Tissue regeneration observed in a porous acellular bovine pericardium used to repair a myocardial defect in the right ventricle of a rat model

ObjectiveNonliving synthetic materials have been widely used to repair myocardial defects; however, material-related failures do occur. To overcome these problems, an acellular bovine pericardium with a porous structure fixed with genipin (the AGP patch) was developed.MethodsThe AGP patch was used to repair a surgically created myocardial defect in the right ventricle of a rat model. A commercially available expanded polytetrafluoroethylene (e-PTFE) patch was used as a control. At retrieval, a computerized mapping system was used to acquire local epicardial electrograms of each implanted sample, and the appearance of each retrieved sample was grossly examined. The retrieved samples were then processed for histologic examination.ResultsThe amplitude of local electrograms on the AGP patch increased significantly with increasing implantation duration, whereas only low-amplitude electrograms were observed on the e-PTFE patch throughout the entire course of the study. No aneurysmal dilation of the implanted patches was seen for either studied group. Additionally, no tissue adhesion was observed on the outer (epicardial) surface of the AGP patch, whereas a moderate tissue adhesion was observed on the e-PTFE patch. On the inner (endocardial) surface, intimal thickening was observed for both studied groups; however, no thrombus formation was found. Intact layers of endothelial and mesothelial cells were identified on the inner and outer surfaces of the AGP patch, respectively. At 4 weeks postoperatively, smooth muscle cells, together with neomuscle fibers (with a few neocollagen fibrils), neoglycosaminoglycans, and neocapillaries, were observed to fill the pores in the AGP patch, an indication of tissue regeneration. These observations were more pronounced at 12 weeks postoperatively. In contrast, no apparent tissue regeneration was observed in the e-PTFE patch.ConclusionThe present study indicated that the AGP patch holds promise to become a suitable patch for surgical repair of myocardial defects