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.     

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.     

携带血管生成素的骨髓基质干细胞移植治疗缺血性心脏病

目的 评价转染血管生成素基因的自体骨髓间充质干细胞移植治疗慢性缺血性心脏病的疗效.方法 腺病毒介导的血管生成素基因转染自体骨髓基质干细胞并移植于置入Ameriod缩窄环的猪慢性心肌缺血模型上,通过冠状动脉造影、心脏彩超、核磁心肌灌注成像、病理学观察等评价治疗效果.结果 置环后的动物均为有效的动物模型.转染血管生成索的骨髓基质干细胞移植后侧支血管增生明显,血管计数增加,Rentrop分数、左室射血分数改善,梗死区缩小而移植细胞的成活率高.结论 携带血管生成素基因的自体骨髓基质干细胞移植治疗缺血性心脏病可明显改善心功能,使局部血液循环改善明显.     

The coronary delivery of marrow stromal cells for myocardial regeneration: pathophysiologic and therapeutic implications

OBJECTIVES: Bone marrow stromal cells contain "adult stem cells." We tested the hypothesis that coronary-infused bone marrow stromal cells may populate the infarcted heart and undergo milieu-dependent differentiation to regenerate functional tissues with different phenotypic features. METHODS: Isogenic adult rats were used as donors and recipients to simulate autologous transplantation clinically. Myocardial infarction was created by proximal occlusion of left coronary artery in 12 recipient rats. Isolated bone marrow stromal cells were purified, expanded, and retrovirally transduced with LacZ reporter gene for cell labeling. Stromal cells were then infused into the briefly distally clamped ascending aorta of recipient rats 2 weeks after left coronary artery ligation. The hearts were harvested immediately (n = 2) or 4 weeks (n = 10) later to trace the implanted cells and identify their phenotypes. RESULTS: Viable cells labeled with LacZ reporter gene were identified in 8 recipient hearts. Immediately after cell infusion, the labeled cells were trapped within the coronary capillaries. After 4 weeks, they could be detected individually or in clusters within myocardial scar expressing fibroblastic phenotype or outside the infarction area with morphologic features of normal cardiomyocytes. Some were incorporated into endocardium and capillary endothelium. CONCLUSIONS: Our findings suggest that bone marrow stromal cells can traffic through the coronary system to the injured heart and form cardiomyocytes or fibroblasts, depending on the specific microenvironment. Endothelial progenitor cells in the stromal cell population may be involved in the postinfarction neovascularization process. Whether therapeutic use of bone marrow stromal cells can improve the myocardial healing and remodeling process after infarction is worthy of further investigation.     

Left Ventricular Function and Infarct Size 20 Months after Primary Angioplasty for Acute Myocardial Infarction

Objective –To study changes in left ventricular function and infarct size during long-term follow-up after acute myocardial infarction treated with primary angioplasty. Design –From 1996 to 1998, 100 consecutive patients were treated with primary angioplasty for acute ST-elevation myocardial infarction. Angioplasty was successful in 95% of the patients. Global left ventricular ejection fraction (LVEF) was determined by radionuclide ventriculography before discharge, after 6 weeks and after a mean follow-up time of 20 months. Infarct size was assessed by technetium 99m-tetrofosmin myocardial perfusion tomography (SPECT) at rest, performed at the same time intervals. Results –Mean LVEF was 56% at discharge, 55% after 6 weeks and 57% after 20 months of follow-up. No significant improvement in LVEF was observed. Only 8% of the patients at follow-up had LVEF lower than 40%. After 1 week, a mean perfusion defect of 19% was measured by SPECT. After 6 weeks and 20 months of follow-up, the mean perfusion defects were reduced to 14% ( p < 0.001) and 15%, respectively. Conclusion –Left ventricular function was well preserved with a mean LVEF of 57% 20 months after primary angioplasty for acute myocardial infarction. No significant change in LVEF was observed from 1 week after angioplasty to follow-up. Infarct sizes as assessed by SPECT imaging with tetrofosmin were reduced from 1 to 6 weeks, but did not change further during long-term follow-up. The reduction in the perfusion defects over time was probably due to gradual relief of stunning.     

Left ventricular function and infarct size 20 months after primary angioplasty for acute myocardial infarction

OBJECTIVE: To study changes in left ventricular function and infarct size during long-term follow-up after acute myocardial infarction treated with primary angioplasty. DESIGN: From 1996 to 1998, 100 consecutive patients were treated with primary angioplasty for acute ST-elevation myocardial infarction. Angioplasty was successful in 95% of the patients. Global left ventricular ejection fraction (LVEF) was determined by radionuclide ventriculography before discharge, after 6 weeks and after a mean follow-up time of 20 months. Infarct size was assessed by technetium 99m-tetrofosmin myocardial perfusion tomography (SPECT) at rest, performed at the same time intervals. RESULTS: Mean LVEF was 56% at discharge, 55% after 6 weeks and 57% after 20 months of follow-up. No significant improvement in LVEF was observed. Only 8% of the patients at follow-up had LVEF lower than 40%. After 1 week, a mean perfusion defect of 19% was measured by SPECT. After 6 weeks and 20 months of follow-up, the mean perfusion defects were reduced to 14% (p < 0.001) and 15%, respectively. CONCLUSION: Left ventricular function was well preserved with a mean LVEF of 57% 20 months after primary angioplasty for acute myocardial infarction. No significant change in LVEF was observed from 1 week after angioplasty to follow-up. Infarct sizes as assessed by SPECT imaging with tetrofosmin were reduced from 1 to 6 weeks, but did not change further during long-term follow-up. The reduction in the perfusion defects over time was probably due to gradual relief of stunning.     

骨髓单个核细胞移植治疗急性心肌梗死

目的探讨自体骨髓单个核细胞(BMMNCs)移植对急性心肌梗死后心脏功能及结构的影响。方法中国小型猪16头,随机分为对照组(n=6)及移植组(n=10)。建立急性心肌梗死模型后,分别注入BMMNCs/生理盐水。两组动物于术中监测血流动力学指标,术后进行影像学检查。移植组分别于2、4周后获取心脏标本,检测移植细胞标记物Hoechst33342。结果心梗4周后,移植组心梗范围较对照组显著缩小(P<0.01);血流动力学指标较对照组明显改善;局部室壁运动评分优于对照组,组间差异有统计学意义(P<0.05)。在术后2周获得的心肌标本内,可见多量Hoechst33342和MHC双阳性细胞。结论成体BMMNCs移植后,有可能抑止心室重构的发展,提高心室运动功能。     

Mesenchymal stem cell implantation in a swine myocardial infarct model: engraftment and functional effects

Background. A novel therapeutic option for the treatment of acute myocardial infarction involves the use of mesenchymal stem cells (MSCs). The purpose of this study was to investigate whether implantation of autologous MSCs results in sustained engraftment, myogenic differentiation, and improved cardiac function in a swine myocardial infarct model.

Methods. MSCs were isolated and expanded from bone marrow aspirates of 14 domestic swine. A 60-minute left anterior descending artery occlusion was used to produce anterior wall infarction. Piezoelectric crystals were placed within the ischemic region for measurement of regional wall thickness and contractile function. Two weeks later animals autologous, Di-I–labeled MSCs (6 × 10⁷) were implanted into the infarct by direct injection. Hemodynamic and functional measurements were obtained weekly until the time of sacrifice. Immunohistochemistry was used to assess MSC engraftment and myogenic differentiation.

Results. Microscopic analysis showed robust engraftment of MSCs in all treated animals. Expression of muscle-specific proteins was seen as early as 2 weeks and could be identified in all animals at sacrifice. The degree of contractile dysfunction was significantly attenuated at 4 weeks in animals implanted with MSCs (5.4% ± 2.2% versus −3.37% ± 2.7% in control). In addition, the extent of wall thinning after myocardial infarction was markedly reduced in treated animals.

Conclusions. Mesenchymal stem cells are capable of engraftment in host myocardium, demonstrate expression of muscle specific proteins, and may attenuate contractile dysfunction and pathologic thinning in this model of left ventricular wall infarction. MSC cardiomyoplasty may have significant clinical potential in attenuating the pathology associated with myocardial infarction.     

骨髓细胞移植对梗死区心肌基本结构及左心室功能的影响

目的 探讨骨髓细胞移植对梗死区心肌基本结构及左心室功能的影响。方法 骨髓细胞注射人心肌梗死区域，1、2、4、8周后取心肌标本，组织切片染色观察组织结构；术后1、2、4、8周通过微机生物信号记录分析系统测定左心室功能指标。结果 移植组梗死区心肌观察到带荧光的骨髓细胞，部分已分化成肌源性细胞，电子显微镜观察到不同分化阶段的新生心肌细胞，并与成熟心肌细胞以闰盘相联接。HE染色显示对照组梗死区结构紊乱，而移植组梗死区内细胞呈有序排列；VG染色显示移植组胶原纤维融合较少，排列基本处于有序状态。移植组左心室功能的恢复明显优于对照组，且其恢复随时间的延长而增加。结论 骨髓细胞移植后对梗死心肌的基本结构起到了保护作用，并可促进左心室功能的恢复。     

Autotransplantation of unmanipulated bone marrow into scarred myocardium is safe and enhances cardiac function in humans

Stem cell transplants into damaged myocardium may have the potential to improve cardiac function. We investigated the safety of transplanting unmanipulated autologous bone marrow into infarcted myocardium of patients undergoing coronary bypass surgery and assessed its efficacy to improve cardiac function. Fourteen patients with one or more areas of transmural myocardial infarction were studied. Autologous bone marrow was obtained by sternal bone aspirate at the time of surgery, diluted in autologous serum at a ratio of 1:2, and then injected 1 cm apart into the mid-depth of the left ventricular scar. There were no deaths, no perioperative myocardial infarctions, and no significant ventricular arrhythmias. Dobutamine stress echocardiography demonstrated overall improvement in the global and regional left ventricular function 6 weeks and 10 months after surgery. Of 34 infarcted left ventricular segments, 11 were injected with bone marrow alone, 13 were revascularized with a bypass graft alone, and 10 received bone marrow transplantation and a bypass graft in combination. Only the left ventricle segmental wall motion score of the areas injected with bone marrow and receiving a bypass graft in combination improved at low dose and at peak dobutamine stress. These findings suggest that transplantation of unmanipulated autologous bone marrow into scar tissue of the human heart is safe and enhances cardiac function only when used in combination with myocardial revascularization. This benefit can be seen after 6 weeks of the bone marrow transplant and is maintained after 10 months of follow-up.     

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.     

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.     

Xenotransplant cardiac chimera: immune tolerance of adult stem cells

BACKGROUND: Bone marrow stromal cells have been shown to engraft into xenogeneic fetal recipients. In view of the potential clinical utility as an alternative source for cellular and gene therapies, we studied the fate of xenogeneic marrow stromal cells after their systemic transplantation into fully immunocompetent adult recipients without immunosuppression. METHODS: Bone marrow stromal cells were isolated from C57B1/6 mice and retrovirally transduced with LacZ reporter gene for cell labeling. We then injected 6 x 10(6) labeled cells into immunocompetent adult Lewis rats. One week later, the recipient animals underwent coronary artery ligation and were sacrificed at various time points ranging from 1 day to 12 weeks after ligation. Hearts, blood, and bone marrow samples were collected for histologic and immunohistochemical studies. RESULTS: Labeled mice cells engrafted into the bone marrow cavities of the recipient rats for at least 13 weeks after transplantation without any immunosuppression. On the other hand, circulating mice cells were positive only for the animals with 1-day-old myocardial infarction. At various time points, numerous mice cells could be found in the infarcted myocardium that were not seen before coronary ligation. Some of these cells subsequently showed positive staining for cardiomyocyte specific proteins, while other labeled cells participated in angiogenesis in the infarcted area. CONCLUSIONS: The marrow stromal cells are adult stem cells with unique immunologic tolerance allowing their engraftment into a xenogeneic environment, while preserving their ability to be recruited to an injured myocardium by way of the bloodstream and to undergo differentiation to form a stable cardiac chimera.     

Autologous stem cell transplantation in acute myocardial infarction: The ASTAMI randomized controlled trial. Intracoronary transplantation of autologous mononuclear bone marrow cells, study design and safety aspects

OBJECTIVES: Intracoronary transplantation of different cell populations has been used in acute myocardial infarction (AMI) with promising results. The primary objective of the Autologous Stem cell Transplantation in Acute Myocardial Infarction (ASTAMI) study is to test whether intracoronary transplantation of autologous mononuclear bone marrow cells (mBMC) improves left ventricular ejection fraction (LVEF) after anterior wall AMI. DESIGN: The ASTAMI study is a randomized, controlled, prospective study. One hundred patients with acute anterior wall ST-elevation myocardial infarction (STEMI) treated with acute percutaneous coronary intervention (PCI) are randomized in a 1:1 way to either intracoronary transplantation of autologous mBMC 5-8 d after PCI or to control. Left ventricular function, exercise capacity, biochemical status, functional class, quality of life and complications are validated at baseline and during a 12-month follow-up. RESULTS: By August 2004, out of 1004 patients with STEMI, 49 patients have been included in the study. Twenty-four patients have been randomized to intracoronary mBMC transplantation. Twenty patients had chest pain and 16 patients had ischemic ECG changes during the mBMC transplantation procedure. One patient had ventricular fibrillation 24 h after transplantation. CONCLUSIONS: Intracoronary transplantation of autologous mBMC in the acute phase after AMI is feasible and seems safe in the short term.     

肝细胞生长因子及骨髓间充质干细胞联合移植治疗慢性缺血性心脏病的实验研究

目的研究经肝细胞生长因子(HGF)及骨髓间充质干细胞(MSCs)联合移植治疗慢性缺血性心脏病的疗效。方法采集香猪髂骨骨髓,用密度梯度法和贴壁分离法相结合的方法分离、培养MSCs,通过细胞表面标记(CD34、CD44、CD71、Ⅷ因子和desmin)成份鉴定;HGF基因的重组腺病毒(AdHGF)+MSCs共培养并检验HGF对MSCs生物学特征的影响。经左胸冠状动脉回旋支放置Ameroid环建立慢性心肌缺血香猪模型,将40只小型香猪采用随机对照分为5组(n=8),于缺血心肌处分别注射5×106/ml MSCs+4×109pfu 200μl AdHGF(MSCs+AdHGF组)、4×109pfu 200μl AdHGF(AdHGF组)、5×106/ml MSCs 200μl(MSCs组),4×109pfu 200μl AdNull(AdNull组)和生理盐水1 ml(对照组)。治疗4周后行心脏超声心动图,数字减影动脉造影(DSA),单光子发射计算机体层摄影(SPECT)心肌灌注检查及心肌凋亡细胞等检测。结果流式细胞仪检测MSCs表面标记CD44、CD71阳性,CD34、Ⅷ因子、desmin阴性;增殖细胞抗原(PCNA)蛋白表达显示HGF具有较强刺激MSCs增殖分化作用;彩色超声心动图检查提示:经治疗后MSCs+AdHGF组左心室舒张期末容积(LVEDV)、左心室射血分数(LVEF)、短轴缩短率(FS)明显改善,差异有统计学意义(P<0.05);DSA检测缺血区新生血管数MSCs+AdHGF组较AdHGF组、MSCs组明显增多,差异有统计学意义(P<0.05);SPECT显示MSCs+AdHGF组左室心肌增厚、灌注明显改善,运动增强,差异有统计学意义(P<0.05);心肌HE染色血管密度,MSCs+AdHGF组明显高于AdHGF组和MSCs组[(39.4±1.2)个/HPF vs.(36.5±1.4)个/HPF、(34.5±1.7)个/HPF,P<0.05];心肌TUNEL染色法检测,MSCs+AdHGF组、AdHGF组细胞凋亡率明显低于MSCs组(P<0.05)。结论 MSCs+AdHGF联合具有促进慢性缺血心肌新血管生成、抑制细胞凋亡、改善心功能等作用;MSCs+AdHGF联合治疗缺血性心脏病作用较单纯HGF或MSCs移植更明显。     

Myocardial Perfusion Defects and the Left Ventricular Ejection Fraction Disclosed by Scintigraphy in Patients with Primary Hyperparathyroidism

Patients with primary hyperparathyroidism (PHPT) have increased risk of cardiovascular disease. For patients undergoing preoperative parathyroid imaging with ^99mTc-sestamibi single photon emission computed tomography (SPECT), we combined cervical SPECT and gated cardiac SPECT to achieve information about the localization of parathyroid adenomas, myocardial perfusion, and the left ventricular ejection fraction (LVEF) at rest. A series of 22 patients with PHPT and no history of myocardial infarction or angina pectoris were recruited consecutively. At 60 minutes after injection of 700 MBq ^99mTc-sestamibi, SPECT of the neck and gated myocardial perfusion SPECT were performed at the same time. All of the patients who underwent parathyroidectomy had the parathyroid adenoma localized as predicted from the SPECT. Five patients (23%) had myocardial perfusion defects extending more than 15% (range 15–25%), and they had higher plasma parathyroid hormone levels (p = 0.03), and lower LVEF (p = 0.007) than patients without perfusion defects. We suggest that patients with hyperparathyroidism and suspected cardiovascular disease undergo^99m Tc-sestamibi parathyroid SPECT simultaneously with gated myocardial perfusion SPECT to obtain information about the resting perfusion status and cardiac systolic function. The results from myocardial perfusion SPECT can lead to initiation of cardiovascular treatment and eventually perioperative precautions.     

冠状动脉旁路移植术同期经旁路血管移植自体干细胞治疗缺血性心衰

目的 评价冠状动脉旁路移植手术同期经旁路血管移植自体骨髓干细胞治疗缺血性心衰的可行性和安全性.方法 40例需外科手术治疗的陈旧性心梗伴左室功能不全病人,在冠状动脉旁路移植手术同期经旁路血管移植自体骨髓单个核细胞.结果 全组手术死亡1例.手术早期无心梗发生,无肝、肾功能衰竭,无新发恶性心律失常.结论 冠状动脉旁路移植术同期经旁路血管移植自体骨髓单个核细胞治疗冠心病陈旧心梗,为缺血性心衰病人提供了一个全新的综合治疗选择.     

急性心梗后骨髓细胞心肌内移植促进心肌细胞再生的实验研究

目的 研究急性梗死心肌内移植骨髓细胞的促进心肌再生作用。方法 局部注射将骨髓细胞移植入大鼠急性心肌梗死模型的急性心肌梗死区域，1、2、4、8周后处死动物，取心肌标本行组织形态学检查和梗死面积测量。结果 梗死区心肌标本观察到带荧光的骨髓细胞，部分已分化成肌源性细胞，电镜观察到不同分化阶段的新生心肌细胞。与成熟心肌细胞以闰盘相联。骨髓细胞移植组梗死心肌面积明显小于对照组。结论 在梗死心肌内移植的骨髓细胞具有心肌再生能力，并能缩小梗死心肌面积。     

Transcoronary implantation of bone marrow stromal cells ameliorates cardiac function after myocardial infarction

OBJECTIVES: Bone marrow stromal cells are capable of differentiating into cardiomyogenic cells. We tested the hypothesis that transcoronary implantation of bone marrow stromal cells may regenerate infarcted myocardium and reduce cardiac dysfunction. METHODS: Isolated bone marrow stromal cells from the isogenic donor rats were transfected with LacZ reporter gene for cell labeling. To induce cardiomyogenic differentiation, the bone marrow stromal cells were treated with 5-azacytidine before implantation. Two weeks after left coronary ligation, these cells (1 x 10(6) in 150 microL) were infused into the briefly distally occluded ascending aorta of the recipient rats (n = 15) to simulate direct coronary infusion clinically. Control animals were infused with cell-free medium (n = 14). Cardiac function was evaluated by echocardiography at preimplantation and 4 and 8 weeks postimplantation. The hearts were then immunohistochemically studied to identify phenotypic changes of implanted bone marrow stromal cells. RESULTS: Immediately after cell infusion, the bone marrow stromal cells were trapped within coronary vessels in both infarcted and noninfarcted areas. However, after 8 weeks, most of the cells were identified in the scar and periscar tissue, expressing sarcomeric myosin heavy chain and cardiomyocyte-specific protein troponin I-C. Some bone marrow stromal cells were found to be connected to the adjacent host cardiomyocytes with gap junction. Two-way repeated-measures analysis of variance revealed significant improvement in fractional shortening and end-diastolic and end-systolic diameter of the left ventricle (P =.0465,.002,.0004, respectively) in the bone marrow stromal cell group. CONCLUSIONS: Although bone marrow stromal cells had been reported to improve cardiac function when injected directly into the myocardial scar, this study demonstrated for the first time that bone marrow stromal cells can be delivered via the coronary artery, as they are capable of targeted migration and differentiation into cardiomyocytes in the scar tissue to improve cardiac function.     

Improvement of cardiac function by bone marrow cell implantation in a rat hypoperfusion heart model

BACKGROUND: Local bone marrow cell implantation can induce angiogenesis. In the present study we investigated whether angiogenesis induced by bone marrow cell implantation improves deteriorated cardiac function in a rat heart model of hypoperfusion. METHODS: A hypoperfusion heart model was created in Dark Agouti rats by ligating the left anterior descending artery placed against a copper wire (phi275 microm), then pulling out the wire immediately. The left ventricular (LV) anterior wall was injected directly at six points, each with 1 x 10(7) bone marrow cells in 10 microL of phosphate-buffered saline or with phosphate-buffered saline only, respectively. Echocardiography was performed to evaluate the cardiac function 7, 30, 60, and 90 days after treatment. Microvessel density and blood flow in the LV anterior wall were estimated 60 days after treatment. RESULTS: Both the increase of LV end-systolic diameter and the decrease of percent of fractional shortening caused by myocardial ischemia were attenuated effectively by bone marrow cell implantation treatment. Bone marrow cell implantation treatment also increased the levels of angiopoietin-1 and vascular endothelial growth factor in the LV anterior wall. The microvessel density, blood flow, and thickness of the LV anterior wall significantly also increased after bone marrow cell implantation treatment compared with those after phosphate-buffered saline injection. CONCLUSIONS: The local implantation of autologous bone marrow cells induced angiogenesis and improved the perfusion of ischemic myocardium, thereby preventing LV remodeling and improving deteriorated cardiac function caused by myocardial hypoperfusion.