1University Heart Center Hamburg, Transplant and Stem Cell Immunobiology Lab (TSI), University Hospital Hamburg, 2Stanford University School of Medicine
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Stubbendorff, M., Deuse, T., Hammel, A., Robbins, R. C., Reichenspurner, H., Schrepfer, S. Orthotopic Aortic Transplantation: A Rat Model to Study the Development of Chronic Vasculopathy. J. Vis. Exp. (46), e1989, doi:10.3791/1989 (2010).
Research models of chronic rejection are essential to investigate pathobiological and pathophysiological processes during the development of transplant vasculopathy (TVP).
The commonly used animal model for cardiovascular chronic rejection studies is the heterotopic heart transplant model performed in laboratory rodents. This model is used widely in experiments since Ono and Lindsey (3) published their technique. To analyze the findings in the blood vessels, the heart has to be sectioned and all vessels have to be measured.
Another method to investigate chronic rejection in cardiovascular questionings is the aortic transplant model (1, 2). In the orthotopic aortic transplant model, the aorta can easily be histologically evaluated (2). The PVG-to-ACI model is especially useful for CAV studies, since acute vascular rejection is not a major confounding factor and Cyclosporin A (CsA) treatment does not prevent the development of CAV, similar to what we find in the clinical setting (4). A7-day period of CsA is required in this model to prevent acute rejection and to achieve long-term survival with the development of TVP.
This model can also be used to investigate acute cellular rejection and media necrosis in xenogeneic models (5).
Rats weighing approximately 250-300g are purchased from Charles River (Sandhofer Weg 7, D-97633 Sulzfeld).
Transplants are performed using PVG rats as donors, and ACI rats as recipients.
Rats are housed under conventional conditions, fed standard rat chow and water ad libidum.
All surgical instruments are sterilized prior to use.
Anesthetize rat with isoflurane (2,5-3%) using an induction chamber.
Anesthetize rat with isoflurane (2,5-3%) using an induction chamber. Body temperature is maintained during the surgical procedure.
For several reasons we found the orthotopic aortic transplantation model a more accurate way to investigate the development of TVP compared to the heterotopic heart transplantation model:
Regarding the surgical technique, the aortic transplant model embodies an easily feasible method, requiring solely the accomplishment of end-to-end-anastomosis, whereas the heterotopic heart transplant model may be considered a more complex and error-prone challenge to the surgeon s skills, requiring end-to-side anastomosis on two major vessels.
Analysis and measurement of histological specimens is drastically facilitated since transplant vasculopathy may be examined in one single vessel of a sole defined diameter instead of the exploration of numerous small cardiac vessels showing a vast variety in size and constitution which could handicap the investigator in gaining objective and credible results. The thoracic aorta of the recipient may serve as normal control, offering an easy and reliable object of comparison in diameter and morphological appearance, while in the heterotopic heart transplantation model it is difficult to compare peri- or myocardial vessels underlying a great interindividual variability.
In addition to these findings, aortic allografts are not as prone to disruptive histological alterations that may result from the applied surgical procedures. Fibrosis or infarctions may occur in and possibly affect heterotopic heart transplant tissue and embedded vessels, rendering them unsuitable for evaluation.
Due to its size and constitution, the aorta is an ideal subject to simple and exact investigation of morphological, biochemical and molecular remodeling within each one of the three layers of the vascular wall, such as the degree of concentric intimal thickening, myocyte necrosis in the media or increased synthesis of cytokines and growth factors.
The immune response generated by an aortic allograft is indeed sufficient to trigger chronic alterations in the transplant, but was found insufficient to induce acute rejection episodes (2). Thanks to this intermediate immunogenicity of the graft, no transplant is lost to acute rejection and no initial immunosuppressive treatment with CsA is required. The model thus enables to investigate the initial effects of drugs on chronic allograft vasculopathy without the influence or adulteration by prophylactic immunosuppression often seen in heterotopic heart transplants (2, 4).
No conflicts of interest declared.
The authors thank Christiane Pahrmann for her histological work.
Sonja Schrepfer has received a research grant from the Deutsche Forschungsgemeinschaft (DFG) (SCHR992/3 1 and SCHR992/4-1).]
|Surgical microscope (magnification 25x)|
|ice cold 0.9% saline|
|prewarmed 0.9% sterile saleine|
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