Biomedical subjects

Yury Ladilov

Publications and source records attributed to Yury Ladilov.

5 recordsLinked to original sources

PubMed2006

Ischemic acidosis causes apoptosis in coronary endothelial cells through activation of caspase-12.

OBJECTIVE: Myocardial ischemia has been shown to induce apoptosis of endothelial cells (EC). However, the mechanism of this endothelial injury is still poorly understood. To analyse the signaling pathway of ischemia-induced EC apoptosis was the aim of the present study. METHODS: The primary culture of rat coronary EC was exposed to simulated ischemia (glucose-free anoxia at pH(o) 6.4). Apoptosis was defined by staining of nuclei with Hoechst-33342 and TUNEL. Cytosolic Ca2+ and pH were measured with Fura-2 and BCECF, respectively. RESULTS: Apoptosis (29.2+/-1.7% of cells) induced by exposure to simulated ischemia for 2 h was accompanied by cytosolic Ca2+ overload (1090+/-52 nmol/l) and acidosis (pHi = 6.52+/-0.13). Simulated ischemia had no significant effect on caspase-8 cleavage, but induced cleavage of caspase-3 and caspase-12 and led to a slight release of cytochrome C. Prevention of cytosolic acidosis (anoxia at pH(o) 7.4) had no effect on cytochrome C release, but significantly reduced apoptosis, attenuated cytosolic Ca2+ overload, and prevented cleavage of caspase-12. A similar effect was achieved by inhibition of Ca2+ release channels in the endoplasmic reticulum with ryanodine and xestospongin C. Knock-down of caspase-12 with small interfering RNA suppressed caspase-3 activation and reduced apoptotic cell number by about 70%. CONCLUSION: Acidosis, rather than anoxia, is an important trigger of apoptosis in EC under simulated ischemia. The main pathway of the simulated ischemia-induced apoptosis consists of the Ca2+ leak from the ER followed by activation of caspase-12 and caspase-3.

Acidosis↗

PubMed2006

Intramyocardial delivery of human CD133+ cells in a SCID mouse cryoinjury model: Bone marrow vs. cord blood-derived cells.

OBJECTIVE: The regenerative potential of endothelial and hematopoietic progenitor cells in the heart may vary according to their origin. This study was designed to compare the functional effects of CD133+ cells from human cord blood and bone marrow in a mouse model of myocardial injury. METHODS: 5 x 10(5) CD133+ cells from bone marrow (BM(CD133)) or cord blood (UCB(CD133)) were injected in the necrosis border zone of NOD/SCID (non-obese diabetic/severe combined immunodeficiency) mice with left ventricular cryoinjury (CI+). Transplanted cells were tracked by immunostaining for hNuclear antigen and by PCR for hDNA. Echocardiography was used to measure contractility. Scar size, capillary density, and cardiomyocyte apoptosis were evaluated by histology. In addition, the myogenic and endothelial differentiation capacity of BM(CD133) and UCB(CD133) was compared in vitro. RESULTS: DNA was detected 4 weeks after cell injection by PCR, but hNuc+ cells were found by immunostaining only after 48 h. Capillary density in both BM(CD133) and UCB(CD133) cell-treated CI+ mice was higher than in control CI+ mice, but not different between BM(CD133) and UCB(CD133) cell-treated hearts. There were no differences in scar size and myocardial mass among BM(CD133), UCB(CD133) and control CI+ mice, but cardiomyocyte apoptosis was reduced by both BM(CD133) and UCB(CD133) cells. The post-injury deterioration of shortening fraction (46.2+/-1% in sham-operated mice and 41.3+/-0.8% in control CI+ mice) was prevented by BM(CD133) cells (45.4+/-0.9%), but not by UCB(CD133) cells (40.8+/-0.7%). On the other hand, both BM(CD133) and UCB(CD133) cells abolished post-injury mortality. In vitro, neither cultivated BM(CD133) or UCB(CD133) cells developed into myocytes, but both readily differentiated towards an endothelial cell phenotype. CONCLUSIONS: While both cord blood and marrow CD133+ cells have some beneficial effects on post-injury angiogenesis and survival, only marrow cells appear to improve myocardial contractility.

AC133 Antigen↗

PubMed2006

Importance of endothelial nitric oxide synthase for the hypothermic protection of lungs against ischemia-reperfusion injury.

OBJECTIVES: The hypothesis that the protective effects of mild hypothermia against the pulmonary ischemia-reperfusion injury are mediated by endothelial nitric oxide synthase was tested. METHODS: Endothelial nitric oxide synthase knock-out and wild-type mice were sham operated or underwent a 1-hour occlusion of the left pulmonary hilum, followed by 5 hours of reperfusion. Temperature in the left pleural cavity during ischemia was maintained at either 36 degrees C (normothermia) or 32 degrees C (hypothermia). Inflammatory response (myeloperoxidase activity), endothelial barrier function (extravasation of Evans blue-labeled albumin), and endothelial nitric oxide synthase expression and phosphorylation were determined at the end of reperfusion. RESULTS: After normothermic ischemia both strains had a similar mortality (wild-type, 22.9%; knock-out, 15.4%), which was completely abolished by hypothermia. Endothelial barrier function was disturbed after normothermic ischemia in both wild-type and knock-out mice. Mild hypothermia significantly reduced pulmonary Evans blue extravasation in wild-type mice, but not in knock-out mice. Myeloperoxidase activity increased after normothermic ischemia to the same degree in both strains. This response was significantly attenuated by hypothermia in wild-type mice, but not in knock-out mice. In wild-type mice, endothelial nitric oxide synthase expression and phosphorylation were higher after hypothermic ischemia than after normothermic ischemia. No effect of ischemia on expression of inducible nitric oxide synthase was found in wild-type or knock-out mice. CONCLUSION: Hypothermic protection against pulmonary ischemia-reperfusion injury is dependent on endothelial nitric oxide synthase and is associated with increased expression and phosphorylation of endothelial nitric oxide synthase.

Animals↗

PubMed2003

Reoxygenation-induced rigor-type contracture.

The hypothesis tested was that reoxygenation-induced contracture of myocardial cells, a form of reperfusion injury, can be due to a rigor-type mechanism. Isolated adult cardiomyocytes were exposed to 30- or 60-min anoxia (pH 6.4) and reoxygenation (pH 7.4). In cardiomyocytes, cytosolic Ca(2+) and cell length, and in isolated rat hearts left ventricular end-diastolic pressure (LVEDP) were measured. During reoxygenation, cardiomyocytes developed contracture. When energy recovery was slowed down, less Ca(2+) overload was required for contracture: (1) after 30-min anoxia Ca(20) (cytosolic Ca(2+) concentration in cells with 20% cell length reduction) was 1.42 +/- 0.11 micromol/l; (2) after 30-min anoxia with partial mitochondrial inhibition during reoxygenation (NaCN, 0.1 mmol/l) Ca(20) was reduced to 0.69 +/- 0.05 micromol/l; (3) after 60-min anoxia Ca(20) was reduced to 0.78 +/- 0.05 micromol/l and (4) when energy recovery was accelerated (succinate, 0.2 mmol/l), Ca(20) rose to 1.35 +/- 0.05 micromol/l. In isolated hearts, the reperfusion-induced rise in LVEDP was modulated by the same interventions. Slow recovery of energy production favors reoxygenation-induced contracture in cardiomyocytes and hearts. This shows that rigor contracture contributes to reoxygenation-induced cell injury.

Animals↗

PubMed2002

Role of protein phosphatases in hypoxic preconditioning.

To find a protein kinase C (PKC)-independent preconditioning mechanism, hypoxic preconditioning (HP; i.e., 10-min anoxia and 10-min reoxygenation) was applied to isolated rat hearts before 60-min global ischemia. HP led to improved recovery of developed pressure and reduced end-diastolic pressure in the left ventricle during reperfusion. Protection was unaffected by the PKC inhibitor bisindolylmaleimide (BIM; 1 micromol/l). It was abolished by the inhibitor of protein phosphatases 1 and 2A cantharidin (20 or 5 micromol/l) and partially enhanced by the inhibitor of protein phosphatase 2A okadaic acid (5 nmol/l). In adult rat cardiomyocytes treated with BIM and exposed to 60-min simulated ischemia (anoxia, extracellular pH 6.4), HP led to attenuation of anoxic Na(+)/Ca(2+) overload and of hypercontracture, which developed on reoxygenation. This protection was prevented by treatment with cantharidin but not with okadaic acid. In conclusion, HP exerts PKC-independent protection on ischemic-reperfused rat hearts and cardiomyocytes. Protein phosphatase 1 seems a mediator of this protective mechanism.

Animals↗