OBJECTIVETo investigate the proper time of cryo-preserving tracheal allograft so as to minimize its antigenicity.

METHODSOn a dog model, this study was carried out by allografting a tracheal into a muscular flap formed with sternocephalic muscle and sternohyoid--sternothyroid muscle. The tracheal was treated with cryopreservation in defferent intervals. The viability of the graft was evaluated by the examination of fiberoptic bronchoscopy, histopathology and microangiography. The blood flow of the tracheal mucous was measured with a blood flowmeter and the survival area was decided in the calculation of the percentage.

RESULTSThere are no significant differences in the mucous membrane appearance and the mucosal blood flow one week after the surgery among the non-cryopreservation group and the groups treated with cryopreservation in 1 day, 2 weeks, 4 weeks, 6 weeks and 8 weeks. The graft was found to start necrosis 2 weeks after the transplantation with the infiltration of mononuclear cells examined under light microscope in almost all of the groups, especially in the non-cryopreservation group and the groups treated with cryopreservation in 1 day, 2 weeks. However, there was no significant difference among the autograft group and the allograft groups cryopreservated in 6 weeks and 8 weeks, and the infiltration of the mononuclear cells was not found in these groups either.

CONCLUSIONThe antigenicity of the tracheal allografts could be significantly decreased by the treatment of cryopreservation over 6 weeks.