Effects of intracoronary infusion of peripheral blood stem-cells mobilised with granulocyte-colony stimulating factor on left ventricular systolic function and restenosis after coronary stenting in myocardial infarction: the MAGIC cell randomised clinical trial

Stem cell and exosome therapies for regenerating damaged myocardium in heart failure

Finding novel treatments for cardiovascular diseases (CVDs) is a hot topic in medicine; cell-based therapies have reported promising news for controlling dangerous complications of heart disease such as myocardial infarction (MI) and heart failure (HF). Various progenitor/stem cells were tested in various in-vivo, in-vitro, and clinical studies for regeneration or repairing the injured tissue in the myocardial to accelerate the healing. Fetal, adult, embryonic, and induced pluripotent stem cells (iPSC) have revealed the proper potency for cardiac tissue repair. As an essential communicator among cells, exosomes with specific contacts (proteins, lncRNAs, and miRNAs) greatly promote cardiac rehabilitation. Interestingly, stem cell-derived exosomes have more efficiency than stem cell transplantation. Therefore, stem cells induced pluripotent stem cells (iPSCs), embryonic stem cells (ESCs), cardiac stem cells (CDC), and skeletal myoblasts) and their-derived exosomes will probably be considered an alternative therapy for CVDs remedy. In addition, stem cell-derived exosomes have been used in the diagnosis/prognosis of heart diseases. In this review, we explained the advances of stem cells/exosome-based treatment, their beneficial effects, and underlying mechanisms, which will present new insights in the clinical field in the future.

Mesenchymal stem cell secretome: A promising therapeutic strategy for erectile dysfunction?

Objective

The secretome, comprising bioactive chemicals released by mesenchymal stem cells (MSCs), holds therapeutic promise in regenerative medicine. This review aimed to explore the therapeutic potential of the MSC secretome in regenerative urology, particularly for treating erectile dysfunction (ED), and to provide an overview of preclinical and clinical research on MSCs in ED treatment and subsequently to highlight the rationales, mechanisms, preclinical investigations, and therapeutic potential of the MSC secretome in this context.

Methods

The review incorporated an analysis of preclinical and clinical research involving MSCs in the treatment of ED. Subsequently, it delved into the existing knowledge regarding the MSC secretome, exploring its therapeutic potential. The methods included a comprehensive examination of relevant literature to discern the processes underlying the therapeutic efficacy of the MSC secretome.

Results

Preclinical research indicated the effectiveness of the MSC secretome in treating various models of ED. However, the precise mechanisms of its therapeutic efficacy remain unknown. The review provided insights into the anti-inflammatory, pro-angiogenic, and trophic properties of the MSC secretome. It also discussed potential advantages, such as avoiding issues related to cellular therapy, including immunogenicity, neoplastic transformation, and cost.

Conclusion

This review underscores the significant therapeutic potential of the MSC secretome in regenerative urology, particularly for ED treatment. While preclinical studies demonstrate promising outcomes, further research is essential to elucidate the specific mechanisms underlying the therapeutic efficacy before clinical application. The review concludes by discussing future perspectives and highlighting the challenges associated with the clinical translation of the MSC secretome in regenerative urology.

Exosome-bearing hydrogels and cardiac tissue regeneration

BACKGROUND

In recent years, cardiovascular disease in particular myocardial infarction (MI) has become the predominant cause of human disability and mortality in the clinical setting. The restricted capacity of adult cardiomyocytes to proliferate and restore the function of infarcted sites is a challenging issue after the occurrence of MI. The application of stem cells and byproducts such as exosomes (Exos) has paved the way for the alleviation of cardiac tissue injury along with conventional medications in clinics. However, the short lifespan and activation of alloreactive immune cells in response to Exos and stem cells are the main issues in patients with MI. Therefore, there is an urgent demand to develop therapeutic approaches with minimum invasion for the restoration of cardiac function.

MAIN BODY

Here, we focused on recent data associated with the application of Exo-loaded hydrogels in ischemic cardiac tissue. Whether and how the advances in tissue engineering modalities have increased the efficiency of whole-based and byproducts (Exos) therapies under ischemic conditions. The integration of nanotechnology and nanobiology for designing novel smart biomaterials with therapeutic outcomes was highlighted.

CONCLUSION

Hydrogels can provide suitable platforms for the transfer of Exos, small molecules, drugs, and other bioactive factors for direct injection into the damaged myocardium. Future studies should focus on the improvement of physicochemical properties of Exo-bearing hydrogel to translate for the standard treatment options.

Natural Herbal Medicine as a Treatment Strategy for Myocardial Infarction through the Regulation of Angiogenesis

Methods

We conducted a literature search on the bioactive components of medicinal plants and their effects on angiogenesis after MI. We searched for articles in Web of Science, MEDLINE, PubMed, Scopus, Google Scholar, and China National Knowledge Infrastructure databases before April 2021.

Results

In this article, we summarized the mechanisms by which copper ions, microRNA, Akt1, inflammation, oxidative stress, mitochondria, and pericytes are involved in angiogenesis after myocardial infarction. In addition, we reviewed the angiogenic effects of natural herbal medicines such as Salvia miltiorrhiza Bunge Bunge, Carthamus tinctorius L., Pueraria lobata, Astragalus, Panax ginseng C.A. Mey., Panax notoginseng (Burkill) F.H. Chen, Cinnamomum cassia (L.) J. Presl, Rehmannia glutinosa (Gaertn.) DC., Leonurus japonicus Houtt, Scutellaria baicalensis Georgi., and Geum macrophyllum Willd.

Conclusions

Some herbs have the effect of promoting angiogenesis. In the future, natural proangiogenic drugs may become candidates for the treatment of cardiovascular diseases.

Mobilized and apheresis-collected endothelial progenitor cells with plerixafor

BACKGROUND

Endothelial progenitor cells (EPCs) are immature cells able to proliferate and contribute to endothelial repair, vascular homeostasis, neovascularization, and angiogenesis. It therefore seems likely that circulating EPCs have therapeutic potential in ischemic and vascular diseases. In this study we evaluated the efficiency of EPC mobilization and collection by large volume leukapheresis in subjects with hematological diseases, treated with plerixafor in association with G-CSF.

METHODS

Twenty-two patients with lymphoid malignancies underwent rHuG-CSF and plerixafor treatment followed by leukapheresis. Blood samples before and after treatment and apheresis liquid sample were taken and analyzed by flow cytometry in order to quantified EPC.

RESULTS

The percentage of CD34+ cells and EPCs among circulating total nuclear cells (TNCs) increased significantly by approximately 2-fold and 3-fold, respectively, after plerixafor treatment. Consequently, the absolute number of CD34+ cells and EPCs were increased 4-fold after plerixafor treatment. The median PB concentration of EPCs before and after treatment were 0.77/μL (0.31-2.15) and 3.41/μL (1.78-4.54), respectively, P < .0001. The total EPCs collected per patient were 3.3×10⁷ (0.8×10⁷ -6.8×10⁷ ).

CONCLUSION

We have shown that plerixafor in combination with G-CSF allows the mobilization and collection of large amounts of EPCs along with CD34+ cells in lymphoid neoplasm patients. The possibility to collect and to store these cells could represent a promising therapeutic tool for the treatment of ischemic complications without the need of in vitro expansion.

Cardiovascular Regeneration via Stem Cells and Direct Reprogramming: A Review

Despite recent advancements in treatment strategies, cardiovascular disease such as heart failure remains a significant source of global mortality. Stem cell technology and cellular reprogramming are rapidly growing fields that will continue to prove useful in cardiac regenerative therapeutics. This review provides information on the role of human pluripotent stem cells (hPSCs) in cardiac regeneration and discusses the practical applications of hPSC-derived cardiomyocytes (CMCs). Moreover, we discuss the practical applications of hPSC-derived CMCs while outlining the relevance of directly-reprogrammed CMCs in regenerative medicine. This review critically summarizes the most recent advances in the field will help to guide future research in this developing area.

Cardiovascular disease (CVD) is the leading causes of morbidity and death globally. In particular, a heart failure remains a major problem that contributes to global mortality. Considerable advancements have been made in conventional pharmacological therapies and coronary intervention surgery for cardiac disorder treatment. However, more than 15% of patients continuously progress to end-stage heart failure and eventually require heart transplantation. Over the past year, numerous numbers of protocols to generate cardiomyocytes (CMCs) from human pluripotent stem cells (hPSCs) have been developed and applied in clinical settings. Number of studies have described the therapeutic effects of hPSCs in animal models and revealed the underlying repair mechanisms of cardiac regeneration. In addition, biomedical engineering technologies have improved the therapeutic potential of hPSC-derived CMCs in vivo. Recently substantial progress has been made in driving the direct differentiation of somatic cells into mature CMCs, wherein an intermediate cellular reprogramming stage can be bypassed. This review provides information on the role of hPSCs in cardiac regeneration and discusses the practical applications of hPSC-derived CMCs; furthermore, it outlines the relevance of directly reprogrammed CMCs in regenerative medicine.

Stem cells therapy in acute myocardial infarction: a new era?

Stem cells transplantation after acute myocardial infarction (AMI) has been claimed to restore cardiac function. However, this therapy is still restricted to experimental studies and clinical trials. Early un-blinded studies suggested a benefit from stem cell therapy following AMI. More recent blinded randomized trials have produced mixed results and, notably, the last largest pan-European clinical trial showed the inconclusive results. Furthermore, mechanisms of potential benefit remain uncertain. This review analytically evaluates 34 blinded and un-blinded clinical trials comprising 3142 patients and is aimed to: (1) identify the pros and cons of stem cell therapy up to a 6-month follow-up after AMI comparing benefit or no effectiveness reported in clinical trials; (2) provide useful information for planning future clinical programs of cardiac stem cell therapy.

The Use of Bioactive Polymers for Intervention and Tissue Engineering: The New Frontier for Cardiovascular Therapy

Coronary heart disease remains one of the leading causes of death in most countries. Healthcare improvements have seen a shift in the presentation of disease with a reducing number of ST-segment elevation myocardial infarctions (STEMIs), largely due to earlier reperfusion strategies such as percutaneous coronary intervention (PCI). Stents have revolutionized the care of these patients, but the long-term effects of these devices have been brought to the fore. The conceptual and technologic evolution of these devices from bare-metal stents led to the creation and wide application of drug-eluting stents; further research introduced the idea of polymer-based resorbable stents. We look at the evolution of stents and the multiple advantages and disadvantages offered by each of the different polymers used to make stents in order to identify what the stent of the future may consist of whilst highlighting properties that are beneficial to the patient alongside the role of the surgeon, the cardiologist, engineers, chemists, and biophysicists in creating the ideal stent.

Key Success Factors for Regenerative Medicine in Acquired Heart Diseases

Stem cell therapy offers a breakthrough opportunity for the improvement of ischemic heart diseases. Numerous clinical trials and meta-analyses appear to confirm its positive but variable effects on heart function. Whereas these trials widely differed in design, cell type, source, and doses reinjected, cell injection route and timing, and type of cardiac disease, crucial key factors that may favour the success of cell therapy emerge from the review of their data. Various types of cell have been delivered. Injection of myoblasts does not improve heart function and is often responsible for severe ventricular arrythmia occurrence. Using bone marrow mononuclear cells is a misconception, as they are not stem cells but mainly a mix of various cells of hematopoietic lineages and stromal cells, only containing very low numbers of cells that have stem cell-like features; this likely explain the neutral results or at best the modest improvement in heart function reported after their injection. The true existence of cardiac stem cells now appears to be highly discredited, at least in adults. Mesenchymal stem cells do not repair the damaged myocardial tissue but attenuate post-infarction remodelling and contribute to revascularization of the hibernated zone surrounding the scar. CD34+ stem cells - likely issued from pluripotent very small embryonic-like (VSEL) stem cells - emerge as the most convincing cell type, inducing structural and functional repair of the ischemic myocardial area, providing they can be delivered in large amounts via intra-myocardial rather than intra-coronary injection, and preferentially after myocardial infarct rather than chronic heart failure.

Pathway-specific reporter genes to study stem cell biology

Little is known on the phenotypic characteristics of stem cells (SCs) after they are transplanted to the myocardium, in part due to lack of noninvasive platforms to study SCs directly in the living subject. Reporter gene imaging has played a valuable role in the noninvasive assessment of cell fate in vivo. In this study, we validated a pathway-specific reporter gene that can be used to noninvasively image the phenotype of SCs transplanted to the myocardium. Rat mesenchymal SCs (MSCs) were studied for phenotypic evidence of myogenic characteristics under in vitro conditions. After markers of myogenic characteristics were identified, we constructed a reporter gene sensor, comprising the firefly luciferase (Fluc) reporter gene driven by the troponin T (TnT) promoter (cardio MSCs had threefold expression in polymerase chain reaction compared to control MSCs) using a two-step signal amplification strategy. MSCs transfected with TnT-Fluc were studied and validated under in vitro conditions, showing a strong signal after MSCs acquired myogenic characteristics. Lastly, we observed that cardio MSCs had higher expression of the reporter sensor compared to control cells (0.005 ± 0.0005 vs 0.0025 ± 0.0008 Tnt-Fluc/ubiquitin-Fluc, P < .05), and that this novel sensor can detect the change in the phenotype of MSCs directly in the living subject. Pathway-specific reporter gene imaging allows assessment of changes in the phenotype of MSCs after delivery to the ischemic myocardium, providing important information on the phenotype of these cells. Imaging sensors like the one described here are critical to better understanding of the changes that SCs undergo after transplantation.

Cardiac mesenchymal cells from failing and nonfailing hearts limit ventricular dilation when administered late after infarction

Although cell therapy-mediated cardiac repair offers promise for treatment/management of heart failure, lack of fundamental understanding of how cell therapy works limits its translational potential. In particular, whether reparative cells from failing hearts differ from cells derived from nonfailing hearts remains unexplored. Here, we assessed differences between cardiac mesenchymal cells (CMC) derived from failing (HF) versus nonfailing (Sham) hearts and whether the source of donor cells (i.e., from HF vs. Sham) limits reparative capacity, particularly when administered late after infarction. To determine the impact of the donor source of CMCs, we characterized the transcriptional profile of CMCs isolated from sham (Sham-CMC) and failing (HF-CMC) hearts. RNA-seq analysis revealed unique transcriptional signatures in Sham-CMC and HF-CMC, suggesting that the donor source impacts CMC. To determine whether the donor source affects reparative potential, C57BL6/J female mice were subjected to 60 min of regional myocardial ischemia and then reperfused for 35 days. In a randomized, controlled, and blinded fashion, vehicle, HF-CMC, or Sham-CMC were injected into the lumen of the left ventricle at 35 days post-MI. An additional 5 weeks later, cardiac function was assessed by echocardiography, which indicated that delayed administration of Sham-CMC and HF-CMC attenuated ventricular dilation. We also determined whether Sham-CMC and HF-CMC treatments affected ventricular histopathology. Our data indicate that the donor source (nonfailing vs. failing hearts) affects certain aspects of CMC, and these insights may have implications for future studies. Our data indicate that delayed administration of CMC limits ventricular dilation and that the source of CMC may influence their reparative actions.NEW & NOTEWORTHY Most preclinical studies have used only cells from healthy, nonfailing hearts. Whether donor condition (i.e., heart failure) impacts cells used for cell therapy is not known. We directly tested whether donor condition impacted the reparative effects of cardiac mesenchymal cells in a chronic model of myocardial infarction. Although cells from failing hearts differed in multiple aspects, they retained the potential to limit ventricular remodeling.

Human Amniotic Mesenchymal Stem Cells Promote Endogenous Bone Regeneration

Bone regeneration has become a research hotspot and therapeutic target in the field of bone and joint medicine. Stem cell-based therapy aims to promote endogenous regeneration and improves therapeutic effects and side-effects of traditional reconstruction of significant bone defects and disorders. Human amniotic mesenchymal stem cells (hAMSCs) are seed cells with superior paracrine functions on immune-regulation, anti-inflammation, and vascularized tissue regeneration. The present review summarized the source and characteristics of hAMSCs and analyzed their roles in tissue regeneration. Next, the therapeutic effects and mechanisms of hAMSCs in promoting bone regeneration of joint diseases and bone defects. Finally, the clinical application of hAMSCs from current clinical trials was analyzed. Although more studies are needed to confirm that hAMSC-based therapy to treat bone diseases, the clinical application prospect of the approach is worth investigating.

NFATc1+CD31+CD45- circulating multipotent stem cells derived from human endocardium and their therapeutic potential

Many studies have shown the existence of cardiac stem cells in the myocardium and epicardial progenitor cells in the epicardium. However, the characteristics of stem cells in the endocardium has not been fully elucidated. In this study, we investigated the origin of newly identified cells in the blood and their therapeutic potential. The new population of cells, identified from human peripheral blood, was quite different from previously reported stem cells. These newly identified cells, which we named Circulating Multipotent Stem (CiMS) cells, were multipotent, and therefore differentiated into multiple lineages in vitro and in vivo. In order to determine the origin of these cells, we collected peripheral blood from a group of patients who underwent bone marrow, liver, heart, or kidney transplantation. We identified the endocardium as the origin of these cells because the Short Tandem Repeat profile of CiMS cells from the recipient had changed from the recipient's profile to the donor's profile after heart transplantation. CiMS cells significantly increased after stimuli to the endocardium, such as catheter ablation for arrhythmia or acute myocardial infarction. CiMS cells circulate in human peripheral blood and are easily obtainable, suggesting that these cells could be a promising tool for cell therapy.

Predicting Angiogenesis by Endothelial Progenitor Cells Relying on In-Vitro Function Assays and VEGFR-2 Expression Levels

Clinical trials have demonstrated the safety and efficacy of autologous endothelial progenitor cell (EPC) therapy in various diseases. Since EPCs' functions are influenced by genetic, systemic and environmental factors, the therapeutic potential of each individual EPCs is unknown and may affect treatment outcome. Therefore, our aim was to compare EPCs function among healthy donors in order to predict blood vessel formation (angiogenesis) before autologous EPC transplantation. Human EPCs were isolated from the blood of ten volunteers. EPCs proliferation rate, chemoattractant ability, and CXCR4 mRNA levels were different among donors (p < 0.0001, p < 0.01, p < 0.001, respectively). A positive correlation was found between SDF-1, CXCR4, and EPCs proliferation (R = 0.736, p < 0.05 and R = 0.8, p < 0.01, respectively). In-vivo, blood vessels were counted ten days after EPCs transplantation in a subcutaneous mouse model. Mean vessel density was different among donors (p = 0.0001); nevertheless, donors with the lowest vessel densities were higher compared to control (p < 0.05). Finally, using a linear regression model, a mathematical equation was generated to predict blood vessel density relying on: (i) EPCs chemoattractivity, and (ii) VEGFR-2 mRNA levels. Results reveal differences in EPCs functions among healthy individuals, emphasizing the need for a potency assay to pave the way for standardized research and clinical use of human EPCs.

SDF-1 induces TNF-mediated apoptosis in cardiac myocytes

Chemokines are small secreted proteins with chemoattractant properties that play a key role in inflammation. One such chemokine, Stromal cell-derived factor-1 (SDF-1) also known as CXCL12, and its receptor, CXCR4, are expressed and functional in cardiac myocytes. SDF-1 both stimulates and enhances the cellular signal which attracts potentially beneficial stem cells for tissue repair within the ischemic heart. Paradoxically however, this chemokine is known to act in concert with the inflammatory cytokines of the innate immune response which contributes to cellular injury through the recruitment of inflammatory cells during ischemia. In the present study, we have demonstrated that SDF-1 has dose dependent effects on freshly isolated cardiomyocytes. Using Tunnel and caspase 3-activation assays, we have demonstrated that the treatment of isolated adult rat cardiac myocyte with SDF-1 at higher concentrations (pathological concentrations) induced apoptosis. Furthermore, ELISA data demonstrated that the treatment of isolated adult rat cardiac myocyte with SDF-1 at higher concentrations upregulated TNF-α protein expression which directly correlated with subsequent apoptosis. There was a significant reduction in SDF-1 mediated apoptosis when TNF-α expression was neutralized which suggests that SDF-1 mediated apoptosis is TNF-α-dependent. The fact that certain stimuli are capable of driving cardiomyocytes into apoptosis indicates that these cells are susceptible to clinically relevant apoptotic triggers. Our findings suggest that the elevated SDF-1 levels seen in a variety of clinical conditions, including ischemic myocardial infarction, may either directly or indirectly contribute to cardiac cell death via a TNF-α mediated pathway. This highlights the importance of this receptor/ligand in regulating the cardiomyocyte response to stress conditions.

Effect of human thymus adipose tissue-derived mesenchymal stem cells on myocardial infarction in rat model

Background and objective

Stem cell (SC) therapy exhibits promising therapeutic efficiency against cardiovascular disease. The thymus adipose tissue (TAT) is familiar to cardiac surgeons with sternotomy; however, the application of TAT in SC therapy remains unknown. We assessed the effectiveness of TAT-derived mesenchymal SCs (TAT-MSCs) in the rat myocardial infarction (MI) model.

Methods

The human TATs were obtained from the patients who underwent coronary artery bypass graft surgery. In cell studies, we performed the cumulative population doubling level assessment, fluorescence-activated cell sorting analysis, and differentiation study. In animal studies, we segregated Sprague-Dawley rats (ischemia-reperfusion model) into three (sham, vehicle, and TAT-MSC) groups based on their corresponding treatment. Trans-thoracic echocardiogram (TTE) was obtained to assess the recovery of heart function in the 1st, 4th, 8th, and 12th week after surgical manipulations. After echocardiographic study, infarcted area of the heart was measured using triphenyl tetrazolium chloride (TTC) stain.

Results

The sham group exhibited significantly better systolic and diastolic function (SDF) than the other groups did. After one week of TAT-MSC or vehicle injection, the TAT-MSC group exhibited a significant improvement in the E/E' value (25.75 ± 1.09 vs. 24.20 ± 0.91, p < 0.001) compared to the vehicle group. Although statistically insignificant, the trend of improvement in SDF was better in the TAT-MSC group than in the vehicle group. The infarcted area measured by TTC staining was 22.81 ± 6.41% and 29.95 ± 9.09% in the TAT-MSC and vehicle groups, respectively (p = 0.04).

Conclusion

Although TTE results exhibited insignificant variations in SDF, a trend with improvement in the SDF of the heart was observed in the TAT-MSC group compared to the vehicle group. The infarcted area of heart indicated significant reduction in the TAT-MSC group compared to the vehicle group as confirmed by histopathological study.

Angiogenic Factor AGGF1-Primed Endothelial Progenitor Cells Repair Vascular Defect in Diabetic Mice

Hyperglycemia-triggered vascular abnormalities are the most serious complications of diabetes mellitus (DM). The major cause of vascular dysfunction in DM is endothelial injury and dysfunction associated with the reduced number and dysfunction of endothelial progenitor cells (EPCs). A major challenge is to identify key regulators of EPCs to restore DM-associated vascular dysfunction. We show that EPCs from heterozygous knockout Aggf1^+/- mice presented with impairment of proliferation, migration, angiogenesis, and transendothelial migration as in hyperglycemic mice fed a high-fat diet (HFD) or db/db mice. The number of EPCs from Aggf1^+/- mice was significantly reduced. Ex vivo, AGGF1 protein can fully reverse all damaging effects of hyperglycemia on EPCs. In vivo, transplantation of AGGF1-primed EPCs successfully restores blood flow and blocks tissue necrosis and ambulatory impairment in HFD-induced hyperglycemic mice or db/db mice with diabetic hindlimb ischemia. Mechanistically, AGGF1 activates AKT, reduces nuclear localization of Fyn, which increases the nuclear level of Nrf2 and expression of antioxidative genes, and inhibits reactive oxygen species generation. These results suggest that Aggf1 is required for essential function of EPCs, AGGF1 fully reverses the damaging effects of hyperglycemia on EPCs, and AGGF1 priming of EPCs is a novel treatment modality for vascular complications in DM.

The Human Coronary Collateral Circulation, Its Extracardiac Anastomoses and Their Therapeutic Promotion

Cardiovascular disease remains the leading global cause of death, and the number of patients with coronary artery disease (CAD) and exhausted therapeutic options (i.e., percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG) and medical treatment) is on the rise. Therefore, the evaluation of new therapeutic approaches to offer an alternative treatment strategy for these patients is necessary. A promising research field is the promotion of the coronary collateral circulation, an arterio-arterial network able to prevent or reduce myocardial ischemia in CAD. This review summarizes the basic principles of the human coronary collateral circulation, its extracardiac anastomoses as well as the different therapeutic approaches, especially that of stimulating the extracardiac collateral circulation via permanent occlusion of the internal mammary arteries.

CD133+ bone marrow stem cells (BMSC) control platelet activation - Role of ectoNTPDase-1 (CD39)

BACKGROUND

We previously demonstrated CD133+ bone marrow stem cells (BMSC) to promote hepatic proliferation for liver regeneration. Here, we evaluated the capacity of CD133+BMSC to utilize platelets for homing to vasculature and concomitant controlling their aggregability upon ADP stimulation.

METHODS

CD133+BMSC and platelets were co-cultured along micro endothelial cells under variable flow conditions and tested for homing levels along vasculature. Aggregometry and FACS analysis were utilized to evaluate platelet reactivity following co-incubation ± CD133+BMSC. RT-PCR and FACS analyses served to characterize ADP degrading ectonucleoside triphosphate diphosphohydrolase-1 (ectoNTPDase-1/CD39) expression on various cell types.

RESULTS

Platelets attracted human CD133+BMSC to autologous micro endothelium under shear stress unaffected by ADP stimulation. However, CD133+BMSC inhibited ADP-mediated platelet activation and aggregation. Latter was dependent on ectoNTPDase-1 expression levels. Platelet aggregatory control was increased with CD133+BMSC compared to CD133+PHSC. Different effects of those stem cell subtypes positively correlated with their FACS-detected expression levels of ectoNTPDase-1.

CONCLUSION

We provide evidence that CD133+BMSC are capable of controlling ADP-dependent platelet aggregation and activation by direct interaction dependent on cellular expression of ectoNTPDase-1. Whether different capacities of BMSC modulate platelet-depending thrombogenicity at sites of regeneration impact effectiveness and adverse event profiles of regenerative treatment requires further evaluation.

Apheresis on aged patients/donors with complicated backgrounds like ischemic heart disease, arrhythmia, and others

Peripheral blood stem cells (PBSCs) are currently one of the most important stem cell sources for hematopoietic stem cell transplantation as well as cell therapy for ischemic heart disease or critical limb ischemia. Thus, it is sometimes necessary to collect autologous PBSCs from donors who have comorbidities. In terms yield, a sufficient number of PBSCs can be collected from donors with comorbidities for performing cell therapy if their age is < 60 years or up to a maximum of 70 years, although the number of PBSCs collected from older donors would probably be lower than that obtained from younger donors. On the other hand, granulocyte colony-stimulating factor (G-CSF) administration sometimes results in severe adverse events (AEs), such as ischemic heart disease and vascular thrombosis. Therefore, it is very important to perform strict medical check-ups according to the standards for donor operations in each country before apheresis. The apheresis procedure and G-CSF administration should be performed after administering the appropriate treatment. There is very less information available regarding AEs related to citrate administration during apheresis in aged donors with complicated medical histories. Medical staff should have knowledge of the electrocardiogram (ECG) QTc prolongation that occurs during apheresis owing to hypocalcemia caused by citrate administration, necessitating electrocardiographic monitoring of patients. Calcium should be administered during apheresis to prevent citrate related symptoms.

The march of pluripotent stem cells in cardiovascular regenerative medicine

Cardiovascular disease (CVD) continues to be the leading cause of global morbidity and mortality. Heart failure remains a major contributor to this mortality. Despite major therapeutic advances over the past decades, a better understanding of molecular and cellular mechanisms of CVD as well as improved therapeutic strategies for the management or treatment of heart failure are increasingly needed. Loss of myocardium is a major driver of heart failure. An attractive approach that appears to provide promising results in reducing cardiac degeneration is stem cell therapy (SCT). In this review, we describe different types of stem cells, including embryonic and adult stem cells, and we provide a detailed discussion of the properties of induced pluripotent stem cells (iPSCs). We also present and critically discuss the key methods used for converting somatic cells to pluripotent cells and iPSCs to cardiomyocytes (CMs), along with their advantages and limitations. Integrating and non-integrating reprogramming methods as well as characterization of iPSCs and iPSC-derived CMs are discussed. Furthermore, we critically present various methods of differentiating iPSCs to CMs. The value of iPSC-CMs in regenerative medicine as well as myocardial disease modeling and cardiac regeneration are emphasized.

Endothelial progenitor cells in age-related vascular remodeling

Accumulating evidence has demonstrated that endothelial progenitor cells (EPCs) could facilitate the reendothelialization of injured arteries by replacing the dysfunctional endothelial cells, thereby suppressing the formation of neointima. Meanwhile, other findings suggest that EPCs may be involved in the pathogenesis of age-related vascular remodeling. This review is presented to summarize the characteristics of EPCs and age-related vascular remodeling. In addition, the role of EPCs in age-related vascular remodeling and possible solutions for improving the therapeutic effects of EPCs in the treatment of age-related diseases are discussed.

Modulation of Inflammatory Reactions by Low-Dose Ionizing Radiation: Cytokine Release of Murine Endothelial Cells Is Dependent on Culture Conditions

Background

In many European countries, patients with a variety of chronical inflammatory diseases are treated with low-dose radiotherapy (LD-RT). In contrast to high-dose irradiation given to tumor patients, little is known about radiobiological mechanisms underlying this clinical successful LD-RT application. The objective of this study was to gain a better insight into the modulation of inflammatory reactions after LD-RT on the basis of endothelial cells (EC) as major participants and regulators of inflammation.

Methods

Three murine EC lines were cultivated under 2D and 3D culture conditions and irradiated with doses from 0.01 Gy to 2 Gy. To simulate an inflammatory situation, cells were activated with TNF-α. After LD-RT, a screening of numerous inflammatory markers was determined by multiplex assay, followed by detailed analyses of four cytokines (KC, MCP-1, RANTES, and G-CSF). Additionally, the monocyte binding to EC was analyzed.

Results

Cytokine concentrations were dependent on culture condition, IR dose, time point after IR, and EC origin. IR caused nonlinear dose-dependent effects on secretion of the proinflammatory cytokines KC, MCP-1, and RANTES. The monocyte adhesion was significantly enhanced after IR as well as activation.

Conclusions

The study shows that LD-RT, also using very low radiation doses, has a clear immunomodulatory effect on EC as major participants and regulators of inflammation.

Activation and Migration of Adventitial Fibroblasts Contributes to Vascular Remodeling

The rat carotid artery balloon injury model was used to prove the activation and migration of adventitial fibroblasts. We found that at day 7 after injury, adventitial fibroblasts proliferated, transformed into myofibroblasts under transmission electron microscopy in the model group. Simultaneously, we proved that the adventitial cells migrated to the media and intima on seventh day after injury by directly labeled the adventitial cells by the in vivo gene transfer technique. Moreover, we captured the precise moment when the adventitial fibroblasts migrated from the adventitia to the media through the external elastic plate under transmission electron microscope. This study provides direct evidences that adventitial fibroblasts activate and migrate to the media and intima, then actively take part in revascularization. Anat Rec, 301:1216-1223, 2018. © 2018 Wiley Periodicals, Inc.

Pursuing meaningful end-points for stem cell therapy assessment in ischemic cardiac disease

Despite optimal interventional and medical therapy, ischemic heart disease is still an important cause of morbidity and mortality worldwide. Although not included in standard of care rehabilitation, stem cell therapy (SCT) could be a solution for prompting cardiac regeneration. Multiple studies have been published from the beginning of SCT until now, but overall no unanimous conclusion could be drawn in part due to the lack of appropriate end-points. In order to appreciate the impact of SCT, multiple markers from different categories should be considered: Structural, biological, functional, physiological, but also major adverse cardiac events or quality of life. Imaging end-points are among the most used - especially left ventricle ejection fraction (LVEF) measured through different methods. Other imaging parameters are infarct size, myocardial viability and perfusion. The impact of SCT on all of the aforementioned end-points is controversial and debatable. 2D-echocardiography is widely exploited, but new approaches such as tissue Doppler, strain/strain rate or 3D-echocardiography are more accurate, especially since the latter one is comparable with the MRI gold standard estimation of LVEF. Apart from the objective parameters, there are also patient-centered evaluations to reveal the benefits of SCT, such as quality of life and performance status, the most valuable from the patient point of view. Emerging parameters investigating molecular pathways such as non-coding RNAs or inflammation cytokines have a high potential as prognostic factors. Due to the disadvantages of current techniques, new imaging methods with labelled cells tracked along their lifetime seem promising, but until now only pre-clinical trials have been conducted in humans. Overall, SCT is characterized by high heterogeneity not only in preparation, administration and type of cells, but also in quantification of therapy effects.

Pushing the Right Buttons: Improving Efficacy of Therapeutic DNA Vectors

Gene therapy represents a potent therapeutical application for regenerative medicine. So far, viral and nonviral approaches suffer from major drawbacks hindering efficient gene therapeutic applicability: the immunogenicity of viral systems on the one hand, and the low gene transfer efficiency of nonviral systems on the other hand. Therefore, there is a high demand for improvements of therapeutical systems at several levels. This review summarizes different DNA vector modifications to enhance biological efficacy and efficiency of therapeutical vectors, aiming for low toxicity, high specificity, and biological efficacy-the cornerstones for successful translation of gene therapy into the clinic. We aim to provide a step-by-step instruction to optimize their vectors to achieve the desired outcome of gene therapy. Our review provides the means to either construct a potent gene therapeutic vector de novo or to specifically address a bottleneck in the chain of events mandatory for therapeutic success. Although most of the introduced techniques can be translated into different areas, this review primarily addresses improvements for applications in transient gene therapy in the field of tissue engineering.

Stem cells and heart disease - Brake or accelerator?

After two decades of intensive research and attempts of clinical translation, stem cell based therapies for cardiac diseases are not getting closer to clinical success. This review tries to unravel the obstacles and focuses on underlying mechanisms as the target for regenerative therapies. At present, the principal outcome in clinical therapy does not reflect experimental evidence. It seems that the scientific obstacle is a lack of integration of knowledge from tissue repair and disease mechanisms. Recent insights from clinical trials delineate mechanisms of stem cell dysfunction and gene defects in repair mechanisms as cause of atherosclerosis and heart disease. These findings require a redirection of current practice of stem cell therapy and a reset using more detailed analysis of stem cell function interfering with disease mechanisms. To accelerate scientific development the authors suggest intensifying unified computational data analysis and shared data knowledge by using open-access data platforms.

Harnessing Epicardial Progenitor Cells and Their Derivatives for Rescue and Repair of Cardiac Tissue After Myocardial Infarction

PURPOSE OF REVIEW

Ischemic heart disease and stroke lead to the greatest number of deaths worldwide. Despite decreased time to intervention and improvements in the standard of care, 1 out of 5 patients that survive a myocardial infarction (MI) still face long-term chronic heart failure and a 5-year mortality rate of about 50%. Based on their multi-potency for differentiation and paracrine activity, epicardial cells and their derivatives have potential to rescue jeopardized tissue and/or promote cardiac regeneration. Here we review the diagnosis and treatment of MI, basic epicardial cell biology, and potential treatment strategies designed to harness the reparative properties of epicardial cells.

RECENT FINDINGS

During cardiac development, epicardial cells covering the surface of the heart generate migratory progenitor cells that contribute to the coronary vasculature and the interstitial fibroblasts. Epicardial cells also produce paracrine signals required for myocardial expansion and cardiac growth. In adults with myocardial infarction, epicardial cells and their derivatives provide paracrine factors that affect myocardial remodeling and repair. At present, the intrinsic mechanisms and extrinsic signals that regulate epicardial cell fate and paracrine activity in adults remain poorly understood.

SUMMARY

Human diseases that result in heart failure due to negative remodeling or extensive loss of viable cardiac tissue require new, effective treatments. Improved understanding of epicardial cell function(s) and epicardial-mediated secretion of growth factors, cytokines and hormones during cardiac growth, homeostasis and injury may lead to new ways to treat patients with myocardial infarction.

Regenerative Therapy for Stroke

Stroke remains a leading cause of death and disability worldwide. An increasing number of animal studies and preclinical trials have, however, provided evidence that regenerative cell-based therapies can lead to functional recovery in stroke patients. Stem cells can differentiate into neural lineages to replace lost neurons. Moreover, they provide trophic support to tissue at risk in the penumbra surrounding the infarct area, enhance vasculogenesis, and help promote survival, migration, and differentiation of the endogenous precursor cells after stroke. Stem cells are highly migratory and seem to be attracted to areas of brain pathology such as ischemic regions. The pathotropism may follow the paradigm of stem cell homing to bone marrow and leukocytes migrating to inflammatory tissue. The molecular signaling therefore may involve various chemokines, cytokines, and integrins. Among these, stromal cell-derived factor-1 (SDF-1)/CXC chemokine receptor-4 (CXCR4) signaling is required for the interaction of stem cells and ischemia-damaged host tissues. SDF-1 is secreted primarily by bone marrow fibroblasts and is required for BMSC homing to bone marrow. Overexpression of SDF-1 in ischemic tissues has been found to enhance stem cell recruitment from peripheral blood and to induce neoangiogenesis. Furthermore, SDF-1 expression in the lesioned area peaked within 7 days postischemia, in concordance with the time window of G-CSF therapy for stroke. Recent data have shown that SDF-1 expression is directly proportional to reduced tissue oxygen tension. SDF-1 gene expression is regulated by hypoxic-inducible factor-1 (HIF-1), a hypoxia-dependent stabilization transcription factor. Thus, ischemic tissue may recruit circulating progenitors regulated by hypoxia through differential expression of HIF-1α and SDF-1. In addition to SDF-1, β2-integrins also play a role in the homing of hematopoietic progenitor cells to sites of ischemia and are critical for their neovascularization capacity. In our recent report, increased expression of β1-integrins apparently contributed to the local neovasculization of the ischemic brain as well as its functional recovery. Identification of the molecular pathways involved in stem cell homing into the ischemic areas could pave the way for the development of new treatment regimens, perhaps using small molecules, designed to enhance endogeneous mobilization of stem cells in various disease states, including chronic stroke and other neurodegenerative diseases. For maximal functional recovery, however, regenerative therapy may need to follow combinatorial approaches, which may include cell replacement, trophic support, protection from oxidative stress, and the neutralization of the growth-inhibitory components for endogenous neuronal stem cells.

Stem Cell Therapy for Ischemic Heart Disease: Beginning or End of the Road?

Despite improvements in emergency treatment, myocardial infarction is often the beginning of a downward spiral leading to congestive heart failure. Other than heart transplantation, current therapeutic means aim at enabling the organism to survive with a heart that is working at a fraction of its original capacity. It is therefore no surprise that cardiac stem cell therapy has raised many hopes. However, neither the ideal source and type of stem cell nor the critical cell number and mode of application have been defined so far. Early reports on myocardial repair by adult bone marrow stem cells from rodent models promoted an unparalleled boost of clinical and experimental cell therapy studies. The phenomenon of stem/progenitor cell-induced angiogenesis in ischemic myocardium has ever since been reproduced by numerous groups in a variety of small and large animal models. Myogenesis, however, is an altogether different matter. Many of the initial clinical studies were fueled by the suggestion that early hematopoietic stem cells have a plasticity high enough to enable cross-lineage differentiation into cells of cardiomyocyte phenotype, but the initial enthusiasm has largely faded. The myogenic potential of stroma cell-derived mesenchymal stem cells is much better documented in animal models, but transfer to the clinical setting faces a variety of obstacles. In clinical pilot trials, we and others have demonstrated the feasibility and safety of administering progenitor cells derived from autologous bone marrow to the myocardium of patients with ischemic heart disease. Clinical efficacy data are still rare, but the few controlled trials that have been completed uniformly show a tendency towards better heart function in cell-treated patients. This review is an attempt to describe the scientific basis for cardiac cell therapy from the point of view of the clinician, focusing on problems that arise with beginning translation into the clinical setting.

Cell therapy for heart disease after 15 years: Unmet expectations

Over the past two decades cardiac cell therapy (CCT) has emerged as a promising new strategy to cure heart diseases at high unmet need. Thousands of patients have entered clinical trials for acute or chronic heart conditions testing different cell types, including autologous or allogeneic bone marrow (BM)-derived mononuclear or selected cells, BM- or adipose tissue-derived mesenchymal cells, or cardiac resident progenitors based on their potential ability to regenerate scarred or dysfunctional myocardium. Nowadays, the original enthusiasm surrounding the regenerative medicine field has been cushioned by a cumulative body of evidence indicating an inefficient or modest efficacy of CCT in improving cardiac function, along with the continued lack of indisputable proof for long-term prognostic benefit. In this review, we have firstly comprehensively outlined the positive and negative results of cell therapy studies in patients with acute myocardial infarction, refractory angina and chronic heart failure. Next, we have discussed cell therapy- and patient-related variables (e.g. cell intrinsic and extrinsic characteristics as well as criteria of patient selection and proposed methodologies) that might have dampened the efficacy of past cell therapy trials. Finally, we have addressed critical factors to be considered before embarking on further clinical trials.

Implantation of a Poly-L-Lactide GCSF-Functionalized Scaffold in a Model of Chronic Myocardial Infarction

A previously developed poly-l-lactide scaffold releasing granulocyte colony-stimulating factor (PLLA/GCSF) was tested in a rabbit chronic model of myocardial infarction (MI) as a ventricular patch. Control groups were constituted by healthy, chronic MI and nonfunctionalized PLLA scaffold. PLLA-based electrospun scaffold efficiently integrated into a chronic infarcted myocardium. Functionalization of the biopolymer with GCSF led to increased fibroblast-like vimentin-positive cellular colonization and reduced inflammatory cell infiltration within the micrometric fiber mesh in comparison to nonfunctionalized scaffold; PLLA/GCSF polymer induced an angiogenetic process with a statistically significant increase in the number of neovessels compared to the nonfunctionalized scaffold; PLLA/GCSF implanted at the infarcted zone induced a reorganization of the ECM architecture leading to connective tissue deposition and scar remodeling. These findings were coupled with a reduction in end-systolic and end-diastolic volumes, indicating a preventive effect of the scaffold on ventricular dilation, and an improvement in cardiac performance.

Current State of Stem Cell Therapy for Ischemic Heart Disease

Improvements in the care of patients with ischemic cardiovascular disease have led to improved survival but also a burgeoning population of patients with advanced ischemic heart disease. Cell therapies offer a novel approach toward cardiac "rejuvenation" via stimulation of new blood vessel growth, enhancing tissue perfusion, and via preservation or even regeneration of myocardial tissue, leading to improvements in cardiac performance after myocardial infarction and in patients with advanced heart failure. Here, we summarize and offer some thoughts on the state of the field of cell therapy for ischemic heart disease, targeting three separate conditions that have been the subject of significant clinical research: enhancing left ventricular recovery after MI, improving outcomes and symptoms in patients with congestive heart failure (CHF), and treatment of patients with refractory angina, despite maximal medical therapy.

Strategy to Prime the Host and Cells to Augment Therapeutic Efficacy of Progenitor Cells for Patients with Myocardial Infarction

Cell therapy in myocardial infarction (MI) is an innovative strategy that is regarded as a rescue therapy to repair the damaged myocardium and to promote neovascularization for the ischemic border zone. Among several stem cell sources for this purpose, autologous progenitors from bone marrow or peripheral blood would be the most feasible and safest cell-source. Despite the theoretical benefit of cell therapy, this method is not widely adopted in the actual clinical practice due to its low therapeutic efficacy. Various methods have been used to augment the efficacy of cell therapy in MI, such as using different source of progenitors, genetic manipulation of cells, or priming of the cells or hosts (patients) with agents. Among these methods, the strategy to augment the therapeutic efficacy of the autologous peripheral blood mononuclear cells (PBMCs) by priming agents may be the most feasible and the safest method that can be applied directly to the clinic. In this review, we will discuss the current status and future directions of priming PBMCs or patients, as for cell therapy of MI.

Stem cell-based therapy: Improving myocardial cell delivery

Stem cell-based therapies form an exciting new class of medicine that attempt to provide the body with the building blocks required for the reconstruction of damaged organs. However, delivering cells to the correct location, while preserving their integrity and functional properties, is a complex undertaking. These challenges have led to the development of a highly dynamic interdisciplinary research field, wherein medical, biological, and chemical sciences have collaborated to develop strategies to overcome the physiological barriers imposed on the cellular therapeutics. In this respect, improving the acute retention and subsequent survival of stem cells is key to effectively increase the effect of the therapy, while proper tissue integration is imperative for stem cells to functionally replace lost cells in damaged organs. In this review, we will use the heart as an example to highlight the current knowledge of therapeutic stem cell utilization, the existing pitfalls and limitations, and the approaches that have been developed to overcome them.

Discrepancy between short-term and long-term effects of bone marrow-derived cell therapy in acute myocardial infarction: a systematic review and meta-analysis

Background

Bone marrow-derived cell therapy has been used to treat acute myocardial infarction. However, the therapeutic efficacy of this approach remains controversial. Here, we performed a systematic review and meta-analysis to evaluate short-term and long-term effectiveness of bone marrow-derived therapy.

Methods

We searched eight databases (Ovid-Medline, Ovid-EMBASE, Cochrane Library, KoreaMed, KMBASE, KISS, RISS, and KisTi) up to December 2014. Demographic characteristics, clinical outcomes, and adverse events were analyzed. We identified 5534 potentially relevant studies; 405 were subjected to a full-text review. Forty-three studies with 2635 patients were included in this review.

Results

No safety issues related to cell injection were reported during follow-up. At 6 months, cell-injected patients showed modest improvements in left ventricular ejection fraction (LVEF) compared with the control group. However, there were no differences between groups at other time points. In the cardiac MRI analysis, there were no significant differences in infarct size reduction between groups. Interestingly, mortality tended to be reduced at the 3-year follow-up, and at the 5-year follow-up, cell injection significantly decreased all-cause mortality.

Conclusions

This meta-analysis demonstrated discrepancies between short-term LV functional improvement and long-term all-cause mortality. Future clinical trials should include long-term follow-up outcomes to validate the therapeutic efficacy of cell therapy.

Tumor Necrosis Factor α Regulates Endothelial Progenitor Cell Migration via CADM1 and NF-kB

Shortly after the discovery of endothelial progenitor cells (EPCs) in 1997, many clinical trials were conducted using EPCs as a cellular based therapy with the goal of restoring damaged organ function by inducing growth of new blood vessels (angiogenesis). Results were disappointing, largely because the cellular and molecular mechanisms of EPC-induced angiogenesis were not clearly understood. Following injection, EPCs must migrate to the target tissue and engraft prior to induction of angiogenesis. In this study EPC migration was investigated in response to tumor necrosis factor α (TNFα), a pro-inflammatory cytokine, to test the hypothesis that organ damage observed in ischemic diseases induces an inflammatory signal that is important for EPC homing. In this study, EPC migration and incorporation were modeled in vitro using a coculture assay where TNFα treated EPCs were tracked while migrating toward vessel-like structures. It was found that TNFα treatment of EPCs increased migration and incorporation into vessel-like structures. Using a combination of genomic and proteomic approaches, NF-kB mediated upregulation of CADM1 was identified as a mechanism of TNFα induced migration. Inhibition of NF-kB or CADM1 significantly decreased migration of EPCs in vitro suggesting a role for TNFα signaling in EPC homing during tissue repair. Stem Cells 2016;34:1922-1933.

Therapeutic Angiogenesis With Bone Marrow—Derived Stem Cells

Despite that advances in medical treatment and interventional procedures have reduced the mortality rate in patients with coronary artery disease, the number of patients with refractory myocardial ischemia and congestive heart failure is rapidly increasing. Experimental studies have demonstrated that bone marrow (BM) contains adult stem cells that can induce neovascularization and improve heart function in ischemic myocardium. Recent insights into the understanding of the mechanisms involved in proliferation, recruitment, mobilization, and incorporation of BM-derived stem cells into the myocardium and blood vessels have prompted development of cellular transplantation therapy for heart diseases refractory to conventional therapy. Initial preliminary clinical studies indicated potential clinical benefit of BM therapy in patients with acute myocardial infarction and chronic myocardial ischemia. Nevertheless, many obstacles remain, such as long-term safety and optimal timing and treatment strategies for BM cell therapy, and these issues need to be addressed in rationally designed, randomized clinical trials.

Mobilization of Endothelial Progenitor Cells Following Creation of Arteriovenous Access in Patients with End-Stage Renal Disease

BACKGROUND

A patent arteriovenous (AV) fistula induces activation of regional vascular endothelium and vascular shear force. Shear stress is an important physiological force in mobilizing endothelial progenitor cells (EPCs). This study aimed to explore the perioperative changes of circulating EPC levels for patients who require hemodialysis and underwent radiocephalic fistula operation.

METHODS

This prospective cohort study included patients who received a radiocephalic fistula surgery when they were between 25 and 65 years of age. The subjects were followed for 90 days postoperatively for any stenotic events or immaturity of the fistula. Blood samples were obtained on the day before surgery and at postoperation day (POD) 3 and 30. CD133+/KDR+ cells, defined as EPCs, were analyzed using flow cytometry. Blood flow of the fistula was followed on POD 3 and 30.

RESULTS

A total of 30 patients were enrolled in the study from July 2009 to December 2011. One patient dropped out of the study and seven patients developed a stenotic (or immature) AV fistula (7/29, 24.1%). There were positive linear relationships between EPC numbers and shear rate postoperatively, which were more significant on POD 30. In addition, postoperative mobilization of EPCs was significantly higher in patients who developed a stenotic fistula than those without.

CONCLUSIONS

The mobilization of circulating EPCs correlated with a compromised arteriovenous fistula. The biological significance of increased EPC numbers need to be determined in future studies.

KEY WORDS

Arteriovenous fistula; Endothelial progenitor cells.

BM ageing: Implication for cell therapy with EPCs

The bone marrow (BM) is a well-recognized source of stem/progenitor cells for cell therapy in cardiovascular diseases (CVDs). Preclinical and clinical studies suggest that endothelial progenitor cells (EPCs) contribute to reparative process of vascular endothelium and participate in angiogenesis. As for all organs and cells across the lifespan, BM and EPCs are negatively impacted by ageing due to microenvironment modifications and EPC progressive dysfunctions. The encouraging results in terms of neovascularization observed in young animals after EPC administration were mitigated in aged patients treated for ischemic CVDs. The limited efficacy of EPC-based therapy in clinical setting might be ascribed at least partly to ageing. In this review, we comprehensively discussed the age-related changes of BM and EPCs and their implication for cardiovascular cell-therapies. Finally, we examined alternative approaches under investigation to enhance EPC potency.

Application of autologous platelet-rich plasma to enhance wound healing after lower limb revascularization: A case series and literature review

Dermal tissue loss in patients affected by critical limb ischemia represents a serious wound-healing problem, with high morbidity, prolonged hospital stay, and high patient care costs. Treatment of ischemic foot lesions requires limb revascularization by endovascular or open surgical intervention and individualized patient-specific wound care, including antibiotic therapy; devitalized/infected wound debridement; and advanced wound dressing. In selected patients, spinal cord stimulation, vacuum-assisted closure therapy, and bioengineered tissue or skin substitutes and growth factors have been shown to improve wound healing. In this study, we present our preliminary results on topical application of autologous platelet-rich plasma to enhance the process of wound healing after revascularization of lower limbs in patients affected by critical limb ischemia.

G-CSF contributes at the healing of tunica media of arteriotomy-injured rat carotids by promoting differentiation of vascular smooth muscle cells

Restenosis is a complex pathophysiological disease whose causative mechanisms are not fully understood. Previous studies allowed us to demonstrate the efficacy of bone marrow mesenchymal stromal cells (MSCs) transplantation in limiting the pathophysiological remodeling in a model of arteriotomy-induced (re) stenosis. In the current research we studied the effectiveness of G-CSF treatment on male rate rats that were subjected carotid arteriotomy in order to evaluate a potentially effective non-invasive strategy that recapitulates the MSC-mediated recovery of injured vessels. WKY male rats were subjected carotid arteriotomy and given a nine day treatment (3 days pre- to 6 days post-arteriotomy) with G-CSF or saline. Carotids were harvested 7 and 30 days following arteriotomy (early- and late-phase, respectively). Although morphometrical analysis did not reveal differences in lumen narrowing between G-CSF- and PBS-carotids 30 days following arteriotomy, we detected a noticeable conservative effect of G-CSF treatment on vascular wall morphology. Histological and molecular analysis revealed an increase in cellularity within the tunica media with a concomitant increase of the VSMCs differentiation markers both at early- and late-phases of (re) stenotic response in G-CSF-treated carotids (Sm22-alpha, Myocd, and Smtn). These findings were accompanied by the downregulation of oxidative stress-related genes in G-CSF-injured rats. The effect exerted by G-CSF in our model of arteriotomy-induced (re) stenosis seemed support the recovery of the architecture of the tunica media of injured vessels by: (i) inducing VSMCs differentiation; and (ii) limiting the oxidative-stress response induced by arteriotomy.

Stem cell therapy for heart failure

"During the past decade, studies in animals and humans have suggested that cell therapy has positive effects for the treatment of heart failure. This clinical effect may be mediated by angiogenesis and reduction in fibrosis rather than by regeneration of myocytes. Increased microvasculature and decreased scar also likely lead to improved cardiac function in the failing heart. The effects of cell therapy are not limited to one type of cell or delivery technique. Well-designed, large-scale, randomized clinical trials with objective end points will help to fully realize the therapeutic potential of cell-based therapy for treating heart failure."

G-CSF Predicts Cardiovascular Events in Patients with Stable Coronary Artery Disease

Granulocyte-colony-stimulating-factor (G-CSF) induces mobilization of progenitor cells but may also exert pro-inflammatory and pro-thrombotic effects. Treatment with recombinant G-CSF after acute myocardial infarction is currently under examination and has been associated with in-stent restenosis. However, it is not known whether plasma levels of endogenous G-CSF are also associated with an increased cardiovascular risk. Therefore we included 280 patients with angiographically proven stable coronary artery disease. G-CSF was measured by specific ELISA and patients were followed for a median of 30 months for the occurrence of major adverse cardiovascular events (MACE: death, myocardial infarction, re-hospitalization). Those with cardiac events during follow-up showed significant higher G-CSF levels (32.3 pg/mL IQR 21.4-40.5 pg/mL vs. 24.6 pg/mL IQR 16.4-34.9 pg/mL; p<0.05) at baseline. Patients with G-CSF plasma levels above the median had a 2-fold increased risk for MACE (p<0.05). This was independent from established cardiovascular risk factors. In addition, G-CSF above the median was a predictor of clinical in-stent restenosis after implantation of bare-metal stents (6.6% vs. 19.4%; p<0.05) but not of drug-eluting stents (7.7% vs. 7.6%; p = 0.98). This data suggests that endogenous plasma levels of G-CSF predict cardiovascular events independently from established cardiac risk factors and are associated with increased in-stent restenosis rates after implantation of bare metal stents.

Role of a Burr Hole and Calvarial Bone Marrow-Derived Stem Cells in the Ischemic Rat Brain: A Possible Mechanism for the Efficacy of Multiple Burr Hole Surgery in Moyamoya Disease

Objective

This study investigates the role of a burr hole and calvarial bone marrow-derived stem cells (BMSCs) in a transient ischemic brain injury model in the rat and postulates a possible mechanism for the efficacy of multiple cranial burr hole (MCBH) surgery in moyamoya disease (MMD).

Methods

Twenty Sprague-Dawley rats (250 g, male) were divided into four groups : normal control group (n=5), burr hole group (n=5), ischemia group (n=5), and ischemia+burr hole group (n=5). Focal ischemia was induced by the transient middle cerebral artery occlusion (MCAO). At one week after the ischemic injury, a 2 mm-sized cranial burr hole with small cortical incision was made on the ipsilateral (left) parietal area. Bromodeoxyuridine (BrdU, 50 mg/kg) was injected intraperitoneally, 2 times a day for 6 days after the burr hole trephination. At one week after the burr hole trephination, brains were harvested. Immunohistochemical stainings for BrdU, CD34, VEGF, and Doublecortin and Nestin were done.

Results

In the ischemia+burr hole group, BrdU (+), CD34 (+), and Doublecortin (+) cells were found in the cortical incision site below the burr hole. A number of cells with Nestin (+) or VEGF (+) were found in the cerebral parenchyma around the cortical incision site. In the other groups, BrdU (+), CD34 (+), Doublecortin (+), and Nestin (+) cells were not detected in the corresponding area. These findings suggest that BrdU (+) and CD34 (+) cells are bone marrow-derived stem cells, which may be derived from the calvarial bone marrow through the burr hole. The existence of CD34 (+) and VEGF (+) cells indicates increased angiogenesis, while the existence of Doublecortin (+), Nestin (+) cells indicates increased neurogenesis.

Conclusion

Based on these findings, the BMSCs through burr holes seem to play an important role for the therapeutic effect of the MCBH surgery in MMD.