Hemosiderin Deposits Confounds Tracking of Iron-Oxide-Labeled Stem Cells: An Experimental Study (original) (raw)
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Stem Cells, 2006
Stem cells offer a promising approach to the treatment of myocardial infarction and prevention of heart failure. We have used iron labeling of bone marrow stromal cells (BM-SCs) to noninvasively track cell location in the infarcted rat heart over 16 weeks using cine-magnetic resonance imaging (cine-MRI) and to isolate the BMSCs from the grafted hearts using the magnetic properties of the donor cells. BMSCs were isolated from rat bone marrow, characterized by flow cytometry, transduced with lentiviral vectors expressing green fluorescent protein (GFP), and labeled with iron particles. BMSCs were injected into the infarct periphery immediately following coronary artery ligation, and rat hearts were imaged at 1, 4, 10, and 16 weeks postinfarction. Signal voids caused by the iron particles in the BMSCs were detected in all rats at all time points. In mildly infarcted hearts, the volume of the signal void decreased over the 16 weeks, whereas the signal void volume did not decrease significantly in severely infarcted hearts. High-resolution three-dimensional magnetic resonance (MR) microscopy identified hypointense regions at the same position as in vivo. Donor cells containing iron particles and expressing GFP were identified in MR-targeted heart sections after magnetic cell separation from digested hearts. In conclusion, MRI can be used to track cells labeled with iron particles in damaged tissue for at least 16 weeks after injection and to guide tissue sectioning by accurately identifying regions of cell engraftment. The magnetic properties of the iron-labeled donor cells can be used for their isolation from host tissue to enable further characterization. STEM CELLS 2006;
Journal of the American College of Cardiology, 2010
The purpose of this study was to compare the ability of human CD34 ϩ hematopoietic stem cells and bone marrow mesenchymal stem cells (MSC) to treat myocardial infarction (MI) in a model of permanent left descendent coronary artery (LDA) ligation in nude rats. Background Transplantation of human CD34 ϩ cells and MSC has been proved to be effective in treating MI, but no comparative studies have been performed to elucidate which treatment prevents left ventricular (LV) remodelling more efficiently. Methods Human bone marrow MSC or freshly isolated CD34 ϩ cells from umbilical cord blood were injected intramyocardially in infarcted nude rats. Cardiac function was analyzed by echocardiography. Ventricular remodelling was evaluated by tissue histology and electron microscopy, and neo-formed vessels were quantified by immunohistochemistry. Chronic local inflammatory infiltrates were evaluated in LV wall by hematoxylin-eosin staining. Apoptosis of infarcted tissue was evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling assay. Results Both cell types induced an improvement in LV cardiac function and increased tissue cell proliferation in myocardial tissue and neoangiogenesis. However, MSC were more effective for the reduction of infarct size and prevention of ventricular remodelling. Scar tissue was 17.48 Ϯ 1.29% in the CD34 group and 10.36 Ϯ 1.07% in the MSC group (p Ͻ 0.001 in MSC vs. CD34). Moreover, unlike MSC, CD34 ϩ-treated animals showed local inflammatory infiltrates in LV wall that persisted 4 weeks after transplantation. Conclusions Mesenchymal stem cells might be more effective than CD34 ϩ cells for the healing of the infarct. This study contributes to elucidate the mechanisms by which these cell types operate in the course of MI treatment.
Journal of Biomedical Science, 2007
Marrow-derived mesenchymal stem cells (MSCs) have been heralded as a source of great promise for the regeneration of the infarcted heart. There is no clear data indicating whether or not in vitro differentiation of MSCs into major myocardial cells can increase the beneficial effects of MSCs. The aim of this study is to address this issue. To induce MSCs to transdifferentiate into cardiomyocyte-like and endothelial-like cells, 5-azacytidine and vascular endothelial growth factor (VEGF) were used, respectively. Myocardial infarction in rabbits was generated by ligating the left anterior descending coronary artery. Animals were divided into three experimental groups: I, control group; II, undifferentiated mesenchymal stem cell transplantation group; III, differentiated mesenchymal stem cell transplantation group; which respectively received peri-infarct injections of culture media, autologous undifferentiated MSCs and autologous differentiated MSCs. General pathology, immunohistochemistry, electron microscopy and echocardiography were performed in order to search for myocardial regeneration and improvement of cardiac function. In Groups II and III, implanted cells transdifferentiate into myocardial cells within 28 days post injection in a similar manner, and well-developed ultra structures formed within transplanted cells. Improvements in left ventricular function and reductions in infarcted area were observed in both cell-transplanted groups to the same degree. Vascular density was similar in Groups II and III and significantly higher in these groups compared with the control group. There is no need for prior differentiation induction of marrow-derived MSCs before transplantation and peri-infarct implantation of MSCs can efficiently regenerate the infarcted myocardium and improve cardiac function.
Stem Cells and Development, 2007
Systemic delivery of bone marrow-derived mesenchymal stem cells (MSCs) is a noninvasive approach for myocardial repair. We aimed to test this strategy in a pig model of myocardial infarction. Pigs (n ؍ 8) received autologous MSCs (1 ؋ 10 6 /kg body weight) labeled with fluorescent dye 48 h post proximal left anterior descending artery (LAD) occlusion. Hemodyamics, infarct size, and myocardial function were assessed at baseline and after 1 month. Morphologic analysis revealed that labeled MSCs migrated in the peri-infarct region, resulting in smaller infarct size (32 ؎ 7 vs. 19 ؎ 7%, p ؍ 0.01), higher fractional area shortening (23 ؎ 3 vs. 34.0 ؎ 7%, p ؍ 0.001), lower left ventricular end diastolic pressure (18.7 ؎ 5 vs. 10.2 ؎ 4 mmHg, p ؍ 0.02) and higher ؉dp/dt (4,570 ؎ 540 vs. 6,742 ؎ 700 mmHg/s, p ؍ 0.03) during inotropic stimulation. Systemic intravenous delivery of MSCs to pigs limits myocardial infarct size and is an attractive approach for tissue repair.
2010
Magnetic resonance imaging (MRI) can track progenitor cells following direct intramyocardial injection. However, in the vast majority of post-myocardial infarction (MI) clinical trials, cells are delivered by the intracoronary (IC) route, which results in far greater dispersion within the myocardium. Therefore, we assessed whether the more diffuse distribution of cells following IC delivery could be imaged longitudinally with MRI. In 11 pigs (7 active, 4 controls), MI was induced by 90-min balloon occlusion of the left anterior descending coronary artery. Seven (0) days [median (interquartile range)] following MI, bone marrow progenitor cells (BMCs) were colabeled with an iron-fluorophore and a cell viability marker and delivered to the left anterior descending coronary artery distal to an inflated over-the-wire percutaneous transluminal coronary angioplasty balloon. T2*-weighted images were used to assess the location of the magnetically labeled cells over a 6-wk period post-MI. Immediately following cell delivery, hypointensity characteristic of the magnetic label was observed in the infarct border rather than within the infarct itself. At 6 wk, the cell signal hypointensity persisted, albeit with significantly decreased intensity. BMC delivery resulted in significant improvement in infarct volume and ejection fraction (EF): infarct volume in cell-treated animals decreased from 7.1 Ϯ 1.5 to 4.9 Ϯ 1.0 ml (P Ͻ 0.01); infarct volume in controls was virtually unchanged at 4.64 Ϯ 2.1 to 4.39 Ϯ 2.1 ml (P ϭ 0.7). EF in cell-treated animals went from 30.4 Ϯ 5.2% preinjection to 34.5 Ϯ 2.5% 6 wk postinjection (P ϭ 0.013); EF in control animals went from 34.3 Ϯ 4.7 to 31.9 Ϯ 6.8% (P ϭ 0.5). Immunohistochemical analysis revealed intracellular colocalization of the iron fluorophore and cell viability dye with the labeled cells continuing to express the same surface markers as at baseline. MRI can track the persistence and distribution of magnetically labeled BMCs over a 6-wk period following IC delivery. Signal hypointensity declines with time, particularly in the first week following delivery. These cells maintain their original phenotype during this time course. Delivery of these cells appears safe and results in improvement in infarct size and left ventricular ejection fraction. magnetic resonance imaging; myocardial infarction ATHEROSCLEROTIC CORONARY ARTERY disease is widely prevalent and is the commonest cause of premature death in the developed world (21). In patients surviving myocardial infarction
2006
Aims Mesenchymal stem cells (MSCs), rare bone marrow-derived stem cell precursors of nonhaematopoietic tissues, have shown promise in potentially repairing infarcted myocardium. These and similar cell types are being tested clinically, but understanding of delivery and subsequent biodistribution is lacking. This study was designed to quantitatively compare MSC engraftment rates after intravenous (IV), intracoronary (IC), or endocardial (EC) delivery in a porcine myocardial infarction (MI) model. Methods and results Allogeneic, male MSCs were cultured from porcine bone marrow aspirates. Iridium nanoparticles were added during culturing and internalized by the MSCs. An MI was induced in female swine (27-40 kg in size) by prolonged balloon occlusion of the mid-left anterior descending artery. Animals (n ¼ 6 per group) were randomized to one of three delivery methods. Cellular engraftment was determined 14 + 3 days post-delivery by measuring ex-vivo the iridium nanoparticle concentration in the infarct. Confirmation of cellular engraftment utilized both DiI and fluorescence in situ hybridization (FISH) labelling techniques. During MSC infusion, no adverse events were noted. However, following IC infusion, half of the pigs exhibited decreased blood flow distal to the infusion site. At 14 days, the mean number of engrafted cells within the infarct zone was significantly greater (P 0.01) following IC infusion than either EC injection or IV infusion and EC engraftment was greater than IV engraftment (P 0.01). There was less systemic delivery to the lungs following [EC vs. IV (P ¼ 0.02), EC vs. IC (P ¼ 0.06)]. Both DiI and FISH labelling demonstrated the presence of engrafted male MSCs within the female infarcted tissue. Conclusion IC and EC injection of MSCs post-MI resulted in increased engraftment within infarcted tissue when compared with IV infusion, and IC was more efficient than EC. However, IC delivery was also associated with a higher incidence of decreased coronary blood flow. EC delivery into acutely infarcted myocardial tissue was safe and well tolerated and was associated with decreased remote organ engraftment with compared with IC and IV deliveries.
Stem Cell Research & Therapy, 2012
Introduction: A number of questions remain unanswered in the field of cell therapy for acute myocardial infarction, including what is the optimal cell type, and can therapeutic efficacy be enhanced by conditioning regimens. In this study, we sought to address these questions by directly comparing the effect of bone marrowderived mesenchymal stem cells and unrestricted somatic stem cells delivered 24 hours post-myocardial infarction and by determining if the therapeutic efficacy of unrestricted somatic stem cells could be enhanced by exposing the cells to guiding factors before cell transplantation. Methods: Unrestricted somatic stem cells were guided by exposure to 50 ng/mL basic fibroblast growth factor, 20 ng/mL hepatocyte growth factor and 20 ng/mL bone morphogenetic protein-2 for 24 hours. Using a Sprague-Dawley rat model of acute myocardial infarction, we transplanted cells by intramyocardial injection 24 hours postmyocardial infarction. Cardiac function was serially measured using echocardiography, and histological analyses of infarct morphology, angiogenesis and apoptosis were obtained. Transcriptomic and proteomic changes were assessed using microarray and real-time quantitative PCR. Results: When assessed 28 days after the myocardial infarction, the delivery of mesenchymal stem cells 24 hours post-myocardial infarction did not improve ejection fraction (P = 0.19), and did not prevent the decline in ejection fraction observed in the absence of cell therapy (P = 0.17). The administration of unrestricted somatic stem cells also did not improve ejection fraction (P = 0.11), but did prevent a further decline in ejection fraction (P = 0.001). Delivery of guided unrestricted somatic stem cells significantly improved ejection fraction (P = 0.03). Guided unrestricted somatic stem cells restored function to a greater extent than mesenchymal stem cells (P = 0.03). The infarct area (P = 0.2), apoptosis (P = 0.07) and angiogenesis (P = 0.09) did not differ between groups. Microarray analysis revealed that, following pre-implantation guiding, the gene groupings of mitosis, signalling and angiogenesis were highly overrepresented, mediators of apoptosis were overrepresented, and cardiomyocyteassociated genes were not differentially expressed. Conclusions: These results suggest that guided unrestricted somatic stem cells have a moderate capacity to repair cardiac damage and that they are more effective than mesenchymal stem cells in restoring cardiac function after a myocardial infarction. The mechanism of the benefit was not fully elucidated in this study, but these observations may be mediated by favorable dysregulation of angiogenic and apoptotic gene groupings.
Annals of Thoracic Surgery, 2002
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
Circulation, 2007
Background-Granulocyte-colony stimulating factor (G-CSF) after myocardial infarction does not affect systolic function when compared with placebo. In contrast, intracoronary infusion of bone marrow cells appears to improve ejection fraction. We aimed to evaluate the G-CSF mobilization of subsets of stem cells. Methods and Results-We included 78 patients (62 men; 56Ϯ8 years) with ST-elevation myocardial infarction treated with primary percutaneous intervention Ͻ12 hours after symptom onset. Patients were randomized to double-blind G-CSF (10 g/kg/d) or placebo. Over 7 days, the myocardium was exposed to 25ϫ10 9 G-CSF mobilized CD34 ϩ cells, compared with 3ϫ10 9 cells in placebo patients (PϽ0.001); and to 4.9ϫ10 11 mesenchymal stem cells, compared with 2.0ϫ10 11 in the placebo group (PϽ0.001). The fraction of CD34 ϩ cells/leukocyte increased during G-CSF treatment (from 0.3Ϯ0.2 to 1.1Ϯ0.9 ϫ10 Ϫ3 , PϽ0.001 when compared with placebo), whereas the fraction of putative mesenchymal stem cells/leukocyte decreased (from 22Ϯ17 to 14Ϯ11 ϫ10 Ϫ3 , Pϭ0.01 when compared with placebo). An inverse association between number of circulating mesenchymal stem cells and change in ejection fraction was found (regression coefficient Ϫ6.8, Pϭ0.004), however none of the mesenchymal cell subtypes analyzed, were independent predictors of systolic recovery. Conclusions-The dissociated pattern for circulating CD34 ϩ and mesenchymal stem cells could be attributable to reduced mesenchymal stem cell mobilization from the bone marrow by G-CSF, or increased homing of mesenchymal stem cells to the infarcted myocardium. The inverse association between circulating mesenchymal stem cells and systolic recovery may be of clinical importance and should be explored further. (Circulation. 2007;116[suppl I]:I-24-I-30.)
PLoS ONE, 2014
Introduction: Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) have recently been shown to express key cardiac proteins and improve in vivo cardiac function when administered following myocardial infarction. However, the efficacy of hiPSC-derived cell therapies, in direct comparison to current, well-established stem cell-based therapies, is yet to be elucidated. The goal of the current study was to compare the therapeutic efficacy of human mesenchymal stem cells (hMSCs) with hiPSC-CMs in mitigating myocardial infarction (MI). Methods: Male athymic nude hyrats were subjected to permanent ligation of the left-anterior-descending (LAD) coronary artery to induce acute MI. Four experimental groups were studied: 1) control (non-MI), 2) MI, 3) hMSCs (MI+MSC), and 4) hiPSC-CMs (MI+hiPSC-derived cardiomyocytes). The hiPSC-CMs and hMSCs were labeled with superparamagnetic iron oxide (SPIO) in vitro to track the transplanted cells in the ischemic heart by high-field cardiac MRI. These cells were injected into the ischemic heart 30-min after LAD ligation. Four-weeks after MI, cardiac MRI was performed to track the transplanted cells in the infarct heart. Additionally, echocardiography (M-mode) was performed to evaluate the cardiac function. Immunohistological and western blot studies were performed to assess the cell tracking, engraftment and cardiac fibrosis in the infarct heart tissues.