Long-term expression of isomyosins and myoendocrine functions in ectopic grafts of atrial tissue.

Abstract

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 a-and a-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.

Heme Oxygenase-1 Induction Enhances Cell Survival and Restores Contractility to Unvascularized Three-Dimensional Adult Cardiomyocyte Grafts ImplantedIn Vivo

“…The potential for spontaneous structural reorganization of atrial cells was reported in 1986 by Jockusch et al, 35 but in neonatal myocardium where greater plasticity is expected. In that study, subcutaneously implanted minced neonatal atrial tissue spontaneously reformed into ''organ-like'' chambered structures with blood-filled lumens by 5-11 weeks postimplant.…”

“…This myocyte population might in itself be sufficient for infarct repair purposes, even if engrafted adult cardiomyocytes have little proliferation. The unique properties of atrial myocytes, such as remodeling capacity, 35 atrial natriuretic hormone secretion, [36][37][38] and the potential to form gap junctions with ventricular myocytes, 39 might be har- nessed to advantage in infarct repair. Recently, atrial wall has been reported to harbor a repository of putative cardiac stem cells, [40][41][42][43][44] even in human hearts.…”

Use of a novel collagen matrix with oriented pore structure for muscle cell differentiation in cell culture and in grafts

“…In order to prevent graft rejection, nude (nu/nu) and eGFP transgenic individuals were used as hosts for transplantation experiments [12,20]. Reconstituted muscles in CS were grafted into the bed of the previously excised anterior tibial muscle (TA) using the transplantation procedure previously described for donor muscles [12,21]. The skin of the lower leg was opened and deflected and the tibialis anterior (TA) and extensor digitorum longus (EDL) muscles of the host animal were removed under deep anaesthesia, using blunt scissors to reduce bleeding.…”