Abstract
Background Tracheal transplantation seems to be the logical step in the process of reconstruction
of the trachea following a long-segment resection, which is usually done to treat
malignant disease or benign stenosis of the airway caused by a traumatic, congenital,
inflammatory, or iatrogenic lesion. Immunosuppression following transplant is essential
but not ideal after oncoresection.
Methods The tracheal allografts, harvested from Sprague Dawley rats, were implanted in the
Wistar strain rat. The harvested tracheal grafts were divided into groups and subgroups,
based on the layers of trachea, method of decellularization, and immunosuppression.
The antigenicity of different layers of trachea and the effect of various decellularization
methods were studied within three time frames, that is, day 3, 9, and 15.
Result On structural analysis, the day 3 and day 15 samples showed no meaningful comparison
could be made, due to extensive neutrophil infiltration in all three layers. The day
9 tracheal grafts showed loss of epithelium, with no signs of regeneration in most
of the allografts. The subepithelial lymphoid infiltration was found to be severe
in nonimmunosuppressed allografts. The group in which both inner and outer layers
were removed showed moderate-to-severe infiltrate of lymphoid cells in all the allografts,
but there was no cartilage loss, irrespective of the method of decellularization.
The irradiated specimens retained the cartilage but showed extensive ischemic damage.
Conclusion Rat trachea is a good model for tracheal transplant research but not adequately sturdy
to sustain mechanical debridement. Irradiation and chemical decellularization eliminates
the immune response but causes intense ischemic damage. Out of the three time frames,
day 9 seemed to be the best to study the immune response. To substantiate the results
obtained in this study, the immunohistochemical study of the allografts is needed
to be performed among a larger group of animals.
Keywords
decellularized tracheal allograft - immune-mediated rejection - rodent model - tracheal
allograft antigenicity - tracheal transplantation
