Optimal time for cardiomyocyte transplantation to maximize myocardial function after left ventricular injury

Background. This study was designed to determine the optimal time for cell transplantation after myocardial injury.

Methods. The left ventricular free wall of adult rat hearts was cryoinjured and the animals were sacrificed at 0, 1, 2, 4, and 8 weeks for histologic studies. Fetal rat cardiomyocytes (transplant) or culture medium (control) were transplanted immediately (n = 8), 2 weeks (n = 8), and 4 weeks (n = 12) after cryoinjury. At 8 weeks, rat heart function, planimetry, and histologic studies were performed.

Results. Cryoinjury produced a transmural injury. The inflammatory reaction was greatest during the first week but subsided during the second week after cryoinjury. Scar size expanded (p < 0.01) at 4 and 8 weeks. Cardiomyocytes transplanted immediately after cryoinjury were not found 8 weeks after cryoinjury. Scar size and myocardial function were similar to the control hearts. Cardiomyocytes transplanted at 2 and 4 weeks formed cardiac tissue within the scar, limited (p < 0.01) scar expansion, and had better (p < 0.001) heart function than the control groups. Developed pressure was greater (p < 0.01) in the hearts with transplanted cells at 2 weeks than at 4 weeks.

Conclusions. Cardiomyocyte transplantation was most successful after the inflammatory reaction resolved but before scar expansion.     

Vascular endothelial growth factor transgene expression in cell-transplanted hearts

OBJECTIVE: We evaluated the effect of transplanted cell type, time, and region of the heart on transgene expression to determine the potential of combined gene and cell delivery for myocardial repair. METHODS: Lewis rats underwent myocardial cryoinjury 3 weeks before transplantation with heart cells (a mixed culture of cardiomyocytes, smooth muscle cells, endothelial cells and fibroblasts, n = 13), vascular endothelial growth factor-transfected heart cells (n = 13), skeletal myoblasts (n = 13), vascular endothelial growth factor-transfected skeletal myoblasts (n = 13), or medium (control, n = 12). Vascular endothelial growth factor expression in the scar, border zone, and normal myocardium was evaluated at 3 days and at 1, 2, and 4 weeks by means of quantitative polymerase chain reaction. Transplanted cells and vascular endothelial growth factor protein were identified immunohistologically on myocardial sections. RESULTS: Vascular endothelial growth factor levels were very low in control scars but increased transiently after medium injection. Transplantation with heart cells and skeletal myoblasts significantly increased vascular endothelial growth factor expression in the scar and border zone. Transplantation of vascular endothelial growth factor-transfected heart cells and vascular endothelial growth factor-transfected skeletal myoblasts further augmented vascular endothelial growth factor expression, resulting in 4- to 5-fold greater expression of vascular endothelial growth factor in the scar at 1 week. Peak vascular endothelial growth factor expression was greater and earlier in vascular endothelial growth factor-transfected heart cells than in vascular endothelial growth factor-transfected skeletal myoblasts. Vascular endothelial growth factor was primarily expressed by the transplanted cells. Some of the transplanted heart cells and vascular endothelial growth factor-transfected heart cells were identified in the endothelial layer of blood vessels in the scar. CONCLUSIONS: Transplantation of heart cells and skeletal myoblasts induces vascular endothelial growth factor expression in myocardial scars and is greatly augmented by prior transfection with a vascular endothelial growth factor transgene. Vascular endothelial growth factor expression is limited to the scar and border zone for 4 weeks. Both heart cells and skeletal myoblasts may be excellent delivery vehicles for cell-based myocardial gene therapy.     

Autologous heart cell transplantation improves cardiac function after myocardial injury

Background. Fetal ventricular cardiomyocyte transplantation into a cardiac scar improved ventricular function, but these cells were eventually eliminated by rejection. We therefore examined the feasibility of autologous adult heart cell transplantation.

Methods. A transmural scar was produced in the left ventricular free wall of adult rats by cryoinjury. The left atrial appendage was harvested, and the atrial heart cells were cultured and their number expanded ex vivo. Three weeks after cryoinjury, either a cell suspension (2 × 10⁶ cells, n = 12 rats, transplant group) or culture medium (n = 10 rats, control group) was injected into the scar. Rats having a sham operation (n = 5) did not undergo cryoinjury or transplantation with cells or culture medium.

Results. Five weeks after injection, ventricular function was evaluated in a Langendorff preparation, measuring systolic, diastolic, and developed pressures over a range of intraventricular balloon volumes. Systolic and developed pressures were greater in the transplant group than in the control group (p = 0.0001). Rats with a sham operation had the greatest systolic, diastolic, and developed pressures (p = 0.0001). Histologic studies demonstrated survival of the transplanted heart cells within the scar. The area of the scar was smaller (p = 0.0003) and its thickness greater (p = 0.0003) in rats in the transplant group. Left ventricular chamber volume was smaller in the transplant group (p = 0.043).

Conclusions. Transplantation of autologous cultured adult atrial heart cells limited scar thinning and dilatation and improved myocardial function compared with results in control hearts. This technique may lead to a novel therapy to prevent scar expansion after a myocardial infarction and prevent the development of congestive heart failure.     

Mesenchymal stem cells participate in angiogenesis and improve heart function in rat model of myocardial ischemia with reperfusion.

OBJECTIVE: The effect of transplanted mesenchymal stem cells (MSCs) on the left ventricular (LV) function and morphology in a rat myocardial infarct heart with reperfusion model were analyzed. METHODS: One week after 60 min of myocardial ischemia and reperfusion by left anterior descending artery (LAD) occlusion, 1.0x10(7) 6-diamidino-2-phenylindole (DAPI)-labeled MSCs were injected into the infarcted myocardium and compared with controls, and sham-operated rats, in which a cell-free serum medium was injected into the infarcted region or the myocardial wall, respectively. Measurement of vascular endothelial growth factor (VEGF) expression 1 week after MSC injection using Western blot analysis (n=5), and immunohistochemical staining using HE staining and fluorescent microscopy of the DAPI-positive regions from MSC implantation, cTnT immunostaining of potential myocardial-like cells, and SM-actin and CD31 immunostaining demonstrating neovascular transformation of implanted MSCs 1 week, 2 weeks and 4 weeks after transplantation (n=5). Hemodynamic measurements were performed after 4 weeks in vivo. Subsequently, hearts were quickly removed and cut for histological analysis using HE staining with measurement of the infarcted LV-area, the LV-wall thickness within the scar segment compared to non-infarcted scar segments, and the capillary density counting capillary vessels with 400x light microscopy (n=10). RESULTS: Measurement of hemodynamics 4 weeks after transplantation in vivo showed LV function to be significantly greater in MSCs than in the control group. Semi-quantitative histomorphometric examinations showed a significantly lower infract size, a greater LV-wall thickness, and a lower Hochman-Choo expansion index in the MSC-treated group compared to the control group. Immunofluorescence demonstrated that transplanted MSCs were positive for cTnT, suggesting that a small number of transplanted MSCs can differentiate into cardiomyocytes. Other MSCs were positive for CD31 and SM-actin. The transplanted MSCs in MI area had significantly higher expression rates of cTnT, CD31 and SM-actin 2 weeks after transplantation. HE staining showed marked augmentation of neovascularization in the MSC group. Semi-quantitative analysis demonstrated that capillary density was significantly higher in the MSC group than in the control group. CONCLUSION: Implanted MSCs could improve cardiac structure and function through the combined effect of myogenesis and angiogenesis.     

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.     

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.     

Improved heart function with myogenesis and angiogenesis after autologous porcine bone marrow stromal cell transplantation

OBJECTIVE: The study evaluated the utility of transplanting bone marrow stromal cells in a porcine myocardial infarction model. METHODS: A myocardial infarction was created by occluding the distal left anterior descending artery in pigs with coils and Gelfoam sponge. Sternal bone marrow was aspirated, and stromal cells were cultured and induced to differentiate to a myogenic phenotype with 5-azacytidine. Four weeks after coronary artery occlusion, sestamibi technetium single-photon emission computed tomographic scans were performed, and then either a graft of 100 x 10(6) bone marrow stromal cells (n = 5, 30% labeled with bromodeoxyuridine) or culture medium (n = 6) was injected into the infarct region. Four weeks later the tomographic scans were repeated and cardiac function was assessed with pressure and volume measurements. Morphologic and histologic characteristics of the heart were also studied. RESULTS: Histologic examination found bromodeoxyuridine-labeled cells within the infarct region in islands that had sarcomeres and Z-bands and stained positively for cardiac specific troponin I. The bone marrow stromal cell transplant sites had a greater (P <.05) capillary density than did the control sites. The tomographic scans showed that the hearts with the cell transplants had increases in stroke volume, regional perfusion, and wall motion (P <.05 for all groups) relative to the control hearts. The pressure-volume analysis showed improvement (P <.05) in end-systolic elastance and preload recruitable stroke work in the transplantation group relative to the control group. The left ventricular chamber size was smaller (P <.05) and the scar thickness was greater (P <.05) in the hearts with transplanted cells than in the control hearts (P =.06). CONCLUSION: 5-Azacytidine-treated bone marrow stromal cells transplanted into the myocardial infarct region formed islands of cardiac-like tissue, induced angiogenesis, prevented thinning and dilatation of the infarct region, and improved regional and global contractile function.     

Optimal temporal delivery of bone marrow mesenchymal stem cells in rats with myocardial infarction.

OBJECTIVE: This study was designed to determine the optimal time point for bone marrow mesenchymal stem cell (MSC) transplantation after myocardial infarction (MI). METHODS: MSCs from donor rats were labeled with DAPI before transplantation. The animals underwent MI by ligation of left anterior descending coronary artery, and received intramyocardial injection of MSCs at 1h, 1 week and 2 weeks after MI, respectively. Sham-operated and MI control groups received equal volume phosphate buffered saline. Cardiac function, histological analysis and immunoblot for troponin T were performed 4 weeks after cell transplantation. RESULTS: MSC transplantation attenuated left ventricular chamber dilation, reduced infarct size, and improved cardiac function in rats after MI. The greatest benefit was achieved in rats that received cells 1 week after MI, engrafted MSC survival, angiogenesis and functional cardiomyocytes in the injured hearts were more abundant in these rats than that in other transplantation groups. CONCLUSIONS: The optimal functional benefit of MSC transplantation was observed in 1-week transplantation group. At this time point scar formation has not occurred and the inflammation is reduced, which should facilitate integration of transplanted cells and functional recovery.     

Beneficial effect of autologous cell transplantation on infarcted heart function: comparison between bone marrow stromal cells and heart cells

BACKGROUND: Cell transplantation may restore function after myocardial infarction, but the optimal cell type remains controversial. We compared autologous bone marrow stromal cells (BMCs) with autologous heart cells (HCs) in a porcine myocardial infarction model. METHODS: Yorkshire pigs underwent coil occlusion of the left anterior descending artery. Bone marrow stromal cells were obtained from sternal marrow and HCs were obtained by left ventricular biopsy, then cultured for 4 weeks. Four weeks after infarction, a 99mTc-sestamibi single-photon emission tomography (99mTc-MIBI SPECT) scan was performed and the pigs were then transplanted with BMCs (n = 7), HCs (n = 7), or culture medium (n = 14). Four weeks after transplantation, 99mTc-MIBI SPECT scanning was repeated to evaluate regional perfusion. Pressure-volume loops were constructed from micromanometer and conductance catheter data to evaluate left ventricular function. Hearts were evaluated histologically. RESULTS: Bone marrow stromal cells and HCs engrafted within the infarct and assumed a myocyte morphology. SPECT MIBI scans showed increased perfusion in the infarct in cell-transplanted pigs, while perfusion decreased in the control pigs. Heart cell transplantation improved preload-recruitable stroke work and HC and BMC transplantation both shifted the end-systolic pressure-volume relation to the left. Both BMCs and HCs prevented thinning and expansion of the infarct region, and some BMCs differentiated into endothelial cells in newly formed blood vessels perfusing the infarct. CONCLUSIONS: Both BMCs and HCs engrafted in the infarct region and improved let ventricular function by preventing infarct thinning. Bone marrow stromal cells demonstrated greater plasticity in vivo, and may offer a practical alternative to HC transplantation to restore function and perfusion after a myocardial infarction.     

Erythropoietin improves the efficiency of endothelial progenitor cell therapy after myocardial infarction in mice: effects on transplanted cell survival and autologous endothelial progenitor cell mobilization

BackgroundEndothelial progenitor cells (EPCs) participate in vascular repair and angiogenesis. Thus, EPC transplantation into ischemic myocardium might improve cardiac function; however, the vast majority of cells die within a short period. The present study was designed to investigate whether exogenous erythropoietin (EPO) delivery could improve the survival of transplanted EPCs and enhance the efficiency of EPC-based cell therapy.MethodsMyocardial infarction was induced in wild-type mice by ligating the left anterior descending coronary artery. Enhanced green fluorescent protein-EPCs with or without EPO were transplanted into peri-infarct myocardium. Enhanced green fluorescent protein-EPCs were detected 7 and 28 d after surgery. The amount of circulating EPCs was analyzed 3 and 28 d after surgery. The stromal cell-derived factor-1α and vascular endothelial growth factor concentrations, microvessel density, apoptosis, fibrosis in the peri-infarct myocardium, and cardiac function were compared among the groups.ResultsMore enhanced green fluorescent protein-EPCs were found in the hearts treated with EPC + EPO than in those treated with EPC alone. The circulating EPC level was markedly elevated after EPC + EPO treatment compared with EPC application alone. Stromal cell-derived factor-1α and vascular endothelial growth factor were increased accordingly, along with increased microvessel density, decreased apoptosis, and reduced fibrosis in the peri-infarct myocardium. Left ventricular fractional shortening was greater and the interventricular septum was thicker after EPC + EPO treatment compared with EPC treatment alone.ConclusionsEPO improved the efficiency of EPC therapy in mice with myocardial infarction. This effect was associated with enhanced transplanted EPC survival and autologous EPC mobilization.     

Enhanced cytoprotection and angiogenesis by bone marrow cell transplantation may contribute to improved ischemic myocardial function.

OBJECTIVES: Heat shock proteins (HSPs) are cytoprotective proteins. Vascular endothelial growth factor (VEGF) is the most potent angiogenic factor. This study aimed to elucidate the possible role of cytoprotection and angiogenesis on cardiac function after bone marrow cell transplantation (BMT). METHODS: Myocardial infarction was induced in inbred Lewis rats by left anterior descending artery ligation. A total of 5 x 10(6) bone marrow-mononuclear cells were transplanted into the ischemic zone by direct injection. At 1, 3, 7, 14 and 28 days post-transplantation, cardiac function was evaluated by echocardiography. The expressions of HSP32, HSP70 and VEGF were assessed by immunofluorescence and RT-PCR. The number of vessels was examined by immunohistochemistry. The differentiation of the transplanted cells was determined by immunofluorescence. RESULTS: Echocardiography showed BMT led to sustained improvement in cardiac function, as assessed by left ventricle ejection fraction and fraction of shortening. Immunofluorescence revealed that the expressions of HSP32, HSP70 and VEGF were promoted in both transplanted bone marrow cells and recipient cardiomyocytes. RT-PCR showed that the mRNA expression levels of HSP32, HSP70 and VEGF in the BMT group were markedly higher in comparison with injection of peripheral blood cells or saline (P<0.01) by day 7. Seven days later, the vessel count showed that angiogenesis had been induced to a significantly greater degree in the BMT groups. Fourteen days later, specific markers for myocardial or vascular endothelial cells were detected in the transplanted bone marrow cells. CONCLUSIONS: BMT upregulated the expressions of HSP32, HSP70 and VEGF in both transplanted bone marrow cells and recipient endogenous cardiomyocytes in the early phase post-transplantation. This enhanced cytoprotection and angiogenesis, and contributed to the functional recovery following cardiac infarction. In the late phase, the transplanted bone marrow cells might differentiate into both myocardial and vascular endothelial cells that enhanced the ischemic cardiac function further.     

Promoting angiogenesis protects severely hypertrophied hearts from ischemic injury

BACKGROUND: Myocardial hypertrophy is associated with progressive contractile dysfunction, increased vulnerability to ischemia-reperfusion injury, and is, therefore, a risk factor in cardiac surgery. During the progression of hypertrophy, a mismatch develops between the number of capillaries and cardiomyocytes per unit area, suggesting an increase in diffusion distance and the potential for limited supply of oxygen and nutrients. We hypothesized that promoting angiogenesis in hypertrophied hearts increases microvascular density, thereby improves tissue perfusion and substrate availability, maintains myocardial function, and improves postischemic recovery. METHODS: Left ventricular hypertrophy was created in 10-day-old rabbits by aortic banding and progression was monitored by echocardiography. At 4 weeks (compensated hypertrophy), 2 microg of vascular endothelial growth factor (VEGF) or placebo was administered intrapericardially. After 2 weeks, microvascular density, coronary flow (CF), and glucose uptake (GU) were measured. Tolerance to ischemia was determined by cardiac function measurements before and after ischemia-reperfusion using an isolated heart preparation. RESULTS: Microvascular density increased significantly following VEGF treatment (1.43 +/- 0.08/nuclei/field vs 1.04 +/- 0.06/nuclei/field untreated hypertrophy). Concomitantly, there was an increase in CF (7 +/- 0.5 vs 5 +/- 0.4 mL/min/g) and GU (1.24 +/- 0.2 vs 0.69 +/- 0.2 micromoles/g/30 minutes; p 相似文献   

Gene therapy for myocardial angiogenesis

Objectives: We studied the therapeutic potential of ex vivo vascular endothelial growth factor (VEGF) gene-transduced H9c2 cell transplantation for myocardial neovascularization. Methods: The left ventricular free wall of adult Sprague-Dawley rats was cryodamaged. Two weeks after, naked plasmid encoding VEGF (VEGF1: 1μg/100 μl, VEGF5: 5μg/100μl), or VEGF transfected H9c2 myoblasts (0.5× 10⁶ cells/200 μl) were injected into the center of scar tissue. Four weeks after cryoinjury, scar diameters in the each group were measured. Neovascularization in the scar tissue was then quantified histologically. Results: Average scar tissue diameter 4 weeks after cryoinjury was as follows: TE (controls): 6.77±0.31 mm, H9c2: 5.08±0.43 mm; VEGF1: 5.90±0.20 mm; VEGF5: 4.50±0.24 mm. Scar tissue diameter was smaller in the 3 groups than in the control group (p<0.05). Capilary density by histological examination increased in naked plasmid injection groups (VEGF1: 1,209.9±305.3/mm²; VEGF5: 1,072.0±230.8/mm²) versus control (708.2±144.9/mm², p<0.05, p<0.05), and H9c2 cell transplantation group (1,379.4±391.6/mm²) versus controls (p<0.05). Conclusion: VEGF-transfected H9c2 myoblasts can transplantation group was markedly similar to direct myocardial injection in naked plasmid encoding VEGF groups.     

脐带间充质干细胞分化为内皮细胞促进血管新生

目的 探讨脐带间充质干细胞能否在体内外分化为内皮细胞,参与血管新生.方法 体外实验采用内皮细胞生长因子和碱性成纤维细胞生长因子对脐带间充质于细胞进行诱导,观察其形态变化.体内实验将脐带间充质干细胞移植到小鼠后肢缺血模型中,采用免疫组织化学鉴定细胞在体内的迁移和分化,激光多普勒血流成像仪鉴定缺血局部血流恢复情况.结果 在体外脐带间充质干细胞能够形成血管网样结构.在体内脐带间充质干细胞能够分化为内皮细胞,表达CD31抗体,参与实验组的动物血管重建.与小鼠的血管网络发生整合,实验组的动物后肢血流灌注明显好于对照组.结论 脐带间充质干细胞能够分化为内皮细胞,参与血管新生,为治疗性血管新生提供新的细胞选择.     

Stem cell therapy in the aging hearts of Fisher 344 rats: synergistic effects on myogenesis and angiogenesis

OBJECTIVE: Advanced age is a major risk factor for ventricular dysfunction and reduction of cardiac reserve. Finding novel approaches to prevent and attenuate heart dysfunction associated with advanced age is a major therapeutic challenge. The present study was designed to test whether engrafted embryonic stem cells could improve myocardial function in aging hearts. METHODS: Cultured mouse embryonic stem cells used for cell therapy were transfected with green fluorescent protein. Aging rats in the cell-treated group received intramyocardial injection of embryonic stem cells. Hemodynamic measurement, myocyte counting, and evaluation of blood flow were performed 6 weeks after cell transplantation. RESULTS: Embryonic stem cell therapy partially improved cardiac reserve, as reflected by the in vivo response to isoproterenol (INN: isoprenaline) stimulation in aging hearts 6 weeks after cell implantation. The functional benefits from engrafted embryonic stem cells were associated with increased myocyte numbers and enhanced left ventricular blood perfusion in the aging heart. The characteristic phenotype of engrafted embryonic stem cells was identified in the transplanted heart on the basis of green fluorescent protein-positive spots that were further demonstrated to differentiate into cardiac tissue with positive staining for cardiac alpha-myosin heavy chain. CONCLUSIONS: Regenerating cardiomyocytes and increasing regional blood perfusion in the aging heart after embryonic stem cell transplantation synergistically resulted in improvement of cardiac function. Embryonic stem cell transplantation might hold significant clinical potential in attenuating the progressive decrease of cardiac function associated with advanced aging.     

Autologous porcine heart cell transplantation improved heart function after a myocardial infarction

OBJECTIVE: Fetal cardiomyocyte transplantation improved heart function after cardiac injury. However, cellular allografts were rejected despite cyclosporine (INN: ciclosporin) therapy. We therefore evaluated autologous heart cell transplantation in an adult swine model of a myocardial infarction. METHODS: In 16 adult swine a myocardial infarction was created by occlusion of the distal left anterior descending coronary artery by an intraluminal coil. Four weeks after infarction, technetium 99m-sestamibi single photon emission tomography showed minimal perfusion and viability in the infarcted region. Porcine heart cells were isolated and cultured from the interventricular septum at the time of infarction and grown in vitro for 4 weeks. Through a left thoracotomy, either cells (N = 8) or culture medium (N = 8) was injected into the infarct zone. RESULTS: Four weeks after cell transplantation, technetium 99m-sestamibi single photon emission tomography demonstrated greater wall motion scores in the pigs receiving transplantation than in control animals (P =.01). Pigs receiving transplantation were more likely to have an improvement in perfusion scores (P =.03). Preload recruitable stroke work (P =.009) and end-systolic elastance (P =. 02) were greater in the pigs receiving transplantation than in control animals. Scar areas were not different, but scar thickness was greater (P =.02) in pigs receiving transplantation. Cells labeled with bromodeoxyuridine in vitro could be identified in the infarct zone 4 weeks after transplantation. Swine receiving transplantation gained more weight than control animals (P =.02). CONCLUSION: Autologous porcine heart cell transplantation improved regional perfusion and global ventricular function after a myocardial infarction.     

Significant improvement of heart function by cotransplantation of human mesenchymal stem cells and fetal cardiomyocytes in postinfarcted pigs

BACKGROUND: Viable cardiomyocytes after myocardial infarction (MI) are unable to repair the necrotic myocardium due to their limited capability of regeneration. The present study investigated whether intramyocardial transplantation of human mesenchymal stem cells (hMSCs) or cotransplantation of hMSCs plus human fetal cardiomyocytes (hFCs; 1:1) reconstituted impaired myocardium and improved cardiac function in MI pigs. METHODS AND RESULTS: Cultured hMSCs were transfected with green fluorescent protein (GFP). Six weeks after MI induction and cell transplantation, cardiac function was significantly improved in MI pigs transplanted with hMSCs alone. However, the improvement was even markedly greater in MI pigs cotransplanted with hMSCs plus hFCs. Histological examination demonstrated that transplantation of hMSCs alone or hMSCs plus hFCs formed GFP-positive engrafts in infarcted myocardium. In addition, immunostaining for cardiac alpha-myosin heavy chain and troponin I showed positive stains in infarcted regions transplanted with hMSCs alone or hMSCs plus hFCs. CONCLUSIONS: Our data demonstrate that transplantation of hMSCs alone improved cardiac function in MI pigs with a markedly greater improvement from cotransplantation of hMSCs plus hFCs. This improvement might result from myocardial regeneration and angiogenesis in injured hearts by engrafted cells.     

Myogenic cell transplantation improves in vivo regional performance in infarcted rabbit myocardium

BACKGROUND: Although cardiac transplantation is an ideal treatment for end-stage heart disease, inadequate donor availability has stimulated efforts to manage terminally injured myocardium by other innovative methods. Autologous skeletal myoblast transplantation, or cellular cardiomyoplasty, is one method to potentially mediate myocardial repair within chronically injured hearts. However, few investigators have documented the ability of myogenic cells to alter load-insensitive indices of systolic and diastolic performance in vivo. In this study, both systolic and diastolic regional myocardial function were evaluated following left ventricular cryoinjury and compared with function after myogenic cell transplantation. METHODS: Left ventricular pressure and segment length were determined in 9 rabbits by micromanometry and sonomicrometry 1 week following cryoinjury and 3 weeks after myoblast transplantation. At study termination, the extent of myoblast engraftment was determined by histologic analysis. Systolic performance was based on the linear regression of stroke work and end-diastolic segment length. Diastolic properties were evaluated by the curvilinear relationships between left ventricular pressure and strain, and left ventricular pressure and end-diastolic segment length. RESULTS: Although mean indices of systolic performance were unchanged after cell transplantation, systolic performance improved in 3 animals. In contrast, myoblast engraftment was associated with significantly improved diastolic properties (strain and dynamic stiffness) in all animals. CONCLUSIONS: These data quantify temporal changes in regional myocardial performance and suggest that cellular cardiomyoplasty improves diastolic compliance prior to affecting systolic performance. Cellular cardiomyoplasty, a potential therapeutic option for ischemic heart disease, appears to reverse diastolic creep and thus may represent a clinical alternative to transplantation in the near future.     

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.     

Autologous smooth muscle cell transplantation improved heart function in dilated cardiomyopathy

BACKGROUND: Transplantation of myocytes into scarred myocardium has been shown to inhibit ventricular remodeling and maintain myocardial contractility. However, the effect of cell transplantation on hearts with global rather than regional dysfunction is unknown. Therefore, we evaluated the effect of transplantation of autologous smooth muscle cells on the morphometry and function of dilated cardiomyopathic hearts. METHODS: Smooth muscle cells were isolated from the ductus deferens of 13-week-old BIO 53.58 hamsters with dilated cardiomyopathy, and cultured for 4 weeks before transplantation. Smooth muscle cells (4 x 10(6) cells) or culture medium were injected into 17-week-old animals in the transplantation and control groups (n = 12 each), respectively. Prelabeling of the smooth muscle cells with 5-bromo-2'-deoxyuridine was performed before transplantation in a group of transplanted hamsters. Another group (sham, n = 12) underwent the operation but did not receive an injection either of smooth muscle cells or of culture medium. Four weeks after transplantation, heart function was evaluated in a Langendorff preparation. RESULTS: Musclelike tissue, labeled with 5-bromo-2'-deoxyuridine, was found at the site of transplantation in the cell-transplanted animals. The cell-transplanted hearts were smaller (p < 0.001), and had greater developed pressures and maximum rate of increase of left ventricular pressure (both p < 0.001) than control and sham hearts. Control hamsters injected with culture medium did not differ from sham-operated animals. CONCLUSIONS: Transplantation of autologous smooth muscle cells prevented cardiac dilatation and improved ventricular function in hamsters with dilated cardiomyopathy.