Heart and en-bloc thymus transplantation in miniature swine.
BACKGROUND
Donor-specific tolerance to organ allografts might be induced by cotransplantation of a sufficient amount of vascularized donor thymus. To facilitate donor thymus-induced cardiac allograft tolerance, we have developed a novel technique for heart and en-bloc thymus transplantation in swine.


METHODS
Donor heart and en-bloc thymus grafts were prepared by a technique that preserves the entire arterial supply and venous drainage of the right thymic lobe. En-bloc grafts (n = 4) were transplanted heterotopically into the abdomens of major histocompatibility complex-matched miniature swine. Recipients received 12 days of cyclosporine intravenously. Grafts were monitored by palpation, electrocardiographic monitoring, and periodic open biopsy. Engraftment of the donor thymus was demonstrated by measuring the proportion of recipient-type thymocytes in the donor thymus with flow cytometry.


RESULTS
All of the heart and en-bloc thymus grafts had normal cardiac contractility and immediate perfusion of the thymus. All en-bloc grafts were accepted for more than 200 days without significant acute cellular rejection or cardiac allograft vasculopathy. Thymic tissue of en-bloc grafts displayed normal architecture and supported thymopoiesis of recipient-type cells.


CONCLUSIONS
We have validated a new technique of donor thymus transplantation that could have utility in human heart transplantation.
Johnston
Douglas R
DR
Transplantation Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
Muniappan
Ashok
A
Hoerbelt
Ruediger
R
Guenther
Dax A
DA
Shoji
Tsuyoshi
T
Houser
Stuart L
SL
Sachs
David H
DH
Madsen
Joren C
JC
D000818:Animals; D006085:Graft Survival / Q000276:immunology; D016027:Heart Transplantation; D007108:Immune Tolerance / Q000276:immunology*; D023421:Models, Animal; D016377:Organ Transplantation / Q000379:methods; D013552:Swine; D013950:Thymus Gland / Q000637:transplantation*