[Establishment of a modified larynx transplantation model with inbred F344 rat]

As a non-vital organ, transplantation of larynx lags behind that of the other organs, but it is supposed that if induction of immunologic tolerance of the host to the allograft comes true, larynx transplantation would be an optimal approach for management of advanced laryngeal cancer as well as functional reconstruction of the larynx. This study was designed to establish a modified rat model of larynx transplantation to improve survival rate of the recipients and vitality of the allografts, and provide an optimal rat model for further research on immunology and induction of immunologic tolerance in larynx transplantation.

A Strome's model of larynx transplantation was repeated with inbred F344 rats (40 rats in Stroma model A and 40 rats in Stroma model B). A modified model of larynx transplantation was developed (40 rats), in which both superior thyroid arteries and ascending pharyngeal arteries were preserved, combining with the hyoid, base of the tongue, hypopharynx, larynx, thyroid, part of the cervical trachea and cervical esophagus as an allograft complexity. The blood supply of the allograft was reconstructed through end-to-end anastomosis of the donors' carotid arteries with the recipients' carotid artery and anterior jugular vein. The recipients were injected with 15 ml of 5% glucose normal saline (GNS) through contralateral external jugular vein intraoperatively, and injected subcutaneously with 5 ml of 5% GNS daily for 3-5 days postoperatively. Morphology of the allografts and patency of the arteries and veins were observed under microscope 7 days after operation, and vitality of the allogafts was assessed pathologically. Survival of the recipients and vitality of the allografts in Strome model and modified model were compared.

Survival rates of the recipient rats were 70% in Strome model A, 85% in Strome model B, and 95% in modified model; the survival rates of the allografts were 30% in Strome model A, 40% in Strome model B, and 80% in modified model, respectively.

Compare with Strome models, the modified model of larynx transplantation reduces mortality of the recipients through enhancing perioperative care, improves vitality of the allografts through including both ascending pharyngeal arteries and superior thyroid arteries in the allograft complexity, which increases blood supply of the allografts and reduces micro-circulation resistance, therefore, reduces the micro-circulation malfunction of the allografts.