Technique for retransplanting heterotopic heart grafts in mice

Modified suture technique in a mouse heart transplant model

BACKGROUND

The mouse abdominal heart transplantation model is a basic and important immunological research model. We developed a technique for placing entire everting sutures instead of half inverting and half everting sutures for anastomosis between donor and recipients' caval veins. The purpose of this study was to evaluate this modified method.

METHODS

Each technique was used in 25 mice subjected to isogenic abdominal heart transplantation. Recipient operation time, graft warm ischaemia time, time of caval anastomosis, and re-beating time were recorded. After transplantation, the heartbeat was palpated through the abdominal wall once a day for 100 days.

RESULTS

Recipient operation time (40.7 ± 2.5 min vs. 44.3 ± 2.3 min, p < 0.01), cava-caval anastomosis time (8.4 ± 1.3 min vs. 12.1 ± 1.2 min, p < 0.01), and warm ischaemia time were significantly shorter (23.4 ± 1.7 min vs. 27.2 ± 1.6 min, p < 0.01) with the modified technique. Re-beating time was 1.2 ± 0.4 minutes with the modified technique vs. 1.5 ± 0.5 minutes (p = 0.04). There was a tendency for less surgical complications in the modified group, but there were no differences in survival rates.

CONCLUSION

The new suturing technique for mouse cardiac transplantation facilitates easier anastomosis of the outflow tract, thereby reducing operation, warm ischaemia, and re-beating times.

CCR5 is required for regulation of alloreactive T-cell responses to single class II MHC-mismatched murine cardiac grafts

The effector CD4 T-cell response in wild-type C57BL/6 recipients of single class II MHC-disparate B6.H-2(bm12) cardiac allografts is restricted by CD4(+)CD25(+) regulatory T cells (Tregs) resulting in long-term allograft survival. To investigate the role chemokine receptors might play in Treg function, this study tested the requirement for CCR5 on Tregs to suppress the alloimmune response in C57BL/6 recipients of B6.H-2(bm12) cardiac allografts. In contrast to the long-term survival of B6.H-2(bm12) allografts in wild-type recipients (>100 days), the allografts were acutely rejected within 25 days in CCR5(-/-) recipients with intense infiltration of CD4 T cells. Numbers and duration of donor-reactive CD4 T cells producing IFN-gamma and IL-4 were markedly increased in spleens of B6.CCR5(-/-) versus wild-type recipients. Wild-type and B6.CCR5(-/-) mice had equivalent numbers of splenic FoxP3(+) Tregs before and following transplantation, and these Tregs were equivalently suppressive in vitro. However, diminished numbers of FoxP3(+) Tregs infiltrated B6.H-2(bm12) allografts in B6.CCR5(-/-) recipients. Adoptive transfer of wild-type, but not CCR5-deficient, CD4(+)CD25(+) Tregs to CCR5(-/-) recipients restored long-term survival of B6.H-2(bm12) cardiac grafts. Collectively, these results indicate that CCR5 expression is required for the regulatory functions of Tregs that restrict alloreactive CD4 T-cell responses to single class II MHC-mismatched cardiac allografts.

Novel technique for blood circuit reconstruction in mouse heart transplantation model

PURPOSE

The surgical technique of heterotopic abdominal heart transplantation in mice, a standard model for transplantation immunology research, is very challenging restricting the widespread use of this model. A novel technique for the blood circuit reconstruction in heterotopic abdominal heart transplantation was developed.

METHOD

The new method makes use of the suprahepatic inferior vena cava instead of the pulmonary artery of the donor heart for the anastomosis to the infrarenal vena cava of the recipient.

FINDINGS

The sutures for the double vessel anastomoses were completed within 20.8+/-1.3 min, which was significantly shorter than 27.5+/-1.3 min in the traditional method. Similarly, the heart rebeating time postoperation (1.1+/-0.2 min) was significantly shortened as compared to 2.1+/-0.4 min using the traditional method.

CONCLUSION

This novel technique facilitated abdominal heart transplantation in mice with reduced warm ischemia and grafted heart rebeating time.