Tolerance to Limb Tissue Allografts between Swine Matched for Major Histocompatibility Complex Antigens:

A Methodology for Determining Standard of Care Status for a New Surgical Procedure: Hand Transplantation

BACKGROUND

Hand allotransplantation was initially criticized as unethical and unlikely to succeed. The results proved to be better than anticipated, now raising the issue of whether hand transplantation is the standard of care. The purpose of this article is to outline a reasonable methodology for determining whether a surgical procedure is the standard of care, and then to apply that methodology to hand transplantation.

METHODS

Publications on ethics and definitions of medical (not legal) standard of care were reviewed. All hand transplantations completed in the United States were evaluated regarding their status as experimental, standard of care, or both. Then, the stakeholders, physicians, public insurers, and regulators were examined to determine whether they accepted hand transplantation as the standard of care. Utility and incremental cost-utility ratio were determined. Hand transplantation was considered the standard of care when stakeholders were using, insuring, and regulating the procedure.

RESULTS

The public expresses a desire for hand transplantation. A minority of surgeons consider the procedure the standard of care. Ethical committees, institutional review boards, and scholarly articles deem the procedure ethical. A series of institutions have carried out the procedure with a record of successes. Some institutions perform the surgical procedure as the standard of care. Scholarly work demonstrates beneficial outcomes. Some commercial and federal government insurers are willing to cover the cost of the procedure. Utility determination justifies the procedure. There are no incremental cost-utility ratio analysis studies that justify the procedure.

CONCLUSION

Hand transplantation is moving from acceptance as an ethical surgical experiment to the standard of care.

Recipient bone marrow engraftment in donor tissue after long-term tolerance to a composite tissue allograft

BACKGROUND

An important component of a composite tissue limb allograft (CTA) is the vascularized bone marrow and bone marrow stroma, which when transplanted could create immediate marrow space and engraftment. We have previously demonstrated that tolerance to musculoskeletal allografts can be achieved with a 12-day course of cyclosporine without the presence of long-term peripheral donor cell chimerism. The objective of this study was to determine the fate of the donor bone marrow after transplantation of a limb allograft in a miniature swine model.

METHODS

CTAs from donor swine were heterotopically transplanted into six MHC-matched, minor-antigen-mismatched recipients, and a 12-day course of cyclosporine was given. Previous animals transplanted without cyclosporine rejected their grafts in less than 42 days. A non-MHC-linked marker, pig allelic antigen (PAA), was used to distinguish host and donor cells. Three PAA- animals received PAA+ CTAs, and three PAA+ animals received PAA- CTAs. Bone marrow was harvested from the donor limb grafts and the recipient and analyzed by flow cytometry and histology. Thymus, spleen, and mesenteric lymph nodes were also harvested from the recipient swine and evaluated for the presence of donor cells by flow cytometry.

RESULTS

All animals receiving cyclosporine demonstrated permanent tolerance to their allografts. Donor bone marrow cells were present in all grafts at the time of transplantation and during the immediate postoperative period. By 48 weeks, donor cells were no longer detectable within the marrow space of the allograft. In long-term animals host bone marrow cells replaced donor cells in the graft marrow space. No evidence of donor cell engraftment was found in recipient animals.

CONCLUSION

This study demonstrates that in long-term tolerant recipients of musculoskeletal allografts there is no evidence of persistent donor bone marrow cells in the hematopoietic tissues of the graft or the host. Rather, the recipient's bone marrow cells and lymphocytes repopulate the donor marrow space of the graft.