Mobilization of stem cells by granulocyte colony-stimulating factor for the regeneration of myocardial tissue after myocardial infarction

Clinical application of adult stem cells for therapy for cardiac disease

INTRODUCTION

Cardiovascular disease is a major cause of death worldwide. Different medical and surgical therapeutic options are well established, but a significant number of patients are not amenable to standard therapeutic options. Cell-based therapies after clinical application have shown different results in recent years. Here, we are giving a comprehensive overview on major available clinical data regarding cell therapy.

BACKGROUND

Cell-based therapies and tissue engineering provide new promising platforms to develop upcoming therapeutic options. Initial clinical trials were able to generate promising results. A variety of different stem cell types have been used for the clinical application. Different adult cardiac stem cells and progenitor cells, including mesenchymal, CD34(+) and CD133(+) autologous human bone marrow-derived stem cells (BMCs), human myoblasts, and peripheral blood-derived stem and progenitor cells (PBSCs) have been used for the therapy for end-stage heart failure. Future experiments will show the importance of novel cell populations and clarify the mechanism causing cell therapy-mediated observed effects.

CONCLUSION

Several clinical trials have reported on sole therapy, as well as combined application of autologous adult stem cells with conventional revascularization. The reported promising findings encourage further research in the field of the translational research.

Human adipose tissue-derived adult stem cells can lead to multiorgan engraftment

Recent studies have demonstrated the existence of a population of adipose tissue-derived adult stem cells that can undergo multilineage differentiation in vitro; however, it is unclear whether these cells maintain their multilineage differentiation in vivo. The objective of the present study was to examine the in vivo characteristics and behavior of a potential population of human adipose tissue-derived adult stem cells. Herein, we demonstrate that human adipose tissue-derived adult stem cells differentiate into the epithelium of the gastrointestinal tract, liver, and bronchi, and an endothelial lineage after transplantation into irradiated nonobese mice with diabetes or severe combined immunodeficiency. These findings may contribute to clinical tissue repair after injury.

G-CSF treatment after myocardial infarction: impact on bone marrow-derived vs cardiac progenitor cells

OBJECTIVE

Besides its classical function in the field of autologous and allogenic stem cell transplantation, granulocyte colony-stimulating factor (G-CSF) was shown to have protective effects after myocardial infarction (MI) by mobilization of bone marrow-derived progenitor cells (BMCs) and in addition by activation of multiple signaling pathways. In the present study, we focused on the impact of G-CSF on migration of BMCs and the impact on resident cardiac cells after MI.

MATERIALS AND METHODS

Mice (C57BL/6J) were sublethally irradiated, and BM from green fluorescent protein (GFP)-transgenic mice was transplanted. Coronary artery ligation was performed 10 weeks later. G-CSF (100 microg/kg) was daily injected for 6 days. Subpopulations of enhanced GFP(+) cells in peripheral blood, bone marrow, and heart were characterized by flow cytometry. Growth factor expression in the heart was analyzed by quantitative real-time polymerase chain reaction. Perfusion was investigated in vivo by gated single photon emission computed tomography (SPECT).

RESULTS

G-CSF-treated animals revealed a reduced migration of c-kit(+) and CXCR-4(+) BMCs associated with decreased expression levels of the corresponding growth factors, namely stem cell factor and stromal-derived factor-1 alpha in ischemic myocardium. In contrast, the number of resident cardiac Sca-1(+) cells was significantly increased. However, SPECT-perfusion showed no differences in infarct size between G-CSF-treated and control animals 6 days after MI.

CONCLUSION

Our study shows that G-CSF treatment after MI reduces migration capacity of BMCs into ischemic tissue, but increases the number of resident cardiac cells. To optimize homing capacity a combination of G-CSF with other agents may optimize cytokine therapy after MI.

Therapeutic myocardial angiogenesis

Armed with an improved understanding of the mediators of angiogenesis, physicians and scientists have made significant efforts at harnessing this naturally occurring process in order to treat patients with a variety of peripheral vascular and coronary ischemic syndromes. There is a growing population of patients with end-stage coronary artery disease (CAD) who are no longer candidates for mechanical revascularization, yet suffer from chronic myocardial ischemia who may benefit from regeneration of the depleted microvasculature.

Endothelial progenitor cells as therapeutic vectors in cardiovascular disorders: from experimental models to human trials

Cell-based therapy approaches for the restoration of blood flow in ischemic organs has recently received growing interest. A considerable number of reports have documented the presence of circulating, bone marrow-derived endothelial progenitor cells (EPC) in adult peripheral blood. These putative cells are thought to participate in postnatal growth of new blood vessels. Mounting evidence from animal studies point to potential therapeutic applications of EPCs in the treatment of a wide range of cardiovascular (CV) disorders, while preliminary results from the pilot clinical trials still remain equivocal. Here, we review the experimental data that has accumulated so far from animal and clinical studies regarding the potential importance of EPCs. In addition, we discuss the potential hurdles as well as future options of EPC-based therapy.

Mobilization of bone marrow stem cells by granulocyte colony-stimulating factor ameliorates radiation-induced damage to salivary glands

PURPOSE

One of the major reasons for failure of radiotherapeutic cancer treatment is the limitation in dose that can be applied to the tumor because of coirradiation of the normal healthy tissue. Late radiation-induced damage reduces the quality of life of the patient and may even be life threatening. Replacement of the radiation-sterilized stem cells with unirradiated autologous stem cells may restore the tissue function. Here, we assessed the potential of granulocyte colony-stimulating factor (G-CSF)-mobilized bone marrow-derived cells (BMC) to regenerate and functionally restore irradiated salivary glands used as a model for normal tissue damage.

EXPERIMENTAL DESIGN

Male-eGFP+ bone marrow chimeric female C57BL/6 mice were treated with G-CSF, 10 to 60 days after local salivary gland irradiation. Four months after irradiation, salivary gland morphology and flow rate were assessed.

RESULTS

G-CSF treatment induced homing of large number of labeled BMCs to the submandibular glands after irradiation. These animals showed significant increased gland weight, number of acinar cells, and salivary flow rates. Donor cells expressed surface markers specific for hematopoietic or endothelial/mesenchymal cells. However, salivary gland acinar cells neither express the G-CSF receptor nor contained the GFP/Y chromosome donor cell label.

CONCLUSIONS

The results show that BMCs home to damaged salivary glands after mobilization and induce repair processes, which improve function and morphology. This process does not involve transdifferentiation of BMCs to salivary gland cells. Mobilization of BMCs could become a promising modality to ameliorate radiation-induced complications after radiotherapy.

Intravenous mesenchymal stem cell therapy early after reperfused acute myocardial infarction improves left ventricular function and alters electrophysiologic properties

Direct intramyocardial injection of mesenchymal stem cells (MSCs) improves left ventricular ejection fraction (LVEF) and may increase ventricular arrhythmia in hearts with myocardial infarction (MI). We hypothesized that intravenous MSCs given early after acute MI would engraft in injured myocardium, improve LV function, and result in pro-arrhythmic electrical remodeling. We created an apical infarction in swine by balloon occlusion/reperfusion, administered diI-labeled allogeneic bone marrow derived MSCs intravenously 30 min post-reperfusion and measured LVEF and wall thickness at baseline, 1 month, and 3 months. Epicardial effective refractory periods (ERPs) were determined before sacrifice. At 3 months, treated pigs [n=7] had significantly higher LVEF than controls [n=8] (49+/-2% vs. 44+/-3%, P=0.015) and significantly less wall thickening of non-infarcted myocardium. ERPs were significantly shorter than controls at all pacing cycle lengths (P<or=0.002), suggesting a pro-arrhythmic potential. DiI was found in the lungs, in infarct, and peri-infarct myocardium.

CONCLUSION

IV infusion of MSCs soon after acute MI in swine improves LVEF and limits wall thickening in the remote non-infarcted myocardium, consistent with a beneficial effect on post-MI ventricular remodeling. Since there is no need for immune suppression or clinical expertise, IV infusion of MSCs may expand the potential clinical application of stem cell therapy.

G-CSF administration after myocardial infarction in mice attenuates late ischemic cardiomyopathy by enhanced arteriogenesis

Granulocyte-colony stimulating factor (G-CSF) has been shown to improve cardiac function after myocardial infarction (MI) by bone marrow cell mobilization and by protecting cardiomyocytes from apoptotic cell death. However, its role in collateral artery growth (arteriogenesis) has not been elucidated. Here, we investigated the effect of G-CSF on arteriolar growth and cardiac function in a murine MI model. Mice were treated with G-CSF (100 microg/kg/day) directly after MI for 5 consecutive days. G-CSF application resulted in a significant increase of circulating mononuclear cells expressing stem cell markers. Arterioles in the border zone of infarcted myocardium showed an increased expression of ICAM-1 accompanied by an accumulation of bone marrow derived cells and a pronounced proliferation of endothelial and smooth muscle cells. Histology of G-CSF treated mice revealed a lower amount of granulation tissue (67.8 vs. 84.4%) associated with a subsequent reduction in free LV wall thinning and scar extension (23.1 vs. 30.8% of LV). Furthermore, G-CSF treated animals showed a significant improvement of post-MI survival (68.8 vs. 46.2%). Pressure-volume relations revealed a partially restored myocardial function at day 30 (EF: 32.5 vs. 17.2%). Our results demonstrate that G-CSF administration after MI stimulates arteriogenesis and attenuates ischemic cardiomyopathy after MI.

Stem cell transplantation for the treatment of myocardial infarction

Stem cell transplantation provides a potential regenerative therapy for the heart damaged by myocardial infarction. Numerous scientific studies have been undertaken in animals and humans to analyze the safety and efficacy of this new approach. However, at the present time, the results have been mixed and inconclusive, and the mechanism of stem cell transplantation therapy remains unclear. This review discusses the controversies and problems that need to be addressed in future investigations.