title: Rapamycin, mycophenolate mofetil, methylprednisolone, and cytotoxic T-lymphocyte-associated antigen 4 immunoglobulin-based conditioning regimen to induce partial tolerance to hind limb allografts without cytoreductive conditioning.
abstract: BACKGROUND
  Composite tissue allograft transplantation may represent the next frontier in the field of reconstructive surgery. However, the main obstacles precluding the routine use of composite tissue allotransplants are rejection and toxicity associated with life-long immunosuppressive therapy. In this study, we investigated a nontoxic immunosuppressant and cytotoxic T-lymphocyte-associated antigen 4 immunoglobulin (CTLA4-Ig)-based protocol to induce donor-specific tolerance to hind limb allografts in rats.
  
  
  METHODS
  Fully mismatched, 4- to 10-week-old Brown Norway (BN, RT1n) and Lewis (RT1) rats were used as cell/organ donors and recipients, respectively. Recipients were treated with CTLA4-Ig (2 mg/kg/d) on days -30, -28, -26, -24, and -22, rapamycin, mycophenolate mofetil, and methylprednisolone (RAPA/MMF/MP) combined therapy (from days -30 to day 100), a single dose of anti-lymphocyte serum (10 mg, on day -30), and donor bone marrow (10 x 10(7) T-cell-depleted cells) transplantation (BMT, on day -30). Thirty days after BMT, chimeric animals received hind limb allotransplantations (on day 0). The RAPA/MMF/MP combined therapy was changed to Cyclosporine (CsA, 8 mg/kg/d) on day 100 and maintained thereafter at this level.
  
  
  RESULTS
  Hematopoietic chimerism of 17.6 +/- 9.5% at day 0, was stable (15.2 +/- 5.6%) at 230 days post-BMT; there was no sign of graft-versus-host disease. Chimeric recipients (Lewis) permanently accepted (>200 days) donor (BN)-specific (RT11, n = 6) hind limbs, yet rapidly rejected (20 +/- 2 days) third-party hind limbs (Wistar Furth [WF]). Lymphocytes of graft-tolerant animals demonstrated hyporesponsiveness in mixed lymphocyte cultures in a donor-specific manner. Tolerant graft histology showed no signs of acute and chronic rejection.
  
  
  CONCLUSIONS
  The immunosuppressant and CTLA4-Ig-based conditioning regimen with donor BMT produced mixed chimerism and induced partial donor-specific tolerance to hind limb allografts.
authors.affiliation: Institute of Plastic Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, Shanxi Province, China.
authors.forename: H
authors.initials: H
authors.lastname: Pan
authors.forename: L
authors.initials: L
authors.lastname: Wang
authors.forename: X
authors.initials: X
authors.lastname: Zhang
authors.forename: G
authors.initials: G
authors.lastname: Zhang
authors.forename: H
authors.initials: H
authors.lastname: Mai
authors.forename: Y
authors.initials: Y
authors.lastname: Han
authors.forename: S
authors.initials: S
authors.lastname: Guo
mesh_terms: D000069594:Abatacept; D000082:Acetaminophen / Q000627:therapeutic use; D000698:Analgesia; D000700:Analgesics / Q000627:therapeutic use; D000818:Animals; D002047:Buprenorphine / Q000627:therapeutic use; D006614:Hindlimb / Q000637:transplantation*; D007108:Immune Tolerance / Q000276:immunology*; D018796:Immunoconjugates / Q000627:therapeutic use*; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D008297:Male; D008775:Methylprednisolone / Q000627:therapeutic use*; D009173:Mycophenolic Acid / Q000031:analogs & derivatives* / Q000627:therapeutic use; D010149:Postoperative Pain / Q000517:prevention & control; D051381:Rats; D011914:Rats, Inbred BN; D011917:Rats, Inbred Lew; D020123:Sirolimus / Q000627:therapeutic use*; D019172:Transplantation Conditioning / Q000379:methods*; D014184:Transplantation, Homologous
chemical_list: D000700:Analgesics; D018796:Immunoconjugates; D007166:Immunosuppressive Agents; D000082:Acetaminophen; D002047:Buprenorphine; D000069594:Abatacept; D009173:Mycophenolic Acid; D020123:Sirolimus; D008775:Methylprednisolone