Heterotopic cardiac xenotransplantation in rodents: Report of a refined technique in a hamster-to-rat model

Abstract

With great interest we read the article by Dedja et al.,reporting a refined technique for hamster-to-rat heterotopic cardiac xenotransplantation. 1 The article provides novel insights in the distinct technique implemented at the authors' institution and describes methodological improvements, adaptions, and further changes of the suture technique for heterotopic heart transplantation in rodents, initially described by Abbott et al. and Ono and Lindsay. 2,3 Further, Dedja et al. refined earlier instructions for this experimental model to perform heterotopic cardiac xenotransplantation in the hamster-to-rat combination. [1][2][3] We feel that particularly, the step-by-step instructions on both the microsurgical procedures and the anesthetic interventions are thoroughly described, which allows for an easy adoption of this experimental model by the reader.In view of using this model for the study of specific immunological processes in xenograft rejection, however, the technique described bears the major drawback in that the procedure is associated with an enhancement of nonspecific ischemia/reperfusion injury, which may markedly interfere with immunological analyses of xenograft rejection. We therefore would like to suggest additional refinements in order to alleviate the assessment of the purely adaptive immune responses during experimental cardiac xenograft rejection. It should be favored to reduce functional graft impairment due to innate immunity and nonspecific ischemia/reperfusion (I/R) injury.Dedja et al. describe in detail the harvest of the hamster donor organ.1 This includes heparinization via the abdominal inferior vena cava (IVC), subsequent thoracotomy, isolation and transection of both the proximal aorta and pulmonary trunk, organ preservation by manual retrograde injection of ice-cold Celsior 1 solution (Imtix, Sangstat Italia, Milan, Italy) into the proximal aorta, mass ligature of the residual pericardial structures as well as minor back table preparation of the graft. We support this straight forward harvesting protocol, particularly the use of a mass ligature for combined transection of all residual pericardial tissues. This procedure, which was first described by Heron, indeed helps to drastically reduce the time of harvest and thus the graft's total ischemia time.4 Nonetheless, Dedja et al. use retrograde manual injection of the preservation solution via the ascending aorta at 10 ml/min or more slowly for the preservation of the graft subsequent to the thoracotomy as well as the isolation and transection of the great thoracic vessels. By this, the graft has to be considered to be exposed to a certain period of warm ischemia, which ideally should be omitted. We favor to cannulate the intraabdominal aorta and to begin the cold perfusion of the graft by standardized continuous infusion of preservation solution at a stable pressure of 100 cm H 2 O already before thoracotomy. This also guarantees that the donor blood is flushed out of the coronary system to minimize the risk of coronary microthrombosi...

Simvastatin does not prevent acute cardiac allograft rejection in CD28-deficient mice

“…The operative technique has been described previously in detail [17][18][19]. The viability of the allografts was controlled once daily by palpation and inspection of the ventral aspect of the recipients' neck.…”