A major limitation to the application of stem-cell therapy to repair ischemic heart damage is the low survival of transplanted cells in the heart, possibly due to poor oxygenation. We hypothesized that hyperbaric oxygenation (HBO) can be used as an adjuvant treatment to augment stem-cell therapy. Therefore, the goal of this study was to evaluate the effect of HBO on the engraftment of rat bonemarrow-derived mesenchymal stem cells (MSCs) transplanted in infarct rat hearts. Myocardial infarction (MI) was induced in Fisher-344 rats by permanently ligating the left-anterior-descending coronary artery. MSCs, labeled with fluorescent superparamagnetic iron oxide (SPIO) particles, were transplanted in the infarct and peri-infarct regions of the MI hearts. HBO (100% oxygen at 2 ATA for 90 min) was administered daily for 2 weeks. Four MI groups were used: untreated (MI); HBO; MSC; MSC+HBO. Echocardiography, electro-vectorcardiography, and magnetic resonance imaging were used for functional evaluations. The engraftment of transplanted MSCs in the heart was confirmed by SPIO fluorescence and Prussian-blue staining. Immunohistochemical staining was used to identify key cellular and molecular markers including CD29, troponin-T, connexin-43, VEGF, α-smooth-muscle actin, and von-Willebrand factor in the tissue. Compared to MI and MSC groups, the MSC+HBO group showed a significantly increased recovery of cardiac function including left-ventricular (LV) ejection fraction, fraction-shortening, LV wall-thickness, and QRS vector. Further, HBO treatment significantly increased the engraftment of CD29-positive cells, expression of connexin-43, troponin-T and VEGF, and angiogenesis in the infarct tissue. Thus, HBO appears to be a potential and clinically-viable adjuvant treatment for myocardial stem-cell therapy.

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The results showed that post-MI exposure of rats to daily cycles of hyperoxygenation (oxygen cycling) improved stem cell engraftment, cardiac function, and increased NOS3 expression.

Trimetazidine [1-(2,3,4-trimethoxybenzyl)piperazine; TMZ] is an anti-ischemic cardiac drug; however, its efficacy and mechanism of cardioprotection upon reperfusion are largely unknown. The objective of this study was to determine whether TMZ, given before reperfusion, could attenuate myocardial reperfusion injury. Ischemia/reperfusion (I/R) was induced in rat hearts by ligating the left anterior descending (LAD) coronary artery for 30 min followed by 48 h of reperfusion. TMZ (5 mg/kg b.wt.) was administered 5 min before reperfusion. The study used three experimental groups: control (ϪI/R; ϪTMZ), I/R (ϩI/R; ϪTMZ), and TMZ (ϩI/R; ϩTMZ). Echocardiography and EPR oximetry were used to assess cardiac function and oxygenation, respectively. The ejection fraction, which was significantly depressed in the I/R group (62 Ϯ 5 versus 84 Ϯ 3% in control), was restored to 72 Ϯ 3% in the TMZ group. Myocardial pO 2 in the TMZ group returned to baseline levels (ϳ20 mm Hg) within 1 h of reperfusion, whereas the I/R group showed a significant hyperoxygenation even after 48 h of reperfusion. The infarct size was significantly reduced in the TMZ group (26 Ϯ 3 versus 47 Ϯ 5% in I/R). TMZ treatment significantly attenuated superoxide levels in the tissue. Tissue homogenates showed a significant increase in p38 and p-Akt and decrease in caspase-3 levels in the TMZ group. In summary, the results demonstrated that TMZ is cardioprotective when administered before reperfusion and that this protection appears to be mediated by activation of p38 mitogen-activated protein kinase and Akt signaling. The study emphasizes the importance of administering TMZ before reflow to prevent reperfusion-mediated cardiac injury and dysfunction.Ischemic heart disease is the leading cause of mortality among both men and women in the United States, and in the world. Clinical interventions such as coronary angioplasty, coronary artery bypass graft surgery, or percutaneous transluminal coronary angioplasty are routinely used to reintroduction of blood flow to an ischemic region of the myocardium. Such interventions are unavoidably accompanied by an enzymatic cascade of reactions that result in damage to the myocardium, termed ischemia/reperfusion (I/R) injury.Although the etiology of I/R injury is intricate, oxidative stress occurs due to an imbalance between free-radical production and the heart's ability to prevent the damage caused by free radicals. Numerous studies have shown that the generation of reactive oxygen species (ROS) in the oxygendeprived tissue plays a crucial role in the cellular oxidative damage that happens during I/R (Zweier et al., 1989;Ambrosio et al., 1993;Griendling and FitzGerald, 2003). The generation of free radicals that occurs during I/R has been reported by several groups (Bolli et al., 1988;Zweier et al., 1989) and has revealed that ROS production peaks within the first few minutes of reperfusion. Free-radical scavengers (e.g., antioxidants) have been shown to protect the heart from oxidative damage resulting from the form...

Doxorubicin (DOX) is a drug commonly used for the treatment of cancer. The development of resistance to DOX is common, and high cumulative doses cause potentially lethal cardiac side effects. HO-3867 (3,5-bis(4-fluorobenzylidene)-1-[(2,2,5,5-tetramethyl-2,5-dihydro-1-hydroxy-pyrrol-3-yl)methyl]piperidin-4-one), a synthetic curcumin analog, has been shown to exhibit both anticancer and cardioprotective effects. However, its cardioprotection in the setting of a conventional cancer therapy has not been established. This work investigated the use of HO-3867 and DOX to achieve a complementary outcome, i.e., increased toxicity toward cancer cells, and reduced cardiac toxicity. Combination treatment was investigated using DOXresistant MCF-7 breast cancer cells [MCF-7 multidrug-resistant (MDR)] and BALB/c mice. Lower doses of HO-3867 and DOX (5 and 2.5 M, respectively) reduced viability of MCF-7 MDR cells to an extent significantly greater than that when either drug was used alone, an effect equivalent to that induced by exposure to 50 M DOX. In normal cardiac cells, the loss of viability from combination treatment was significantly lower than that induced by 50 M DOX. Increases in apoptotic markers, e.g., cleaved caspase-3, and decreases in fatty acid synthase and pAkt expressions were observed by Western blotting. Mice treated with both HO-3867 and DOX showed significant improvement in cardiac functional parameters compared with mice treated with DOX alone. Reduced expression of Bcl-2 and pAkt was observed in mice treated with DOX alone, whereas mice given combination treatment showed levels similar to control. The study indicates that combination treatment of HO-3867 and DOX is a viable option for treatment of cancer with reduced cardiotoxic side effects.

Pulmonary hypertension (PH) is a disorder of lung vasculature characterized by arterial narrowing. Phosphatase-and-tensin homolog on chromosome 10 (PTEN), associated in the progression of multiple cancers, is implicated in arterial remodeling. However, the involvement of PTEN in PH remains unclear. The objective of the present study was to determine the role of PTEN in pulmonary vascular remodeling using established models of PH. The study used rat models of PH, induced by monocrotaline (MCT) administration (60 mg/kg) or continuous hypoxic exposure (10% oxygen) for 3 weeks. Pulmonary artery smooth muscle cells (SMCs) were used for in vitro confirmation. Development of PH was verified by hemodynamic, morphological and histopathology analyses. PTEN and key downstream proteins in pulmonary and cardiac tissues were analyzed by western blotting and RT-PCR. PTEN was significantly decreased (MCT, 53%; Hypoxia, 40%), pAkt was significantly increased (MCT, 42%; Hypoxia, 55%) in tissues of rats with PH. Similar results were observed in SMCs exposed to hypoxia (1% oxygen) for 48 h. Ubiquitination assay showed that PTEN degradation occurs via proteasomal degradation pathway. Western blotting demonstrated a significant downregulation of cell-cycle regulatory proteins p53 and p27, and upregulation of cyclin-D1 in the lungs of both models. The results showed that PTEN-mediated modulation of PI3K pathway was independent of the focal adhesion kinase and fatty acid synthase. The study, for the first time, established that PTEN plays a key role in the progression of pulmonary hypertension. The findings may have potential for the treatment of pulmonary hypertension using PTEN as a target.

Increased phosphorylation of the 70 kDa ribosomal S6 kinase (p70s6k) signaling is strongly correlated with the degree of muscle adaptation following exercise. Here, we compare the phosphorylation of p70s6k, Akt and mTOR in the tibialis anterior (TA) muscles of lean and obese Zucker rats following a bout of eccentric exercise. Exercise increased p70S6k (Thr 389) phosphorylation immediately after (33.3 ± 7.2%) and during recovery [1-hr; (24.0 ± 14.9%), and 3-hr (24.6 ± 11.3%)], in the lean TA and at 3-hr (33.5 ± 8.0%) in the obese TA. mTOR (Ser 2448) phosphorylation was elevated in the lean TA immediately after exercise (96.5 ± 40.3%) but remained unaltered in the obese TA. Exercise increased Akt (Thr 308) and Akt (Ser 473) phosphorylation in the lean but not the obese TA. These results suggest that insulin resistance is associated with alterations in the ability of muscle to activate p p70s6k signaling following an acute bout of exercise.

Adult stem cells have shown great promise toward repairing infarcted heart and restoring cardiac function. Mesenchymal stem cells (MSCs), because of their inherent multipotent nature and their ability to secrete a multitude of growth factors and cytokines, have been used for cardiac repair with encouraging results. Preclinical studies showed that MSCs injected into infarcted hearts improve cardiac function and attenuate fibrosis. Although stem cell transplantation is a promising therapeutic option to repair the infarcted heart, it is faced with a number of challenges, including the survival of the transplanted cells in the ischemic region, due to excessive oxidative stress present in the ischemic region. The objective of this study was to determine the effect of Carvedilol (Carv), a nonselective ␤-blocker with antioxidant properties, on the survival and engraftment of MSCs in the infarcted heart. MSCs were subjected to a simulated host-tissue environment, similar to the one present in the infarcted myocardium, by culturing them in the presence of hydrogen peroxide (H 2 O 2 ) to induce oxidative stress. MSCs were treated with 2.5 M Carv for 1 h in serum-free medium, followed by treatment with H 2 O 2 for 2 h. The treated cells exhibited significant protection against H 2 O 2 -induced cell death versus untreated controls as determined by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assays. Likewise, transplantation of MSCs after permanent left coronary artery ligation and treatment of animals after myocardial infarction (MI) with Carv (5 mg/kg b.wt.) led to significant improvement in cardiac function, decreased fibrosis, and caspase-3 expression compared with the MI or MSC-alone groups.