Masamichi Ono

Amelioration of Pulmonary Emphysema by In Vivo Gene Transfection With Hepatocyte Growth Factor in Rats

Background—Hepatocyte growth factor (HGF) is an important mitogen and morphogen that contributes to the repair process after lung injury. The goal of the present study was to characterize its role in pulmonary emphysema, which may lead to the development of new treatment strategies with HGF. Methods and Results—HGF mRNA and protein levels in lung tissue and plasma from elastase-induced emphysema rats transiently increased, then declined significantly to below the basal level in a time-dependent manner (P<0.01). Furthermore, changes in HGF were correlated with histologically progressive emphysematous changes and deterioration in pulmonary physiology. Use of the HVJ (hemagglutinating virus of Japan) envelope method resulted in successful transfection of cDNA encoding human HGF, as demonstrated by an efficient expression of HGF in alveolar endothelial and epithelial cells. Transfection of HGF resulted in a more extensive pulmonary vasculature and inhibition of alveolar wall cell apoptosis, and those effects led to improved exercise tolerance and gas exchange (P<0.05), which persisted for more than 1 month. Conclusions—Decreased HGF expression due to a failure in sustained endogenous production after injury was associated with emphysema-related histopathologic and physiological changes in the present rat model. In addition, induction of HGF expression by a gene-transfection method resulted in improved pulmonary function via inhibition of alveolar cell apoptosis, enhancement of alveolar regeneration, and promotion of angiogenesis.

Skeletal myoblast sheet transplantation improves the diastolic function of a pressure-overloaded right heart

OBJECTIVEnThe development of right ventricular dysfunction has become a common problem after surgical repair of complex congenital heart disease. A recent study reported that tissue-engineered skeletal myoblast sheet transplantation improves left ventricular function in patients with dilated and ischemic cardiomyopathy. Therefore myoblast sheet transplantation might also improve ventricular performance in a rat model of a pressure-overloaded right ventricle.nnnMETHODSnSeven-week-old male Lewis rats underwent pulmonary artery banding. Four weeks after pulmonary artery banding, myoblast sheet transplantation to the right ventricle was performed in the myoblast sheet transplantation group (n = 20), whereas a sham operation was performed in the sham group (n = 20).nnnRESULTSnFour weeks after performing the procedure, a hemodynamic assessment with a pressure-volume loop showed a compensatory increase in systolic function in both groups. However, only the myoblast sheet transplantation group showed a significant improvement in the diastolic function: end-diastolic pressure (sham vs myoblast sheet transplantation, 10.3 +/- 3.1 vs 5.0 +/- 3.7 mm Hg; P < .001), time constant of isovolumic relaxation (11.1 +/- 2.5 vs 7.6 +/- 1.2 ms, P < .001), and end-diastolic pressure-volume relationship (16.1 +/- 4.5 vs 7.6 +/- 2.4/mL, P < .005). The right ventricular weight and cell size similarly increased in both groups. A histologic assessment demonstrated significantly suppressed ventricular fibrosis and increased capillary density in the myoblast sheet transplantation group in comparison with those in the sham group. Reverse transcription-polymerase chain reaction demonstrated an increased myocardial gene expression of hepatocyte growth factor and vascular endothelial growth factor in the myoblast sheet transplantation group but not in the sham group.nnnCONCLUSIONSnSkeletal myoblast sheet transplantation improved the diastolic dysfunction and suppressed ventricular fibrosis with increased capillary density in a rat model of a pressure-overloaded right ventricle. This method might become a novel strategy for the myocardial regeneration of right ventricular failure in patients with congenital heart disease.

Hepatocyte Growth Factor Suppresses Vascular Medial Hyperplasia and Matrix Accumulation in Advanced Pulmonary Hypertension of Rats

Background—Pulmonary hypertension (PH) is a progressive disease characterized by raised pulmonary vascular resistance, thought to be curable only through lung transplantation. Pathophysiologically, proliferation of pulmonary artery smooth muscle cells triggers pulmonary arterial stenosis and/or regurgitation, especially in advanced PH. Methods and Results—Using a rat model of advanced pulmonary vascular disease produced by injecting monocrotaline, we show that hepatocyte growth factor (HGF) targets pulmonary arterioles and blocks the progression of PH. In these rats, endogenous HGF production was dramatically downregulated during developing experimental PH, but c-Met/HGF receptor was abundant in the medial layers of pulmonary arterioles. HGF gene transfection 2 weeks after the monocrotaline injection resulted in milder medial hyperplasia in lung arterioles and inhibited overgrowth of pulmonary artery smooth muscle cells. Notably, exogenous HGF reduced lung expression levels of endothelin-1 and transforming growth factor-&bgr;, which are critically involved in PH-linked fibrogenic events. Overall, medial wall thickening of pulmonary arteries was almost completely prevented by HGF, and the total collagen deposition in the lung decreased; both effects contributed to the suppression of pulmonary artery hypertension. Conclusions—Our results suggest that the loss of endogenous HGF may be a feature of the pathogenesis of PH and that HGF supplementation may minimize pathological lung conditions, even advanced PH.

Effect of a Polymorphonuclear Elastase Inhibitor (Sivelestat Sodium) on Acute Lung Injury After Cardiopulmonary Bypass: Findings of a Double-Blind Randomized Study

PurposeWe evaluated the effect of sivelestat sodium (SiV), a novel synthesized polymorphonuclear (PMN) elastase inhibitor, on acute lung injury (ALI) caused by cardiopulmonary bypass (CPB).MethodsFourteen patients who underwent cardiopulmonary surgery using CPB, followed by the development of both systemic inflammatory response syndrome (SIRS) and ALI, were treated with either 0.2u2009mg/kg per hour SiV (SiV group, n = 7) or saline (control group, n = 7) for 4 days from the time of arrival in the intensive care unit.ResultsThe SiV group had a significantly lower ratio of serum PMN elastase and interleukin (IL)-8, a significantly lower ratio of the respiratory index, and a significantly higher ratio of PaO2/FiO2 after 24u2009h of treatment than the control group.ConclusionSivelestat sodium suppressed the production of PMN elastase and IL-8, resulting in improved respiratory function in patients with ALI caused by CPB.

Bcl-2 expression enhances myoblast sheet transplantation therapy for acute myocardial infarction

Myoblast sheet transplantation is a promising novel treatment modality for heart failure after an ischemic insult. However, low supply of blood and nutrients may compromise sheet survival. The aim of this study was to investigate the effect of mitochondria-protective Bcl-2-modified myoblasts in cell sheet transplantation therapy. In the Bcl-2-expressing rat L6 myoblast sheets (L6-Bcl2), increased expression of myocyte markers and angiogenic mediators was evident compared to wild-type (L6-WT) sheets. The L6-Bcl2 sheets demonstrated significant resistance to apoptotic stimuli, and their differentiation capacity in vitro was increased. We evaluated the therapeutic effect of Bcl-2-modified myoblast sheets in a rat model of acute myocardial infarction (AMI). Sixty-four Wistar rats were divided into four groups. One group underwent AMI (n = 22), another AMI and L6-WT sheet transplantation (n = 17), and a third AMI and L6-Bcl2 sheet transplantation (n = 20). Five rats underwent a sham operation. Echocardiography was performed after 3, 10, and 28 days. Samples for histological analysis were collected at the end of the study. After AMI, the Bcl-2-expressing sheets survived longer on the infarcted myocardium, and significantly improved cardiac function. L6-Bcl2 sheet transplantation reduced myocardial fibrosis and increased vascular density in infarct and border areas. Moreover, the number of c-kit-positive and proliferating cells in the myocardium was increased in the L6-Bcl2 group. In conclusion, Bcl-2 prolongs survival of myoblast sheets, increases production of proangiogenic paracrine mediators, and enhances the therapeutic efficacy of cell sheet transplantation.

hHGF overexpression in myoblast sheets enhances their angiogenic potential in rat chronic heart failure.

After severe myocardial infarction (MI), heart failure results from ischemia, fibrosis, and remodeling. A promising therapy to enhance cardiac function and induce therapeutic angiogenesis via a paracrine mechanism in MI is myoblast sheet transplantation. We hypothesized that in a rat model of MI-induced chronic heart failure, this therapy could be further improved by overexpression of the antiapoptotic, antifibrotic, and proangiogenic hepatocyte growth factor (HGF) in the myoblast sheets. We studied the ability of wild type (L6-WT) and human HGF-expressing (L6-HGF) L6 myoblast sheet-derived paracrine factors to stimulate cardiomyocyte, endothelial cell, or smooth muscle cell migration in culture. Further, we studied the autocrine effect of hHGF-expression on myoblast gene expression profiles by use of microarray analysis. We induced MI in Wistar rats by left anterior descending coronary artery (LAD) ligation and allowed heart failure to develop for 4 weeks. Thereafter, we administered L6-WT (nu200a=u200a15) or L6-HGF (nu200a=u200a16) myoblast sheet therapy. Control rats (nu200a=u200a13) underwent LAD ligation and rethoracotomy without therapy, and five rats underwent a sham operation in both surgeries. We evaluated cardiac function with echocardiography at 2 and 4 weeks after therapy, and analyzed cardiac angiogenesis and left ventricular architecture from histological sections at 4 weeks. Paracrine mediators from L6-HGF myoblast sheets effectively induced migration of cardiac endothelial and smooth muscle cells but not cardiomyocytes. Microarray data revealed that hHGF-expression modulated myoblast gene expression. In vivo, L6-HGF sheet therapy effectively stimulated angiogenesis in the infarcted and non-infarcted areas. Both L6-WT and L6-HGF therapies enhanced cardiac function and inhibited remodeling in a similar fashion. In conclusion, L6-HGF therapy effectively induced angiogenesis in the chronically failing heart. Cardiac function, however, was not further enhanced by hHGF expression.

Resolution of pulmonary arteriovenous fistula by redirection of hepatic venous blood

We report an 8-year-old girl whose unilateral pulmonary arteriovenous fistula (PAVF) disappeared after we redirected hepatic venous blood to the affected lung. This case provides strong evidence that formation of a PAVF depends only on the presence or absence of hepatic venous blood in the pulmonary circulation.

The clinical pathway for fast track recovery of school activities in children after minimally invasive cardiac surgery.

BACKGROUNDnMinimally invasive cardiac surgery is now becoming standard in the correction of simple congenital cardiac malfbrmations. We introduced a clinical pathway for fast track recovery of school activities in children after minimally invasive cardiac surgery, and assessed the function of the pathway in children with atrial or ventricular septal defects, comparing minimally invasive surgery to repair through a conventional full sternotomy.nnnMETHODSnWe studied 15 children of school age who underwent repair of an atrial or ventricular septal defect through a lower midline sternotomy, and 10 children undergoing repair through a full sternotomy. The clinical pathway was for extubation to take place in the operating room, echocardiographic evaluation on the 5th postoperative day, and discharge home on the 7th postoperative day, with return to school within 2 weeks, and resumption of all gymnastic activity within 6 weeks of the minimally invasive surgery.nnnRESULTSnIn those having a lower midline sternotomy, postoperative hospital stay was 7.4 +/- 0.8 days, with return to school 8.0 +/- 2.4 days after discharge. They resumed gymnastics 41 +/- 11 days after the minimally invasive surgery. In those having a full sternotomy, in contrast, these parameters were 13.5 +/- 2.7, 23.1 +/- 8.4, and 95 +/- 43 days, respectively. Of the 15 children undergoing a minimally invasive approach, 12 (80%) fulfilled the criterions of our clinical pathway.nnnCONCLUSIONSnWe conclude that minimally invasive cardiac surgery can safely be performed in children. In addition to its cosmetic role, the technique has added value in promoting early return to normal school life, including gymnastics.

Infectious false aneurysm of the right ventricular outflow tract after repair of congenital heart defect treated with Freestyle® aortic bioprosthesis

OBJECTIVESnFalse aneurysm of the right ventricular outflow tract (RVOT) is one of complications after surgery of congenital heart disease. It is controversial about materials for reconstruction of RVOT in this setting, when associated with pulmonary hypertension or bacterial infection. Pulmonary homograft seems to be the first choice, but its availability is extremely limited in Japan.nnnMETHODSnTherefore, we used Freestyle stentless bioprosthesis to reconstruct the RVOT in a 14-year-old boy who developed infectious false aneurysm of RVOT after total correction of pulmonary atresia with ventricular septal defect.nnnRESULTS AND DISCUSSIONnAfter describing the patient, the prosthesis alternative to the pulmonary homograft was discussed.

Incidence and Risk Factors for Right Ventricular Outflow Tract Obstruction after the Arterial Switch Operation

Background The aim of this study was to evaluate the incidence and risk factors for the development of right ventricular outflow tract obstruction (RVOTO) after the arterial switch operation (ASO). Methods Between 1983 and 2014, a total of 688 patients underwent ASO. RVOTO was defined as any obstruction of the right ventricular outflow tract (RVOT) requiring reintervention. Results RVOTO developed in 79 patients (11%) at a median time of 3.8 years (range, 1 day‐23.6 years) after ASO. Freedom from RVOT reintervention was 96 ± 1, 89 ± 1, and 83 ± 2% at 1, 10, and 25 years, respectively. Independent risk factors for the development of RVOTO in a Coxs regression model were side‐by‐side great arteries (p < 0.001), aortic arch anomalies (p < 0.001), use of a pericardial patch for augmentation of the coronary buttons (p < 0.001), and a peak gradient more than 20 mm Hg over the RVOT at discharge (p < 0.001). Conclusion The incidence of RVOTO after ASO is not negligible. Complex morphology, such as side‐by‐side great arteries and aortic arch anomalies influences the development of RVOTO.