Different routes of donor-derived hematopoietic stem cell transplantation for donor-specific chimerism induction across MHC barrier.

Transplantation of donor-derived stem cells can improve organ allograft survival in animal models. This study was designed to investigate the effect of different routes of bone marrow cell (BMC) transplantation on donor-specific tolerance induction across MHC barrier under short-term CsA monotherapy and alphabetaTCR/CsA treatment protocols. Forty-eight BMC transplantations were performed between BN(RT1(n)) donors and LEW(RT1(1)) recipients. Intraosseous and intravenous BMC transplantation was studied in six groups of eight animals each receiving 35 x 10(6) (n = 4) and 70 x 10(6) (n = 4) bone marrow cells. Groups I and II (controls) received BMC transplantation but no treatment, groups III and IV CsA monotherapy, and groups V, VI alphabetaTCR/CsA protocol for 7 days. Flow cytometry monitored immunodepletion and donor-specific chimerism for MHC class I RT1(n)/CD4, RT1(n)/CD8 and RT1(n)/CD45RA antigens. All animals survived without graft-versus-host disease. At day 63 under CsA monotherapy a low level of chimerism for RT1(n)/CD4 was induced after intraosseous (1.9%) and intravenous (0.8%) transplantation of (70 x 10(6)) BMC. Under alphabetaTCR/CsA protocol chimerism for RT1(n)/CD4 revealed 6.5% and 0.9% in intraosseous and intravenous (70 x 10(6)) BMC transplantation, respectively. The total number of chimerism in intraosseous and intravenous (70 x 10(6)) BMC transplantation groups was 9.9% and 3.4%, respectively. Following intraosseous BMC transplantation under alphabetaTCR/CsA protocol chimerism was 50% higher in a group receiving 70 x 10(6) (9.9%) vs 35 x 10(6) (4.9%) BMC. Intraosseous transplantation of donor BMC under alphabetaTCR/CsA protocol was 75% more efficient in induction of donor-specific chimerism compared to intravenous transplantation.