Biological properties of human skeletal myoblasts genetically modified to simultaneously overexpress the pro-angiogenic factors vascular endothelial growth factor-A and fibroblast growth factor-4.

Myocardial infarction results in cardiomyocyte loss and may eventually lead to cardiac failure. Skeletal myoblast transplantation into the scar area may compensate for this observed cell loss by strengthening the weakened myocardium and inducing myogenesis. Moreover, skeletal myoblasts may serve as potential transgene carriers for the myocardium (i.e., delivering pro-angiogenic factors, which may potentially improve blood perfusion in infarcted heart). We examined the influence of the simultaneous overexpression of two potent pro-angiogenic factors, fibroblast growth factor-4 (FGF-4) and vascular endothelial growth factor (VEGF), on human primary myoblast proliferation, cell cycle, resistance to hypoxic stress conditions and myogenic gene expression, as well as the induction of pro-angiogenic activities. We used a bicistronic plasmid vector encoding two factors introduced via an efficient myoblast electroporation method. The levels of overexpressed proteins were assessed, and their functionality at capillary formation was evaluated. This combined approach led to a high level of non-viral transient overexpression of both pro-angiogenic proteins, which proved to be potent regulators of blood vessel development assayed in capillary formation tests. We demonstrated in in vitro conditions that the transfection of human skeletal myoblasts with both FGF-4 and VEGF did not affect their basic biological properties such as the cell cycle, proliferation or expression of myogenic lineage-specific genes, and the modified cells adapted to oxidative stress conditions. Overall, the results obtained suggest that the applied combined approach with the use of two pro-angiogenic genes overexpressed in skeletal muscle stem cells may be an interesting alternative for the effective therapy of myocardial infarction in animal models and/or prospective clinical trials.

Transient and stable transfections of mouse myoblasts with genes coding for pro-angiogenic factors.

Cardiomyocyte loss in the ischaemic heart can be the reason of many complications, eventually being even the cause of patient's death. Despite many promises, cell therapy with the use of skeletal muscle stem cells (SMSC) still remains to be modified and improved. Combined cell and gene therapy seems to be a promising strategy to heal damaged myocardium. In the present study we have investigated the influence of a simultaneous overexpression of two potent pro-angiogenic genes encoding the fibroblast growth factor-4 (FGF-4) and the vascular endothelial growth factor-A (VEGF-A) on a myogenic murine C2C12 cell line. We have demonstrated in in vitro conditions that myoblasts which overexpressed these factors exhibited significant changes in the cell cycle and pro-angiogenic potential with only slight differences in the expression of the myogenic genes. There was not observed the influence of transient or stable overexpression of FGF-4 and VEGF on cell apoptosis/necrosis in standard or oxidative stress conditions comparing to non transfected controls. Overall, our results suggest that the possible transplantation of myoblasts overexpressing pro-angiogenic factors may potentially improve the functionality of the injured myocardium although the definite proof must originate from in situ conducted pre-clinical studies.

The clinical evaluation of fillings made witch Ketac-Cem after endodontic treatment in dogs.

The aim of this study was the clinical evaluation of glass-ionomer material Ketac-Cem used after the root canal therapy as filling. The investigations were carried out in 18 dogs. The filling was evaluated according to Rydge's modified scale. The evaluations were done shortly after treatment and repeated after two years. The investigated material is frequently used in veterinary stomatology. Only 22.22% of fillings were qualified to replacement at the second evaluation.

Modulation of the cytoskeleton and intracellular calcium in leukocytes exhibiting a cancer-associated chemotaxis defect.

Monocyte chemotaxis is severely depressed in patients with advanced tumors, but the cellular basis for this chemotactic defect is not known. Because the actomyosin cytoskeleton is thought to play a primary role in chemotaxis, we have employed flow cytometry to examine several aspects of the contractile machinery including myosin II, myosin light chain kinase (MLCK), actin, and cytoplasmic calcium in unstimulated and in formylpeptide-stimulated neutrophils and monocytes. Serum-pretreated polymorphonuclear leukocytes (PMNs) and monocytes from healthy blood donors or PMNs and monocytes isolated from tumor patients were studied. Leukocytes pretreated with serum from cancer patients exhibited decreased baseline myosin staining and a vastly different response to formylpeptide stimulation compared with leukocytes pretreated with normal human serum. In contrast, similar amounts of MLCK were observed in neutrophils and monocytes preincubated with normal or cancer serum with or without stimulation with formylpeptide. The fluorescent calcium indicator fluo-3 showed that resting and fMLP-stimulated levels of intracellular calcium were not significantly different in control and cancer serum-pretreated human leukocytes or in leukocytes isolated from tumor patients. Similarly, resting and fMLP-stimulated levels of F-actin in cancer patients' leukocytes as assessed by NBD-phallacidin staining did not differ significantly from those of normal leukocytes. Because the actomyosin cytoskeleton is intricately involved in leukocyte chemotaxis, alterations in the cytoskeleton may dramatically affect cell motility. The cytoskeletal alterations and changes in the response of leukocytes pretreated with cancer patients' serum to formylpeptide stimulation as described here may result in decreased chemotaxis by these cells.

Autoradiographic analysis of formylpeptide chemoattractant binding, uptake and intracellular processing by neutrophils.

Formylpeptide chemoattractant binds specifically to leukocyte cell surface receptors and during chemotactic activation, is internalized and processed by these cells. Using electron microscope autoradiographic techniques, we have examined the binding, uptake and disposition of fNle-Leu-Phe-Nle-[125I]Tyr-Lys by rabbit peritoneal neutrophils. Cells were incubated with ligand for 15 min at 4 degrees C, rinsed and then further incubated in buffer at 4 degrees C, 15 degrees C, 24 degrees C, or 37 degrees C for 0-40 min. For all cells incubated at 4 degrees C, grains were predominantly localized on the plasma membrane. Initially, this formylpeptide was seen in small clusters or microaggregates that were not associated with coated pits. Upon further incubation at 37 degrees C for 1 min, formylpeptide clustering on the plasma membrane increased and extensive internalization of formylpeptide was observed. Endocytosis of formylpeptide-receptor complexes clearly involved uncoated membrane pits and vesicles but did not appear to involve coated pits or coated vesicles. In the following 3 min, peptide proceeded in waves through compartments composed of small uncoated endocytic vesicles, then large vesicles, and then into dense granules. After 4 min at 37 degrees C, the most active phase of intracellular processing subsided. The percentage of grains in the cytoplasm, granule and small vesicle compartments very gradually increased during the remainder of the 40 min incubation. Formylpeptide neither bound at 4 degrees C nor accumulated at 37 degrees C on the cell surface in proximity to the underlying Golgi/centrosome region of the cell. At 24 degrees C, processing was slowed but formylpeptide-receptor complexes proceeded through a similar series of compartments. The t1/2 for formylpeptide uptake at 37 degrees C was 15-20 s, whereas at 24 degrees C the t 1/2 was approximately 10 min. No uptake was observed at 15 degrees C. The distinctive characteristics of formylpeptide binding and receptor-complex uptake seen here may be essential in initiating and maintaining continued chemotactic responsiveness.