Vascularized bone grafts within composite tissue allotransplants can autocreate tolerance through mixed chimerism with partial myeloablative conditioning: an experimental study in rats.
BACKGROUND
Certain composite tissue allotransplants contain vascularized bone grafts (e.g., hand/forearm composite tissue allotransplants). The authors investigated the role of the vascularized bone graft within the hind-limb osteomyocutaneous flap in inducing tolerance.


METHODS
Brown Norway and Lewis rats were used as composite tissue allotransplant donors and recipients, respectively. Experimental groups were as follows: group I, syngeneic controls (Lewis to Lewis); group II, allogeneic controls (both received no pretransplantation total body irradiation); and groups III, IV, and V, which received 5 mg of antilymphocyte globulin administered intraperitoneally (on days -1 and 10), 1 mg/kg of tacrolimus administered intraperitoneally (on days 0 to 10), and total body irradiation (600, 400, and 200 cGy, respectively, 1 day before composite tissue allotransplantation). Each Lewis rat in groups II, III, IV, and V received a composite tissue allotransplant on day 0 in the form of a Brown Norway hind-limb osteomyocutaneous flap. Different donor hematopoietic cell lineages in recipients' peripheral blood were assessed by flow cytometry on posttransplantation days 15, 30, 60, 90, 120, and 150. Secondary Brown Norway skin grafts in recipients with composite tissue allotransplant acceptance were performed at 150 days after transplantation.


RESULTS
Allotransplanted hind-limb osteomyocutaneous flaps produced chimerism and donor multilineage hematopoietic cells in groups III, IV, and V; composite tissue allotransplant acceptance rates in these groups were 37.5, 16.7, and 0 percent, respectively. Graft-versus-host disease occurred in 62.5 percent of group III recipients. Recipients with acute graft-versus-host disease produced a higher percentage of donor T cells compared with composite tissue allotransplant-accepting recipients (p < 0.05). Secondary Brown Norway skin graft acceptance in composite tissue allotransplant-accepting recipients confirmed durable tolerance.


CONCLUSIONS
Vascularized bone grafts contained within composite tissue allotransplants can autocreate chimerism and tolerance in rats with partial myeloablative tacrolimus-based conditioning.
Huang
Wei-Chao
WC
Taoyuan and Taipei, Taiwan From the Graduate Institute of Clinical Medical Sciences, the College of Medicine, Chang Gung University; the Division of Plastic and Reconstructive Surgery, Chang Gung Memorial Hospital at Chiayi; the Division of Plastic Surgery, Taipei University Hospital; and the Departments of Plastic and Reconstructive Surgery and Pathology, Chang Gung Memorial Hospital at Lin-Kou.
Lin
Jeng-Yee
JY
Wallace
Christopher Glenn
CG
Chuang
Wen-Yu
WY
Wei
Fu-Chan
FC
Liao
Shuen-Kuei
SK
D000818:Animals; D001835:Body Weight; D001854:Bone Marrow Cells / Q000166:cytology / Q000276:immunology; D016025:Bone Transplantation / Q000276:immunology* / Q000379:methods*; D001842:Bone and Bones / Q000098:blood supply; D006084:Graft Rejection / Q000188:drug therapy / Q000276:immunology / Q000517:prevention & control; D006085:Graft Survival / Q000276:immunology; D006086:Graft vs Host Disease / Q000276:immunology; D007108:Immune Tolerance / Q000187:drug effects* / Q000276:immunology; D007166:Immunosuppressive Agents / Q000494:pharmacology; D008297:Male; D051381:Rats; D011914:Rats, Inbred BN; D011917:Rats, Inbred Lew; D016038:Skin Transplantation / Q000276:immunology / Q000379:methods; D013524:Surgical Flaps / Q000098:blood supply; D016559:Tacrolimus / Q000494:pharmacology; D018183:Transplantation Chimera / Q000276:immunology*; D019172:Transplantation Conditioning / Q000379:methods*; D014184:Transplantation, Homologous
D007166:Immunosuppressive Agents; D016559:Tacrolimus