Résumé :
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PURPOSE :in order to easily study heart development or reconstruction, we have developed a model of ectopic (in time and location) foetal heart graft. RESULTS : In this model ,rat foetal heart (E15-E20) , is grafted in the pavilion ear of an adult rat. Location in the pavilion ear protects the graft from automutilation, and allows easy studies of the development and function of the graft, during the whole course of his development, using external recording technologies. Histological studies demonstrate an early stage of extensive ischemic necrosis, followed some days after,by a reconstruction process , grossly recapitulating heart ontogenesis. This often leads to a partially functional heart with blood filled cavities, pace-maker and beating activities and to some extent with blood flow, as assessed by histological, ultrasound, IRM and electrical activity studies. Immunohistochemistry and microelectronic studies demonstrate progressive acquisition of adult myocyte phenotype of the graft cells. Furthermore the fact of grafting induces a elevation of serum IGF1 level.(50%). DISCUSSION : this experimental model allows study of the cellular and cytokine environment associated with cardiac reconstruction of a foetal heart .That knowledge could potentially give insights to optimize adult cardiac repair using cellular therapy. By example, modifying cytokine network during a cellular therapy of genetic diseased heart, in a way mimicking the one observed during the foetal heart graft,, could potentially favour engineered cells to engraft successfully in the diseased heart. In that context of cellular therapy, we intend to study the potential mobilisation of host stem cell induced by foetal heart grafting as well as their potential engraftment in the foetal graft.
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