Experimental small bowel transplantation using newborn intestine in rats: III. Long-term cryopreservation of rat newborn intestine

Background: If long-term organ cryopreservation can be attained, a signific ant achievement will have been made to address the problem for donor shorta ge. Fetal intestine has been known to revascularize naturally without vascu lar anastmosis. The authors have confirmed previously that the newborn inte stine also could develop to maturity in the host omentum. Here, the authors examined whether the cryopreserved newborn intestine could revascularize i n the syngeneic combination using the 2 different solutions and whether cry opreservation affect their antigenicity in the allogeneic combination. Methods: Inbred rat strains of LEW (MHC haplotype; RT1(1)) and BN (RT1(n)) were used. LEW newborn intestinal grafts were stored in RPMI-1640 or Univer sity of Wisconsin solution with 10% DEMSO (n = 10 in each group). The graft s were placed into a cold (4 degreesC) preservation solution for 30 minutes and then placed into a freezing chamber and cooled to -80 degreesC at -1 d egreesC/min after 12 hours quenched to -180 degreesC in liquid nitrogen for longer than 30 days. Then, the cryopreserved grafts under the 2 different solutions were transplanted syngenicaly (LEW to LEW). The cryopreserved BN grafts also were implanted into the LEW omentum pouch. The allotransplantat ion was received with a 14-day high-dose course of tacrolimus (0.64 mg/kg, intramuscularly). The grafts were evaluated histologically at 4 weeks after transplantation. Fresh newborn intestines implanted in this syngeneic and allogeneic combination were evaluated as each control group. Result: In the syngeneic combination, more than 90% of the mature intestine were obtained. There was no significant difference among the different sol ution and the fresh group. However, in the allogeneic combination, both fre sh and cryo preserved grafts were histologically poor. Conclusions: This is the first report showing that long-term cryopreservati on was not harmful for neovascularization of newborn intestine. Long-term c ryopreservation did not reduce the antigenicity of the newborn intestine.