Prevascularization with gelatin microspheres containing basic fibroblast growth factor enhances the benefits of cardiomyocyte transplantation

OBJECTIVE: The effects of cell transplantation on the ischemic failing heart have already been documented. However, the area in and around infarct regions is not a good environment for cells to survive in because they are exposed to poor conditions in which certain requirements cannot be adequately supplied. We therefore designed a study to investigate the efficacy of prevascularization in ischemic regions before cell transplantation. METHODS: Rats with myocardial infarction were randomized into 4 groups: 11 rats received a culture medium injection to the left ventricular wall (control group), 11 received fetal cardiomyocyte transplantation (TX group), 11 received gelatin hydrogel microspheres incorporating basic fibroblast growth factor (FGF group), and 11 received basic fibroblast growth factor pretreatment sequentially, followed by cardiomyocyte transplantation (FGF-TX group). Four weeks later, left ventricular function was assessed by means of echocardiography and cardiac catheterization. RESULTS: In the FGF and FGF-TX groups neovascularization was found in the scar tissue 1 week later. The TX, FGF, and FGF-TX groups showed better fractional shortening than the control group (TX, FGF, FGF-TX, and control: 28% +/- 4.4%, 24% +/- 8.6%, 27% +/- 7.3%, and 17% +/- 4.6%, respectively; P <.01). Left ventricular maximum time-varying elastance was higher in the FGF-TX group than in the TX and FGF groups (FGF-TX, TX, and FGF: 0.52 +/- 0.23, 0.30 +/- 0.08, and 0.27 +/- 0.20 mm Hg/microL, respectively; P <.01). Histologically, more transplanted cells survived in the FGF-TX group than in the TX group. CONCLUSIONS: Prevascularization with basic fibroblast growth factor-incorporated microspheres enhances the benefits of cardiomyocyte transplantation. We expect that this system will contribute to regeneration medicine through its extensive application to other growth factors.     

Improved therapeutic efficacy in cardiomyocyte transplantation for myocardial infarction with release system of basic fibroblast growth factor

Several studies have demonstrated that cell transplantation was effective for the therapy of myocardial infarction. However, little care has been taken for the blood supply indispensable to cell transplantation. This study is an investigation to evaluate the feasibility of in advance angiogenesis by gelatin microspheres incorporating basic fibroblast growth factor (bFGF) for the transplantation therapy of cardiomyocytes with an ischemic cardiomyopathy model. Rats with myocardial infarction received the intramuscular injection of culture medium (Control), or that containing fetal cardiomyocytes (TX) or gelatin microspheres incorporating bFGF (FGF), and gelatin microspheres incorporating bFGF plus fetal cardiomyocytes 1 week later (FGF-TX). The left ventricle (LV) function of rat hearts was assessed by echocardiography and cardiac catheterization 4 weeks later. The LV maximum time-varying elastance was significantly higher in the FGF-TX group than in other groups. The combination of bFGF-induced angiogenesis and cardiomyocyte transplantation is a promising procedure to improve the LV function in rats with myocardial infarction.     

Bone marrow mononuclear cell transplantation had beneficial effects on doxorubicin-induced cardiomyopathy

BackgroundCell transplantation is a promising therapy for treating end-stage heart failure. Bone marrow mononuclear cells (BMMNC) have been used to enhance angiogenesis in ischemic heart disease. However, the effect of BMMNC transplantation in non-ischemic dilated cardiomyopathy is unknown. In this study, we evaluated the efficacy of BMMNC transplantation in doxorubicin-induced cardiomyopathy in a rat model.MethodsDoxorubicin (15 mg/kg, IP) was introduced into 52 Lewis rats. They were divided into 3 groups at 4 weeks after injection: transplant group (TX, BMMNC [1×10⁶] implantation, n = 18), control group (CN, saline injection, n = 18), and sham group (SH, thoracotomy, n = 16). At 4 weeks after surgery, we used echocardiography to measure systolic left ventricular diameter (LVDs), diastolic left ventricular diameter (LVDd), fractional shortening (FS), and left ventricular wall thickness/LVDs. We used a Langendorff apparatus to measure systolic, diastolic, and developed pressures. We used radioimmunoassay to measure circulating atrial natriuretic peptide concentration, and we performed histologic study, including electron-microscopic study.ResultsLeft ventricular wall thickness/LVDs in the TX group was the largest of all groups (p < 0.05). Systolic and developed pressures in the TX group were the greatest (p < 0.005). Systolic left ventricular diameter, FS, and end-diastolic pressure in the TX group were smaller than in the SH group (p < 0.05). These cardiac parameters did not differ significantly between TX and CN groups, but secondary changes (decreased heart weight, developed ascites, and increased atrial natriuretic peptide concentration) caused by doxorubicin-induced heart failure were most attenuated in the TX group. In the TX group, vascular density was greatest (p < 0.05) in the left ventricular free wall and in the septum. In addition, electron microscopy showed that myocardium in the TX group was most maintained.ConclusionBone marrow mononuclear cell transplantation had beneficial effects in doxorubicin-induced cardiomyopathy.     

Serial assessment of left ventricular function after valve replacement for isolated aortic regurgitation

Between 1978 and 1990, serial echocardiographic studies were performed on consecutive twenty-five patients of isolated aortic regurgitation (AR) before and after aortic valve replacement (AVR). The mean follow up period was 55 +/- 30 months. The serial changes in left ventricular end-diastolic dimension (LVDd), left ventricular end-systolic dimension (LVDs), fractional shortening (FS), and ejection fraction (EF) were assessed. According to preoperative echocardiographic studies, 25 patients were divided into two groups: Group I with LVDs greater than 50 mm and FS less than 25%, Group II with LVDs less than or equal to 50 mm and/or FS greater than or equal to 25%. One year after AVR, echocardiographic studies revealed normalization of LVDd and LVDs in Group II, and persistent left ventricular enlargement with lower FS and EF levels in Group I. However three years after AVR, LVDd, LVDs, and FS and EF of Group I returned to normal levels. It was concluded that in order to normalize the left ventricular function in isolated AR patients, those who had LVDs greater than 50 mm and FS less than 25% required three years after AVR, those patients who had LVDs less than or equal to 50 mm and/or FS greater than or equal to 25%, required only one year after AVR.     

Local myocardial overexpression of growth hormone attenuates postinfarction remodeling and preserves cardiac function

BACKGROUND: Ventricular remodeling with chamber dilation and wall thinning is seen in postinfarction heart failure. Growth hormone induces myocardial hypertrophy when oversecreted. We hypothesized that localized myocardial hypertrophy induced by gene transfer of growth hormone could inhibit remodeling and preserve cardiac function after myocardial infarction. METHODS: Rats underwent direct intramyocardial injection of adenovirus encoding either human growth hormone (n = 9) or empty null vector as control (n = 9) 3 weeks after ligation of the left anterior descending coronary artery. Analysis of the following was performed 3 weeks after delivery: hemodynamics, ventricular geometry, cardiomyocyte fiber size, and serum growth hormone levels. RESULTS: The growth hormone group had significantly better systolic cardiac function as measured by maximum left ventricular pressure (73.6 +/- 6.9 mm Hg versus control 63.7 +/- 7.8 mm Hg, p < 0.05) and maximum dP/dt (2845 +/- 453 mm Hg/s versus 1949 +/- 605 mm Hg/s, p < 0.005), and diastolic function as measured by minimum dP/dt (-2520 +/- 402 mm Hg/s versus -1500 +/- 774 mm Hg/s, p < 0.01). Ventricular geometry was preserved in the growth hormone group (ventricular diameter 12.2 +/- 0.7 mm versus control 13.1 +/- 0.4 mm, p < 0.05; borderzone wall thickness 2.0 +/- 0.2 mm versus 1.5 +/- 0.1 mm, p < 0.001), and was associated with cardiomyocyte hypertrophy (6.09 +/- 0.63 microm versus 4.66 +/- 0.55 microm, p < 0.005). Local myocardial expression of growth hormone was confirmed, whereas serum levels were undetectable after 3 weeks. CONCLUSIONS: Local myocardial overexpression of growth hormone after myocardial infarction resulted in cardiomyocyte hypertrophy, attenuated ventricular remodeling, and improved systolic and diastolic cardiac function. The induction of localized myocardial hypertrophy presents a novel therapeutic approach for the treatment of ischemic heart failure.     

Cell transplantation to prevent heart failure: a comparison of cell types

BACKGROUND: Autologous cell transplantation may restore viable muscle after a myocardial infarction. We compared the effect of three cell types or an angiotensin-converting enzyme (ACE) inhibitor on preservation of ventricular function after cardiac injury. METHODS: A uniform transmural myocardial scar was created in adult rats by cryoinjury. Three weeks later the rats were randomly assigned to one of four blinded treatments: transplantation with 5 x 10(6) aortic smooth muscle cells (SMC, n = 12), ventricular heart cells (VHC, n = 13), skeletal muscle cells (SKC, n = 13) or culture medium alone (control, n = 11). The ACE inhibitor group (n = 8) received enalapril (1.0 mg/kg per day), also beginning 3 weeks after cryoinjury. Five and 12 weeks after transplantation, left ventricle (LV) function was assessed in a Langendorff apparatus, and histologic and immunohistological evaluation of the LV scars was performed. RESULTS: At 5 weeks, greater scar elastin content and better LV function was noted with cell transplantation or ACE inhibitor therapy compared with control rats (p < 0.05). Twelve weeks after transplantation, cell-transplanted rats still had greater elastin content and better LV function than control rats, although elastin content and LV function had declined in ACE inhibitor-treated animals to levels below those observed in control rats (p < 0.05). CONCLUSIONS: Transplantation of SMC, VHC, and SKC preserved ventricular function equivalent to the effects of an ACE inhibitor. Muscle cell transplantation, but not ACE inhibitor therapy, continues to be effective later after cryoinjury. No differences were detected between the muscle cells.     

Effects of pre-existing left ventricular hypertrophy on ventricular dysfunction and remodeling following myocardial infarction in rats.

BACKGROUND: Myocardial hypertrophy is a characteristic component of left ventricular (LV) remodeling that may, at least initially, have a beneficial effect on LV function following myocardial infarction (MI). In the present study, we examine the effects of pre-existing left ventricular hypertrophy (LVH) on LV function and chamber enlargement following MI in inbred Lewis rats. METHODS: The one-kidney, one-clip model (1K1C) of hypertension was used to produce LVH. Four weeks after 1K1C, rats were randomized to left anterior descending coronary artery ligation (LVH + MI group, n = 8) or sham ligation (LVH group, n = 11). Another group of rats underwent sham 1K1C. Four weeks later, they were randomized to coronary ligation (MI group, n = 12) or sham ligation (Sham group, n = 12). LV end-diastolic pressure (EDP, mm Hg), end-diastolic volume (EDV, ml), end-systolic volume (ESV, ml) and ejection fraction (EF) (determined by angiography) were measured in all groups 2 months after MI. RESULTS: LV EDP was 20 +/- 2 mm Hg in the LVH + MI group compared with 9 +/- 1 mm Hg in the MI group (p < 0.05). LV EDV and ESV were significantly greater with LVH + MI than with MI alone (EDV 0.90 +/- 0.03 vs 0.75 +/- 0.02 ml; ESV 0.68 +/- 0.02 vs 0.50 +/- 0.03 ml; p < 0.05). Pre-existing LVH resulted in a greater reduction in EF following MI (25 +/- 2% for LVH + MI vs 34 +/- 2% for MI alone; p < 0.05). CONCLUSIONS: Pre-existing LVH is an important determinant of progressive LV dysfunction and remodeling following MI in Lewis inbred rats.     

Toward surgical angiogenesis using slow-released basic fibroblast growth factor.

OBJECTIVE: Therapeutic angiogenesis using basic fibroblast growth factor (bFGF) in coronary artery disease has been documented in a number of papers. However, the effectiveness is discrepant among documents. In this study, we evaluated the distribution of bFGF in the rat heart by different administration methods, and investigated the efficacy of slow-released administration of bFGF using biodegradable hydrogel microspheres (bFGF microspheres) in a pig infarction model toward an enhanced coronary bypass surgery. METHODS: Heart failure due to myocardial infarction was induced in rats and pigs. In the rat study, free form of bFGF (central venous injection, intracoronary injection, and intramyocardial administration) and bFGF microspheres (intramyocardial administration) were given 4 weeks later. The remaining radioactivity of bFGF in the hearts was estimated 1, 24, and 72 h later. On the other hand, the pigs were randomized into two groups 4 weeks after myocardial infarction. While the control group (n=8) had gelatin hydrogel microspheres with saline, the FGF group (n=8) received bFGF microspheres in the left ventricular (LV) wall. RESULTS: In the rat study, after intramyocardial administration of bFGF microspheres, more bFGF remained in the rat heart 72 h later compared with the other methods (P<0.0001). In the pig study, 4 weeks after the treatment, the FGF group had smaller LV diastolic diameter (48.7+/-5.3 vs. 56.7+/-5.2 mm, P<0.01) than the control group. LV end-systolic elastance was higher in the FGF group (2.96+/-1.2 vs. 1.06+/-0.3 mmHg/ml, P<0.01). In microscopic examinations, many neovessels were found in and around the scar tissue, and the vascular density in the FGF group was significantly higher (61.5+/-18.3 vs. 153.0+/-29.0/mm2, P<0.01). In addition, the infarcted LV walls were less expanded and more thickened in the FGF group. CONCLUSIONS: Biodegradable hydrogel microspheres with bFGF improved LV function and inhibited LV remodeling by angiogenesis in pigs with chronic myocardial infarction. bFGF microspheres into ischemic myocardium may revascularize small ungraftable vessels and may potentially increase distal run-off when applied in coronary bypass surgery.     

Fetal cell transplantation: a comparison of three cell types.

OBJECTIVE: We have previously reported that fetal cardiomyocyte transplantation into myocardial scar improves heart function. The mechanism by which this occurs, however, has not been elucidated. To investigate possible mechanisms by which cell transplantation may improve heart function, we compared cardiac function after transplantation of 3 different fetal cell types: cardiomyocytes, smooth muscle cells (nonstriated muscle cells), and fibroblasts (noncontractile cells). METHODS: A left ventricular scar was created by cryoinjury in adult rats. Four weeks after injury, cultured fetal ventricular cardiomyocytes (n = 13), enteric smooth muscle cells (n = 10), skin fibroblasts (n = 10), or culture medium (control, n = 15 total) were injected into the myocardial scar. All rats received cyclosporine A (INN: ciclosporin). Four weeks after transplantation, left ventricular function was evaluated in a Langendorff preparation. RESULTS: The implanted cells were identified histologically. All transplanted cell types formed tissue within the myocardial scar. At an end-diastolic volume of 0.2 mL, developed pressures in cardiomyocytes group were significantly greater than smooth muscle cells and skin fibroblasts groups (cardiomyocytes, 134% +/- 22% of control; smooth muscle cells, 108% +/- 14% of control; skin fibroblasts, 106% +/- 17% of control; P =.0001), as were +dP/dt(max) (cardiomyocytes, 119% +/- 37% of control; smooth muscle cells, 98% +/- 18% of control; skin fibroblasts, 92% +/- 11% of control; P =. 0001) and -dP/dt(max) (cardiomyocytes, 126% +/- 29% of control; smooth muscle cells, 108% +/- 19% of control; skin fibroblasts, 99% +/- 16% control; P =.0001). CONCLUSIONS: Fetal cardiomyocytes transplanted into myocardial scar provided greater contractility and relaxation than fetal smooth muscle cells or fetal fibroblasts. The contractile and elastic properties of transplanted cells determine the degree of improvement in ventricular function achievable with cell transplantation.     

Endothelin receptor antagonism attenuates cardiomyocyte apoptosis after induction of ischemia in rats

OBJECTIVE: Apoptosis has recently been implicated as a process that may contribute to loss of cardiomyocytes and to adverse myocardial remodeling in congestive heart failure (CHF). We investigated to what extent myocardial ischemia and CHF lead to induction of apoptotic gene programs and loss of cardiomyocytes through apoptosis, and subsequently to what extent the beneficial effects of endothelin (ET) receptor antagonism after myocardial infarction (MI) could be attributed to reduction of apoptotic cell loss in the myocardium. DESIGN: Northern blot analysis, analysis of DNA fragmentation, and immunohistochemical analysis were performed after induction of MI in rats. RESULTS: After induction of MI, the mRNA levels of the pro-apoptotic genes FAS, BAX, P53, and CASPASE-1 were significantly increased in the non-ischemic region of the left ventricle (LV) with highest levels of expression in the peri-infarct area. High levels of FAS, BAX, P53, and CASPASE-1 mRNA were also observed in the infarcted region. Concomitantly, numerous TUNEL-positive cells and internucleosomal degradation of DNA were found in tissue from the peri-infarct area and in the infarcted zone, indicating apoptotic cell death. Treatment with bosentan, a mixed ET(A)/ET(B) receptor antagonist, during the first 24 h after induction of MI significantly reduced the area of TUNEL-positive myocardium in the ischemic region (64 +/- 2% of LV circumference in the vehicle group vs 55 +/- 2% of LV circumference in the bosentan group, p < 0.05). Consistently, bosentan also caused a similar reduction of infarct size. CONCLUSION: Our data demonstrate activation of pro-apoptotic genes and provide evidence of cardiomyocyte apoptosis in the viable peri-infarct area and in the infarcted region after MI in rats. Intervention with bosentan may attenuate cardiomyocyte cell loss through apoptosis in the area at risk after induction of ischemia.     

Early mechanical function in the heterotopic heart transplant

The characteristics of left ventricular (LV) function in the nonimmunosuppressed heterotopic heart transplant (TX) with less than 3 hr of cold preservation, were studied in 12 awake chronically instrumented dogs prior to TX (control), 1-12 hr post TX (P1), 12-24 hr post TX (P2), and 24-48 hr post TX (P3). Micromanometers measured LV transmural pressure and ultrasonic transducers measured ventricular dimension in order to allow calculations of myocardial mechanical properties. Immediately after transplant (P1) there was significant (P less than 0.05) depression noted in both diastolic function and systolic function (peak LV pressure, 137 +/- 5 vs 80 +/- 10 mm Hg; dp/dtmax, 2642 +/- 170 vs 1038 +/- 98 mm Hg/sec; maximum velocity of minor axis shortening, 4.46 +/- 0.50 vs 2.41 +/- 0.56; and Emax, 6.5 +/- 1.2 vs 2.0 +/- 1.4 mm Hg/ml). However, the contractility reserve (studied in six dogs) as estimated by postextrasystolic potentiation ratio was maintained (1.41 +/- 0.07 vs 1.37 +/- 0.15), suggesting reversibility of the depressed function. Over the next 2 days the diastolic function and the systolic function (at P3: 109 +/- 6 mm Hg, 1842 +/- 450 mm Hg/sec, 5.54 +/- 0.77 cm/sec, and 4.5 +/- 1.3 mm Hg/ml, respectively) gradually improved toward control. Microscopic examination of the autopsied hearts did not show significant evidence of rejection. Thus, the early depression of function in the heart TX appeared to be the result of ischemia from preservation and surgical trauma.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cardiomyocyte loss in experimental renal failure: prevention by ramipril

BACKGROUND: The development of left ventricular hypertrophy (LVH) and of structural abnormalities of the heart is a key abnormality in renal failure that potentially contributes to the high rate of cardiac death. In renal failure, the behavior of cardiomyocyte volume and number in the development of LVH has so far not been investigated. A potential role of the (local) renin-angiotensin system (RAS) in the genesis of LVH has been suspected. It was the aim of the present study in short-term experimental renal failure (1) to characterize cardiomyocyte volume and number and (2) to study whether they are affected by the angiotensin-converting enzyme (ACE) inhibitor ramipril. METHODS: Sprague-Dawley rats (N = 8 to 10 per group) had a subtotal nephrectomy (SNX) or sham operation and followed for 8 weeks. One SNX group received the ACE inhibitor ramipril (0.5 mg/kg body weight) in the drinking fluid. After perfusion fixation, the morphology of the heart was investigated using stereologic techniques. RESULTS: Systolic blood pressure was slightly, but not significantly, higher in untreated SNX, but the left ventricular (LV) weight and LV weight/body weight ratio (2.32 +/- 0.20 mg/g) were significantly higher in SNX than in sham-operated animals (1.90 +/- 0.16 mg/g). Sarcomeric length was not significantly different between SNX and sham-operated animals. There was an increase in the number of terminal deoxynucleotidyl transferase-mediated uridine triphosphate nick end labeling (TUNEL)-positive myocytes in SNX compared to sham-operated animals and a significant increase in cardiomyocyte volume (15,713 +/- 4557 microm3 vs. 10,067 +/- 2242 microm3, P < 0.01) as well as a decrease of cardiomyocyte numbers per unit myocardial volume (61.2 +/- 16.2 vs. 92.2 +/- 20.9 x 103/mm3) and per left ventricle (70.9 +/- 16.5 x 106 vs. 94.8 +/- 18.1 x 106, P < 0.05). Both abnormalities were abrogated by treatment with ramipril (6347 +/- 972.4 microm3 and 106 +/- 18.9 103/mm3 or 118 +/- 39.5 x 106, respectively), which also completely prevented the increase in LV weight/body weight ratio (1.83 +/- 0.14 mg/g). CONCLUSION: LVH in renal failure is characterized by cardiomyocyte hypertrophy, but also cardiomyocyte drop out. A role of the RAS is suggested by the beneficial effect of ramipril treatment that is not accounted for by differences in blood pressure.     

Left ventricular mechanical unloading restores Beta-2-adrenergic receptor mRNA expression and decreases susceptibility to ischemia and reperfusion in the failing heart

OBJECTIVES: Left ventricular (LV) mechanical unloading is known to reduce the hemodynamic demands of failing LV, resulting in improved myocyte contractility. This study was designed to examine effects of LV unloading on beta-adrenergic receptor (BAR) expression and ischemic susceptibility to ischemia reperfusion. METHODS: Five groups were studied: group 1 [unloading myocardial infarction (MI), n = 6], MI hearts 2 weeks after coronary ligation subjected to LV unloading by heterotopic heart transplantation for 2 weeks; group 2 (2-week MI, n = 6), MI hearts left for 2 weeks without unloading; group 3 (4-week MI, n = 6), MI hearts left for 4 weeks without unloading; group 4 (control, n = 6), normal (non-MI) hearts as a control with no interventions, and group 5 (unloading control, n = 5), normal (non-MI) hearts subjected to LV unloading for 2 weeks. Then, all hearts were isolated and subjected to 20 min of global ischemia and 60 min of reperfusion on Langendorff apparatus. LV pressures and coronary flow were measured throughout the experiment. Either total BAR density or beta(2)-adrenergic receptor (B2AR) mRNA expression in the noninfarcted myocardium was determined by radioligand binding assays or real-time quantitative RT-PCR, respectively. RESULTS: LV unloading improved postischemic functional recovery (unloading MI vs. 2-week MI vs. 4-week MI: 74 +/- 6 vs. 54 +/- 5 vs. 51 +/- 4%; p < 0.05 vs. unloading MI). LV unloading restored B2AR mRNA expression (unloading MI vs. 2-week MI vs. 4-week MI: 4.78 +/- 0.21 vs. 2.80 +/- 0.19 vs. 2.24 +/- 0.17 x 10(7) copy/microg total RNA; p < 0.05 vs. unloading MI). CONCLUSION: LV mechanical unloading restored B2AR mRNA expression and improved postischemic functional recovery.     

Administration of a tumor necrosis factor inhibitor at the time of myocardial infarction attenuates subsequent ventricular remodeling.

BACKGROUND: Tumor necrosis factor (TNF) causes myocardial extracellular matrix remodeling and fibrosis in myocardial infarction and chronic heart failure models. Pre-clinical and clinical trials of TNF inhibition in chronic heart failure have shown conflicting results. This study examined the effects of the administration of a TNF inhibitor immediately after myocardial infarction on the development of heart failure. METHODS: Lewis rats underwent coronary artery ligation and then received either intravenous etanercept (n = 14), a soluble dimerized TNF receptor that inhibits TNF, or saline as control (n = 13). Leukocyte infiltration into the infarct borderzone was evaluated 4 days post-ligation in 7 animals (etanercept = 4, control = 3). After 6 weeks, the following parameters were evaluated in the remaining animals: cardiac function with a pressure-volume conductance catheter, left ventricular (LV) geometry, and borderzone collagenase activity. RESULTS: Etanercept rats had significantly less borderzone leukocyte infiltration 4 days post-infarction than controls (10.7 +/- 0.5 vs 18.0, +/-2.0 cells/high power field; p < 0.05). At 6 weeks, TNF inhibition resulted in significantly reduced borderzone collagenase activity (110 +/- 30 vs 470 +/- 140 activity units; p < 0.05) and increased LV wall thickness (2.1 +/- 0.1 vs 1.8 +/- 0.1 mm, p < 0.05). Etanercept rats had better systolic function as measured by maximum LV pressure (84 +/- 3 mm Hg vs 68 +/- 5 mm Hg, p < 0.05) and the maximum change in left ventricular pressure over time (maximum dP/dt) (3,110 +/- 230 vs 2,260 +/- 190 mm Hg/sec, p < 0.05), and better diastolic function as measured by minimum dP/dt (-3,060 +/- 240 vs -1,860 +/- 230 mm Hg/sec; p < 0.05) and the relaxation time constant (14.6 +/- 0.6 vs 17.9 +/- 1.2 msec; p < 0.05). CONCLUSIONS: TNF inhibition after infarction reduced leukocyte infiltration and extracellular matrix turnover and preserved cardiac function.     

Anesthetic management of a child with dilated cardiomyopathy associated with congenital fiber-type disproportion

A 3-year-old girl, who presented with dilated cardiomyopathy in conjunction with congenital fiber-type disproportion, underwent open reduction for congenital dislocation of the hip. Preoperative echocardiography demonstrated left ventricular dilatation with an ejection fraction (EF) of 0.33. Anesthesia was induced with intravenous ketamine and fentanyl, and maintained with fentanyl administered incrementally to a total dose of 10 micrograms.kg-1 and 1-1.5% isoflurane. During operation, we continuously monitored left ventricular wall motion and measured left ventricular diastolic dimension (LVDd), systolic dimension (LVDs), cardiac output (CO), EF, and fractional shortening (FS) with transesophageal echocardiography (TEE). At the end of surgery, preload (LVDd) and LV contractility (CO, EF, FS) decreased, but LV wall motion remained almost stable throughout the procedure. In conclusion, TEE was useful for intraoperative management of a child with dilated cardiomyopathy.     

Targeted overexpression of leukemia inhibitory factor to preserve myocardium in a rat model of postinfarction heart failure

OBJECTIVE: Myocardial infarction leads to cardiomyocyte loss. The cytokine leukemia inhibitory factor regulates the differentiation and growth of embryonic and adult heart tissue. This study examined the effects of gene transfer of leukemia inhibitory factor in infarcted rat hearts. METHODS: Lewis rats underwent ligation of the left anterior descending coronary artery and direct injection of adenovirus encoding leukemia inhibitory factor (n = 10) or null transgene as control (n = 10) into the myocardium bordering the ischemic area. A sham operation group (n = 10) underwent thoracotomy without ligation. After 6 weeks, the following parameters were evaluated: cardiac function with a pressure-volume conductance catheter, left ventricular geometry and architecture by histologic methods; myocardial fibrosis by Masson trichrome staining, apoptosis by terminal deoxynucleotidal transferase-mediated deoxyuridine triphosphate nick-end labeling assay, and cardiomyocyte size by immunofluorescence. RESULTS: Rats with overexpression of leukemia inhibitory factor had more preserved myocardium and less fibrosis in both the infarct and its border zone. The border zone in leukemia inhibitory factor-treated animals contained fewer apoptotic nuclei (1.6% +/- 0.1% vs 3.3% +/- 0.2%, P < .05) than that in control animals and demonstrated cardiomyocytes with larger cross-sectional areas (910 +/- 60 microm 2 vs 480 +/- 30 microm 2 , P < .05). Leukemia inhibitory factor-treated animals had increased left ventricular wall thickness (2.1 +/- 0.1 mm vs 1.8 +/- 0.1 mm, P < .05) and less dilation of the left ventricular cavity (237 +/- 22 microL vs 301 +/- 16 microL, P < .05). They also had improved cardiac function, as measured by maximum change in pressure over time (3950 +/- 360 mm Hg/s vs 2750 +/- 230 mm Hg/s, P < .05) and the slopes of the maximum change in pressure over time-end-diastolic volume relationship (68 +/- 5 mm Hg/[s . microL] vs 46 +/- 6 mm Hg/[s . microL], P < .05) and the preload recruitable stroke work relationship (89 +/- 10 mm Hg vs 44 +/- 4 mm Hg, P < .05). CONCLUSIONS: Myocardial gene transfer of leukemia inhibitory factor preserved cardiac tissue, geometry, and function after myocardial infarction in rats.     

Long-term cell survival and hemodynamic improvements after neonatal cardiomyocyte and satellite cell transplantation into healed myocardial cryoinfarcted lesions in rats

Cell engraftment is a new strategy for the repair of ischemic myocardial lesions. The hemodynamic effectiveness of this strategy, however, is not completely elucidated yet. In a rat model of cryothermia-induced myocardial dysfunction, we investigated whether syngeneic transplantation of neonatal cardiomyocytes or satellite cells is able to improve left ventricular performance. Myocardial infarction was induced in female Lewis rats by a standardized cryolesion to the obtuse margin of the left ventricle. After 4 weeks, 5 x 10(6) genetically male neonatal cardiomyocytes (n = 16) or satellite cells (n = 16) were engrafted into the myocardial scar. Sham-transplanted animals (n = 15) received injections with cell-free medium. Sham-operated animals (n = 15) served as controls. Left ventricular performance was analyzed 4 months after cell engraftment. Chimerism after this sex-mismatched transplantation was evaluated by detection of PCR-amplified DNA of the Y chromosome. The average heart weight of the infarcted animals significantly exceeded that of controls (p < 0.05). In sham-transplanted animals, mean aortic pressure, left ventricular systolic pressure, aortic flow (indicator of cardiac output), and left ventricular systolic reserve were significantly lower (p < 0.05) compared with sham-operated controls. This was associated with deterioration of ventricular diastolic function (maximal negative dP/dt, time constants of isovolumic relaxation; p < 0.05). Transplantation of satellite cells was found more effective than transplantation of neonatal cardiomyocytes, resulting in i) normalization of mean aortic pressure compared with sham-operated controls, and ii) significantly improved left ventricular systolic pressure and aortic flow (p < 0.05) compared with sham-transplanted animals. Left ventricular systolic reserve and diastolic function, however, were improved by neither satellite cell nor neonatal cardiomyocyte transplantation. Analysis of male genomic DNA revealed 3.98 +/- 2.70 ng in hearts after neonatal cardiomyocyte engraftment and 6.16 +/- 4.05 ng in hearts after satellite cell engraftment, representing approximately 10(3) viable engrafted cells per heart. Our study demonstrates i) long-term survival of both neonatal cardiomyocytes and satellite cells after transplantation into cryoinfarcted rat hearts, ii) slight superiority of satellite cells over neonatal cardiomyocytes in improving global left ventricular pump performance, and iii) no effect of both transplant procedures on diastolic dysfunction.     

Matrix metalloproteinase inhibition modifies left ventricular remodeling after myocardial infarction in pigs

BACKGROUND: Global and regional shape changes that occur within the left ventricular wall after myocardial infarction have been termed infarct expansion. A potential mechanism for this postinfarction remodeling is activation of the matrix metalloproteinases. Accordingly, the present study examined the effects of matrix metalloproteinase inhibition on left ventricular global geometry after myocardial infarction in pigs. METHODS: Myocardial infarction was created in pigs by means of occlusion of the first and second obtuse marginal branches of the circumflex coronary artery, resulting in a uniform left ventricular free wall infarct size of 21% +/- 2%. At 5 days after infarction, the pigs were randomized to undergo broad-spectrum matrix metalloproteinase inhibition (n = 9; PD166793, 20 mg. kg(-1). d(-1) by mouth) or myocardial infarction alone (n = 8). Ten pigs served as noninfarction control animals. Left ventricular end-diastolic area, determined by means of echocardiography, was measured 8 weeks after infarction. RESULTS: Left ventricular end-diastolic area increased in both the myocardial infarction plus broad-spectrum matrix metalloproteinase inhibition and myocardial infarction only groups compared to reference control animals (3.7 +/- 0.2 cm(2)), but was reduced with broad-spectrum matrix metalloproteinase inhibition compared to myocardial infarction alone (4.5 +/- 0.2 vs 4.9 +/- 0.2 cm(2), respectively; P <.05). Regional radial stress within the infarct region increased in both infarction groups when compared to values obtained from reference control animals (599 +/- 152 g/cm(2)), but was attenuated in the myocardial infarction plus broad-spectrum matrix metalloproteinase inhibition group compared to the myocardial infarction alone group (663 +/- 108 vs 1242 +/- 251 g/cm(2), respectively; P <.05). Similarly, regional myocardial stiffness increased in both the myocardial infarction plus broad-spectrum matrix metalloproteinase inhibition and the myocardial infarction only groups compared with that observed in reference control animals (14 +/- 1 rkm, P <.05) but was lower with broad-spectrum matrix metalloproteinase inhibition than with myocardial infarction alone (42 +/- 6 vs 68 +/- 10 rkm, respectively; P <.05). CONCLUSIONS: Matrix metalloproteinase inhibition reduced postinfarction left ventricular dilation, reduced regional myocardial wall stress, and modified myocardial material properties. These unique findings suggest that increased myocardial matrix metalloproteinase activation after infarction contributes directly to the left ventricular remodeling process.     

Long-term improvement of cardiac function in rats after infarction by transplantation of embryonic stem cells

OBJECTIVE: This study was designed to investigate the feasibility of and potential functional improvement with embryonic stem cell transplantation in rats 32 weeks after myocardial infarction. METHODS: Before cell transplantation, cultured embryonic stem cells were transfected with the complementary DNA of green fluorescent protein to identify engrafted cells in myocardium. Myocardial infarction was induced by ligation of the left coronary artery. Either 3 x 10(5) mouse embryonic stem cells or an equivalent volume of cell-free medium was injected into injured myocardium within 20 minutes after induction of myocardial infarction. RESULTS: Embryonic stem cell transplantation significantly increased the survival rate in rats undergoing myocardial infarction during the experimental period of 32 weeks. Hemodynamic and echocardiographic data showed that embryonic stem cell transplantation significantly improved ventricular function relative to the myocardial infarction plus medium control group. Tissue positive for green fluorescent protein was found in the injured myocardium with cell transplantation. The proportion of myocardium positively immunostained by antibodies against alpha-myosin heavy chain and cardiac troponin I was greater in the infarcted area with embryonic stem cell transplantation than in the injured myocardium with medium injection. Single green fluorescent protein-positive cells with a rod shape and clear striations were observed in cardiomyocytes isolated from infarcted hearts with embryonic stem cell transplantation. In addition, the number of blood vessels in injured myocardium was greater in the cell-transplanted myocardial infarction group than in the medium-injected myocardial infarction group. CONCLUSIONS: Engrafted embryonic stem cells differentiated into cardiomyocytes in injured myocardium, caused an angiogenetic effect, and subsequently improved cardiac function during the 32-week observation period.     

二维斑点追踪成像评价萝卜硫素对2型糖尿病大鼠左心室功能的影响

目的观察二维斑点追踪成像(2D-STI)技术用于评价萝卜硫素(SFN)对2型糖尿病(T2DM)大鼠左心室功能影响的价值。方法将30只T2DM SD大鼠模型随机均分为T2DM组、T2DM+低SFN组、T2DM+高SFN组;另以10只健康大鼠为对照组(NC组)。对T2DM+低SFN组、T2DM+高SFN组每天左下腹皮下注射0.5、1.0 mg/kg体质量SFN,T2DM组和NC组注射等量生理盐水;3个月后检测各组大鼠常规超声心动图参数,包括左心室舒张末期内径(LVDd)、左心室收缩末期内径(LVDs)、左心室射血分数(LVEF)及左心室短轴缩短率(FS),以2D-STI技术测得左心室短轴二尖瓣水平圆周应变。之后处死大鼠,取心肌组织,以天狼猩红染色观察心肌纤维化,免疫组织化学染色观察结缔组织生长因子(CTGF)表达。结果各组大鼠间体质量、随机血糖、LVDd、LVDs、LVEF、FS及局部圆周应变差异均有统计学意义(P均0.05)。T2DM组、T2DM+低SFN组、T2DM+高SFN组大鼠体质量、LVEF、FS及局部圆周应变均低于NC组(P均0.05),而随机血糖、LVDd、LVDs均高于NC组(P均0.05);T2DM+低SFN组、T2DM+高SFN组体质量、LVEF、FS、局部圆周应变高于T2DM组(P均0.05),而随机血糖、LVDd、LVDs低于T2DM组(P均0.05)。与NC组比较,其他3组大鼠心肌组织胶原沉积及CTGF阳性表达均增加,T2DM+低SFN组、T2DM+高SFN组均低于T2DM组(P均0.05),而T2DM+低SFN组与T2DM+高SFN组上述指标差异均无统计学意义(P均0.05)。结论 SFN可提高T2DM大鼠左心室局部圆周应变,减轻心肌纤维化,改善左心室心肌运动功能;2D-STI技术可用于评价SFN对T2DM大鼠左心室功能的影响。