Experience from experimental cell transplantation therapy of myocardial infarction: what have we learned?

Applications of the amniotic membrane in tissue engineering and regeneration: the hundred-year challenge

The amniotic membrane (Amnio-M) has various applications in regenerative medicine. It acts as a highly biocompatible natural scaffold and as a source of several types of stem cells and potent growth factors. It also serves as an effective nano-reservoir for drug delivery, thanks to its high entrapment properties. Over the past century, the use of the Amnio-M in the clinic has evolved from a simple sheet for topical applications for skin and corneal repair into more advanced forms, such as micronized dehydrated membrane, amniotic cytokine extract, and solubilized powder injections to regenerate muscles, cartilage, and tendons. This review highlights the development of the Amnio-M over the years and the implication of new and emerging nanotechnology to support expanding its use for tissue engineering and clinical applications.

High concentrations of H7 human embryonic stem cells at the point of care for acute myocardial infarction

Background

Embryonic stem cell (ESC)-derived cardiomyocytes have become one of the most attractive sources of cellular therapy for minimizing heart tissue damage following myocardial infarction (MI). In this study, we investigated the differentiation of BMS-189453-induced H7 human ESCs (hESCs) and purified ESCs in the treatment of induced acute MI.

Methods

BMS-189453 was used to induce the differentiation of H7 hESCs into myocardial ESCs. We further purified ESCs cells. The expression levels of the myocardial-specific protein cardiac troponin T (cTnT) and the ventricular-specific protein Myosin Light Chain 2 (MLC-2V) were detected by western blot. Quantitative reverse transcription-polymerase chain reaction (QRT-PCR) was used to detect the expression of iroquois homeobox 4 (IRX4), an important transcription factor related to ventricular muscle development. Ultrasound, radionuclides, and Holter monitoring were used to evaluate the therapeutic effect of ESCs on acute MI induced in pigs.

Results

Compared with untreated myocardial tissue, myocardial ESCs and purified ESCs improved the outcome in pigs with MI. Treatment with non-purified ESCs and purified ESCs improved the myocardial perfusion grade and ventricular wall motion score index, increased the viable myocardial ratio (VMR), improved the ejection fraction and left ventricular end-diastolic diameter, and reduced the MI area. Further, compared with non-purified ESCs, purified ESCs resulted in fewer side effects and reduced the incidence of ventricular arrhythmias.

Conclusions

In the pig model of acute MI, treatment with ESCs significantly improved myocardial function, increased myocardial mass, and reduced scar tissue formation. Purified ESCs have a better treatment effect than non-purified ESCs and can reduce the incidence of ventricular arrhythmias. This study has unearthed new prospects for the clinical treatment of MI.

Comparison of Human Embryonic Stem Cell-Derived Cardiomyocytes, Cardiovascular Progenitors, and Bone Marrow Mononuclear Cells for Cardiac Repair

Cardiomyocytes derived from human embryonic stem cells (hESC-CMs) can improve the contractility of injured hearts. We hypothesized that mesodermal cardiovascular progenitors (hESC-CVPs), capable of generating vascular cells in addition to cardiomyocytes, would provide superior repair by contributing to multiple components of myocardium. We performed a head-to-head comparison of hESC-CMs and hESC-CVPs and compared these with the most commonly used clinical cell type, human bone marrow mononuclear cells (hBM-MNCs). In a nude rat model of myocardial infarction, hESC-CMs and hESC-CVPs generated comparable grafts. Both similarly improved systolic function and ventricular dilation. Furthermore, only rare human vessels formed from hESC-CVPs. hBM-MNCs attenuated ventricular dilation and enhanced host vascularization without engrafting long-term or improving contractility. Thus, hESC-CMs and CVPs show similar efficacy for cardiac repair, and both are more efficient than hBM-MNCs. However, hESC-CVPs do not form larger grafts or more significant numbers of human vessels in the infarcted heart.

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Transplantation of hBM-MNCs can halt the negative remodeling of the infarcted heart

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Both hESC-derived cardiovascular progenitors and definitive cardiomyocytes improve contractility

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hBM-MNCs lead to greater vessel number than hESC-derived cells

Human Placenta-Derived Multipotent Cells (hPDMCs) Modulate Cardiac Injury: From Bench to Small and Large Animal Myocardial Ischemia Studies

Cardiovascular disease is the leading cause of death globally, and stem cell therapy remains one of the most promising strategies for regeneration or repair of the damaged heart. We report that human placenta-derived multipotent cells (hPDMCs) can modulate cardiac injury in small and large animal models of myocardial ischemia (MI) and elucidate the mechanisms involved. We found that hPDMCs can undergo in vitro cardiomyogenic differentiation when cocultured with mouse neonatal cardiomyocytes. Moreover, hPDMCs exert strong proangiogenic responses in vitro toward human endothelial cells mediated by secretion of hepatocyte growth factor, growth-regulated oncogene-α, and interleukin-8. To test the in vivo relevance of these results, small and large animal models of acute MI were induced in mice and minipigs, respectively, by permanent left anterior descending (LAD) artery ligation, followed by hPDMC or culture medium-only implantation with follow-up for up to 8 weeks. Transplantation of hPDMCs into mouse heart post-acute MI induction improved left ventricular function, with significantly enhanced vascularity in the cell-treated group. Furthermore, in minipigs post-acute MI induction, hPDMC transplantation significantly improved myocardial contractility compared to the control group ( p=0.016) at 8 weeks postinjury. In addition, tissue analysis confirmed that hPDMC transplantation induced increased vascularity, cardiomyogenic differentiation, and antiapoptotic effects. Our findings offer evidence that hPDMCs can modulate cardiac injury in both small and large animal models, possibly through proangiogenesis, cardiomyogenesis, and suppression of cardiomyocyte apoptosis. Our study offers mechanistic insights and preclinical evidence on using hPDMCs as a therapeutic strategy to treat severe cardiovascular diseases.

Adipose-derived stem cells from both visceral and subcutaneous fat deposits significantly improve contractile function of infarcted rat hearts

Adipose-derived stem cells (ASCs) from subcutaneous and visceral adipose tissues have been studied individually. No studies have compared their abilities in treatment of heart failure. This study was designed to evaluate whether ASCs from the two sources could provide a long-term improvement of cardiac function in infarcted hearts. Rat subcutaneous and visceral adipose tissues were excised for isolation of ASCs. Morphology, yield, proliferation, surface markers, differentiation, and cytokine secretion of the subcutaneous ASCs (S-ASCs) and visceral ASCs (V-ASCs) were analyzed. Then a rat model of myocardial infarction (MI) was established by a coronary occlusion. Seven days after occlusion, S-ASCs (n = 22), V-ASCs (n = 22), and Dulbecco's modified Eagle medium (DMEM, n = 20) were injected into the infarct rim, respectively. Cardiac function was then monitored with MRI for up to 6 months. The hearts were then removed for histological assessments. The yield of V-ASCs per gram of the visceral adipose depot was significantly greater than that of S-ASCs in 1 g of the subcutaneous adipose depot. On the other hand, the S-ASCs showed a greater proliferation rate and colony-forming unit relative to the V-ASCs. In addition, the infarcted hearts treated with either S-ASCs or V-ASCs showed a significantly greater left ventricular ejection fraction (LVEF) than those treated with DMEM at 4 weeks and 6 months following the cell/DMEM transplantation. Moreover, the infarct sizes of both S-ASC- and V-ASC-treated hearts were significantly smaller than that in the DMEM-treated hearts. MRI showed the implanted ASCs at the end of 6 months of recovery. Despite the differences in cell yield, proliferation, and colony formation capacity, both S-ASCs and V-ASCs provide a long-lasting improvement of cardiac contractile function in infarcted hearts. We conclude that the subcutaneous and visceral adipose tissues are equally effective cell sources for cell therapy of heart failure.

The Therapeutic Effect of Cell Transplantation Versus Noncellular Biomaterial Implantation on Cardiac Structure and Function Following Myocardial Infarction

Although numerous studies demonstrated that localized delivery of either cells or biomaterials improved postinfarction cardiac function, the underlying mechanisms for this effect remain unclear. We performed a comparison of the effects of fetal, neonatal, and human embryonic stem cell-derived cardiac cell as well as mesenchymal stem cell transplantation versus biomaterial (collagen/extracellular matrix) implantation therapy in rat myocardial infarction model in our laboratory, specifically comparing their effects on infarct wall thickness, neovascularization, infarct wall motion, and left ventricular ejection fraction (LVEF). Both cell and biomaterial treatment had similar beneficial effects on cardiac structure (increasing infarct wall thickness and preventing infarct expansion) and function (preventing paradoxical LV systolic bulging and improving LVEF). In this review, we also discussed the underlying mechanisms of cell and biomaterial therapies, their advantages and disadvantages, and future research directions in the field of regenerative cardiology.

Applications of amniotic membrane and fluid in stem cell biology and regenerative medicine

The amniotic membrane (AM) and amniotic fluid (AF) have a long history of use in surgical and prenatal diagnostic applications, respectively. In addition, the discovery of cell populations in AM and AF which are widely accessible, nontumorigenic and capable of differentiating into a variety of cell types has stimulated a flurry of research aimed at characterizing the cells and evaluating their potential utility in regenerative medicine. While a major focus of research has been the use of amniotic membrane and fluid in tissue engineering and cell replacement, AM- and AF-derived cells may also have capabilities in protecting and stimulating the repair of injured tissues via paracrine actions, and acting as vectors for biodelivery of exogenous factors to treat injury and diseases. Much progress has been made since the discovery of AM and AF cells with stem cell characteristics nearly a decade ago, but there remain a number of problematic issues stemming from the inherent heterogeneity of these cells as well as inconsistencies in isolation and culturing methods which must be addressed to advance the field towards the development of cell-based therapies. Here, we provide an overview of the recent progress and future perspectives in the use of AM- and AF-derived cells for therapeutic applications.