Composite tissue allografts in rats: IV. Graft-versus-host disease in recipients of vascularized bone marrow transplants

This laboratory has used a composite tissue allograft model as a vehicle fo r studies on a new type of bone marrow transplant, the vascularized bone ma rrow transplant. The model consists of a rat hind limb transplant that inco rporates integumentary musculoskeletal, and lymphopoietic tissues. These tr ansplants, in comparison with conventional marrow transplants, have the adv antage of providing a syngeneic microenvironment and immediate engraftment of both mature and progenitor hemopoietic cells at the time of transplantat ion. The characteristics of graft-versus-host disease were studied in this model. Lewis X Brown Norway F1 (LBN RT-1((1+n))) rats received hind limbs f rom Lewis (LEW RT-1((1)) donors (n = 19). Animals were observed daily for s igns of graft-versus-host disease. Necropsies were performed. A minority of animals developed lethal disease (7 of 19 recipients) and demonstrated cac hexia with concomitant histopathologic changes of the disease. Acute and ch ronic groups emerged with distinct clinical courses, which are similar to o ther models of this disease. Recipients of vascularized bone marrow transpl ants (limb transplants) showed clinical and histopathologic changes of the disease. The transplants may be used as a model of graft-versus-host diseas e in humans. Most interestingly, the transplant has a lower incidence of di sease compared with other methods of bone marrow transplantation and repres ents an alternative to conventional bone marrow transplantation, which dese rves further exploration. It may be possible to develop a new technique for bone marrow transplantation based on this surgical approach. It is propose d that the transfer of vascularized blocks of bone/marrow into prospective recipients as opposed to cellular bone marrow transplants may be preferable .