Is stem cell-based therapy going on or out for cardiac disease?

Stem cell therapies for congenital heart disease

Congenital heart disease (CHD) is the most prevalent congenital anomaly in newborn babies. Cardiac malformations have been induced in different animal model experiments, by perturbing some molecules that take part in the developmental pathways associated with myocyte differentiation, specification, or cardiac morphogenesis. The exact epigenetic, environmental, or genetic, basis for these molecules perturbations is yet to be understood. But, scientist have bridged this gap by introducing autologous stem cell into the defective hearts to treat CHD. The choice of stem cells to use has also raised an issue. In this review, we explore different stem cells that have been recently used, as an update into the pool of this knowledge and we suggested the future perspective into the choice of stem cells to control this disease. We propose that isolating mesenchymal stem cells from neonate will give a robust heart regeneration as compared to adults. This source are easily isolated. To unveil stem cell therapy beyond its possibility and safety, further study is required, including largescale randomized, and clinical trials to certify the efficacy of stem cell therapy.

Characteristics of circulating CD31(+) cells from patients with coronary artery disease

Recently, we reported the properties of CD31-expressing cells in healthy individuals. However, the characteristics of CD31-expressing cells derived from coronary artery disease (CAD) patients remain unknown. This study aimed to investigate the relationship between circulating CD31⁺ cells and CAD as well as their biological characteristics. Analysis with flow cytometry revealed that CD31⁺ cells (C-CD31) from the peripheral blood (PB) of CAD patients exhibited low levels of T-cell marker and high levels of macrophage marker compared with the PB-CD31⁺ cells from healthy individuals (H-CD31). In addition, the expression levels of multiple pro-angiogenic and chemokine genes were significantly down-regulated in C-CD31. However, inflammatory gene IL-1α was highly up-regulated in C-CD31. Patients with unstable angina (UA) had significantly more CD31⁺ cells in the PB than healthy control group (P < 0.001). Moreover, there were significant correlations between the number of CD31⁺ cells and cardiovascular (CV) disease activity (R = 0.318, P = 0.006) and the number of diseased coronaries (R = 0.312, P = 0.005). For the diagnostic category of UA, the area under curve was 0.803 (P < 0.001). In conclusion, C-CD31 have impaired angiogenic potential and the number of circulating CD31⁺ cells were correlated with CV risk. These findings may contribute to the understanding of the pathogenesis of CAD.

Amniotic mesenchymal stem cells display neurovascular tropism and aid in the recovery of injured peripheral nerves

Recently, we reported that human amniotic membrane-derived mesenchymal stem cells (AMMs) possess great angiogenic potential. In this study, we determined whether local injection of AMMs ameliorates peripheral neuropathy. AMMs were transplanted into injured sciatic nerves. AMM injection promoted significant recovery of motor nerve conduction velocity and voltage amplitude compared to human adipose-derived mesenchymal stem cells. AMM implantation also augmented blood perfusion and increased intraneural vascularity. Whole-mount fluorescent imaging analysis demonstrated that AMMs exhibited higher engraftment and endothelial incorporation abilities in the sciatic nerve. In addition, the higher expression of pro-angiogenic factors was detected in AMMs injected into the peripheral nerve. Therefore, these data provide novel therapeutic and mechanistic insights into stem cell biology, and AMM transplantation may represent an alternative therapeutic option for treating peripheral neuropathy.

Priming of mononuclear cells with a combination of growth factors enhances wound healing via high angiogenic and engraftment capabilities

Recently, we demonstrated that a specific combination of growth factors enhances the survival, adhesion and angiogenic potential of mononuclear cells (MNCs). In this study, we sought to investigate the changes of the angiogenic potential of MNCs after short-time priming with a specific combination of growth factors. MNCs were isolated using density gradient centrifugation and incubated with a priming cocktail containing epidermal growth factor (EGF), insulin-like growth factor (IGF)-1, fibroblast growth factor (FGF)-2, FMS-like tyrosine kinase (Flt)-3L, Angiopoietin (Ang)-1, granulocyte chemotactic protein (GCP)-2 and thrombopoietin (TPO) (all 400 ng/ml) for 15, 30 and 60 min. Wounds in nonobese diabetic-severe combined immune deficiency (NOD-SCID) mice were created by skin excision followed by cell transplantation. We performed a qRT-PCR analysis on the growth factor–primed cells. The angiogenic factors vascular endothelial growth factor (VEGF)-A, FGF-2, hepatocyte growth factor (HGF), platelet-derived growth factor (PDGF) and interleukin (IL)-8 and the anti-apoptotic factors IGF-1 and transforming growth factor-β1 were significantly elevated in the MNCs primed for 30 min. (T30) compared with the non-primed MNCs (T0). The scratch wound assay revealed that T30- conditioned media (CM) significantly increased the rate of fibroblast-mediated wound closure compared with the rates from T0-CM and human umbilical vein endothelial cells (HUVEC)-CM at 20 hrs. In vivo wound healing results revealed that the T30-treated wounds demonstrated accelerated wound healing at days 7 and 14 compared with those treated with T0. The histological analyses demonstrated that the number of engrafted cells and transdifferentiated keratinocytes in the wounds were significantly higher in the T30-transplanted group than in the T0-transplanted group. In conclusion, this study suggests that short-term priming of MNCs with growth factors might be alternative therapeutic option for cell-based therapies.

Intracoronary and retrograde coronary venous myocardial delivery of adipose-derived stem cells in swine infarction lead to transient myocardial trapping with predominant pulmonary redistribution

OBJECTIVES

To examine the comparative fate of adipose-derived stem cells (ASCs) as well as their impact on coronary microcirculation following either retrograde coronary venous (RCV) or arterial delivery.

BACKGROUND

Local delivery of ASCs to the heart has been proposed as a practical approach to limiting the extent of myocardial infarction. Mouse models of mesenchymal stem cell effects on the heart have also demonstrated significant benefits from systemic (intravenous) delivery, prompting a question about the advantage of local delivery. There has been no study addressing the extent of myocardial vs. systemic disposition of ASCs in large animal models following local delivery to the myocardium.

METHODS

In an initial experiment, dose-dependent effects of ASC delivery on coronary circulation in normal swine were evaluated to establish a tolerable ASC dosing range for intracoronary (IC) delivery. In a set of subsequent experiments, an anterior acute myocardial infarction (AMI) was created by balloon occlusion of the proximal left anterior descending (LAD) artery, followed by either IC or RCV infusion of 10(7) (111)Indium-labeled autologous ASCs 6 days following AMI. Indices of microcirculatory resistance (IMR) and coronary flow reserve (CFR) were measured before sacrifices to collect tissues for analysis at 1 or 24 hr after cell delivery.

RESULTS

IC delivery of porcine ASCs to normal myocardium was well tolerated up to a cumulative dose of 14 × 10(6) cells (approximately 0.5 × 10(6) cells/kg). There was evidence suggesting microcirculatory trapping of ASC: at unit doses of 50 × 10(6) ASCs, IMR and CFR were found to be persistently altered in the target LAD distribution at 7 days following delivery, whereas at 10 × 10(6) ASCs, only CFR was altered. In the context of recent MI, a significantly higher percentage of ASCs was retained at 1 hr with IC delivery compared with RCV delivery (57.2 ± 12.7% vs. 17.9 ± 1.6%, P = 0.037) but this initial difference was not apparent at 24 hr (22.6 ± 5.5% vs. 18.7 ± 8.6%; P = 0.722). In both approaches, most ASC redistributed to the pulmonary circulation by 24 hr postdelivery. There were no significant differences in CFR or IMR following ASC delivery to infarcted tissue by either route.

CONCLUSIONS

Selective intravascular delivery of ASC by coronary arterial and venous routes leads to similarly limited myocardial cell retention with predominant redistribution of cells to the lungs. IC arterial delivery of ASC leads to only transiently greater myocardial retention, which is accompanied by obstruction of normal regions of coronary microcirculation at higher doses. The predominant intrapulmonary localization of cells following local delivery via both methods prompts the notion that systemic delivery of ASC might provide similarly beneficial outcomes while avoiding risks of inadvertent microcirculatory compromise.

Highly angiogenic CXCR4(+)CD31(+) monocyte subset derived from 3D culture of human peripheral blood

Ex vivo expansion of human circulating angiogenic cells is a major challenge in autologous cell therapy for ischemic diseases. Here, we demonstrate that hematosphere-derived CXCR4(+)CD31(+) myeloid cells using peripheral blood possess robust proangiogenic capacity such as formation of vessel-like structures and tip cell-like morphology in Matrigel. We also found that CD31 positive myeloid cells are principal cellular component of hematospheres by magnetic cell sorting. Flow cytometry analysis showed that fresh peripheral blood contained 40.3 ± 15.2% of CXCR4(+)CD31(+) myeloid cells, but at day 5 of hematosphere culture, most of myeloid cells were CXCR4(+)CD31(+) by 86.9 ± 5.4%. Hematosphere culture significantly increased the production of angiogenic niche-supporting cytokines. Moreover, CD31-homophilic interaction and VEGF-VEGF receptor loop signaling were essential for sphere formation and acquisition of angiogenic capacity in hematospheres. Matrigel plug and ischemic hindlimb model provide in vivo evidence that hematosphere-derived myeloid cells have highly vasculogenic capacities, participate in new and mature vessel formation, and exert therapeutic effects on ischemic hindlimb. In conclusion, our strategy for ex vivo expansion of human CXCR4(+)CD31(+) angiogenic cells using hematospheres provides an autologous therapeutic cell source for ischemic diseases and a new model for investigating the microenvironment of angiogenesis.

Mesenchymal stem cells overexpressing GCP-2 improve heart function through enhanced angiogenic properties in a myocardial infarction model

AIMS

In this study, our aim was to evaluate the angio-vasculogenic properties of human adipose tissue-derived mesenchymal stem cells overexpressing the granulocyte chemotactic protein (GCP)-2 (hASCs/GCP-2) and to determine possible therapeutic effects in an experimental ischaemic heart model.

METHODS AND RESULTS

Quantitative real-time (qRT)-PCR results revealed that hASCs/GCP-2 expressed significantly higher levels of pro-angiogenic genes, including vascular endothelial growth factor (VEGF)-A, hepatocyte growth factor (HGF), and interleukin (IL)-8, when compared with control-vector transduced hASCs or human umbilical vascular endothelial cells (HUVECs). In addition, the anti-apoptotic insulin-like growth factor (IGF)-1 and Akt-1 were also highly up-regulated in the hASCs/GCP-2 cells. In vitro cell migration and proliferation assays showed that hASCs/GCP-2-derived conditioned media (CM) significantly accelerated the migration and proliferation of fibroblast cells. Examination of in vitro endothelial differentiation showed that hASCs/GCP-2 cells spontaneously formed vascular-like structures and highly expressed endothelial-specific genes and proteins. In vivo study results of our mouse myocardial infarction (MI) model revealed that hASCs/GCP-2 implantation improved the cardiac function and reduced the infarct size. Finally, transplanted hASCs/GCP-2 cells unexpectedly differentiated into endothelial cells and the engraftment rate was significantly higher than control groups.

CONCLUSION

We suggest that overexpression of GCP-2 in stem cells has the potential to enhance their angiogenic and survival properties.

Endothelial progenitor cell transplantation decreases lymphangiogenesis and adverse myocardial remodeling in a mouse model of acute myocardial infarction

Cardiac lymphatic system in the remodeling after acute myocardial infarction (AMI) has been overlooked. We wanted to investigate the role of bone marrow-derived endothelial progenitor cells (EPCs) and their contribution to lymphatic distribution in myocardial remodeling after AMI. Mouse (C57bl/6J) MI models were created by ligation of the left anterior descending coronary artery and were treated with phosphate buffered saline (PBS) or EPCs. Real-time RT-PCR with 2- to 4-week myocardial tissue samples revealed that lymphangiogenetic factors such as vascular endothelial growth factor (VEGF)-C (8.5 fold, P < 0.05), VEGF-D (6.1 fold, P < 0.05), Lyve-1 (15 fold, P < 0.05), and Prox-1 (11 fold, P < 0.05) were expressed at significantly higher levels in the PBS group than the EPC group. The PBS group also showed a significantly higher density of lymphatic vessels in the peri-infarction area. Echocardiography showed that from 2 weeks after the treatment, left ventricle (LV) dimensions at both systole and diastole were significantly smaller in the EPC group than in the PBS group (P < 0.01) and LV fractional shortening was higher in the EPC group accordingly (P < 0.01). Lymphangiogenic markers increased in a mouse MI model. EPC transplantation decreased lymphangiogenesis and adverse ventricular remodeling after AMI. These novel findings suggest that new lymphatic vessels may be formed in severely damaged myocardium, and may be involved in adverse myocardial remodeling after AMI.

New method to differentiate human peripheral blood monocytes into insulin producing cells: Human hematosphere culture

Strategy to differentiate stem cells into insulin producing cells (IPCs) in vitro has been a promising one to get cell source of β-cell replacement therapy for diabetes. It has been suggested that islets and neurons share features and nestin-positive cells could differentiate into IPCs. We have recently developed a three-dimensional culture system using human peripheral blood cells named as blood-born hematosphere (BBHS). Here we showed that most of BBHS were composed of nestin-positive cells. Under the four-stage differentiation protocol for IPCs, we plated nestin-positive BBHS onto fibronectin-coated dish. These cells form islet-like clusters and most of them expressed insulin. Pancreatic specific genes were turned on, such as transcription factors (Pdx-1, Ngn3 and Nkx6.1), genes related to endocrine function (Glut-2 and PC2) or β cell function (Kir6.2, SUR1). Furthermore islet differentiation was confirmed by dithizone (DTZ) staining to detect zinc ion which binds insulin protein within the cells. Finally, IPCs derived from BBHS showed capability to secrete insulin in response to glucose stimulation. Taken together, our novel protocol successfully induced islet-like human insulin producing cells out of BBHS. This strategy of ex vivo expansion of IPCs using BBHS provides an autologous therapeutic cell source for the treatment of diabetes.

Cardioprotective effects of 3-phosphoinositide-dependent protein kinase-1 on hypoxic injury in cultured neonatal rat cardiomyocytes and myocardium in a rat myocardial infarct model

3-Phosphoinositide-dependent protein kinase-1 (PDK1) is involved in numerous cellular responses. In this study, we investigated the protective effects of PDK1 gene expression against hypoxic conditions in cultured rat CMCs (rCMCs) and in a rat myocardial infarction (MI) model using the lentiviral vector (LeV) system. LeV-PDK1 transfer effectively reduced the apoptotic cell death caused by hypoxic injury as compared to LeV-GFP transfer in rCMCs the expression of survival proteins increased in the LeV-PDK1 group, whereas apoptosis signaling decreased in the rCMCs and in infarcted hearts treated with LeV-PDK1. LeV-PDK1 transfer also reduced apoptosis and infarct size and attenuated myocardial wall thinning and ventricular remodeling in a rat MI model. These findings suggest that PDK1 has a protective role in the injured ischemic myocardium via overexpression of the cell survival pathway in CMCs. Hence PDK1 can be used as a treatment strategy for myocardial salvage inin hypoxic injury.