Myeloablative irradiation, granulocyte-colony stimulating factor, and FK506 can induce macrochimerism and prolong the survival of experimental extremity allografts.
BACKGROUND
A key component of composite tissue allografts is the vascularized limb/bone marrow because of its capacity to reconstitute the marrow cavity of the recipient. The efficacy of a new protocol that uses total body irradiation (TBI), granulocyte colony-stimulation factor (G-CSF), and FK506 to induce high level bone marrow chimerism was evaluated with particular reference to the dose requirement and toxicity of TBI.


METHODS
In total, 82 whole-limb allotransplants from LacZ transgenic rats to LEW rats were performed. TBI was administered just prior to transplantation with various doses ranging from 100 to 1500 R (almost equal to 1-15 Gy). G-CSF was given for 4 d, while FK506 was used for 28 d. The level of chimerism was evaluated by semiquantitative polymerase chain reaction (PCR).


RESULTS
The survival of limb allografts in recipients that were pretreated with a myeloablative TBI dose of >1000 R was prolonged to more than 1 y. Recipients pretreated with <500 R showed no prolongation of limb graft survival. A majority of long-term survivors showed chronic, nonlethal graft-versus-host disease (GVHD). PCR analysis revealed a high level of intra-bone marrow chimerism in the recipient, thus demonstrating successful induction of macrochimerism.


CONCLUSIONS
Vascularized limb/bone marrow graft is a proven method for supplying donor cells to the bone marrow of irradiated recipients. A new protocol involving pretransplant myeloablative TBI with >1000 R followed by treatment with G-CSF and FK506 was found to induce a high level of chimerism and significantly prolong the survival of limb allografts without causing lethal GVHD.
Muramatsu
Keiichi
K
Department of Orthopedic Surgery, Yamaguchi University School of Medicine, Yamaguchi, Japan. muramatu@yamaguchi-u.ac.jp
Kato
Hidetoyo
H
Yoshida
Yuichiro
Y
Moriya
Atsushi
A
Okimoto
Tomoaki
T
Taguchi
Toshihiko
T
D000818:Animals; D006084:Graft Rejection / Q000188:drug therapy; D006085:Graft Survival / Q000187:drug effects / Q000276:immunology / Q000528:radiation effects; D006086:Graft vs Host Disease / Q000517:prevention & control; D016179:Granulocyte Colony-Stimulating Factor / Q000494:pharmacology*; D006614:Hindlimb / Q000637:transplantation*; D007108:Immune Tolerance / Q000187:drug effects / Q000528:radiation effects; D007166:Immunosuppressive Agents / Q000494:pharmacology; D007763:Lac Operon / Q000235:genetics; D008297:Male; D051381:Rats; D011917:Rats, Inbred Lew; D055647:Rats, Transgenic; D016559:Tacrolimus / Q000494:pharmacology*; D018183:Transplantation Chimera; D019172:Transplantation Conditioning / Q000379:methods; D014184:Transplantation, Homologous; D014916:Whole-Body Irradiation
D007166:Immunosuppressive Agents; D016179:Granulocyte Colony-Stimulating Factor; D016559:Tacrolimus