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Cyclosporine and the reversibility of chronic vascular rejection
R D Guttmann1, R D Forbes, S Zheng
1Centre for Clinical Immunobiology & Transplantation, McGill University, Montreal, Canada.
Insights
A novel rat model effectively mimics chronic vascular rejection in cardiac allografts. Cyclosporine A (CsA) demonstrates efficacy in preventing and reversing these rejection vasculopathies.
Area of Science:
- Transplantation Immunology
- Cardiovascular Pathology
- Pharmacology
Background:
- Chronic vascular rejection is a major cause of cardiac allograft failure.
- Existing models often lack the specific histopathological features of human chronic vascular rejection.
- A reliable preclinical model is crucial for studying rejection mechanisms and therapeutic interventions.
Purpose of the Study:
- To develop and characterize a rat model of chronic vascular rejection in cardiac allografts.
- To evaluate the efficacy of Cyclosporine A (CsA) in preventing and reversing rejection-induced vasculopathy.
- To establish the utility of this model for investigating rejection mechanisms and CsA's action.
Main Methods:
- Development of a cardiac allograft model in inbred rats (WF.1L/Gut donor into LEW recipients).
- Histopathological analysis of cardiac allografts over time post-transplantation.
- Assessment of graft survival and function.
- Evaluation of CsA treatment (15 mg/kg/d) for prevention and reversal of vasculopathy.
Main Results:
- Cardiac allografts survived >200 days without immunosuppression.
- Histopathology revealed cellular rejection, vasculitis, and myointimal arterial wall thickening.
- Widespread occlusive vascular changes, similar to human allografts, were observed by day 60.
- CsA effectively prevented and reversed the observed vasculopathy.
- MHC class I and II incompatibility were not essential for lesion development.
Conclusions:
- The developed rat model reliably replicates chronic vascular rejection in cardiac allografts.
- The model allows for the study of lesion regression mechanisms between days 40-60 post-transplant.
- Vascular lesions can occur independently of MHC class I and II incompatibility.
- CsA is a valuable tool for studying cardiac allograft vasculopathy and its mechanisms of action.
Abstract:
A model of chronic vascular rejection of cardiac allografts has been developed in inbred rats using the WF.1L/Gut congenic strain as donor into LEW recipients. The hearts beat for more than 200 days without the need for exogenous immunosuppression. The histopathology is characterized by cellular rejection, vasculitis, and myointimal arterial wall thickening, and by day 60 posttransplant, there are widespread occlusive vascular changes similar to those seen in human cardiac allografts. CsA, at a dose of 15 mg/kg/d, is effective in preventing as well as reversing the vasculopathy. These data (1) confirm other studies of ours on the reliability of the experimental model using this strain combination, (2) establish the time window of days 40 to 60 whereby mechanisms of lesion regression can be studied, (3) prove the MHC class I and class II antigen incompatibility are not a necessary condition for the generation of the vascular lesions, (4) show that CsA is a useful probe for study of the vasculopathy, and (5) suggest that the model is a useful probe of the mechanism of action of CsA.