transplanted group. Nasal mucosal epithelial cell sheet was confirmed to be useful as an effective graft material after middle ear surgery and hopefully become a novel therapy in the future.

Effects of inflammatory changes in the middle ear mucosa on middle ear total pressure

Conclusions. Inflammation of the middle ear mucosa leads to inhibition of transmucosal carbon dioxide (CO2) diffusion. Furthermore, CO2 diffusion is inhibited more severely in ears with a histologically higher grade of inflammation. Objectives. To investigate the effect of inflammatory changes in the middle ear mucosa on transmucosal gas exchange, and the relationship between the histologic inflammation grade of the middle ear mucosa and the middle ear total pressure (METP). Materials and methods. Twenty-six rabbits were used for this study. Changes in the METP and the oxygen partial pressure in the middle ear (PmO2) were measured in the otitis media group and the untreated group, and were compared between the two groups. Inflammatory changes in the middle ear mucosa were classified into four grades histologically, and the relationship between the histologic inflammatory grade and the maximum METP was examined. Results. The maximum METP in the otitis media group was significantly decreased compared with the untreated group (p<0.05), but there was no difference between the two groups in the rate of decrease of the PmO2. Furthermore, the maximum METP in grade III inflammation was significantly decreased compared with that in grade II inflammation (p<0.05).