Tracheal Replacement by Allogenic Aorta in the Pig: PCR for the SRY Gene on Trachea and Graft

Gender prediction on SRY gene assay revealed positive results for samples from a male control minipig and negative results for the female control minipig. IGF1 amplification, used as a positive control of the PCR assay, was positive in both controls. SRY gene amplification was positive in the two aorta grafted into male minipigs studied at 10 months and 11 months, respectively (Fig 6).
Enormous progress in surgical techniques, tissue typing, immunogenetics, and immunosuppressive therapy (IT) has rendered most organs transplantable. Airway transplantation remains an exception.
Several intrinsic factors account for the difficulty in finding an ideal tracheal substitute. Ischemia is critical, and even vascularized flaps with or without artificial material scaffolding do not work efficiently. The only exception, in which a short transplanted tracheal segment did not have ischemia, was a pharyngo-laryngo-tracheal transplantation in which arteries and veins were reanastomosed. Contrary to earlier beliefs, the trachea bears heavy antigenicity, especially in the mucosa, accounting for uniform rejection of fresh allografts.

Cryopreservation, which reduces acute rejection, does not prevent chronic rejection with subsequent vascular occlusion and degeneration. Heavy IT would therefore be necessary but would make tracheal replacement for extensive malignancies particularly hazardous. This is also the case for laryngeal transplantation, in which early attempts were accompanied by rapid recurrence of the primary tumor, an outcome that quashed interest in the procedure. None of the attempts, including prostheses, allografts, and autologous grafts (trachea, esophagus, bowel, skin, and bladder), have overcome the many hurdles of tracheal replacement. Tissue-engineered airway and guided tissue regeneration are virtually the only techniques that seem to offer any real promise. As has been shown, a bioartificial trachea with smooth-muscle cells, ciliated respiratory epithelium, and extracellular cartilaginous matrix can be engineered on a vascularized scaffold, but still lacks the three-dimensional aspect and the biomechanical profile of a functioning trachea. Orthotopic transplantation of aortic allografts has been used successfully for many years for treating infrarenal aortic prosthesis infection.


Figure 6. SRY and IGF1 gene amplification on 2% agarose gel. PHA = phytohemagglutinin.

This entry was posted in Allogenic Aorta and tagged airway, lung cancer, transplants.