Objective To establish a chronic rejection (CR) model of mouse heart transplantation and analyze its characteristics. Methods Allogeneic BALB/c and C57BL/6 mice were used as donor and recipient for heart transplantation, and intraperitoneal injection of cytotoxic T lymphocyte-associated antigen 4-immunoglobulin (CTLA4-Ig) was given 1 and 2 days after surgery. Graft survival time, donor specific antibody (DSA) level, graft pathology and inflammatory cell infiltration were observed. Results In allogeneic transplantation model, graft survival time was prolonged after CTLA4-Ig treatment [(28.2±4.1) d vs. (7.0±0.7) d, P < 0.01]. The level of serum DSA-IgG increased at 2, 3 and 4 weeks after surgery, while the level of DSA-IgM remained unchanged. Myocardial cell injury, inflammatory cell infiltration, interstitial fibrosis and C4d deposition in capillaries were aggravated 3 weeks after operation and worsened 4 weeks after operation. The infiltrated immune cells were mainly macrophages, T cells and plasma cells. Conclusions Mouse allogeneic heart transplantation combined with CTLA4-Ig successfully establishes a CR model, which provides a basis for subsequent studies on the pathogenesis and intervention of CR.

Early diagnosis of acute rejection is of significance for the protection of renal allograft function. Pathological puncture biopsy is the gold standard for the diagnosis of acute rejection of renal allografts. Nevertheless, it may provoke multiple complications, such as bleeding, infection and renal parenchymal injury, which limit its widespread application. In recent years, the sensitivity of contrast-enhanced ultrasound in the diagnosis of acute rejection has been constantly improved. Ultrasound-targeted microbubble technique has further enhanced the diagnostic specificity of contrast-enhanced ultrasound, making it possible to replace pathological puncture biopsy. Besides, in the field of acute rejection treatment, microbubble ultrasonic cavitation may promote local delivery of immunosuppressants by inducing sonoporation and exhibit anti-rejection effect. In this article, the application of contrast-enhanced ultrasound in the diagnosis and treatment of acute rejection after kidney transplantation was reviewed, aiming to provide reference for widespread application of contrast-enhanced ultrasound in kidney transplantation.