The requirements for the oncogenic conversion of the c‐abl proto‐oncogene have been determined by the expression of N‐terminal deleted forms and viral gag‐fused forms of the c‐abl proteins from a selectable retroviral vector. To activate the transforming potential of c‐abl, it is necessary that (i) specific N‐terminal amino acids are deleted to release the kinase from negative regulation in vivo; (ii) an N‐terminal myristylation site is part of the activated kinase; (iii) the fatty‐acylated, activated kinase is overproduced. The N‐terminal amino acids found to be necessary for the cellular inhibition of c‐abl tyrosine phosphorylation are part of a homologous region present in many non‐receptor tyrosine kinases, the v‐crk oncogene and phospholipase C‐II. Overproduction of a deregulated and myristylated c‐abl tyrosine kinase induces the transformation of NIH 3T3 cells.

Ischemic disorders of the heart can cause an irreversible loss of cardiomyocytes resulting in a substantial decrease of cardiac output. The therapy of choice is heart transplantation, a technique that is hampered by the low number of donor organs. In the present study, we describe the specific labeling, rapid but gentle purification and characterization of cardiomyocytes derived from mouse pluripotent embryonic stem (ES) cells. To isolate the subpopulation of ventricular-like cardiomyocytes, ES cells were stable transfected with the enhanced green fluorescent protein (EGFP) under transcriptional control of the ventricular-specific 2.1 kb myosin light chain-2v (MLC-2v) promoter and the 0.5 kb enhancer element of the cytomegalovirus (CMV(enh).). First fluorescent cells were detected at day 6 + 8 of differentiation within EBs. Four weeks after initiation of differentiation 25% of the cardiomyocyte population displayed fluorescence. Immunohistochemistry revealed the exclusive cardiomyogenic nature of EGFP-positive cells. This was further corroborated by electrophysiological studies where preferentially ventricular phenotypes, but no pacemaker-like cardiomyocytes, were detected among the EGFP-positive population. The enzymatic digestion of EBs, followed by Percoll gradient centrifugation and fluorescence-activated cell sorting, resulted in a 97% pure population of cardiomyocytes. Based on this study, ventricular-like cardiomyocytes can be generated in vitro from EBs and labeled using CMV(enh)./MLC-2v-driven marker genes facilitating an efficient purification. This method may become an important tool for future cell replacement therapy of ischemic cardiomyopathy especially after the proof of somatic differentiation of human ES cells in vitro.

Granulocyte colony-stimulating factor treatment after PCI in subacute STEMI is feasible and relatively safe. However, patients do not benefit from G-CSF when PCI is performed late. Granulocyte colony-stimulating factor results in improved myocardial perfusion of the infarcted area, which may reflect enhanced neovascularization.

Combining transcriptional targeting by the CMV(enh)/MLC1.5 promoter and AAV vectors devoid of binding the AAV-2 primary receptor results in an efficient cardiac gene transfer with a significantly reduced hepatic transduction.

Catheter-based percutaneous transluminal gene delivery (PTGD) into the coronary artery still falls behind the expectations of an efficient myocardial gene delivery system. In this study gene delivery was applied by selective pressureregulated retroinfusion through the coronary veins to prolong adhesion of replication defective adenovirus within the targeted myocardium. Adenoviral vectors consisted either of luciferase (Ad.rsv-Luc) or ␤-galactosidase (Ad.rsv-␤Gal) reporter gene under control of an unspecific promotor derived from the Rous sarcoma virus (RSV). In this pig model, selective retrograde gene delivery into the anterior cardiac vein during a brief period of ischemia substantially