Ectopic grafts of atrial tissue maintain their specific isomyosin expression and myoendocrine functions independently of their anatomical environment.
Atrial phenotype appears cell-intrinsic in grafts; hypothesis-generating for cardiac differentiation but leaves open human translation.
Tissue fragments of newborn rat atria were transplanted under the dorsal skin or into the bed of the anterior tibial muscle of nude mice. After 5-11 weeks, the grafts, which had reorganized into beating atrium-like structures, were analyzed and compared to ventricular tissue transplanted the same way. As revealed by monoclonal antibodies against alpha- and beta-type myosin heavy chains, atrial grafts retained a typical pattern of myosin expression distinct from that of ventricular grafts. The majority of ectopic atrial myocytes contained specific atrial granules in which cardiodilatin-immunoreactive material has been localized. Specific granules and cardiodilatin immunoreactivity were not found in myocytes of ventricular grafts. We conclude that the long-term maintenance of isomyosin expression and of the myoendocrine function of atrial tissue is largely independent of the anatomical environment.
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Jockusch et al. (1986) studied this question.
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