Anti-ACTN2 monoclonal antibody, clone TB-31

Background: Acute myocardial infarction (MI) leads to an irreversible loss of proper cardiac function. Application of stem cell therapy is an attractive option for MI treatment. Adipose tissue has proven to serve as a rich source of stem cells (ADSCs). Taking into account the different morphogenesis, anatomy, and physiology of adipose tissue, we hypothesized that ADSCs from different adipose tissue depots may exert a diverse multipotency and cardiogenic potential. Methods: The omental, pericardial, and epicardial adipose tissue samples were obtained from organ donors and patients undergoing heart transplantation at our institution. Human foreskin fibroblasts were used as the control group. Isolated ADSCs were analyzed for adipogenic and osteogenic differentiation capacity and proliferation potential. The immunophenotype and constitutive gene expression of alkaline phosphatase (ALP), GATA4, Nanog, and OCT4 were analyzed. DNA methylation inhibitor 5-azacytidine was exposed to the cells to stimulate the cardiogenesis. Finally, reprogramming towards cardiomyocytes was initiated with exogenous overexpression of seven transcription factors (ESRRG, GATA4, MEF2C, MESP1, MYOCD, TBX5, ZFPM2) previously applied successfully for fibroblast transdifferentiation toward cardiomyocytes. Expression of cardiac troponin T (cTNT) and alpha-actinin (Actn2) was analyzed 3 weeks after initiation of the cardiac differentiation. Results: The multipotent properties of isolated plastic adherent cells were confirmed with expression of CD29, CD44, CD90, and CD105, as well as successful differentiation toward adipocytes and osteocytes; with the highest osteogenic and adipogenic potential for the epicardial and omental ADSCs, respectively. Epicardial ADSCs demonstrated a lower doubling time as compared with the pericardium and omentum-derived cells. Furthermore, epicardial ADSCs revealed higher constitutive expression of ALP and GATA4. Increased Actn2 and cTNT expression was observed after the transduction of seven reprogramming factors, with the highest expression in the epicardial ADSCs, as compared with the other ADSC subtypes and fibroblasts. Conclusions: Human epicardial ADSCs revealed a higher cardiomyogenic potential as compared with the pericardial and omental ADSC subtypes as well as the fibroblast counterparts. Epicardial ADSCs may thus serve as the valuable subject for further studies on more effective methods of adult stem cell differentiation toward cardiomyocytes.

Aims Significant T wave inversion in young asymptomatic athletes is rare but poses a significant clinical challenge. Pre-participation sports screening programs identify such subjects. Clinical concern that such ECG changes represent an occult cardiomyopathy or forme fruste hypertrophic cardiomyopathy leads to diagnostic and therapeutic dilemma. We sought to genotype a cohort of such subjects with a normal cardiac phenotype identified in our unit over a 3-year period. Methods Ten athletes were referred from external screening. All exhibited deep T wave inversion inferolaterally. All had negative family history for sudden death and had a normal phenotype. A panel of 133 cardiac genes were screened. Results Ten male subjects with mean age of 39 years were screened. Seven had no evidence of mutations. Three subjects demonstrated variants of uncertain significance in 5 different genes: alpha-2-actinin (ACTN2), myopalladin (MYPN), the calcium channel genes CACNA1C and TRPM4 and potassium channel gene KCNQ1. The variants found have not been described in cardiomyopathies or channelopathies. At 3-year follow-up, one patient had undergone detraining, and his ECG showed complete resolution of all T wave changes. He did not have any demonstrated variants. Conclusions The absence of mutations in target genes and heterogeneous sequence variations identified in this study suggest that inferolateral T wave inversion in athletes without a phenotype may potentially represent a benign repolarization syndrome related to athletic adaptation. This was the first study to assess a phenotype-genotype correlation in this population. Further genetic studies need to be undertaken in this area.