Vascular Neonatal Thymus Transplantation in Rabbits

Successful vascular adult thymus transplant has been reported in different animal models but not in rabbits. These animal models are slightly larger than the murine and substantially smaller than the porcine. We describe in rabbits a supermicrosurgical technique for vascular neonatal thymus transplant and provide histologic evidence of tissue viability.

Newborn (New Zealand, n = 12, 6 female) and adult (New Zealand, n = 12, 6 female) rabbits were used as donors and recipients, respectively. Whole thymuses were extracted from donors and grafted into recipients. Immediate direct vascularization was accomplished by anastomosis to the right common carotid artery and the right external vena cava. At day 14, graft sites were surgically explored, and grafted thymuses were explanted for histologic evaluation. All recipients were followed over 2 weeks for clinical signs of graft-vs-host reaction.

The vascular pedicles of the thymus grafts ranged 0.5 to 0.8 mm in vessel diameter. From the 12 transplants, 3 recipients (3/12; 25%) died during the surgical procedure because of blood loss after clamp release. On histology, from the 9 (9/12; 75%) successful at revascularization, none (0/9; 0%) had signs of acute rejection or necrosis, and all (9/9; 100%) evidenced normal cytoarchitecture. No clinical signs of graft-vs-host reaction were evidenced during follow-up.

Vascular neonatal thymus transplant in rabbits is surgically feasible. This technique will enable a novel approach for studying the biology of the thymus.