Application of tissue-engineered pericardial patch in rat models of myocardial infarction.

Myocardial infarction (MI) is a major cause of mortality and morbidity in industrialized societies. Myocardial tissue engineering is an alternative and promising approach for substituting injured myocardium through development and seeding of appropriate scaffolds. In this study, we investigated the efficacy of using an acellular pericardium to deliver autologous mesenchymal stem cells (MSCs) to the infarcted site for regeneration of the myocardium. MI was induced in two groups of rats; G1 or MI group, and G2 or patch-implanted group. In G2 group, rats had undergone transplantation of a pericardial patch which was previously seeded with adipose tissue derived MSCs. To evaluate the efficacy of the pericardial patches, biopsies were taken one month after transplantation. In order to evaluate the extent of regeneration, inflammation and fibrosis, histopathological investigations including hematoxylin and eosin (H&E), Sirius Red and trichrome staining were performed. In addition, immunohistochemical investigations by Desmin as well as CD68, CD45 and CD34 antibodies were performed. Furthermore, Tunnel assay was performed to detect the extent of apoptosis. H&E assessments of biopsies from the patch-implanted group confirmed presence of pre-seeded pericardium containing MSCs along with neo-vessels. Immunohistochemical assessments demonstrated higher number of CD34 positive cells and Desmin-positive cells in the patch implanted group (p < 0.05); these findings are suggestive of cardiomyocyte regeneration in G2 rats. This study demonstrates the advantages of application of natural acellular scaffolds as cell delivery devices and it emphasizes neovascularization following this approach. However, further investigations are required to analyze long-term cardiac function in recipients.