Transcoronary transplantation of progenitor cells after myocardial infarction

Maturation of pluripotent stem cell-derived cardiomyocytes: limitations and challenges from metabolic aspects

Acute coronary syndromes, such as myocardial infarction (MI), lack effective therapies beyond heart transplantation, which is often hindered by donor scarcity and postoperative complications. Human induced pluripotent stem cells (hiPSCs) offer the possibility of myocardial regeneration by differentiating into cardiomyocytes. However, hiPSC-derived cardiomyocytes (hiPSC-cardiomyocytes) exhibit fetal-like calcium flux and energy metabolism, which inhibits their engraftment. Several strategies have been explored to improve the therapeutic efficacy of hiPSC-cardiomyocytes, such as selectively enhancing energy substrate utilization and improving the transplantation environment. In this review, we have discussed the impact of altered mitochondrial biogenesis and metabolic switching on the maturation of hiPSC-cardiomyocytes. Additionally, we have discussed the limitations inherent in current methodologies for assessing metabolism in hiPSC-cardiomyocytes, and the challenges in achieving sufficient metabolic flexibility akin to that in the healthy adult heart.

Cellular and molecular mechanisms driving cardiac tissue fibrosis: On the precipice of personalized and precision medicine

Cardiac fibrosis is a significant contributor to heart failure, a condition that continues to affect a growing number of patients worldwide. Various cardiovascular comorbidities can exacerbate cardiac fibrosis. While fibroblasts are believed to be the primary cell type underlying fibrosis, recent and emerging data suggest that other cell types can also potentiate or expedite fibrotic processes. Over the past few decades, clinicians have developed therapeutics that can blunt the development and progression of cardiac fibrosis. While these strategies have yielded positive results, overall clinical outcomes for patients suffering from heart failure continue to be dire. Herein, we overview the molecular and cellular mechanisms underlying cardiac tissue fibrosis. To do so, we establish the known mechanisms that drive fibrosis in the heart, outline the diagnostic tools available, and summarize the treatment options used in contemporary clinical practice. Finally, we underscore the critical role the immune microenvironment plays in the pathogenesis of cardiac fibrosis.

Prognostic Value of Endothelial Progenitor Cells in Acute Myocardial Infarction Patients

Objective

To determine prognostic role of endothelial progenitor cells (EPCs) in intensive care patients with acute myocardial infarction (AMI).

Materials and Methods

From December 2018 to July 2021, a total of 91 eligible patients with AMI were consecutively examined in a single intensive care unit (ICU) in China. Patients with a history of acute coronary artery disease were excluded from the study. Samples were collected within 24 hr of onset of symptoms. EPCs, defined as coexpression of CD34+/CD133+ cells or CD133+/CD34+/KDR+, were studied using flow cytometry and categorized by quartiles. Based on the 28-days mortality outcome, the patients were further divided into two groups: death and survival. The study incorporated various variables, including cardiovascular risk factors such as body mass index, hypertension, diabetes, hypercholesterolemia, atherosclerotic burden, and medication history, as well as clinical characteristics such as APACHEⅡscore, central venous-arterial carbon dioxide difference (GAP), homocysteine, creatinine, C-reactive protein, HbAlc, and cardiac index. Cox regression analysis was employed to conduct a multivariate analysis.

Results

A total of 91 patients with AMI who were admitted to the ICU were deemed eligible for inclusion in the study. Among these patients, 23 (25.3%) died from various causes during the follow-up period. The counts of EPCs were found to be significantly higher in the survival group compared to the death group (P < 0.05). In the univariate analysis, it was observed that the 28-days mortality rate was associated with the several factors, including the APACHEⅡscore (P=0.00), vasoactive inotropic score (P=0.03), GAP (P=0.00), HCY (P=0.00), creatinine (P=0.00), C-reactive protein (P=0.00), HbAlc (P=0.00), CI (P=0.01), quartiles of CD34+/CD133+ cells (P=0.00), and quartiles of CD34+/CD133+/KDR+ cells (P=0.00). CD34+/CD133+/KDR+ cells retained statistical significance in Cox regression models even after controlling for clinical variables (HR: 6.258 × 10-10 and P=0.001). Nevertheless, no significant correlation was observed between CD34+/CD133+ cells and all-cause mortality.

Conclusions

The decreased EPCs levels, especially for CD34+/CD133+/KDR+ cells subsets, were an independent risk factor for 28-days mortality in AMI patients.

Cardiac regeneration - Past advancements, current challenges, and future directions

Cardiovascular disease is the leading cause of mortality and morbidity worldwide. Despite improvements in the standard of care for patients with heart diseases, including innovation in pharmacotherapy and surgical interventions, none have yet been proven effective to prevent the progression to heart failure. Cardiac transplantation is the last resort for patients with severe heart failure, but donor shortages remain a roadblock. Cardiac regenerative strategies include cell-based therapeutics, gene therapy, direct reprogramming of non-cardiac cells, acellular biologics, and tissue engineering methods to restore damaged hearts. Significant advancements have been made over the past several decades within each of these fields. This review focuses on the advancements of: 1) cell-based cardiac regenerative therapies, 2) the use of noncoding RNA to induce endogenous cell proliferation, and 3) application of bioengineering methods to promote retention and integration of engrafted cells. Different cell sources have been investigated, including adult stem cells derived from bone marrow and adipose cells, cardiosphere-derived cells, skeletal myoblasts, and pluripotent stem cells. In addition to cell-based transplantation approaches, there have been accumulating interest over the past decade in inducing endogenous CM proliferation for heart regeneration, particularly with the use of noncoding RNAs such as miRNAs and lncRNAs. Bioengineering applications have focused on combining cell-transplantation approaches with fabrication of a porous, vascularized scaffold using biomaterials and advanced bio-fabrication techniques that may offer enhanced retention of transplanted cells, with the hope that these cells would better engraft with host tissue to improve cardiac function. This review summarizes the present status and future challenges of cardiac regenerative therapies.

Nitric oxide promotes cell-matrix adhesion of endothelial progenitor cells under hypoxia condition via ITGA5 CpG promoter demethylation

Hypoxia or low oxygen tension causes changes in the structure and functional phenotype of the endothelial progenitor cells (EPCs). EPCs are found to be involved in angiogenesis and vascular repair. However, EPC's role in cell-matrix adhesion under hypoxia conditions is not clearly established. Nitric oxide (NO) exerts a wide range of biological functions, especially in regulating the mobilization and vascular repair of EPCs. In contrast, the link between NO and its role in cell-matrix deadhesion under hypoxia is not studied yet. Here, we investigated the protective role of NO in hypoxia-induced cell-matrix deadhesion of EPCs through an epigenetic mechanism. The EPCs were exposed to 2% hypoxia in the presence or absence of 10 μM Spermine NONOate (NO donor). The result demonstrates that hypoxia exposure intensified mitochondrial oxidative damage and energy defects. Using miScript miRNA qPCR array-based screening, the study found miR-148 as a novel target of hypoxia-induced DNMT1 activation. Mechanistically, the study discovered that hypoxia suppressed miR-148 levels and stimulated EPCs cell-matrix deadhesion via increasing DNMT1 mediated Integrin alpha-5 (ITGA5) CpG promoter hypermethylation. Treatment with a mitochondria-targeted antioxidant, MitoTEMPO, or epigenetic DNMT inhibitor, 5'-azacitidine, or miR-148 overexpression in hypoxic EPCs culture, prevented the cell-matrix deadhesion compared to hypoxic EPCs. Further, treatment of spNO or transient expression of eNOS-GFP attenuated hypoxia-induced cell-matrix deadhesion via inhibition of ITGA5 CpG island promoter methylation. In conclusion, the study provides evidence that NO is essential for cell-matrix adhesion of EPCs by epigenetically mitigating ITGA5 CpG promoter hypermethylation under hypoxia conditions. This finding uncovers the previously undefined mechanism of NO-mediated diminution of hypoxia-induced cell-matrix deadhesion and dysfunction induced by low oxygen tension.

Young bone marrow transplantation prevents aging-related muscle atrophy in a senescence-accelerated mouse prone 10 model

BACKGROUND

Young bone marrow transplantation (YBMT) has been shown to stimulate vascular regeneration in pathological conditions, including ageing. Here, we investigated the benefits and mechanisms of the preventive effects of YBMT on loss of muscle mass and function in a senescence-associated mouse prone 10 (SAMP10) model, with a special focus on the role of growth differentiation factor 11 (GDF-11).

METHODS

Nine-week-old male SAMP10 mice were randomly assigned to a non-YBMT group (n = 6) and a YBMT group (n = 7) that received the bone marrow of 8-week-old C57BL/6 mice.

RESULTS

Compared to the non-YBMT mice, the YBMT mice showed the following significant increases (all P < 0.05 in 6-7 mice): endurance capacity (>61.3%); grip strength (>37.9%), percentage of slow myosin heavy chain fibres (>14.9-15.9%). The YBMT also increased the amounts of proteins or mRNAs for insulin receptor substrate 1, p-Akt, p-extracellular signal-regulated protein kinase1/2, p-mammalian target of rapamycin, Bcl-2, peroxisom proliferator-activated receptor-γ coactivator (PGC-1α), plus cytochrome c oxidase IV and the numbers of proliferating cells (n = 5-7, P < 0.05) and CD34+/integrin-α7+ muscle stem cells (n = 5-6, P < 0.05). The YMBT significantly decreased the levels of gp91phox, caspase-9 proteins and apoptotic cells (n = 5-7, P < 0.05) in both muscles; these beneficial changes were diminished by the blocking of GDF-11 (n = 5-6, P < 0.05). An administration of mouse recombinant GDF-11 improved the YBMT-mediated muscle benefits (n = 5-6, P < 0.05). Cell therapy with young bone marrow from green fluorescent protein (GFP) transgenic mice exhibited GFP+ myofibres in aged muscle tissues.

CONCLUSIONS

These findings suggest that YBMT can prevent muscle wasting and dysfunction by mitigating apoptosis and proliferation via a modulation of GDF-11 signalling and mitochondrial dysfunction in SAMP10 mice.

Conditioned medium of bone marrow mesenchymal stem cells improves sperm parameters and reduces histological alteration in rat testicular ischaemia/reperfusion model

Testis ischaemia-reperfusion (I/R) plays a vital role in male infertility. Recent studies have demonstrated that paracrine factors of mesenchymal stem cells exert the transplanted cells' reparative effects. The present experimental study aimed to investigate the effects of conditioned medium (CM) of bone marrow-derived mesenchymal stem cells (BMMSCs). In this study, 21 rats were separated into three groups of 7 animals: sham, I/R and I/R plus CM. Sperm parameters were measured at the end of this study. Moreover, histological parameters were examined. 2-Deoxyuridine 5-triphosphate nick-end labelling (TUNEL) assay was done to assess the apoptotic cells. The count of adhered neutrophils was measured in subtunical venules. Testicular I/R led to a significant reduction in the viability and concentration of sperm and resulted in a significant elevation in the rate of abnormal sperms in comparison with sham. The CM-treated group demonstrated a significant reduction in the rate of abnormal sperm and a significant elevation in the viability and concentration of sperm compared with the I/R group. Based on the morphometric analysis, in the I/R group, epithelial thickness and seminiferous tubule diameter significantly decreased in comparison with sham. A significant reduction was seen between the I/R and sham groups regarding the mean testicular biopsy score (MTBS) value. However, an improvement was observed in the I/R + CM group MTBS value in comparison with the I/R group. TUNEL assay showed that the apoptotic cells in the seminiferous tubules belonging to the I/R group were significantly higher compared with the control. Nevertheless, apoptotic cells were reduced in the I/R + CM group compared with the I/R group. Results of the present study showed that CM of BMMSCs exerts protective effects on the testicular I/R damages.

The secretome obtained under hypoxic preconditioning from human adipose-derived stem cells exerts promoted anti-apoptotic potentials through upregulated autophagic process

BACKGROUND

Hypoxic preconditioning (HP) is a stem cell preconditioning modality designed to augment the therapeutic effects of mesenchymal stem cells (MSCs). Although autophagy is expected to play a role in HP, very little is known regarding the relationship between HP and autophagy.

METHODS AND RESULTS

The adipose-derived stem cell (ASC)-secretome obtained under normoxia (NCM) and ASC-secretome obtained under HP (HCM) were obtained by culturing ASCs for 24 h under normoxic (21% partial pressure of O₂) and hypoxic (1% partial pressure of O₂) conditions, respectively. Subsequently, to determine the in vivo effects of HCM, each secretome was injected into 70% partially hepatectomized mice, and liver specimens were obtained. HCM significantly reduced the apoptosis of thioacetamide-treated AML12 hepatocytes and promoted the autophagic processes of the cells (P < 0.05). Autophagy blockage by either bafilomycin A1 or ATG5 siRNA significantly abrogated the anti-apoptotic effect of HCM (P < 0.05), demonstrating that HCM exerts its anti-apoptotic effect by promoting autophagy. The effect of HCM - reduction of cell apoptosis and promotion of autophagic process - was also demonstrated in a mouse model.

CONCLUSIONS

HP appears to induce ASCs to release a secretome with enhanced anti-apoptotic effects by promoting the autophagic process of ASCs.

Exercise Training Effects on Circulating Endothelial and Progenitor Cells in Heart Failure

Heart failure (HF) is a major public health issue worldwide with increased prevalence and a high number of hospitalizations. Patients with chronic HF and either reduced ejection fraction (HFrEF) or mildly reduced ejection fraction (HFmrEF) present vascular endothelial dysfunction and significantly decreased circulating levels of endothelial progenitor cells (EPCs). EPCs are bone marrow-derived cells involved in endothelium regeneration, homeostasis, and neovascularization. One of the unsolved issues in the field of EPCs is the lack of an established method of identification. The most widely approved method is the use of monoclonal antibodies and fluorescence-activated cell sorting (FACS) analysis via flow cytometry. The most frequently used markers are CD34, VEGFR-2, CD45, CD31, CD144, and CD146. Exercise training has demonstrated beneficial effects on EPCs by increasing their number in peripheral circulation and improving their functional capacities in patients with HFrEF or HFmrEF. There are two potential mechanisms of EPCs mobilization: shear stress and the hypoxic/ischemic stimulus. The combination of both leads to the release of EPCs in circulation promoting their repairment properties on the vascular endothelium barrier. EPCs are important therapeutic targets and one of the most promising fields in heart failure and, therefore, individualized exercise training programs should be developed in rehabilitation centers.

Therapeutic Potential of Mesenchymal Stem Cells versus Omega n − 3 Polyunsaturated Fatty Acids on Gentamicin-Induced Cardiac Degeneration

This study compared the cardioprotective action of mesenchymal stem cells (MSCs) and PUFAs in a rat model of gentamicin (GM)-induced cardiac degeneration. Male Wistar albino rats were randomized into four groups of eight rats each: group I (control group), group II (gentamicin-treated rats receiving gentamicin intraperitoneally (IP) at dose of 100 mg/kg/day for 10 consecutive days), group III (gentamicin and PUFA group receiving gentamicin IP at dose of 100 mg/kg/day for 10 consecutive days followed by PUFAs at a dose of 100 mg/kg/day for 4 weeks), and group IV (gentamicin and MSC group receiving gentamicin IP at dose of 100 mg/kg/day followed by a single dose of MSCs (1 × 10⁶)/rat IP). Cardiac histopathology was evaluated via light and electron microscopy. Immunohistochemical detection of proliferating cell nuclear antigen (PCNA), caspase-3 (apoptosis), Bcl2, and Bax expression was performed. Moreover, cardiac malonaldehyde (MDA) content, catalase activity, and oxidative stress parameters were biochemically evaluated. Light and electron microscopy showed that both MSCs and PUFAs had ameliorative effects. Their actions were mediated by upregulating PCNA expression, downregulating caspase-3 expression, mitigating cardiac MDA content, catalase activity, and oxidative stress parameters. MSCs and PUFAs had ameliorative effects against gentamicin-induced cardiac degeneration, with MSCs showing higher efficacy compared to PUFAs.

Coronary blood flow in heart failure: cause, consequence and bystander

Heart failure is a clinical syndrome where cardiac output is not sufficient to sustain adequate perfusion and normal bodily functions, initially during exercise and in more severe forms also at rest. The two most frequent forms are heart failure of ischemic origin and of non-ischemic origin. In heart failure of ischemic origin, reduced coronary blood flow is causal to cardiac contractile dysfunction, and this is true for stunned and hibernating myocardium, coronary microembolization, myocardial infarction and post-infarct remodeling, possibly also for the takotsubo syndrome. The most frequent form of non-ischemic heart failure is dilated cardiomyopathy, caused by genetic mutations, myocarditis, toxic agents or sustained tachyarrhythmias, where alterations in coronary blood flow result from and contribute to cardiac contractile dysfunction. Hypertrophic cardiomyopathy is caused by genetic mutations but can also result from increased pressure and volume overload (hypertension, valve disease). Heart failure with preserved ejection fraction is characterized by pronounced coronary microvascular dysfunction, the causal contribution of which is however not clear. The present review characterizes the alterations of coronary blood flow which are causes or consequences of heart failure in its different manifestations. Apart from any potentially accompanying coronary atherosclerosis, all heart failure entities share common features of impaired coronary blood flow, but to a different extent: enhanced extravascular compression, impaired nitric oxide-mediated, endothelium-dependent vasodilation and enhanced vasoconstriction to mediators of neurohumoral activation. Impaired coronary blood flow contributes to the progression of heart failure and is thus a valid target for established and novel treatment regimens.

Dare to dream? Cell-based therapies for heart failure after DREAM-HF: Review and roadmap for future clinical study

Clinical trials of cell-based therapies for heart failure have resulted in significant strides forward in our understanding of the potential the failing heart has for regeneration and repair. Yet, two decades on, the need for novel cell-based therapies for heart failure has never been greater. The DREAM-HF trial, which was presented as a late-breaking trial at the American Heart Association Scientific Sessions 2021 did not meet the primary heart failure outcome, but did show a large, clinically significant reduction in major adverse cardiovascular events (MACE) in patients receiving cells, an effect that was most pronounced in patients with evidence of maladaptive inflammation. These results represent an important step forward in our understanding of how cell-based therapies can exert beneficial effects in patients with heart failure and should serve as a guide for future clinical efforts. In light of the results of DREAM-HF, this review serves to provide an understanding of the current state of cell-based therapies for heart failure, as well as to highlight major knowledge gaps and suggest guiding principles for clinical trials of cell therapy going forward. Using the knowledge gained from DREAM-HF along with the trials that preceded it, the potential for breakthrough cell-based therapies for heart failure in the coming decade is immense.

Autologous Umbilical Cord Blood-Derived Mononuclear Cell Therapy Promotes Cardiac Proliferation and Adaptation in a Porcine Model of Right Ventricle Pressure Overload

Congenital heart diseases, including single ventricle circulations, are clinically challenging due to chronic pressure overload and the inability of the myocardium to compensate for lifelong physiological demands. To determine the clinical relevance of autologous umbilical cord blood-derived mononuclear cells (UCB-MNCs) as a therapy to augment cardiac adaptation following surgical management of congenital heart disease, a validated model system of right ventricular pressure overload due to pulmonary artery banding (PAB) in juvenile pigs has been employed. PAB in a juvenile porcine model and intramyocardial delivery of UCB-MNCs was evaluated in three distinct 12-week studies utilizing serial cardiac imaging and end-of-study pathology evaluations. PAB reproducibly induced pressure overload leading to chronic right ventricular remodeling including significant myocardial fibrosis and elevation of heart failure biomarkers. High-dose UCB-MNCs (3 million/kg) delivered into the right ventricular myocardium did not cause any detectable safety issues in the context of arrhythmias or abnormal cardiac physiology. In addition, this high-dose treatment compared with placebo controls demonstrated that UCB-MNCs promoted a significant increase in Ki-67-positive cardiomyocytes coupled with an increase in the number of CD31+ endothelium. Furthermore, the incorporation of BrdU-labeled cells within the myocardium confirmed the biological potency of the high-dose UCB-MNC treatment. Finally, the cell-based treatment augmented the physiological adaptation compared with controls with a trend toward increased right ventricular mass within the 12 weeks of the follow-up period. Despite these adaptations, functional changes as measured by echocardiography and magnetic resonance imaging did not demonstrate differences between cohorts in this surgical model system. Therefore, this randomized, double-blinded, placebo-controlled pre-clinical trial establishes the safety of UCB-MNCs delivered via intramyocardial injections in a dysfunctional right ventricle and validates the induction of cardiac proliferation and angiogenesis as transient paracrine mechanisms that may be important to optimize long-term outcomes for surgically repaired congenital heart diseases.

Impact of Diabetes Mellitus on the Potential of Autologous Stem Cells and Stem Cell-Derived Microvesicles to Repair the Ischemic Heart

Ischemic heart disease remains the leading cause of morbidity and mortality worldwide. Despite the advances in medical management and catheter-based therapy, mortality remains high, as does the risk of developing heart failure. Regenerative therapies have been widely used as an alternative option to repair the damaged heart mainly because of their paracrine-related beneficial effects. Although cell-based therapy has been demonstrated as feasible and safe, randomized controlled trials and meta-analyses show little consistent benefit from treatments with adult-derived stem cells. Mounting evidence from our group and others supports that cardiovascular risk factors and comorbidities impair stem cell potential thus hampering their autologous use. This review aims to better understand the influence of diabetes on stem cell potential. For this purpose, we will first discuss the most recent advances in the mechanistic understanding of the effects of diabetes on stem cell phenotype, function, and molecular fingerprint to further elaborate on diabetes-induced alterations in stem cell extracellular vesicle profile. Although we acknowledge that multiple sources of stem or progenitor cells are used for regenerative purposes, we will focus on bone marrow hematopoietic stem/progenitor cells, mesenchymal stem cells residing in the bone marrow, and adipose tissue and briefly discuss endothelial colony-forming cells.

The Myocardial Microenvironment Modulates the Biology of Transplanted Mesenchymal Stem Cells

PURPOSE

The maximal efficacy of cell therapy depends on the survival of stem cells, as well as on the phenotypic and biologic changes that may occur on these cells after transplantation. It has been hypothesized that the post-ischemic myocardial microenvironment can play a critical role in these changes, potentially affecting the survival and reparative potential of mesenchymal stem cells (MSCs). Here, we use a dual reporter gene sensor for the in vivo monitoring of the phenotype of MSCs and study their therapeutic effect on cardiac function.

PROCEDURES

The mitochondrial sensor was tested in cell culture in response to different mitochondrial stressors. For in vivo testing, MSCs (3 × 10⁵) were delivered in a murine ischemia-reperfusion (IR) model. Bioluminescence imaging was used to assess the mitochondrial biology and the viability of transplanted MSCs, while high-resolution ultrasound provided a non-invasive analysis of cardiac contractility and dyssynchrony.

RESULTS

The mitochondrial sensor showed increased activity in response to mitochondrial stressors. Furthermore, when tested in the living subject, it showed a significant increase in mitochondrial dysfunction in MSCs delivered in IR, compared with those delivered under sham conditions. Importantly, MSCs delivered to ischemic hearts, despite their mitochondrial stress and poor survival, were able to induce a significant improvement in cardiac function, through decreased collagen deposition and resynchronization/contractility of left ventricular wall motion.

CONCLUSIONS

The ischemic myocardium induces changes in the phenotype of transplanted MSCs. Despite their limited survival, MSCs still elicit a certain therapeutic response, as evidenced by improvement in myocardial remodeling and cardiac function. Maximization of the survival and reparative efficacy of stem cells remains a key for the success of stem cell therapies.

Clonal haematopoiesis in chronic ischaemic heart failure: prognostic role of clone size for DNMT3A- and TET2-driver gene mutations

AIMS

Somatic mutations of the epigenetic regulators DNMT3A and TET2 causing clonal expansion of haematopoietic cells (clonal haematopoiesis; CH) were shown to be associated with poor prognosis in chronic ischaemic heart failure (CHF). The aim of our analysis was to define a threshold of variant allele frequency (VAF) for the prognostic significance of CH in CHF.

METHODS AND RESULTS

We analysed bone marrow and peripheral blood-derived cells from 419 patients with CHF by error-corrected amplicon sequencing. Cut-off VAFs were optimized by maximizing sensitivity plus specificity from a time-dependent receiver operating characteristic (ROC) curve analysis from censored data. 56.2% of patients were carriers of a DNMT3A- (N = 173) or a TET2- (N = 113) mutation with a VAF >0.5%, with 59 patients harbouring mutations in both genes. Survival ROC analyses revealed an optimized cut-off value of 0.73% for TET2- and 1.15% for DNMT3A-CH-driver mutations. Five-year-mortality was 18% in patients without any detected DNMT3A- or TET2 mutation (VAF < 0.5%), 29% with only one DNMT3A- or TET2-CH-driver mutations above the respective cut-off level and 42% in patients harbouring both DNMT3A- and TET2-CH-driver mutations above the respective cut-off levels. In carriers of a DNMT3A mutation with VAF ≥ 1.15%, 5-year mortality was 31%, compared with 18% mortality in those with VAF < 1.15% (P = 0.048). Likewise, in patients with TET2 mutations, 5-year mortality was 32% with VAF ≥ 0.73%, compared with 19% mortality with VAF < 0.73% (P = 0.029).

CONCLUSION

The present study defines novel threshold levels for clone size caused by acquired somatic mutations in the CH-driver genes DNMT3A and TET2 that are associated with worse outcome in patients with CHF.

Cell Therapy in Patients with Heart Failure: A Comprehensive Review and Emerging Concepts

This review summarizes the results of clinical trials of cell therapy in patients with heart failure (HF). In contrast to acute myocardial infarction (where results have been consistently negative for more than a decade), in the setting of HF the results of Phase I–II trials are encouraging, both in ischaemic and non-ischaemic cardiomyopathy. Several well-designed Phase II studies have met their primary endpoint and demonstrated an efficacy signal, which is remarkable considering that only one dose of cells was used. That an efficacy signal was seen 6–12 months after a single treatment provides a rationale for larger, rigorous trials. Importantly, no safety concerns have emerged. Amongst the various cell types tested, mesenchymal stromal cells derived from bone marrow (BM), umbilical cord, or adipose tissue show the greatest promise. In contrast, embryonic stem cells are not likely to become a clinical therapy. Unfractionated BM cells and cardiosphere-derived cells have been abandoned. The cell products used for HF will most likely be allogeneic. New approaches, such as repeated cell treatment and intravenous delivery, may revolutionize the field. As is the case for most new therapies, the development of cell therapies for HF has been slow, plagued by multifarious problems, and punctuated by many setbacks; at present, the utility of cell therapy in HF remains to be determined. What the field needs is rigorous, well-designed Phase III trials. The most important things to move forward are to keep an open mind, avoid preconceived notions, and let ourselves be guided by the evidence.

Regenerative Potential of DPSCs and Revascularization: Direct, Paracrine or Autocrine Effect?

A new source of mesenchymal stem cells has recently been discovered, the so-called dental pulp derived stem cells (DPSCs) which therefore could represent potentially tools for regenerative medicine. DPSC originate from the neural crest and are physiologically involved in dentin homeostasis; moreover, they contribute to bone remodeling and differentiation into several tissues including cartilage, bone, adipose and nervous tissues. DPSCs have also been shown to influence the angiogenesis process, for example through the release of secretory factors or by differentiating into vascular and/or perivascular cells. Angiogenesis, that has a pivotal role in tissue regeneration and repair, is defined as the formation of new vessels from preexisting vessels and is mediated by mutual and reciprocal interactions between endothelial cells and perivascular cells. It is also known that co-cultures of perivascular and endothelial cells (ECs) can form a vascular network in vitro and also in vivo. Since DPSCs seem to have characteristics similar to pericytes, understanding the possible mechanism of interaction between DPSCs and ECs during neo-angiogenesis is dramatically important for the development of advanced clinical application in the field of regeneration.

Clinical Application of Novel Therapies for Coronary Angiogenesis: Overview, Challenges, and Prospects

Cardiovascular diseases continue to be the leading cause of death worldwide, with ischemic heart disease as the most significant contributor. Pharmacological and surgical interventions have improved clinical outcomes, but are unable to ameliorate advanced stages of end-heart failure. Successful preclinical studies of new therapeutic modalities aimed at revascularization have shown short lasting to no effects in the clinical practice. This lack of success may be attributed to current challenges in patient selection, endpoint measurements, comorbidities, and delivery systems. Although challenges remain, the field of therapeutic angiogenesis is evolving, as novel strategies and bioengineering approaches emerge to optimize delivery and efficacy. Here, we describe the structure, vascularization, and regulation of the vascular system with particular attention to the endothelium. We proceed to discuss preclinical and clinical findings and present challenges and future prospects in the field.

Neovascularization: The Main Mechanism of MSCs in Ischemic Heart Disease Therapy

Mesenchymal stem cell (MSC) transplantation after myocardial infarction (MI) has been shown to effectively limit the infarct area in numerous clinical and preclinical studies. However, the primary mechanism associated with this activity in MSC transplantation therapy remains unclear. Blood supply is fundamental for the survival of myocardial tissue, and the formation of an efficient vascular network is a prerequisite for blood flow. The paracrine function of MSCs, which is throughout the neovascularization process, including MSC mobilization, migration, homing, adhesion and retention, regulates angiogenesis and vasculogenesis through existing endothelial cells (ECs) and endothelial progenitor cells (EPCs). Additionally, MSCs have the ability to differentiate into multiple cell lineages and can be mobilized and migrate to ischemic tissue to differentiate into ECs, pericytes and smooth muscle cells in some degree, which are necessary components of blood vessels. These characteristics of MSCs support the view that these cells improve ischemic myocardium through angiogenesis and vasculogenesis. In this review, the results of recent clinical and preclinical studies are discussed to illustrate the processes and mechanisms of neovascularization in ischemic heart disease.

Evaluation of the effectiveness of infusion of bone marrow derived cell in patients with heart failure: A network meta-analysis of randomized clinical trials and cohort studies

Background: The aim of this study was to investigate the effectiveness of bone marrow-derived cells (BMC) technology in patients with heart failure and compare it with alternative therapies, including drug therapy, cardiac resynchronization therapy pacemaker (CRT-P), cardiac resynchronization therapy defibrillator (CRT-D).

Methods: A systematic review study was conducted to identify all clinical studies published by 2017. Using keywords such as "Heart Failure, BMC, Drug Therapy, CRT-D, CRT-P" and combinations of the mentioned words, we searched electronic databases, including Scopus, Cochrane Library, and PubMed. The quality of the selected studies was assessed using the Cochrane Collaboration's tool and the Newcastle-Ottawa. The primary and secondary end-points were left ventricular ejection fraction (LVEF) (%), failure cases (Number), left ventricular end-systolic volume (LVES) (ml), and left ventricular end-diastolic volume (LVED) (ml). Random-effects network meta-analyses were used to conduct a systematic comparison. Statistical analysis was done using STATA.

Results: This network meta-analysis covered a total of 57 final studies and 6694 patients. The Comparative effectiveness of BMC versus CRT-D, Drug, and CRT-P methods indicated the statistically significant superiority of BMC over CRT-P (6.607, 95% CI: 2.92, 10.29) in LVEF index and overall CRT-P (-13.946, 95% CI: -18.59, -9.29) and drug therapy (-4.176, 95% CI: -8.02, -.33) in LVES index. In addition, in terms of LVED index, the BMC had statistically significant differences with CRT-P (-10.187, 95% CI: -18.85, -1.52). BMC was also dominant to all methods in failure cases as a final outcome and the difference was statistically significant i.e. BMC vs CRT-D: 0.529 (0.45, 0.62) and BMC vs Drug: 0.516 (0.44, 0.60). In none of the outcomes, the other methods were statistically more efficacious than BMC. The BMC method was superior or similar to the other methods in all outcomes.

Conclusion: The results of this study showed that the BMC method, in general, and especially in terms of failure cases index, had a higher level of clinical effectiveness. However, due to the lack of data asymmetry, insufficient data and head-to-head studies, BMC in this meta-analysis might be considered as an alternative to existing treatments for heart failure.

The State of Art of Regenerative Therapy in Cardiovascular Ischemic Disease: Biology, Signaling Pathways, and Epigenetics of Endothelial Progenitor Cells

Ischemic heart disease is currently a major cause of mortality and morbidity worldwide. Nevertheless, the actual therapeutic scenario does not target myocardial cell regeneration and consequently, the progression toward the late stage of chronic heart failure is common. Endothelial progenitor cells (EPCs) are bone marrow-derived stem cells that contribute to the homeostasis of the endothelial wall in acute and chronic ischemic disease. Calcium modulation and other molecular pathways (NOTCH, VEGFR, and CXCR4) contribute to EPC proliferation and differentiation. The present review provides a summary of EPC biology with a particular focus on the regulatory pathways of EPCs and describes promising applications for cardiovascular cell therapy.

Heart Regeneration by Endogenous Stem Cells and Cardiomyocyte Proliferation: Controversy, Fallacy, and Progress

Ischemic heart disease is the leading cause of death worldwide. Myocardial infarction results in an irreversible loss of cardiomyocytes with subsequent adverse remodeling and heart failure. Identifying new sources for cardiomyocytes and promoting their formation represents a goal of cardiac biology and regenerative medicine. Within the past decade, many types of putative cardiac stem cells (CSCs) have been reported to regenerate the injured myocardium by differentiating into new cardiomyocytes. Some of these CSCs have been translated from bench to bed with reported therapeutic effectiveness. However, recent basic research studies on stem cell tracing have begun to question their fundamental biology and mechanisms of action, raising serious concerns over the myogenic potential of CSCs. We review the history of different types of CSCs within the past decade and provide an update of recent cell tracing studies that have challenged the origin and existence of CSCs. In addition to the potential role of CSCs in heart regeneration, proliferation of preexisting cardiomyocytes has recently gained more attention. This review will also evaluate the methodologic and technical aspects of past and current studies on CSCs and cardiomyocyte proliferation, with emphasis on technical strengths, advantages, and potential limitations of research approaches. While our understanding of cardiomyocyte generation and regeneration continues to evolve, it is important to address the shortcomings and inaccuracies in this field. This is best achieved by embracing technological advancements and improved methods to label single cardiomyocytes/progenitors and accurately investigate their developmental potential and fate/lineage commitment.

Association of Mutations Contributing to Clonal Hematopoiesis With Prognosis in Chronic Ischemic Heart Failure

Question

What is the clinical significance of clonal hematopoiesis of indeterminate potential (CHIP) for chronic heart failure (CHF) owing to ischemic origin?

Findings

In this cohort study, CHIP had a high prevalence in 200 investigated patients with CHF. While no clinical baseline characteristics associated with CHF were different between CHIP carriers and non-CHIP carriers, except for the mean age, harboring mutations in the most prevalent driver genes associated with CHIP, namely DNMT3A and TET2, was associated with a significant and profound increase in death and rehospitalization for heart failure.

Meaning

Clonal hematopoiesis of indeterminate potential is presented as a newly identified risk factor for impaired long-term survival and increased disease progression in patients with CHF that may be well targetable as a valuable approach to precision medicine in patients with CHF carrying specific mutations encoding for clonal hematopoiesis.

Importance

Somatic mutations causing clonal expansion of hematopoietic cells (clonal hematopoiesis of indeterminate potential [CHIP]) are increased with age and associated with atherosclerosis and inflammation. Age and inflammation are the major risk factors for heart failure, yet the association of CHIP with heart failure in humans is unknown.

Objective

To assess the potential prognostic significance of CHIP in patients with chronic heart failure (CHF) owing to ischemic origin.

Design, Setting, and Participants

We analyzed bone marrow–derived mononuclear cells from 200 patients with CHF by deep targeted amplicon sequencing to detect the presence of CHIP and associated such with long-term prognosis in patients with CHF at University Hospital Frankfurt, Frankfurt, Germany. Data were analyzed between October 2017 and April 2018.

Results

Median age of the patients was 65 years. Forty-seven mutations with a variant allele fraction (VAF) of at least 0.02 were found in 38 of 200 patients with CHF (18.5%). The somatic mutations most commonly occurred in the genes DNMT3A (14 patients), TET2 (9 patients), KDM6A (4 patients), and BCOR (3 patients). Patients with CHIP were older and more frequently had a history of hypertension. During a median follow-up of 4.4 years, a total of 53 patients died, and 23 patients required hospitalization for heart failure. There was a significantly worse long-term clinical outcome for patients with either DNMT3A or TET2 mutations compared with non-CHIP carriers. By multivariable Cox proportional regression analysis, the presence of somatic mutations within TET2 or DNMT3A (HR, 2.1; 95% CI, 1.1-4.0; P = .02, for death combined with heart failure hospitalization) and age (HR, 1.04; 95% CI, 1.01-1.07 per year; P = .005) but not a history of hypertension remained independently associated with adverse outcome. Importantly, there was a significant dose-response association between VAF and clinical outcome.

Conclusions and Relevance

Our data suggest that somatic mutations in hematopoietic cells, specifically in the most commonly mutated CHIP driver genes TET2 and DNMT3A, may be significantly associated with the progression and poor prognosis of CHF. Future studies will have to validate our findings in larger cohorts and address whether targeting specific inflammatory pathways may be valuable for precision medicine in patients with CHF carrying specific mutations encoding for CHIP.

A Novel Hepatic Anti-Fibrotic Strategy Utilizing the Secretome Released from Etanercept-Synthesizing Adipose-Derived Stem Cells

Tumor necrosis factor-α (TNF-α)-driven inflammatory reaction plays a crucial role in the initiation of liver fibrosis. We herein attempted to design genetically engineered adipose-derived stem cells (ASCs) producing etanercept (a potent TNF-α inhibitor), and to determine the anti-fibrotic potential of the secretome released from the etanercept-synthesizing ASCs (etanercept-secretome). First, we generated the etanercept-synthesizing ASCs by transfecting the ASCs with mini-circle plasmids containing the gene insert encoding for etanercept. We subsequently collected the secretory material released from the etanercept-synthesizing ASCs and determined its anti-fibrotic effects both in vitro (in thioacetamide [TAA]-treated AML12 and LX2 cells) and in vivo (in TAA-treated mice) models of liver fibrosis. We observed that while etanercept-secretome increased the viability of the TAA-treated AML12 hepatocytes (p = 0.021), it significantly decreased the viability of the TAA-treated LX2 HSCs (p = 0.021). In the liver of mice with liver fibrosis, intravenous administration of the etanercept-secretome induced significant reduction in the expression of both fibrosis-related and inflammation-related markers compared to the control group (all Ps < 0.05). The etanercept-secretome group also showed significantly lower serum levels of liver enzymes as well as pro-inflammatory cytokines, such as TNF-α (p = 0.020) and IL-6 (p = 0.021). Histological examination of the liver showed the highest reduction in the degree of fibrosis in the entanercept-secretome group (p = 0.006). Our results suggest that the administration of etanercept-secretome improves liver fibrosis by inhibiting TNF-α-driven inflammation in the mice with liver fibrosis. Thus, blocking TNF-α-driven inflammation at the appropriate stage of liver fibrosis could be an efficient strategy to prevent fibrosis.

A Path Forward for Regenerative Medicine

Although clinical trials of cell-based approaches to cardiovascular disease have yielded some promising results, no cell-based therapy has achieved regulatory approval for a cardiovascular indication. To broadly assess the challenges to regulatory approval and identify strategies to facilitate this goal, the Cardiac Safety Research Consortium sponsored a session during the Texas Heart Institute International Symposium on Cardiovascular Regenerative Medicine in September 2017. This session convened leaders in cardiovascular regenerative medicine, including participants from academia, the pharmaceutical industry, the US Food and Drug Administration, and the Cardiac Safety Research Consortium, with particular focus on treatments closest to regulatory approval. A goal of the session was to identify barriers to regulatory approval and potential pathways to overcome them. Barriers identified include manufacturing and therapeutic complexity, difficulties identifying an optimal comparator group, limited industry capacity for funding pivotal clinical trials, and challenges to demonstrating efficacy on clinical end points required for regulatory decisions. Strategies to overcome these barriers include precompetitive development of a cell therapy registry network to enable dual-purposing of clinical data as part of pragmatic clinical trial design, development of standardized terminology for product activity and end points to facilitate this registry, use of innovative statistical methods and quality of life or functional end points to supplement outcomes such as death or heart failure hospitalization and reduce sample size, involvement of patients in determining the research agenda, and use of the Food and Drug Administration's new Regenerative Medicine Advanced Therapy designation to facilitate early discussion with regulatory authorities when planning development pathways.

Clinical Studies of Cell Therapy in Cardiovascular Medicine: Recent Developments and Future Directions

Given the rising prevalence of cardiovascular disease worldwide and the limited therapeutic options for severe heart failure, novel technologies that harness the regenerative capacity of the heart are sorely needed. The therapeutic use of stem cells has the potential to reverse myocardial injury and improve cardiac function, in contrast to most current medical therapies that only mitigate heart failure symptoms. Nearly 2 decades and >200 trials for cardiovascular disease have revealed that most cell types are safe; however, their efficacy remains controversial, limiting the transition of this therapy from investigation to practice. Lessons learned from these initial studies are driving the design of new clinical trials; higher fidelity of cell isolation techniques, standardization of conditions, more consistent use of state of the art measurement techniques, and assessment of multiple end points to garner insights into the efficacy of stem cells. Translation to clinical trials has almost outpaced our mechanistic understanding, and individual patient factors likely play a large role in stem cell efficacy. Therefore, careful analysis of dosing, delivery methods, and the ideal patient populations is necessary to translate cell therapy from research to practice. We are at a pivotal stage in the field in which information from many relatively small clinical trials must guide carefully executed efficacy trials. Larger efficacy trials are being launched to answer questions about older, first-generation stem cell therapeutics, while novel, second-generation products are being introduced into the clinical realm. This review critically examines the current state of clinical research on cell-based therapies for cardiovascular disease, highlighting the controversies in the field, improvements in clinical trial design, and the application of exciting new cell products.

Animal- and human-based evidence for the protective effects of stem cell therapy against cardiovascular disorders

The increasing rate of mortality and morbidity because of cardiac diseases has called for efficient therapeutic needs. With the advancement in cell-based therapies, stem cells are abundantly studied in this area. Nearly, all sources of stem cells are experimented to treat cardiac injuries. Tissue engineering has also backed this technique by providing an advantageous platform to improve stem cell therapy. After in vitro studies, primary treatment-based research studies comprise small and large animal studies. Furthermore, these studies are implemented in human models in the form of clinical trials. Purpose of this review is to highlight the animal- and human-based studies, exploiting various stem cell sources, to treat cardiovascular disorders.

Activation of Bone Marrow-Derived Cells and Resident Aortic Cells During Aortic Injury

BACKGROUND

The process of aortic injury, repair, and remodeling during aortic aneurysm and dissection is poorly understood. We examined the activation of bone marrow (BM)-derived and resident aortic cells in response to aortic injury in a mouse model of sporadic aortic aneurysm and dissection.

MATERIALS AND METHODS

Wild-type C57BL/6 mice were transplanted with green fluorescent protein (GFP)+ BM cells. For 4 wk, these mice were either unchallenged with chow diet and saline infusion or challenged with high-fat diet and angiotensin II infusion. We then examined the aortic recruitment of GFP+ BM-derived cells, growth factor production, and the differentiation potential of GFP+ BM-derived and GFP- resident aortic cells.

RESULTS

Aortic challenge induced recruitment of GFP+ BM cells and activation of GFP- resident aortic cells, both of which produced growth factors. Although BM cells and resident aortic cells equally contributed to the fibroblast populations, we did not detect the differentiation of BM cells into smooth muscle cells. Interestingly, aortic macrophages were both of BM-derived (45%) and of non-BM-derived (55%) origin. We also observed a significant increase in stem cell antigen-1 (Sca-1)+ stem/progenitor cells and neural/glial antigen 2 (NG2+) cells in the aortic wall of challenged mice. Although some of the Sca-1+ cells and NG2+ cells were BM derived, most of these cells were resident aortic cells. Sca-1+ cells produced growth factors and differentiated into fibroblasts and NG2+ cells.

CONCLUSIONS

BM-derived and resident aortic cells are activated in response to aortic injury and contribute to aortic inflammation, repair, and remodeling by producing growth factors and differentiating into fibroblasts and inflammatory cells.

Therapeutic Potential of Pluripotent Stem Cells for Cardiac Repair after Myocardial Infarction

Myocardial infarction occurs as a result of acute arteriosclerotic plaque rupture in the coronary artery, triggering strong inflammatory responses. The necrotic cardiomyocytes are gradually replaced with noncontractile scar tissue that eventually manifests as heart failure. Pluripotent stem cells (PSCs) show great promise for widespread clinical applications, particularly for tissue regeneration, and are being actively studied around the world to help elucidate disease mechanisms and in the development of new drugs. Human induced PSCs also show potential for regeneration of the myocardial tissue in experiments with small animals and in in vitro studies. Although emerging evidence points to the effectiveness of these stem cell-derived cardiomyocytes in cardiac regeneration, several challenges remain before clinical application can become a reality. Here, we provide an overview of the present state of PSC-based heart regeneration and highlight the remaining hurdles, with a particular focus on graft survival, immunogenicity, posttransplant arrhythmia, maintained function, and tumor formation. Rapid progress in this field along with advances in biotechnology are expected to resolve these issues, which will require international collaboration and standardization.

Combination of HGF and IGF-1 promotes connexin 43 expression and improves ventricular arrhythmia after myocardial infarction through activating the MAPK/ERK and MAPK/p38 signaling pathways in a rat model

Background

In this study, we hypothesized that the combination of hepatocyte growth factor (HGF) and insulin-like growth factor-1 (IGF-1) alters the expression of connexin 43 (Cx43) and results in a reduced frequency of induced ventricular arrhythmia in rats after myocardial infarction (MI) and explored the preliminary mechanisms involved.

Methods

Cardiomyocytes were cultured in vitro in medium with PBS, HGF, IGF-1, GFs (HGF + IGF-1), HGF + p38 inhibitor, HGF + ERK inhibitor, IGF-1 + p38 inhibitor or IGF-1 + ERK inhibitor. The expression of Cx43 was tested by real-time PCR and Western blotting after 48 hours. MI was induced in 48 male Sprague-Dawley rats. The rats were randomly divided into four groups and received an injection of PBS, HGF, IGF-1 or GFs into the infarct border zone two weeks after MI. Six weeks after injection, the expression levels of Cx43 and programmed stimulation-induced ventricular arrhythmias were examined.

Results

In vitro, the expression of Cx43 mRNA and the Cx43 protein in cardiomyocytes was higher in the HGF, IGF-1, and GFs groups than in the PBS group. GFs had a combinatorial effect on the Cx43 mRNA level but not on the Cx43 protein level. There was a significant reduction in Cx43 mRNA and Cx43 protein levels in the IGF-1 + p38 inhibitor group and IGF-1 + ERK inhibitor group compared to the IGF-1 group. In vivo, programmed stimulation significantly decreased the frequency of ventricular arrhythmia in the GFs, HGF and IGF-1 groups, and this effect was accompanied by increased immunohistochemical staining for Cx43, myocardial Cx43 protein levels and Cx43 mRNA levels in the infarct border zone of the left ventricle compared with those in the PBS group. The combinatorial effect of GFs on Cx43 expression was only observed at the mRNA level.

Conclusions

Both HGF and IGF-1 enhanced the expression of Cx43 and improved induced ventricular arrhythmia in rats with MI. Both synergistic and antagonistic effects of HGF and IGF-1 were not observed. In addition, IGF-1 may function through the MAPK/p38 and ERK1/2 signaling pathways to regulate Cx43 expression.

Efficacy and safety of stem cell therapy in patients with dilated cardiomyopathy: a systematic appraisal and meta-analysis

BACKGROUND

The clinical significance of stem cell therapy in the treatment of dilated cardiomyopathy remains unclear. This systemic appraisal and meta-analysis aimed to assess the efficacy and safety of stem cell therapy in patients with dilated cardiomyopathy. After searching the PubMed, Embase, and Cochrane library databases until November 2017, we conducted a meta-analysis to evaluate the efficacy and safety of stem cell therapy in patients with dilated cardiomyopathy.

METHODS

The weighted mean difference (WMD), standard mean difference (SMD), relative risk (RR), and 95% confidence interval (CI) were summarized in this meta-analysis. Both fixed effects and random effects models were used to combine the data. Sensitivity analyses were conducted to evaluate the impact of an individual dataset on the pooled results.

RESULTS

A total of eight randomized controlled trials, which involved 531 participants, met the inclusion criteria in this systematic appraisal and meta-analysis. Our meta-analysis showed that stem cell therapy improves left ventricular ejection fraction (SMD = 1.09, 95% CI 0.29 to 1.90, I2 = 92%) and reduces left ventricular end-systolic volume (SMD = - 0.36, 95% CI - 0.61 to - 0.10, I2 = 20.5%) and left ventricular end-diastolic chamber size (SMD = - 0.48, 95% CI - 0.89 to - 0.07, I2 = 64.8%) in patients with dilated cardiomyopathy. However, stem cell therapy has no effect on mortality (RR = 0.72, 95% CI 0.50 to 1.02, I2 = 30.2%) and 6-min-walk test (WMD = 51.52, 95% CI - 24.52 to 127.55, I2 = 94.8%).

CONCLUSIONS

This meta-analysis suggests that stem cell therapy improves left ventricular ejection fraction and reduces left ventricular end-systolic volume and left ventricular end-diastolic chamber size in patients with dilated cardiomyopathy. However, future well-designed large studies might be necessary to clarify the effect of stem cell therapy in patients with dilated cardiomyopathy.

Wound healing and fibrosis: current stem cell therapies

Scarring is a result of the wound healing response and causes tissue dysfunction after injury. This process is readily evident in the skin, but also occurs internally across organ systems in the form of fibrosis. Stem cells are crucial to the innate tissue healing response and, as such, present a possible modality to therapeutically promote regenerative healing while minimizing scaring. In this review, the cellular basis of scaring and fibrosis is examined. Current stem cell therapies under exploration for skin wound healing and internal organ fibrosis are discussed. While most therapeutic approaches rely on the direct application of progenitor-type cells to injured tissue to promote healing, novel strategies to manipulate the scarring response are also presented. As our understanding of developmental and stem cell biology continues to increase, therapies to encourage regeneration of healthy functional tissue after damage secondary to injury or disease will continue to expand.

Lipopolysaccharides Improve Mesenchymal Stem Cell-Mediated Cardioprotection by MyD88 and stat3 Signaling in a Mouse Model of Cardiac Ischemia/Reperfusion Injury

Bone marrow-derived mesenchymal stem cells (MSCs) improve cardiac function after ischemia/reperfusion injury, in part, due to the release of cytoprotective paracrine factors. Toll-like receptor 4 (TLR4) is expressed in MSCs and regulates the expression of cytoprotective factors, cytokines, and chemokines. Lipopolysaccharide (LPS) stimulation of TLR4 activates two distinct signaling pathways that are either MyD88 dependent or MyD88 independent/TIR-domain-containing adapter-inducing interferon-β (TRIF) dependent. While it was reported previously that LPS treatment improved MSC-mediated cardioprotection, the mechanism underlying such improved effect remains unknown. To study the role of MyD88 signaling in MSC cardioprotective activity, wild type (WT) and MyD88^-/- MSCs were treated with LPS (200 ng/mL) for 24 h. WT and MyD88^-/- MSCs with or without LPS pretreatment were infused into the coronary circulation of isolated mouse hearts (Langendorff model) and then subjected to ischemia (25 min) and reperfusion (50 min). Saline served as a negative control. Both untreated and LPS-pretreated WT MSCs significantly improved postischemic recovery of myocardial function of isolated mouse hearts, as evidenced by improved left ventricular developed pressure and ventricular contractility assessment (ie, the rate of left ventricle pressure change over time, ± dp/dt). LPS-pretreated WT MSCs conferred better cardiac function recovery than untreated MSCs; however, such effect of LPS was abolished when using MyD88^-/- MSCs. In addition, LPS stimulated stat3 activity in WT MSCs, but not MyD88^-/- MSCs. stat3 small interfering RNA abolished the effect of LPS in improving the cardioprotection of WT MSCs. In conclusion, this study demonstrates that LPS improves MSC-mediated cardioprotection by MyD88-dependent activation of stat3.

Regenerating the field of cardiovascular cell therapy

The retraction of >30 falsified studies by Anversa et al. has had a disheartening impact on the cardiac cell therapeutics field. The premise of heart muscle regeneration by the transdifferentiation of bone marrow cells or putative adult resident cardiac progenitors has been largely disproven. Over the past 18 years, a generation of physicians and scientists has lost years chasing these studies, and patients have been placed at risk with little scientific grounding. Funding agencies invested hundreds of millions of dollars in irreproducible work, and both academic institutions and the scientific community ignored troubling signals over a decade of questionable work. Our collective retrospective analysis identifies preventable problems at the level of the editorial and peer-review process, funding agencies and academic institutions. This Perspective provides a chronology of the forces that led to this scientific debacle, integrating direct knowledge of the process. We suggest a science-driven path forward that includes multiple novel approaches to the problem of heart muscle regeneration.

A Modified Encephalo-Duro-Synangiosis Technique Induced Neovascularization in Symptomatic Atherosclerotic Carotid Artery Occlusion: A Phase I trial

OBJECTIVE

To the best of our knowledge, the present study is the first to assess the safety and feasibility of a modified encephalo-galeo-duro-synangiosis operation in patients with atherosclerotic carotid artery occlusion.

METHODS

Eight patients who had experienced new ipsilateral cerebrovascular events after the diagnosis of carotid artery occlusion were recruited. To facilitate extracranial-to-intracranial collateralization, 5 or 6 burr holes were made, and the dura mater and arachnoid were opened. The patients were closely monitored for complications and underwent conventional angiography, magnetic resonance imaging, and perfusion-weighted magnetic resonance imaging at baseline and 1 year of follow-up. After 10 years, the patients who were still alive were interviewed and assessed for functional outcomes and neurological status.

RESULTS

No surgery-related adverse events were observed, apart from temporary headache and subcutaneous effusion. Four of six patients had developed an extracranial-to-intracranial collateral blood vessels on angiography, and these patients had no incident ischemic events during the follow-up period. During the long-term follow-up period (10 years), 3 patients had died. Of those living, 4 of the 5 patients reported total resolution of the symptoms, with no incident ischemic events. One patient still experienced disability from an ischemic stroke that occurred as a result of the 1-year follow-up angiography.

CONCLUSIONS

Encephalo-duro-galeo-synangiosis for symptomatic carotid occlusion seems to be safe and feasible and might be able to induce extracranial-to-intracranial collaterals in patients with carotid artery occlusion. Further studies are needed to define the optimal therapeutic window and yield of burr hole surgery in the treatment of symptomatic carotid occlusive disease as an adjuvant to extracranial-intracranial bypass.

The role of stem cells in treating coronary artery disease in 2018

The last decade has witnessed the publication of a number of stem cell clinical trials, primarily using bone marrow-derived cells as the injected cell. Much has been learned through these "first-generation" clinical trials. The advances in our understanding include the following: (1) cell therapy is safe; (2) cell therapy has been mildly effective; and (3) human bone marrow-derived stem cells do not transdifferentiate into cardiomyocytes or new blood vessels. The primary mechanism of action for cell therapy is now believed to be through paracrine effects that include the release of cytokines, chemokines, and growth factors that inhibit apoptosis and fibrosis, enhance contractility, and activate endogenous regenerative mechanisms through endogenous circulating or site-specific stem cells. The current direction for clinical trials includes the use of stem cells capable of cardiac lineage.

Enzymatically degradable alginate hydrogel systems to deliver endothelial progenitor cells for potential revasculature applications

The objective of this study was to design an injectable biomaterial system that becomes porous in situ to deliver and control vascular progenitor cell release. Alginate hydrogels were loaded with outgrowth endothelial cells (OECs) and alginate lyase, an enzyme which cleaves alginate polymer chains. We postulated and confirmed that higher alginate lyase concentrations mediated loss of hydrogel mechanical properties. Hydrogels incorporating 5 and 50 mU/mL of alginate lyase experienced approximately 28% and 57% loss of mass as well as 81% and 91% reduction in storage modulus respectively after a week. Additionally, computational methods and mechanical analysis revealed that hydrogels with alginate lyase significantly increased in mesh size over time. Furthermore, alginate lyase was not found to inhibit OEC proliferation, viability or sprouting potential. Finally, alginate hydrogels incorporating OECs and alginate lyase promoted up to nearly a 10 fold increase in OEC migration in vitro than nondegradable hydrogels over the course of a week and increased functional vasculature in vivo via a chick chorioallantoic membrane (CAM) assay. Overall, these findings demonstrate that alginate lyase incorporated hydrogels can provide a simple and robust system to promote controlled outward cell migration into native tissue for potential therapeutic revascularization applications.

Effects of bone marrow mononuclear cells delivered through a graft vessel in patients with previous myocardial infarction and chronic heart failure: An echocardiographic study of left ventricular dyssynchrony

OBJECTIVES

Several trials are investigating the delivery of stem cells to treat ischemic cardiomyopathy. The aim of this study was the echocardiographic evaluation of the effectiveness of isolated coronary artery bypass graft (CABG) combined with bone marrow mononuclear cells (BMMNC) delivered through the graft vessels to improve left ventricular dyssynchrony in patients with previous myocardial infarction and chronic heart failure.

METHODS

42 patients with previous myocardial infarction and chronic heart failure were randomly allocated to either the CABG only group (n = 18) or the CABG with BMMNC graft group (n = 24group). We used 2D strain imaging to measure the absolute difference in time-to-peak radial strain between the earliest and the latest activated segments on LV short-axis images at the apical (RSTa), at the mitral annulus (RSTb), and at the papillary muscle (RSTm) level.

RESULTS

The effective rate of LV dyssynchrony improvement was significantly higher in the CABG + BMMNC than in the CABG only group (RSTb: 91.7% vs 50%, P < .05; RSTm: 78.6% vs 35.7%, P < .05; RSTa: 92.3% vs 50%, P < .05). The deterioration rate of LV synchrony was significantly lower in the CABG + BMMNC than in the CABG only group for RSTb (8.3% vs 70%, P < .05;) and RSTm (0 vs 50%, P < .05), but not for RSTa (18.2% vs 37.5%, P > .05).

CONCLUSIONS

Combining CABG with BMMNC delivering provided a better improvement of left ventricular dyssynchrony than CABG only.

Adult Stem Cell Therapy and Heart Failure, 2000 to 2016: A Systematic Review

Importance

Stem cell therapy is a promising treatment strategy for patients with heart failure, which accounts for more than 10% of deaths in the United States annually. Despite more than a decade of research, further investigation is still needed to determine whether stem cell regenerative therapy is an effective treatment strategy and can be routinely implemented in clinical practice.

Objective

To describe the progress in cardiac stem cell regenerative therapy using adult stem cells and to highlight the merits and limitations of clinical trials performed to date.

Evidence Review

Information for this review was obtained through a search of PubMed and the Cochrane database for English-language studies published between January 1, 2000, and July 26, 2016. Twenty-nine randomized clinical trials and 7 systematic reviews and meta-analyses were included in this review.

Findings

Although adult stem cells were once believed to have the ability to create new heart tissue, preclinical studies suggest that these cells release cardioprotective paracrine factors that activate endogenous pathways, leading to myocardial repair. Subsequent randomized clinical trials, most of which used autologous bone marrow mononuclear cells, have found only a modest benefit in patients receiving stem cell therapy. The lack of a significant benefit may result from variations in trial methods, discrepancies in reporting, and an overreliance on surrogate end points.

Conclusions and Relevance

Although stem cell therapy for cardiovascular disease is not yet ready for routine clinical application, significant progress continues to be made. Physicians should be aware of the current status of this treatment so that they can better inform their patients who may be in search of alternative therapies.

Adult Stem Cells for Regenerative Therapy

Cell therapy has been identified as an effective method to regenerate damaged tissue. Adult stem cells, also known as somatic stem cells or resident stem cells, are a rare population of undifferentiated cells, located within a differentiated organ, in a specialized structure, called a niche, which maintains the microenvironments that regulate the growth and development of adult stem cells. The adult stem cells are self-renewing, clonogenic, and multipotent in nature, and their main role is to maintain the tissue homeostasis. They can be activated to proliferate and differentiate into the required type of cells, upon the loss of cells or injury to the tissue. Adult stem cells have been identified in many tissues including blood, intestine, skin, muscle, brain, and heart. Extensive preclinical and clinical studies have demonstrated the structural and functional regeneration capabilities of these adult stem cells, such as bone marrow-derived mononuclear cells, hematopoietic stem cells, mesenchymal stromal/stem cells, resident adult stem cells, induced pluripotent stem cells, and umbilical cord stem cells. In this review, we focus on the human therapies, utilizing adult stem cells for their regenerative capabilities in the treatment of cardiac, brain, pancreatic, and eye disorders.

New therapies for acute myocardial infarction: current state of research and future promise

Progress has been made into research on new therapies, mechanical and pharmacological approaches and repair/regenerative cellular therapy to treat irreversible cardiovascular pathologies, such as acute myocardial infarction. Research into cellular therapies is exploring the use of new cellular types. Although the therapeutic effects of cell therapy remain modest, results from clinical trials are encouraging. To expand this improvement, advances are being made that involve the paracrine function of stem cells, the use of growth factors, miRNA and new biomaterials. In the near future, these therapies should become part of routine clinical practice.

Regenerative Therapy for Patients with Congenital Heart Disease

Congenital heart disease (CHD) is the most common birth defect, affecting 1 in 100 babies. Among CHDs, single ventricle (SV) physiologies, such as hypoplastic left heart syndrome and tricuspid atresia, are particularly severe conditions that require multiple palliative surgeries, including the Fontan procedure. Although the management strategies for SV patients have markedly improved, the prevalence of ventricular dysfunction continues to increase over time, especially after the Fontan procedure. At present, the final treatment for SV patients who develop heart failure is heart transplantation; however, transplantation is difficult to achieve because of severe donor shortages. Recently, various regenerative therapies for heart failure have been developed that increase cardiomyocytes and restore cardiac function, with promising results in adults. The clinical application of various forms of regenerative medicine for CHD patients with heart failure is highly anticipated, and the latest research in this field is reviewed here. In addition, regenerative therapy is important for children with CHD because of their natural growth. The ideal pediatric cardiovascular device would have the potential to adapt to a child's growth. Therefore, if a device that increases in size in accordance with the patient's growth could be developed using regenerative medicine, it would be highly beneficial. This review provides an overview of the available regenerative technologies for CHD patients.