Stem cells for treatment of cardiovascular diseases: An umbrella review of randomized controlled trials

Assessing the Potential Benefits of Stem Cell Therapy in Cardiac Regeneration for Patients With Ischemic Heart Disease

Myocardial infarction, commonly known as a heart attack, or ischemic heart disease (IHD), remains one of the most fatal health conditions worldwide due to the limited regenerative capacity of the heart muscle after infarction. Conventional medical treatments primarily focus on symptom control and tissue preservation but fail to address the loss of cardiomyocytes, the cells responsible for heart contraction. This systematic review explores the hypothesis that stem cell therapies can enhance cardiac regeneration by replacing or repairing damaged myocardium, with a focus on mesenchymal stem cells (MSCs), induced pluripotent stem cells (iPSCs), and embryonic stem cells (ESCs). The review was restricted to literature published between 2015 and 2024, sourced from PubMed, Web of Science, and Google Scholar. This timeframe reflects advances in stem cell research and regenerative therapies. Findings from trials such as Bone Marrow-Derived Mononuclear Cell Therapy in Acute Myocardial Infarction (BAMI) and Cardiopoietic Stem Cell Therapy in Heart Failure (C-CURE) suggest that stem cell therapies may improve left ventricular ejection fraction (LVEF) and reduce infarct size. However, the heterogeneity of trials, small sample sizes, and short follow-up durations limit the generalizability of these results. Long-term benefits, including improved survival rates and reduced hospital readmissions, remain inconclusive. Ethical concerns, particularly the use of ESCs, pose additional challenges, including controversies over embryonic sources and varying regulatory landscapes. Key areas for advancement include optimizing stem cell survival and differentiation, with genetic engineering to enhance tissue repair capabilities considered the most critical for improving clinical outcomes. The integration of regenerative treatments such as extracellular vesicle therapy, derived from stem cells to modulate repair, also shows promise. Imaging techniques, such as MRI and PET, provide real-time monitoring of stem cell effects, offering insights into therapeutic efficacy and safety. Despite promising results from preclinical models and early-phase trials, the full therapeutic potential of stem cell therapy for IHD remains unrealized. Effective treatment protocols, addressing patient-specific factors, ethical considerations, and long-term outcome evaluations, are essential. This review emphasizes the need for ongoing research and clinical development to maximize the potential of stem cell-based approaches in cardiac repair.

Stem Cell Therapies and Ageing: Unlocking the Potential of Regenerative Medicine

A multifaceted biological process of ageing culminates in the gradual decline of tissue and organ functions, escalating vulnerability to age-related diseases. Stem cell therapies, standing at the frontier of regenerative medicine, hold the potential to mitigate the challenges induced by ageing. By harnessing the unique regenerative capabilities of stem cells, these therapies aim to renew and heal ageing or damaged cells and tissues, thereby bolstering their function. In this chapter, we explore the potential of stem cell-based interventions against age-related degeneration, emphasising their underlying mechanisms, challenges, and future possibilities. As elucidated by the Buck Institute for Research on Aging, ageing is characterised by an accrual of macromolecular damage, genomic instability, and loss of heterochromatin (Campisi et al. Nature 571:183-192, 2019). These aspects culminate in stem cell fatigue and a dwindling tissue regenerative capacity. However, with the advent of stem cell therapy and regenerative medicine, we now hold the tools to reverse these age-induced changes by rejuvenating stem cells, the keystones of tissue regeneration, and fostering their proliferation and differentiation.

Therapeutic efficacy and promise of stem cell-derived extracellular vesicles in Alzheimer's disease and other aging-related disorders

The term extracellular vesicles (EVs) refers to a variety of heterogeneous nanovesicles secreted by almost all cell types, primarily for intercellular communication and maintaining cellular homeostasis. The role of EVs has been widely reported in the genesis and progression of multiple pathological conditions, and these vesicles are suggested to serve as 'liquid biopsies'. In addition to their use as biomarkers, EVs secreted by specific cell types, especially with stem cell properties, have shown promise as cell-free nanotherapeutics. Stem cell-derived EVs (SC-EVs) have been increasingly used as an attractive alternative to stem cell therapies and have been reported to promote regeneration of aging-associated tissue loss and function. SC-EVs treatment ameliorates brain and peripheral aging, reproductive dysfunctions and inhibits cellular senescence, thereby reversing several aging-related disorders and dysfunctions. The anti-aging therapeutic potential of SC-EVs depends on multiple factors, including the type of stem cells, the age of the source stem cells, and their physiological state. In this review, we briefly describe studies related to the promising effects of SC-EVs against various aging-related pathologies, and then we focus in-depth on the therapeutic benefits of SC-EVs against Alzheimer's disease, one of the most devastating neurodegenerative diseases in elderly individuals. Numerous studies in transgenic mouse models have reported the usefulness of SC-EVs in targeting the pathological hallmarks of Alzheimer's disease, including amyloid plaques, neurofibrillary tangles, and neuroinflammation, leading to improved neuronal protection, synaptic plasticity, and cognitive measures. Cell culture studies have further identified the underlying molecular mechanisms through which SC-EVs reduce amyloid beta (Aβ) levels or shift microglia phenotype from pro-inflammatory to anti-inflammatory state. Interestingly, multiple routes of administration, including nasal delivery, have confirmed that SC-EVs could cross the blood-brain barrier. Due to this, SC-EVs have also been tested to deliver specific therapeutic cargo molecule/s (e.g., neprilysin) to the brain. Despite these promises, several challenges related to quality control, scalability, and biodistribution remain, hindering the realization of the vast clinical promise of SC-EVs.

Recent Advances of Using Exosomes as Diagnostic Markers and Targeting Carriers for Cardiovascular Disease

Cardiovascular diseases (CVDs) are the leading cause of human death worldwide. Exosomes act as endogenous biological vectors; they possess advantages of low immunogenicity and low safety risks, also providing tissue selectivity, including the inherent targeting the to heart. Therefore, exosomes not only have been applied as biomarkers for diagnosis and therapeutic outcome confirmation but also showed potential as drug carriers for cardiovascular targeting delivery. This review aims to summarize the progress and challenges of exosomes as novel biomarkers, especially many novel exosomal noncoding RNAs (ncRNAs), and also provides an overview of the improved targeting functions of exosomes by unique engineered approaches, the latest developed administration methods, and the therapeutic effects of exosomes used as the biocarriers of medications for cardiovascular disease treatment. Also, the possible therapeutic mechanisms and the potentials for transferring exosomes to the clinic for CVD treatment are discussed. The advances, in vivo and in vitro applications, modifications, mechanisms, and challenges summarized in this review will provide a general understanding of this promising strategy for CVD treatment.

Ascorbic acid and salvianolic acid B enhance the valproic acid and 5-azacytidinemediated cardiac differentiation of mesenchymal stem cells

BACKGROUND

Cardiovascular diseases remain a major cause of death globally. Cardiac cells once damaged, cannot resume the normal functioning of the heart. Bone marrow derived mesenchymal stem cells (BM-MSCs) have shown the potential to differentiate into cardiac cells. Epigenetic modifications determine cell identity during embryo development via regulation of tissue specific gene expression. The major epigenetic mechanisms that control cell fate and biological functions are DNA methylation and histone modifications. However, epigenetic modifiers alone are not sufficient to generate mature cardiac cells. Various small molecules such as ascorbic acid (AA) and salvianolic acid B (SA) are known for their cardiomyogenic potential. Therefore, this study is aimed to examine the synergistic effects of epigenetic modifiers, valproic acid (VPA) and 5-azacytidine (5-aza) with cardiomyogenic molecules, AA and SA in the cardiac differentiation of MSCs.

METHODS AND RESULTS

BM-MSCs were isolated, propagated, characterized, and then treated with an optimized dose of VPA or 5-aza for 24 h. MSCs were maintained in a medium containing AA and SA for 21 days. All groups were assessed for the expression of cardiac genes and proteins through q-PCR and immunocytochemistry, respectively. Results show that epigenetic modifiers VPA or 5-aza in combination with AA and SA significantly upregulate the expression of cardiac genes MEF2C, Nkx2.5, cMHC, Tbx20, and GATA-4. In addition, VPA or 5-aza pretreatment along with AA and SA enhanced the expression of the cardiac proteins connexin-43, GATA-4, cTnI, and Nkx2.5.

CONCLUSION

These findings suggest that epigenetic modifiers valproic acid and 5-azacytidine in combination with ascorbic acid and salvianolic acid B promote cardiac differentiation of MSCs. This pretreatment strategy can be exploited for designing future stem cell based therapeutic strategies for cardiovascular diseases.

Role of breastfeeding on maternal and childhood cancers: An umbrella review of meta-analyses

Background

Multiple studies and meta-analyses have claimed that breastfeeding is inversely correlated with maternal and childhood cancers. These results could either be causal or confounded by shared risk factors. By conducting an umbrella review, we aimed to consolidate the relationship between breastfeeding and maternal and childhood cancers.

Methods

We searched PubMed, Embase, Web of Science, Elsevier ScienceDirect, and Cochrane Library databases from inception to December 2022. Two reviewers independently extracted the data and assessed the quality of the studies using standardised forms. We considered two types of breastfeeding comparisons ("ever" vs "never" breastfeeding; and "longest" vs "shortest" duration). We estimated the pooled risk and 95% confidence interval (CI) for each meta-analysis.

Results

We included seventeen meta-analyses with 55 comparisons. There was an inverse correlation between breastfeeding and childhood leukaemia (pooled risk = 0.90, 95% CI = 0.81-0.99), neuroblastoma (pooled risk = 0.81, 95% CI = 0.71-0.93), maternal ovarian cancer (pooled risk = 0.76, CI = 0.71-0.81), breast cancer (pooled risk = 0.85, 95% CI = 0.82-0.88), and oesophageal cancer (pooled risk = 0.67, 95% CI = 0.54-0.81) for "ever" vs "never" breastfeeding; and with childhood leukaemia (pooled risk = 0.94, 95% CI = 0.89-0.98), and maternal ovarian cancer (pooled risk = 0.84, 95% CI = 0.78-0.90) and breast cancer (pooled risk = 0.92, 95% CI = 0.89-0.96) for "longest" vs "shortest" breastfeeding duration.

Conclusions

We found evidence that breastfeeding may reduce the risk of maternal breast cancer, ovarian cancers, and childhood leukaemia, suggesting positive implications for influencing women's decision in breastfeeding.

Registration

PROSPERO (CRD42021255608).

Stem cell-based therapy for human diseases

Recent advancements in stem cell technology open a new door for patients suffering from diseases and disorders that have yet to be treated. Stem cell-based therapy, including human pluripotent stem cells (hPSCs) and multipotent mesenchymal stem cells (MSCs), has recently emerged as a key player in regenerative medicine. hPSCs are defined as self-renewable cell types conferring the ability to differentiate into various cellular phenotypes of the human body, including three germ layers. MSCs are multipotent progenitor cells possessing self-renewal ability (limited in vitro) and differentiation potential into mesenchymal lineages, according to the International Society for Cell and Gene Therapy (ISCT). This review provides an update on recent clinical applications using either hPSCs or MSCs derived from bone marrow (BM), adipose tissue (AT), or the umbilical cord (UC) for the treatment of human diseases, including neurological disorders, pulmonary dysfunctions, metabolic/endocrine-related diseases, reproductive disorders, skin burns, and cardiovascular conditions. Moreover, we discuss our own clinical trial experiences on targeted therapies using MSCs in a clinical setting, and we propose and discuss the MSC tissue origin concept and how MSC origin may contribute to the role of MSCs in downstream applications, with the ultimate objective of facilitating translational research in regenerative medicine into clinical applications. The mechanisms discussed here support the proposed hypothesis that BM-MSCs are potentially good candidates for brain and spinal cord injury treatment, AT-MSCs are potentially good candidates for reproductive disorder treatment and skin regeneration, and UC-MSCs are potentially good candidates for pulmonary disease and acute respiratory distress syndrome treatment.

Fecal Microbiota Transplantation and Health Outcomes: An Umbrella Review of Meta-Analyses of Randomized Controlled Trials

Background

Meta-analysis of randomized clinical trials (RCT) demonstrated several health benefits of fecal microbiota transplantation (FMT). However, there has been little comprehensive assessment of the strength and quality of evidence. We conducted an umbrella review to summarize the evidence of the association between FMT and health outcomes.

Methods

PubMed, Embase, and Cochrane library databases were searched from inception to August 6, 2021. The random-effects model was applied to recalculate the effect estimates. We used AMSTAR 2 and GRADE to assess the methodological quality and to grade the evidence.

Results

A total of 7 meta-analyses comprising 26 RCTs (median [IQR] primary study, 6 [2-7]; median [IQR] sample size, 267 [147-431] participants) were included in the current umbrella review describing 45 unique associations. There were 22 statistically significant associations (49%) demonstrating beneficial outcomes of FMT for antibiotic resistance burden, functional constipation, inflammatory bowel disease, and C. difficile infection. FMT does not appear to be associated with positive outcomes in irritable bowel syndrome and metabolic syndrome. Eight significant associations (36%) were supported by moderate-quality evidence, nine associations (41%) were supported by low-quality evidence, and the remaining associations found to be significant were supported by very low-quality evidence.

Conclusion

Although we found that FMT was positively associated with several outcomes, caution should be exercised in choosing this approach, given the insufficient number of primary studies, low methodological quality, and low quality of evidence. Further high-quality randomized controlled trials with long-term follow-up are needed to improve the strength and credibility of the evidence base.

Application of vascular endothelial cells in stem cell medicine

Stem cell medicine is gaining momentum in the development of therapy for various end-stage diseases. The search for new seed cells and exploration of their application prospects are topics of interest in stem cell medicine. In recent years, vascular endothelial cells (VECs) have attracted wide attention from scholars. VECs, which form the inner lining of blood vessels, are critically involved in many physiological functions, including permeability, angiogenesis, blood pressure regulation, immunity, and pathological development, such as atherosclerosis and malignant tumors. VECs have significant therapeutic effects and broad application prospects in stem cell medicine for the treatment of various refractory diseases, including atherosclerosis, myocardial infarction, diabetic complications, hypertension, coronavirus disease 2019, and malignant tumors. On the one hand, VECs and their extracellular vesicles can be directly used for the treatment of these diseases. On the other hand, VECs can be used as therapeutic targets for some diseases. However, there are still some obstacles to the use of VECs in stem cell medicine. In this review, advances in the applications and challenges that come with the use of these cells are discussed.

Mass Customized Outlook for Regenerative Heart Failure Care

Heart failure pathobiology is permissive to reparative intent. Regenerative therapies exemplify an emerging disruptive innovation aimed at achieving structural and functional organ restitution. However, mixed outcomes, complexity in use, and unsustainable cost have curtailed broader adoption, mandating the development of novel cardio-regenerative approaches. Lineage guidance offers a standardized path to customize stem cell fitness for therapy. A case in point is the molecular induction of the cardiopoiesis program in adult stem cells to yield cardiopoietic cell derivatives designed for heart failure treatment. Tested in early and advanced clinical trials in patients with ischemic heart failure, clinical grade cardiopoietic cells were safe and revealed therapeutic improvement within a window of treatment intensity and pre-treatment disease severity. With the prospect of mass customization, cardiopoietic guidance has been streamlined from the demanding, recombinant protein cocktail-based to a protein-free, messenger RNA-based single gene protocol to engineer affordable cardiac repair competent cells. Clinical trial biobanked stem cells enabled a systems biology deconvolution of the cardiopoietic cell secretome linked to therapeutic benefit, exposing a paracrine mode of action. Collectively, this new knowledge informs next generation regenerative therapeutics manufactured as engineered cellular or secretome mimicking cell-free platforms. Launching biotherapeutics tailored for optimal outcome and offered at mass production cost would contribute to advancing equitable regenerative care that addresses population health needs.