Effects of chimerism on the mice heart transplanted survival with the bone marrow infusion

Aims: To evaluate the effects of chimerism on the mice heart transplanted survival with the bone marrow infusion. Methods: Bone marrow cells (BMCs) were obtained from BALB/c mice. These BMCs were injected into the irradiated (2Gy-Co60) C57BL/6 mice through femoral vein. Then Group A mice were treated with Cyclosporine (1 mg/kg) for 21 days and Group B were not treated with Cyclosporine. Group C were treated as the control group without BMCs infusion. Group D were treated with Cyclosporine (1 mg/kg) for 21 days pre-hearttransplantation without BMCs infusion. After 21 days, the C57BL/6 mice received heart allografts from BALB/c. To determine the degree of chimerism in BMCs infusion recipients, peripheral blood were isolated on day 7, 14, 21. Allografts were harvested 10 days after heart transplantation for the histological analysis. Results: (1) Chimerism detected in the peripheral blood of Group A mice on day 7 after BMCs infusion was 6.1 +/- 2.5%, on day 14 was 15.4 +/- 2.9% and on day 21 was 10.7 +/- 2.6%. For the Group B mice on day 7 after BMCs infusion, the chimerism was 2.8 +/- 1.1%, on day 14 was 11.2 +/- 4.8% and on day 21 was 7.4 +/- 3.7%. For the Groups C and D mice, no chimerism was observed. Group A mice had the tendency toward improved level of chimerism than Group B mice. (2) The survival time of Group A (n = 6) was 13.0 +/- 1.4 days which was significantly longer than Group B (n = 6) with the survival time was 8.5 +/- 1.3 days (p<0.001), also longer than the mice in Groups C and D, the survival time of which were 10.0 +/- 1.3 days (p = 0.008) and 9.4 +/- 1.1 days (p = 0.004). There is no significant difference among Groups B, C, and D. (3) The HE staining showed the much more seriously heart rejection in Groups B, C and D than Group A. Conclusions: The chimerism was found in the BMCs infusion groups. Without the CsA treatment combined with chimerism could not protect the transplanted heart. There was no obvious evidence showed that the chimerism alone could improve the survival time of cardiac allografts in mice. Published by Elsevier B.V.