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ABSTRACT: Modular cardiac tissues developed both vascular and cardiac structures in vivo, provided that the host response was attenuated by omitting xenoproteins from the modules. Collagen gel modules (with Matrigel(TM) ) containing cardiomyocytes (CMs) alone or CMs with surface-seeded endothelial cells (ECs; CM/EC modules) were injected into the peri-infarct zone of the heart in syngeneic Lewis rats. After 3 weeks, donor ECs developed into blood vessel-like structures that also contained erythrocytes. However, no donor CMs were found within the implant sites, presumably because host cells including macrophages and T cells infiltrated extensively into the injection sites. To lessen the host response, Matrigel was omitted from the matrix and the modules were rinsed with serum-free medium prior to implantation. Host cell infiltration was attenuated, resulting in a higher degree of vascularization with CM/EC modules than with CM modules without ECs. Most importantly, donor CMs matured into striated muscle-like structures in Matrigel-free implants. Copyright © 2013 John Wiley & Sons, Ltd.
Journal of Tissue Engineering and Regenerative Medicine 03/2013; · 3.28 Impact Factor
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ABSTRACT: We synthesized a cationic microbubble (CMB) with the aim of enhancing its DNA-carrying capacity to improve targeted gene transfection of the ischemic heart for cardiac regeneration. We previously reported that ultrasound-targeted microbubble destruction (UTMD) employing the commercial Definity microbubble (MB) successfully transfected genes into rodent hearts, but the transfection efficiency was modest. We synthesized a CMB and compared its DNA-carrying capacity and reporter gene transfection efficiency with the Definity MB. The CMB bound 70% more plasmid DNA than the Definity MB. UTMD-mediated gene delivery with the CMB enhanced both transfection efficiency and gene expression. In vivo studies assessed the ability of the CMB to deliver the therapeutic AKT gene to the ischemic rat myocardium and evaluated the effects on apoptosis, angiogenesis, and cardiac function. AKT transfection with the CMB reduced infarct size (p < 0.05), increased infarct thickness (p < 0.05), reduced apoptosis (p < 0.05), increased vascular density (p < 0.05), and improved cardiac perfusion and function (p < 0.05) compared to the Definity MB. Delivery of AKT with the CMB resulted in greater cardiac functional improvements compared to the Definity MB. UTMD therapy with this CMB provides an efficient platform for the targeted delivery of factors required to regenerate the ischemic heart and preserve cardiac function.
Biomaterials 12/2012; · 7.40 Impact Factor
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Kai Kang,
Lu Sun,
Yun Xiao,
Shu-Hong Li,
Jun Wu,
Jian Guo,
Shu-Ling Jiang,
Lei Yang,
Terrence M Yau,
Richard D Weisel,
Milica Radisic, Ren-Ke Li
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ABSTRACT: This study investigated whether cytokine enhancement of a biodegradable patch could restore cardiac function after surgical ventricular restoration (SVR) even when seeded with cells from old donors.
SVR can partially restore heart size and improve function late after an extensive anterior myocardial infarction. However, 2 limitations include the stiff synthetic patch used and the limited healing of the infarct scar in aged patients.
We covalently immobilized 2 proangiogenic cytokines (vascular endothelial growth factor and basic fibroblast growth factor) onto porous collagen scaffolds. We seeded human mesenchymal stromal cells from young (50.0 ± 8.0 years, N = 4) or old (74.5 ± 7.4 years, N = 4) donors into the scaffolds, with or without growth factors. The patches were characterized and used for SVR in a rat model of myocardial infarction. Cardiac function was assessed.
In vitro results showed that cells from old donors grew slower in the scaffolds. However, the presence of cytokines modulated the aging-related p16 gene and enhanced cell proliferation, converting the old cell phenotype to a young phenotype. In vivo studies showed that 28 days after SVR, patches seeded with cells from old donors did not induce functional recovery as well as patches seeded with young cells. However, cytokine-enhanced patches seeded with old cells exhibited preserved patch area, prolonged cell survival, and augmented angiogenesis, and rats implanted with these patches had better cardiac function. The patch became an elastic tissue, and the old cells were rejuvenated.
This sustained-release, cytokine-conjugated system provides a promising platform for engineering myocardial tissue for aged patients with heart failure.
Journal of the American College of Cardiology 11/2012; 60(21):2237-49. · 14.16 Impact Factor
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Keith R Brunt,
Yuemei Zhang,
Anton Mihic,
Mingxi Li,
Shu-Hong Li,
Phil Xue,
William Zhang,
Samir Basmaji,
Katherine Tsang,
Richard D Weisel,
Terrence M Yau, Ren-Ke Li
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ABSTRACT: Autologous stem cell therapy has not been as effective as forecasted from preclinical studies. Patient age was reported as an important contributing factor. The goal of this study was to uncover age-dependent mechanisms of stem cell dysfunction and to investigate possible means to restore the cellular function. Bone marrow mesenchymal stem cells (MSCs) were isolated from cardiovascular patients. Cell proliferation and number of colonies were inversely correlated with patient age. Myogenic differentiation of MSCs in culture was induced with 5-azacytidine. Differentiation correlated with age, with less differentiation in MSCs from aged patients. We performed real-time PCR to identify genes in the WNT/β-catenin signaling network and found that transcript levels of CTNNB1, LEF1, FZD8, WNT3A, and SFRP4 were negatively correlated with age, whereas FOSL1, LRP6, and FZD6 were positively correlated with age. Protein evaluation showed that β-catenin nuclear translocation correlated with age and was lower in aged MSCs. Aged MSCs treated with lithium chloride-to increase the bioavailability of β-catenin-recovered their capacity for myogenic differentiation through myocyte enhancer factor 2C but not with the knockdown of β-catenin using small-interfering RNA. This study may be the first to relate reduced nuclear β-catenin bioavailability in MSCs from aged patients. Most important, this abnormality was potentially recoverable, providing a target for improving the function of bone marrow stem cells and their clinical utility in aged patients.
American Journal Of Pathology 09/2012; · 4.89 Impact Factor
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ABSTRACT: Abstract Mesenchymal stem cell (MSC) transplantation has been proposed as a potential therapeutic approach for ischemic heart disease, but the regenerative capacity of these cells decreases with age. In this study, we genetically engineered old human MSCs (O-hMSCs) with tissue inhibitor of matrix metalloproteinase-3 (TIMP3) and vascular endothelial growth factor (VEGF) and evaluated the effects on the efficacy of cell-based gene therapy in a rat myocardial infarction (MI) model. Cultured O-hMSCs were transfected with TIMP3 (O-TIMP3) or VEGF (O-VEGF) and compared with young hMSCs (Y-hMSCs) and non-transfected O-hMSCs for growth, clonogenic capacity, and differentiation potential. In vivo, rats were subjected to left coronary artery ligation with subsequent injection of Y-hMSCs, O-hMSCs, O-TIMP3, O-VEGF, or medium. Echocardiography was performed prior to and at 1, 2, and 4 weeks after MI. Myocardial levels of matrix metalloproteinase-2 (MMP2), MMP9, TIMP3, and VEGF were assessed at 1 week. Hemodynamics, morphology, and histology were measured at 4 weeks. In vitro, genetically modified O-hMSCs showed no changes in growth, colony formation, or multi-differentiation capacity. In vivo, transplantation with O-TIMP3, O-VEGF, or Y-hMSCs increased capillary density, preserved cardiac function, and reduced infarct size compared to O-hMSCs and medium control. O-TIMP3 and O-VEGF transplantation enhanced TIMP3 and VEGF expression, respectively, in the treated animals. O-hMSCs genetically modified with TIMP3 or VEGF can increase angiogenesis, prevent adverse matrix remodeling, and restore cardiac function to a degree similar to Y-hMSCs. This gene-modified cell therapy strategy may be a promising clinical treatment to rejuvenate stem cells in elderly patients.
Rejuvenation Research 09/2012; 15(5):495-506. · 3.83 Impact Factor
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ABSTRACT: Cardiomyocyte apoptosis is an important contributor to the progressive cardiac dysfunction that culminates in congestive heart failure. Bone marrow cells (BMCs) restore cardiac function following ischemia, and transplanted BMCs have been reported to fuse with cells of diverse tissues. We previously demonstrated that the myogenic conversion of bone marrow stromal cells increased nearly two-fold when the cells were co-cultured with apoptotic (TNF-α treated) cardiomyocytes. We therefore hypothesized that cell fusion may be a major mechanism by which BMCs rescue cardiomyocytes from apoptosis. We induced cellular apoptosis in neonatal rat cardiomyocytes by treatment with hydrogen peroxide (H(2) O(2) ). The TUNEL assay demonstrated an increase in apoptosis from 4.5±1.3% in non-treated cells to 19.0±4.4% (P<0.05) in treated cells. We subsequently co-cultured the apoptotic cardiomyocytes with BMCs and assessed cell fusion by flow cytometry. Fusion was rare in the non-treated control cardiomyocytes (0.3%), while H(2) O(2) treatment led to significantly higher fusion rates than the control group (P<0.05), with the highest rate of 7.9±0.3% occurring at 25 μM H(2) O(2) . We found an inverse correlation between cell fusion and completion of cardiomyocyte apoptosis (R(2) =0.9863). An in vivo mouse model provided evidence of cell fusion in the infarcted myocardium following the injection of BMCs. The percentage of cells undergoing fusion was significantly higher in mice injected with BMCs following infarction (8.8±1.3%) compared to mice that did not undergo infarction (4.6±0.6%, P<0.05). Enhancing cell fusion may be one method to preserve cardiomyocytes following myocardial infarction, and this new approach may provide a novel target for cardiac regenerative therapies. © 2012 The Authors Journal of Cellular and Molecular Medicine © 2012 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd.
Journal of Cellular and Molecular Medicine 07/2012; · 4.13 Impact Factor
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ABSTRACT: Objective: To evaluate the overexpression of genes central to cell survival and angiogenesis to enhance the function of human late outgrowth endothelial progenitor cells (EPCs) and their utility for infarct recovery. Ischemic myocardial injury creates a hostile microenvironment, which is characterized by hypoxia, oxidative stress, and inflammation. The infarct microenvironment prevents adhesion, survival, and integration of cell transplants that promote neovascularization. EPCs are dysfunctional as a result of risk factors in cardiovascular patients. Protein kinase B (Akt) and hemeoxygenase-1 (HO-1) are intracellular proteins that play an important role in angiogenesis and cell survival. Methods and Results: Late outgrowth EPCs transduced ex vivo with Akt and HO-1 demonstrate improved adhesion to extracellular matrix, improved migration toward human cardiomyocytes, and an improved paracrine profile under stress. Enhanced late outgrowth EPCs reduce the tumor necrosis factor alpha (TNF-α) burden both in vitro and in vivo, attenuating nuclear factor kappa B (NF-κB) activity and promoting cell survival. Akt and HO-1 enhance late outgrowth EPC neovascularization, resulting in improved cardiac performance and reduced negative remodeling after myocardial infarction in nude mice. Conclusions: Alteration of the infarct microenvironment through gene modification of human late outgrowth EPCs enhances the function and integration of transplanted cells for restoration of cardiac function.
Cell Transplantation 07/2012; · 5.13 Impact Factor
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Norbert Degousee,
Jeremy Simpson,
Shafie Fazel,
Klaus Scholich,
Denis Angoulvant,
Carlo Angioni,
Helmut Schmidt,
Marina Korotkova,
Eva Stefanski,
Xing-Hua Wang, [......],
Efrat Ofek,
Sandra Pierre,
Jagdish Butany,
Per-Johan Jakobsson,
Armand Keating, Ren-Ke Li,
Matthias Nahrendorf,
Gerd Geisslinger,
Peter H Backx,
Barry B Rubin
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ABSTRACT: Microsomal prostaglandin E(2) synthase-1 (mPGES-1), encoded by the Ptges gene, catalyzes prostaglandin E(2) biosynthesis and is expressed by leukocytes, cardiac myocytes, and cardiac fibroblasts. Ptges(-/-) mice develop more left ventricle (LV) dilation, worse LV contractile function, and higher LV end-diastolic pressure than Ptges(+/+) mice after myocardial infarction. In this study, we define the role of mPGES-1 in bone marrow-derived leukocytes in the recovery of LV function after coronary ligation.
Cardiac structure and function in Ptges(+/+) mice with Ptges(+/+) bone marrow (BM(+/+)) and Ptges(+/+) mice with Ptges(-/-) BM (BM(-/-)) were assessed by morphometric analysis, echocardiography, and invasive hemodynamics before and 7 and 28 days after myocardial infarction. Prostaglandin levels and prostaglandin biosynthetic enzyme gene expression were measured by liquid chromatography-tandem mass spectrometry and real-time polymerase chain reaction, immunoblotting, immunohistochemistry, and immunofluorescence microscopy, respectively. After myocardial infarction, BM(-/-) mice had more LV dilation, worse LV systolic and diastolic function, higher LV end-diastolic pressure, more cardiomyocyte hypertrophy, and higher mortality but similar infarct size and pulmonary edema compared with BM(+/+) mice. BM(-/-) mice also had higher levels of COX-1 protein and more leukocytes in the infarct, but not the viable LV, than BM(+/+) mice. Levels of prostaglandin E(2) were higher in the infarct and viable myocardium of BM(-/-) mice than in BM(+/+) mice.
Lack of mPGES-1 in bone marrow-derived leukocytes negatively regulates COX-1 expression, prostaglandin E(2) biosynthesis, and inflammation in the infarct and leads to impaired LV function, adverse LV remodeling, and decreased survival after acute myocardial infarction.
Circulation 05/2012; 125(23):2904-13. · 14.74 Impact Factor
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ABSTRACT: Previous studies have shown that telocytes are found in a variety of tissues. Here, we report the presence of telocytes in the human endometrium. In addition, telocytes were isolated from the rat endometrium and cultured. Immunohistochemistry was performed in vitro and in vivo. Cultured cells showed that telocytes expressed CD34, and similar results were found in the uterine tissue. In both species, telocytes also stained positive for vimentin and connexin 43. Telopodes were observed connecting cell colonies and connecting distant cells. Our findings suggest that telocytes may have a role in cell-to-cell communication over short and long distances within the endometrium.
Journal of Cellular and Molecular Medicine 05/2012; 16(7):1392-6. · 4.13 Impact Factor
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ABSTRACT: ObjectiveWith a rising incidence, dilated cardiomyopathy (DCM) is regarded as a major health care concern. Although both medical therapy
and novel surgical treatments have been applied to treat DCM, the effects of preventing left ventricular (LV) dilatation are
limited, and the mortality rate associated with the disease remains high. Thus novel management strategies for improved treatment
of DCM are awaited.
MethodsResearchers have found that, in models of regional ventricular dysfunction, transplanted cells induced a profound biological
phenomenon that restored contractile function and prevented ventricular dilatation. We have investigated muscle cell transplantation
in hamsters with DCM, and have found that heart cells and smooth muscle cells survived in the host myocardium after transplantation,
which suppressed LV dilatation and wall thinning, and preserved heart function. Our current studies are focusing on the clinical
applicability of these encouraging early findings by evaluating the optimal cell types, the timing of transplantation, and
cryopreservation as cell storage. Concurrently, we are investigating the influence of cell transplantation on myocardial remodelling
in order to outline the mechanism of benefit afforded by donor cell engraftment. We believe that the timing of cell transplantation
with respect to the progression of the underlying disease is critical in preventing ventricular thinning, dilation and preserving
cardiac function.
ConclusionsThis novel approach can be a clinically applicable biological therapy for patients with progressive DCM. More studies to uncover
the specific molecular and cellular effects of cell transplantation on the host myocardium are necessary for future clinical
application.
The Japanese Journal of Thoracic and Cardiovascular Surgery 04/2012; 50(11):457-460.
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ABSTRACT: AimsThe study was designed to evaluate the mechanisms of cardiac regeneration after injury and to determine how to restore that capacity in aged individuals. The adult heart retains a small population of nascent cells that have myeloid, mesenchymal, and mesodermal capabilities, which play an essential role in the recovery of ventricular function after injury. In aged individuals, these cells are diminished and dysfunctional. We evaluated the derivation of some of these cardiac progenitors and a method to restore their number and function.Methods and resultsWe first demonstrated that aged mice have fewer progenitors in both the bone marrow (BM) and the myocardium, which correlated with the extent of cardiac dysfunction after injury. Bone marrow chimerism established in aged mice with young BM donors restored both myocardial progenitors and cardiac function, but neither was restored with aged BM donors. Cardiac micro-chimerism in aged mice was established with young BM cells, which restored cardiac function after injury, even with old peripheral BM cells. The young cardiac-resident BM-derived progenitor cells in the aged myocardium persisted for at least a year, and after myocardial infarction they actively proliferated and enhanced cardiac repair through paracrine mechanisms.Conclusion
Bone marrow reconstitution with young BM cells in aged recipients restored progenitors in both the BM and, most importantly, the myocardium. The number and function of cardiac-resident BM-derived progenitor cells in the aged myocardium prior to injury was the major determinant for successful recovery of cardiac function. The aged heart was rejuvenated with young BM cells.
European Heart Journal 04/2012; · 10.48 Impact Factor
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ABSTRACT: After a myocardial infarction, thinning and expansion of the fibrotic scar contribute to progressive heart failure. The loss of elastin is a major contributor to adverse extracellular matrix remodelling of the infarcted heart, and restoration of the elastic properties of the infarct region can prevent ventricular dysfunction. We implanted cells genetically modified to overexpress elastin to re-establish the elastic properties of the infarcted myocardium and prevent cardiac failure. A full-length human elastin cDNA was cloned, subcloned into an adenoviral vector and then transduced into rat bone marrow stromal cells (BMSCs). In vitro studies showed that BMSCs expressed the elastin protein, which was deposited into the extracellular matrix. Transduced BMSCs were injected into the infarcted myocardium of adult rats. Control groups received either BMSCs transduced with the green fluorescent protein gene or medium alone. Elastin deposition in the infarcted myocardium was associated with preservation of myocardial tissue structural integrity (by birefringence of polarized light; P < 0.05 versus controls). As a result, infarct scar thickness and diastolic compliance were maintained and infarct expansion was prevented (P < 0.05 versus controls). Over a 9-week period, rats implanted with BMSCs demonstrated better cardiac function than medium controls; however, rats receiving BMSCs overexpressing elastin showed the greatest functional improvement (P < 0.01). Overexpression of elastin in the infarcted heart preserved the elastic structure of the extracellular matrix, which, in turn, preserved diastolic function, prevented ventricular dilation and preserved cardiac function. This cell-based gene therapy provides a new approach to cardiac regeneration.
Journal of Cellular and Molecular Medicine 03/2012; 16(10):2429-39. · 4.13 Impact Factor
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ABSTRACT: We evaluated the hypothesis that uterine cells home to the heart after injury and improve cardiac outcomes. Premenopausal women have fewer cardiovascular complications than age-matched men, but the mechanisms responsible for this protection have not been conclusively identified. Hysterectomy was performed in young female rats (leaving the ovaries intact), and 7 days later the left coronary artery was ligated to produce a myocardial infarction (MI). Cardiac function at 28 days post-MI was measured using echocardiography. Fractional shortening was best in non-hysterectomized (non-Hx) females and lower in both Hx females and males. Uteri were then removed from GFP rats and heterotopically transplanted into non-GFP recipients to investigate homing of uterine cells to the infarcted myocardium. Seven days later, the uterine transplant recipients underwent coronary ligation. GFP(+) cells were found in the recipient hearts 7 days after MI and persisted for 6 months. Confocal analysis showed that homed uterine cells were located around blood vessels, suggesting their involvement in neovascularization. We then evaluated uterine cell transplantation by intravenously injecting GFP(+) uterine cells into Hx females immediately after MI. These GFP(+) cells were found to home to the injured myocardium, stimulate angiogenesis, improve cardiac function, and increase survival. This study demonstrates that uterine cells can home to the injured myocardium, enhance tissue repair, and prevent cardiac dysfunction. Uterine cells may play a role in the prevention of cardiovascular complications in females.
Journal of Molecular and Cellular Cardiology 03/2012; 52(6):1265-73. · 5.17 Impact Factor
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ABSTRACT: Stem cell research has expanded at an exponential rate, but its therapeutic applications have progressed much more slowly. Currently, the research focuses on understanding embryonic, adult, and inducible pluripotent stem cells. Translation of adult stem cell research has established a definitive benefit that is greater than that of the current standard of care in the field of cardiovascular medicine. The future of stem cell research and therapy will continue to provide novel avenues of diagnostics, therapeutics, and tissue regeneration. Here we discuss a brief history of stem cell research as it transitioned from the 20th to the 21st century. We address lessons learned in the first decade of the new millennium that could help guide others to translate research into therapy across disciplines. Finally, we highlight future goals and challenges that must be overcome and offer some perspective on the bright future of stem cell research and therapy.
Canadian Journal of Physiology and Pharmacology 03/2012; 90(3):327-35. · 1.95 Impact Factor
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ABSTRACT: After a myocardial infarction (MI), an increase in the cardiac ratio of matrix metalloproteinases (MMPs) relative to their inhibitors (TIMPs) causes extracellular matrix modulation that leads to ventricular dilatation and congestive heart failure. Cell therapy can mitigate these effects. In this study, we tested whether increasing MMP inhibition via cell-based gene transfer of Timp-3 further preserved ventricular morphometry and cardiac function in a rat model of MI. We also measured the effect of treatment timing. We generated MI (coronary artery ligation) in adult rats. Three or 14 days later, we implanted medium (control) or vascular smooth muscle cells transfected with empty vector (VSMCs) or Timp-3 (C-TIMP-3) into the peri-infarct region (n = 15-24/group). We assessed MMP-2 and -9 expression and activity, TIMP-3, and TNF-α expression, cell apoptosis, infarct size and thickness, ventricular morphometry, and cardiac function (by echocardiography). Relative to medium, VSMCs delivered at either time point significantly reduced cardiac expression and activity of MMP-2 and -9, reduced expression of TNF-α, and increased expression of TIMP-3. Cell therapy also reduced apoptosis and scar area, increased infarct thickness, preserved ventricular structure, and reduced functional loss. All these effects were augmented by C-TIMP-3 treatment. Survival and cardiac function were significantly greater when VSMCs or C-TIMP-3 were delivered at 3 (vs. 14) days after MI. Upregulating post-MI cardiac TIMP-3 expression via cell-based gene therapy contributed additional regulation of MMP, TIMP, and TNF-α levels, thereby boosting the structural and functional effects of VSMCs transplanted at 3 or 14 days after an MI in rats. Early treatment may be superior to late, though both are effective.
Cell Transplantation 09/2011; 21(5):1039-53. · 5.13 Impact Factor
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ABSTRACT: Two-photon excitation autofluorescence (produced in myocytes) and second-harmonic generation (produced mainly by collagen) allow label-free visualization of these two important components of myocardium. Because of their different emission wavelengths, these two signals can be separated spectrally. Here, we examine two-photon microscopy images of healthy, infarcted and stem-cell treated rat hearts. We find that in infarcted heart, regions distant from the site of infarct are similar to healthy tissue in composition (mostly myocytes, very little collagen) and organization (densely packed myocytes), but infarct regions are characterized by sparse myocytes and high collagen content indicative of scar tissue formation. Stem cell treated hearts, in contrast, show regions of intertwined myocytes and collagen throughout the infarct, suggesting reduced tissue damage. Finally, these results offer interesting insights into our ongoing polarized light studies of cardiac tissue anisotropy, and reveal that both tissue composition and tissue micro-organization are reflected in polarization-measured linear retardance values.
Journal of Biophotonics 05/2011; 4(5):297-304. · 4.34 Impact Factor
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ABSTRACT: Ultrasound-targeted microbubble destruction (UTMD) uses ultrasound energy to selectively deliver genes into the myocardium using plasmids conjugated to microbubbles. We hypothesized that repeated delivery of stem cell-mobilizing genes could boost the ability of this therapy to enhance cardiac repair and ventricular function after a myocardial infarction.
Beginning 7 days after coronary artery ligation, stem cell factor (SCF) and stromal cell-derived factor (SDF)-1α genes were administered to adult rats using 1, 3, or 6 UTMD treatments (repeat 1, 3, and 6 groups) at 2-day intervals (control=6 treatments with empty plasmid). Cardiac function (echocardiography) and myocardial perfusion (myocardial contrast echocardiography) were assessed on Days -7, 0, and 24 relative to the first treatment. Histological and biochemical assessments were performed on Day 24. Multiple UTMD treatments were associated with an increased presence of myocardial SCF and SDF-1α proteins and their receptors (vs. control and Repeat 1). All UTMD recipients exhibited increased vascular densities and smaller infarct regions (vs. control), with the highest ventricular densities in response to multiple treatments. Myocardial perfusion and ventricular function at Day 24 also improved progressively (vs. control) with the number of UTMD treatments.
Targeted ultrasound delivery of SCF and SDF-1α genes to the infarcted myocardium recruited progenitor cells and increased vascular density. Multiple UTMD treatments enhanced tissue repair, perfusion, and cardiac function. Repeated UTMD therapy may be applied to tailor the number of interventions required to optimize cardiac regeneration after an infarction.
European Heart Journal 01/2011; 32(16):2075-84. · 10.48 Impact Factor
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ABSTRACT: Rapid vascularization of engineered tissues in vitro and in vivo remains one of the key limitations in tissue engineering. We propose that angiogenic growth factors covalently immobilized on scaffolds for tissue engineering can be used to accomplish this goal. The main objectives of this work were: (a) to derive desirable experimental conditions for the covalent immobilization of vascular endothelial growth factor (VEGF) and angiopoietin-1 (Ang1) on porous collagen scaffolds; and (b) to determine whether primary endothelial cells respond to these scaffolds with covalently immobilized angiogenic factors. VEGF and Ang1 were covalently immobilized onto porous collagen scaffolds, using 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) chemistry. To improve covalent immobilization conditions: (a) different reaction buffers [phosphate-buffered saline (PBS), distilled water, or 2-(N-morpholino)ethanesulphonic acid (MES)] were used; and (b) step immobilization was compared to bulk immobilization. In step immobilization, growth factors are applied after EDC activation of the scaffold, while in bulk immobilization, reagents are simultaneously applied to the scaffold. PBS as the reaction buffer resulted in higher amounts of VEGF and Ang1 immobilized (ELISA), higher cell proliferation rates (XTT) and increased lactate metabolism compared to water and MES as the reaction buffers. Step immobilization in PBS buffer was also more effective than bulk immobilization. Immobilized growth factors resulted in higher cell proliferation and lactate metabolism compared to soluble growth factors used at comparable concentrations. Tube formation by CD31-positive cells was also observed in collagen scaffolds with immobilized VEGF or Ang1 using H5V and primary rat aortic endothelial cells but not on control scaffolds.
Journal of Tissue Engineering and Regenerative Medicine 01/2011; 5(1):69-84. · 3.28 Impact Factor
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ABSTRACT: Cardiac cell therapy for older patients who experience a myocardial infarction may require highly regenerative cells from young, healthy (allogeneic) donors. Bone marrow mesenchymal stem cells (MSCs) are currently under clinical investigation because they can induce cardiac repair and may also be immunoprivileged (suitable for allogeneic applications). However, it is unclear whether allogeneic MSCs retain their immunoprivilege or functional efficacy late after myocardial implantation. We evaluated the effects of MSC differentiation on the immune characteristics of cells in vitro and in vivo and monitored cardiac function for 6 months after post-myocardial infarction MSC therapy.
In the in vitro experiments, inducing MSCs to acquire myogenic, endothelial, or smooth muscle characteristics (via 5-azacytidine or cytokine treatment) increased major histocompatibility complex-Ia and -II (immunogenic) expression and reduced major histocompatibility complex-Ib (immunosuppressive) expression, in association with increased cytotoxicity in coculture with allogeneic leukocytes. In the in vivo experiments, we implanted allogeneic or syngeneic MSCs into infarcted rat myocardia. We measured cell differentiation and survival (immunohistochemistry, real-time polymerase chain reaction) and cardiac function (echocardiography, pressure-volume catheter) for 6 months. MSCs (versus media) significantly improved ventricular function for at least 3 months after implantation. Allogeneic (but not syngeneic) cells were eliminated from the heart by 5 weeks after implantation, and their functional benefits were lost within 5 months.
The long-term ability of allogeneic MSCs to preserve function in the infarcted heart is limited by a biphasic immune response whereby they transition from an immunoprivileged to an immunogenic state after differentiation, which is associated with an alteration in major histocompatibility complex-immune antigen profile.
Circulation 12/2010; 122(23):2419-29. · 14.74 Impact Factor
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ABSTRACT: Autologous mesenchymal stem cells (MSCs) have been proven safe in phase I and II clinical trials in patients who have suffered a myocardial infarction. However, their potential for proliferation and differentiation decreases with age, which limits their efficacy in elderly patients. Allogeneic MSCs offer several key advantages over autologous MSCs, including a high regenerative potential and availability for clinical use without the delay required for expansion. It was believed that allogeneic MSCs were immune privileged and thus able to escape the recipient's immune system. In several preclinical studies, allogeneic MSCs were successful in regenerating the myocardium, and the transplanted MSCs improved heart function early after implantation. However, the long-term ability of allogeneic MSCs to preserve heart function is limited because of a transition from an immune privileged to an immunogenic phenotype after the cells differentiate. The initial phase I/II clinical study using allogeneic MSCs in patients with acute myocardial infarction was safe, and no side effects were observed. However, the long-term safety and efficacy of allogeneic MSCs remain to be established. In this review, we discuss the challenges of using allogeneic MSCs for cardiac repair and present strategies to prevent the immune rejection of allogeneic MSCs to increase their potential for use in cardiac patients.
Trends in cardiovascular medicine 11/2010; 20(8):263-8. · 4.37 Impact Factor
