Therapeutic Efficacy of Cryopreserved, Allogeneic Extracellular Vesicles for Treatment of Acute Myocardial Infarction

Different storage and freezing protocols for extracellular vesicles: a systematic review

BACKGROUND

Extracellular vesicles (EVs) have been considered promising tools in regenerative medicine. However, the nanoscale properties of EVs make them sensitive to environmental conditions. Optimal storage protocols are crucial for maintaining EV structural, molecular, and functional integrity. This systematic review aimed to gather evidence on the effects of various storage protocols on EV characteristics and integrity.

STRATEGY

A comprehensive search was conducted for original studies investigating the impacts of storage temperature, freezing techniques, freeze-thaw cycles, and stabilizing strategies on EV concentration, size distribution, morphology, cargo content, and bioactivity. Results from 50 included studies were analyzed.

RESULTS

Data indicated that rapid freezing procedures and constant subzero temperatures (optimally - 80 °C) resulted in appropriate EV quantity and cargo preservation. Subjecting EVs to multiple freeze-thaw cycles decreased particle concentrations, RNA content, impaired bioactivity, and increased EV size and aggregation. Electron microscopy revealed vesicle enlargement, and fusion, along with membrane deformation after being exposed to substandard storage protocols. The addition of stabilizers like trehalose helped EVs to maintain integrity. Of note, storage in native biofluids offered improved stability over purified EVs in buffers.

CONCLUSION

Data emphasize the critical need for precise storage protocols for EVs to ensure reproducible research outcomes and clinical applications. Further studies using reliable methods are necessary to create specific guidelines for improving the stability of EVs in various applications.

The role of CD38 in ischemia reperfusion injury in cardiopulmonary bypass and thoracic transplantation: a narrative review

Background and Objective

Ischemia reperfusion injury (IRI) is often the underlying cause of endothelium breakdown and damage in cardiac or transplantation operations, which can lead to disastrous post-operative consequences. Recent studies of cluster of differentiation 38 (CD38) have identified its critical role in IRI. Our objective is to provide a comprehensive overview of CD38-mediated axis, pathways, and potential CD38 translational therapies for reducing inflammation associated with cardiopulmonary bypass (CPB) or thoracic transplantation and IRI.

Methods

We conducted a review of the literature by performing a search of the PubMed database on 2 April 2023. To find relevant publications on CD38, we utilized the MeSH terms: "CD38" AND "Ischemia" OR "CD38" AND "Transplant" OR "CD38" AND "Heart" from 1990-2023. Additional papers were included if they were felt to be relevant but were not captured in the MeSH terms. We found 160 papers that met this criterion, and following screening, exclusion and consensus a total of 36 papers were included.

Key Content and Findings

CD38 is most notably a nicotine adenine dinucleotide (NAD)+ glycohydrolase (NADase), and a generator of Ca2+ signaling secondary messengers. Ultimately, the release of these secondary messengers leads to the activation of important mediators of cellular death. In the heart and during thoracic transplantation, this pathway is intimately involved in a wide variety of injuries; namely the endothelium. In the heart, activation generally results in vasoconstriction, poor myocardial perfusion, and ultimately poor cardiac function. CD38 activation also prevents the accumulation of atherosclerotic disease. During transplantation, intracellular activation leads to infiltration of recipient innate immune cells, tissue edema, and ultimately primary graft dysfunction (PGD). Specifically, in heart transplantation, extracellular activation could be protective and improve allograft survival.

Conclusions

The knowledge gap in understanding the molecular basis of IRI has prevented further development of novel therapies and treatments. The possible interaction of CD38 with CD39 in the endothelium, and the modulation of the CD38 axis may be a pathway to improve cardiovascular outcomes, heart and lung donor organ quality, and overall longevity.

Advances in the study of exosomes derived from mesenchymal stem cells and cardiac cells for the treatment of myocardial infarction

Acute myocardial infarction has long been the leading cause of death in coronary heart disease, which is characterized by irreversible cardiomyocyte death and restricted blood supply. Conventional reperfusion therapy can further aggravate myocardial injury. Stem cell therapy, especially with mesenchymal stem cells (MSCs), has emerged as a promising approach to promote cardiac repair and improve cardiac function. MSCs may induce these effects by secreting exosomes containing therapeutically active RNA, proteins and lipids. Notably, normal cardiac function depends on intracardiac paracrine signaling via exosomes, and exosomes secreted by cardiac cells can partially reflect changes in the heart during disease, so analyzing these vesicles may provide valuable insights into the pathology of myocardial infarction as well as guide the development of new treatments. The present review examines how exosomes produced by MSCs and cardiac cells may influence injury after myocardial infarction and serve as therapies against such injury. Video Abstract.

Therapeutics of Extracellular Vesicles in Cardiocerebrovascular and Metabolic Diseases

Extracellular vesicles (EVs) are nanoscale membranous vesicles containing DNA, RNA, lipids, and proteins, which play versatile roles in intercellular communications. EVs are increasingly being recognized as the promising therapeutic agents for many diseases, including cardiocerebrovascular and metabolic diseases, due to their ability to deliver functional and therapeutical molecules. In this chapter, the biological characteristics and functions of EVs are briefly summarized. Importantly, the current state of applying EVs in the prevention and treatment of cardiocerebrovascular and metabolic diseases, including myocardial infarction, atrial fibrillation, myocardial hypertrophy, stroke, diabetes, Alzheimer's disease, fatty liver, obesity, thyroid diseases, and osteoporosis, is discussed. Lastly, the challenges and prospects related to the preclinical and clinical application of EVs receive a particular focus.

Endothelial progenitor cell-derived small extracellular vesicles for myocardial angiogenesis and revascularization

BACKGROUND

Endothelial progenitor cells (EPCs) have been well-studied for their differentiation potential and paracrine activity in vitro and in experimental animal studies. EPCs are the precursors of endothelial cells (ECs) and a rich source of pro-angiogenic factors, and hence, possess enormous potential to treat ischemic heart through myocardial angiogenesis. Their proven safety and efficacy observed during the pre-clinical and clinical studies have portrayed them as a near ideal cell type for cell-based therapy of ischemic heart disease.In response to the chemical cues from the ischemic heart, EPCs from the bone marrow and peripheral circulation home-in to the ischemic myocardium and participate in the intrinsic repair process at the molecular and cellular levels through paracrine activity and EC differentiation. EPCs also release small extracellular vesicles (sEVs) loaded with bioactive molecules as part of their paracrine activity for intercellular communication to participate in the reparative process in the heart.

AIM

This literature review is based on the published data regarding the characteristic features of EPC-derived sEVs and their proteomic and genomic payload, besides facilitating safe and effective repair of the ischemic myocardium. In light of the encouraging published data, translational and clinical assessment of EPC-derived sEVs is warranted. We report the recent experimental animal studies and their findings using EPC-derived sEVs on cardiac angiogenesis and preservation of cardiac function.

RELEVANCE FOR PATIENTS

With the promising results from pre-clinical studies, clinical trials should be conducted to assess the clinical utility of EPC-derived sEVs in the treatment of the ischemic myocardium.

Benefits and Risks of Delayed Surgery for Ventricular Septal Rupture after Acute Myocardial Infarction

The timing of surgery for ventricular septal rupture (VSR) after acute myocardial infarction (AMI) remains controversial. This study investigated the benefits and risks of delayed surgery for post-AMI VSR and examined differences in echocardiographic findings between early and delay groups.A total of 38 consecutive patients with post-AMI VSR who underwent surgery at our hospital between May 2003 and November 2020 were retrospectively analyzed. Our strategy was to delay surgery until 2 weeks after AMI. If patients demonstrated organ dysfunction, we considered early surgery. Patients were divided into early (n = 20; 53%) and delay (n = 18; 47%) groups. Risks and benefits were investigated based on echocardiographic findings during the waiting period. The delay group had more preoperative intravenous catheter infections (P = 0.008) but fewer reoperations (P = 0.02) and lower operative mortality (P = 0.04) than the early group. The VSR defect diameter and total pulmonary blood flow to total systemic blood flow (Qp/Qs) increased in both groups while waiting. Nevertheless, the early group had a significantly higher Qp/Qs change rate than the delay group (P = 0.05). The 30 day and hospital mortality rates were 5.3% and 13.2%, respectively.The VSR defect diameter and Qp/Qs in both groups increased with time and can therefore become risk factors. Nonetheless, the benefit of waiting exceeded the risk because our outcomes were better than those previously reported.

From Mesenchymal Stromal Cells to Engineered Extracellular Vesicles: A New Therapeutic Paradigm

Mesenchymal stromal cells (MSCs) are multipotent cells obtained from many tissues including bone marrow, adipose tissue, umbilical cord, amniotic fluid, and placenta. MSCs are the leading cell source for stem cell therapy due to their regenerative and immunomodulatory properties, their low risk of tumorigenesis and lack of ethical constraints. However, clinical applications of MSCs remain limited. MSC therapeutic development continues to pose challenges in terms of preparation, purity, consistency, efficiency, reproducibility, processing time and scalability. Additionally, there are issues with their poor engraftment and survival in sites of disease or damage that limit their capacity to directly replace damaged cells. A key recent development in MSC research, however, is the now widely accepted view that MSCs primarily exert therapeutic effects via paracrine factor secretion. One of the major paracrine effectors are extracellular vesicles (EVs). EVs represent a potential cell-free alternative to stem cell therapy but are also rapidly emerging as a novel therapeutic platform in their own right, particularly in the form of engineered EVs (EEVs) tailored to target a broad range of clinical indications. However, the development of EVs and EEVs for therapeutic application still faces a number of hurdles, including the establishment of a consistent, scalable cell source, and the development of robust GMP-compliant upstream and downstream manufacturing processes. In this review we will highlight the clinical challenges of MSC therapeutic development and discuss how EVs and EEVs can overcome the challenges faced in the clinical application of MSCs.