Infarct Zone: a Novel Platform for Exosome Trade in Cardiac Tissue Regeneration

Advancing Myocardial Infarction Treatment: Harnessing Multi-Layered Recellularized Cardiac Patches with Fetal Myocardial Scaffolds and Acellular Amniotic Membrane

PURPOSE

Myocardial infarction (MI) is a leading cause of irreversible functional cardiac tissue loss, requiring novel regenerative strategies. This study assessed the potential therapeutic efficacy of recellularized cardiac patches, incorporating fetal myocardial scaffolds with rat fetal cardiomyocytes and acellular human amniotic membrane, in adult Wistar rat models of MI.

METHODS

Decellularized myocardial tissue was obtained from 14 to 16 week-old human fetuses that had been aborted. Chemical detergents (0.1% EDTA and 0.2% sodium dodecyl sulfate) were used to prepare the fetal extracellular matrix (ECM), which was characterized for bio-scaffold microstructure and biocompatibility via scanning electron microscopy (SEM) and MTT assay, respectively. Neonatal cardiomyocytes were extracted from the ventricles of one-day-old Wistar rats' littermates and characterized through immunostaining against Connexin-43 and α-smooth muscle actin. The isolated cells were seeded onto decellularized tissues and covered with decellularized amniotic membrane. Sixteen healthy adult Wistar rats were systematically allocated to control and MI groups. MI was induced via arterial ligation. Fourteen days post-operation, the MI group was received the engineered patches. Following a two-week post-implantation period, the animals were euthanized, and the hearts were harvested for the graft evaluation.

RESULTS

Histological analysis, DAPI staining, and ultra-structural examination corroborated the successful depletion of cellular elements, while maintaining the integrity of the fetal ECM and architecture. Subsequent histological and immunohistochemichal (IHC) evaluations confirmed effective cardiomyocyte seeding on the scaffolds. The application of these engineered patches in MI models resulted in increased angiogenesis, reduced fibrosis, and restricted scar tissue formation, with the implanted cardiomyocytes remaining viable at graft sites, indicating prospective in vivo cell viability.

CONCLUSIONS

This study suggests that multi-layered recellularized cardiac patches are a promising surgical intervention for myocardial infarction, showcasing significant potential by promoting angiogenesis, mitigating fibrosis, and minimizing scar tissue formation in MI models. These features are pivotal for enhancing the therapeutic outcomes in MI patients, focusing on the restoration of the myocardial structure and function post-infarction.

Exosomal noncoding RNA: A potential therapy for retinal vascular diseases

Exosomes are extracellular vesicles that can contain DNA, RNA, proteins, and metabolites. They are secreted by cells and play a regulatory role in various biological responses by mediating cell-to-cell communication. Moreover, exosomes are of interest in developing therapies for retinal vascular disorders because they can deliver various substances to cellular targets. According to recent research, exosomes can be used as a strategy for managing retinal vascular diseases, and they are being investigated for therapeutic purposes in eye conditions, including glaucoma, dry eye syndrome, retinal ischemia, diabetic retinopathy, and age-related macular degeneration. However, the role of exosomal noncoding RNA in retinal vascular diseases is not fully understood. Here, we reviewed the latest research on the biological role of exosomal noncoding RNA in treating retinal vascular diseases. Research has shown that noncoding RNAs, including microRNAs, circular RNAs, and long noncoding RNAs play a significant role in the regulation of retinal vascular diseases. Furthermore, through exosome engineering, the expression of relevant noncoding RNAs in exosomes can be controlled to regulate retinal vascular diseases. Therefore, this review suggests that exosomal noncoding RNA could be considered as a biomarker for diagnosis and as a therapeutic target for treating retinal vascular disease.

Extracellular vesicle mediated targeting delivery of growth differentiation factor-15 improves myocardial repair by reprogramming macrophages post myocardial injury

OBJECTIVE

Extracellular vesicles (EVs) have garnered considerable attention among researchers as candidates for natural drug delivery systems. This study aimed to investigate whether extracellular vesicle mediated targeting delivery of growth differentiation factor-15 (GDF15) improves myocardial repair by reprogramming macrophages post myocardial injury.

METHODS

EVs were isolated from macrophages transfected with GDF15 (EXO-GDF15) and control macrophages (EXO-NC). In vitro and vivo experiments, we compared their reprogram ability of macrophages and regeneration activity. Furthermore, proteomic analysis were employed to determine the specific mechanism by which GDF15 repairs the myocardium.

RESULTS

Compared with EXO-NC, EXO-GDF15 significantly regulated macrophage phenotypic shift, inhibited cardiomyocyte apoptosis, and enhanced endothelial cell angiogenesis. Moreover, EXO-GDF15 also significantly regulated macrophage heterogeneity and inflammatory cytokines, reduced fibrotic area, and enhanced cardiac function in infarcted rats. Proteomic analysis revealed a decrease in fatty acid-binding protein 4 (FABP4) protein expression following treatment with EXO-GDF15. Mechanistically, the reprogramming of macrophages by EXO-GDF15 is accomplished through the activation of Smad2/3 phosphorylation, which subsequently inhibits the production of FABP4.

CONCLUSIONS

Extracellular vesicle mediated targeting delivery of growth differentiation factor-15 improves myocardial repair by reprogramming macrophages post myocardial injury via down-regulating the expression of FABP4. EXO-GDF15 may serve as a promising approach of immunotherapy.

Engineered Vesicles and Hydrogel Technologies for Myocardial Regeneration

Increased prevalence of cardiovascular disease and potentially life-threatening complications of myocardial infarction (MI) has led to emerging therapeutic approaches focusing on myocardial regeneration and restoration of physiologic function following infarction. Extracellular vesicle (EV) technology has gained attention owing to the biological potential to modulate cellular immune responses and promote the repair of damaged tissue. Also, EVs are involved in local and distant cellular communication following damage and play an important role in initiating the repair process. Vesicles derived from stem cells and cardiomyocytes (CM) are of particular interest due to their ability to promote cell growth, proliferation, and angiogenesis following MI. Although a promising candidate for myocardial repair, EV technology is limited by the short retention time of vesicles and rapid elimination by the body. There have been several successful attempts to address this shortcoming, which includes hydrogel technology for the sustained bioavailability of EVs. This review discusses and summarizes current understanding regarding EV technology in the context of myocardial repair.

Extracellular vesicles as personalized medicine

Extracellular vesicles (EVs) are released from all cells in the body, forming an important intercellular communication network that contributes to health and disease. The contents of EVs are cell source-specific, inducing distinct signaling responses in recipient cells. The specificity of EVs and their accumulation in fluid spaces that are accessible for liquid biopsies make them highly attractive as potential biomarkers and therapies for disease. The duality of EVs as favorable (therapeutic) or unfavorable (pathological) messengers is context dependent and remains to be fully determined in homeostasis and various disease states. This review describes the use of EVs as biomarkers, drug delivery vehicles, and regenerative therapeutics, highlighting examples involving viral infections, cancer, and neurological diseases. There is growing interest to provide personalized therapy based on individual patient and disease characteristics. Increasing evidence suggests that EV biomarkers and therapeutic approaches are ideal for personalized medicine due to the diversity and multifunctionality of EVs.

Microneedle Patch Loaded with Exosomes Containing MicroRNA-29b Prevents Cardiac Fibrosis after Myocardial Infarction

Myocardial infarction (MI) is a cardiovascular disease that poses a serious threat to human health. Uncontrolled and excessive cardiac fibrosis after MI has been recognized as a primary contributor to mortality by heart failure. Thus, prevention of fibrosis or alleviation of fibrosis progression is important for cardiac repair. To this end, a biocompatible microneedle (MN) patch based on gelatin is fabricated to load exosomes containing microRNA-29b (miR-29b) mimics with antifibrotic activity to prevent excessive cardiac fibrosis after MI. Exosomes are isolated from human umbilical cord mesenchymal stem cells and loaded with miR-29b mimics via electroporation, which can be internalized effectively in cardiac fibroblasts to upregulate the expression of miR-29b and downregulate the expression of fibrosis-related proteins. After being implanted in the infarcted heart of a mouse MI model, the MN patch can increase the retention of loaded exosomes in the infarcted myocardium, leading to alleviation of inflammation, reduction of the infarct size, inhibition of fibrosis, and improvement of cardiac function. This design explored the MN patch as a suitable platform to deliver exosomes containing antifibrotic biomolecules locally for the prevention of cardiac fibrosis, showing the potential for MI treatment in clinical applications.

Peripheral Nerve Regeneration: Opportunities and Challenges

Peripheral nerve injury has detrimental effects on the quality of life for patients and is a worldwide issue with high rates of morbidity. Research on the molecular mechanisms of nerve injury, microsurgical techniques, and advances in stem cell research have led to substantial progress in the field of translational neurophysiology. Current research on peripheral nerve regeneration aims to accelerate peripheral nerve development through pluripotent stem cells and potential use of smart exosomes, pharmacological agents, and bioengineering of nerve conduits. In this article critically reviewed and summarized various methods used for peripheral nerve regeneration and highlight the opportunities and challenges that come along with these strategies.

Single-cell genomics illustrates heterogeneous phenotypes of myocardial fibroblasts under ischemic insults

Myocardial regenerative strategies are promising where the choice of ideal cell population is crucial for successful translational applications. Herein, we explored the regenerative/repair responses of infarct zone cardiac fibroblast(s) (CF) by unveiling their phenotype heterogeneity at single-cell resolution. CF were isolated from the infarct zone of Yucatan miniswine that suffered myocardial infarction, cultured under simulated ischemic and reperfusion, and grouped into control, ischemia, and ischemia/reperfusion. The single-cell RNA sequencing analysis revealed 19 unique cell clusters suggesting distinct subpopulations. The status of gene expression (log2 fold change (log2 FC) > 2 and log2 FC < -2) was used to define the characteristics of each cluster unveiling with diverse features, including the pro-survival/cardioprotective (Clusters 1, 3, 5, 9, and 18), vasculoprotective (Clusters 2 and 5), anti-inflammatory (Clusters 4 and 17), proliferative (Clusters 4 and 5), nonproliferative (Clusters 6, 8, 11, 16, 17, and 18), proinflammatory (Cluster 6), profibrotic/pathologic (Clusters 8 and 19), antihypertrophic (Clusters 8 and 10), extracellular matrix restorative (Clusters 9 and 12), angiogenic (Cluster 16), and normal (Clusters 7 and 15) phenotypes. Further understanding of these unique phenotypes of CF will provide significant translational opportunities for myocardial regeneration and cardiac management.

Future applications of exosomes delivering resolvins and cytokines in facilitating diabetic foot ulcer healing

Type 2 diabetes mellitus (T2DM) increases the risk of many lethal and debilitating conditions. Among them, foot ulceration due to neuropathy, vascular disease, or trauma affects the quality of life of millions in the United States and around the world. Physiological wound healing is stalled in the inflammatory phase by the chronicity of inflammation without proceeding to the resolution phase. Despite advanced treatment, diabetic foot ulcers (DFUs) are associated with a risk of amputation. Thus, there is a need for novel therapies to address chronic inflammation, decreased angiogenesis, and impaired granulation tissue formation contributing to the non-healing of DFUs. Studies have shown promising results with resolvins (Rv) and anti-inflammatory therapies that resolve inflammation and enhance tissue healing. But many of these studies have encountered difficulty in the delivery of Rv in terms of efficiency, tissue targetability, and immunogenicity. This review summarized the perspective of optimizing the therapeutic application of Rv and cytokines by pairing them with exosomes as a novel strategy for targeted tissue delivery to treat non-healing chronic DFUs. The articles discussing the T2DM disease state, current research on Rv for treating inflammation, the role of Rv in enhancing wound healing, and exosomes as a delivery vehicle were critically reviewed to find support for the proposition of using Rv and exosomes in combination for DFUs therapy. The literature reviewed suggests the beneficial role of Rv and exosomes and exosomes loaded with anti-inflammatory agents as promising therapeutic agents in ulcer healing.

Intelligent Hydrogels in Myocardial Regeneration and Engineering

Myocardial infarction (MI) causes impaired cardiac function due to the loss of cardiomyocytes following an ischemic attack. Intelligent hydrogels offer promising solutions for post-MI cardiac tissue therapy to aid in structural support, contractility, and targeted drug therapy. Hydrogels are porous hydrophilic matrices used for biological scaffolding, and upon the careful alteration of ideal functional groups, the hydrogels respond to the chemistry of the surrounding microenvironment, resulting in intelligent hydrogels. This review delves into the perspectives of various intelligent hydrogels and evidence from successful models of hydrogel-assisted treatment strategies.

Exosomal-ribosomal proteins-driven heterogeneity of epicardial adipose tissue derived stem cells under ischemia for cardiac regeneration

Extracellular ribosomal proteins secreted in exosomes elicit biological/regenerative responses; however, ribosomal proteins contained in the exosomes of ischemia-challenged epicardial adipose tissue-derived stem cells (EATDS) remain unexplored. This study focuses on the identification of ribosomal proteins in the exosomes of ischemia-challenged EATDS and their sub-populations based on the key ribosomal proteins using single-cell genomics. Exosomes were isolated from control, ischemic (ISC), and reperfused (ISC/R) EATDS harvested from hyperlipidemic microswine, and the proteins were detected using Liquid chromatography with tandem mass spectrometry (LC-MS/MS). One hundred ninety-nine proteins and 177 proteins were detected in ISC and ISC/R groups, respectively with significant fold-change compared to controls. Five ribosomal proteins, RPL10A, 40SRPS18, 40SRPS30, 60SRPL14, and 40SRPSA, were significant owing to their abundance based on LC-MS/MS data. Expression of these proteins, except RPL10A, at transcript and protein levels were lower in ISC group compared to the control. scRNAseq analysis revealed EATDS heterogeneity based on the upregulation of 40SRPSA, 40SRPL18, and 40SRPS18. Pro-inflammatory sub-populations upregulated CCL5, anti-inflammatory sub-population upregulated IL-11, proliferative sub-population upregulated cell cycle and DNA replication mediators, and non-proliferative population downregulated the cell cycle and DNA replication mediators. Overall, the functional role of extracellular ribosomal proteins in driving unique phenotypes of EATDS population offers promise for designing effective translational approaches for myocardial regeneration.

Potential Clinical Applications of Exosomal Circular RNAs: More than Diagnosis

Exosomes are small vesicles derived from cells used as cell-to-cell communication goods in numerous diseases including tumorigenesis, neurological diseases, cardiovascular diseases and other diseases. Circular RNAs (circRNAs) are an innovative constituent of non-coding endogenous RNAs generated through backsplicing, catalyzed by RNA polymerase Ⅱ. These non-coding RNAs have been suggested to control gene expression through miRNA sponging, RNA-binding protein regulation and translational capabilities. Genome-wide RNA sequence analyses observed that circRNAs were stably improved in exosomes in association to parental cells. Little attention has been dedicated to exosomal circRNAs (exo-circRNAs). However, research has demonstrated that exo-circRNAs may have important regulatory functions because of their stability in cells and within exosomes. If well understood, the precise roles and mechanisms of exo-circRNAs might surge the impending clinical applications of these molecules as markers in the identification, prediction and treatment of various diseases. In this review, we outline recent findings regarding exo-circRNAs which includes their functions and highlights their potential applications and therapeutic targets in human diseases.

Single Cell Genomics Identifies Unique Cardioprotective Phenotype of Stem Cells derived from Epicardial Adipose Tissue under Ischemia

The conventional management strategies of myocardial infarction (MI) are effective to sustain life; however, myocardial regeneration has not been achieved owing to the inherently poor regenerative capacity of the native myocardium. Stem cell-based therapies are promising; however, lineage specificity and undesired differentiation profile are challenging. Herein, we focused on the epicardial fat (EF) as an ideal source for mesenchymal stem cells (MSCs) owing to the proximity and same microvasculature with cardiac muscle. Unfortunately, the epicardial adipose tissue derived stem cells (EATDS) remain understudied regarding their phenotype heterogeneity and cardiac regeneration potential. As EF closely reflects the cardiac pathology during ischemia, the present study aims to determine the EATDS subpopulations under simulated ischemic and reperfused conditions employing single cell RNA sequencing (scRNAseq). EATDS were isolated from three hyperlipidemic Yucatan microswine and were divided into Control, Ischemia (ISC), and Ischemia/reperfusion (ISC/R). The scRNAseq analysis was performed using 10 genomics platform which revealed 18 unique cell clusters suggesting the existence of heterogeneous phenotypes. The upregulated genes were taken into consideration and subsequent functional assessment revealed the cardioprotective phenotypes with diverse mechanisms including epigenetic regulation (Cluster 1), myocardial homeostasis (Cluster 1), cell integrity and cell cycle (Clusters 2 and 3), prevention of fibroblast differentiation (Cluster 4), differentiation to myocardial lineage (Cluster 6), anti-inflammatory responses (Clusters 5, 8, and 11), prevention of ER-stress (Cluster 9), and increasing the energy metabolism (Cluster 10). These unique phenotypes of heterogeneous EATDS population open significant translational opportunities for myocardial regeneration and cardiac management.

Exosomal miR-21 from tubular cells contributes to renal fibrosis by activating fibroblasts via targeting PTEN in obstructed kidneys

Rationale: Ureteral obstruction-induced hydronephrosis is associated with renal fibrosis and progressive chronic kidney disease (CKD). Exosome-mediated cell-cell communication has been suggested to be involved in various diseases, including renal fibrosis. However, little is known regarding how exosomes regulate renal fibrosis in obstructed kidneys.

Methods: We first examined the secretion of exosomes in UUO (unilateral ureteral obstruction) mouse kidneys and TGF-β1-stimulated tubular epithelial cells (NRK-52E). Exosomes from NRK-52E cells were subsequently harvested and incubated with fibroblasts (NRK-49F) or injected into UUO mice via the tail vein. We next constructed Rab27a knockout mice to further confirm the role of exosome-mediated epithelial-fibroblast communication relevant to renal fibrosis in UUO mice. High-throughput miRNA sequencing was performed to detect the miRNA profiles of TGFβ1-Exos. The roles of candidate miRNAs, their target genes and relevant pathways were predicted and assessed in vitro and in vivo by setting specific miRNA mimic, miRNA inhibitor, siRNA or miRNA LNA groups.

Results: Increased renal fibrosis was associated with prolonged UUO days, and the secretion of exosomes was markedly increased in UUO kidneys and TGF-β1-stimulated NRK-52E cells. Purified exosomes from TGF-β1-stimulated NRK-52E cells could activate fibroblasts and aggravate renal fibrosis in vitro and in vivo. In addition, the inhibition of exosome secretion by Rab27a knockout or GW4869 treatment abolished fibroblast activation and ameliorated renal fibrosis. Exosomal miR-21 was significantly increased in TGFβ1-Exos compared with Ctrl-Exos, and PTEN is a certain target of miR-21. The promotion or inhibition of epithelial exosomal miR-21 correspondingly accelerated or abolished fibroblast activation in vitro, and renal fibrosis after UUO was alleviated by miR-21-deficient exosomes in vivo through the PTEN/Akt pathway.

Conclusion: Our findings reveal that exosomal miR-21 from tubular epithelial cells may accelerate the development of renal fibrosis by activating fibroblasts via the miR-21/PTEN/Akt pathway in obstructed kidneys.

A Bibliometric Analysis of Exosomes in Cardiovascular Diseases From 2001 to 2021

Background: Exosomes in cardiovascular diseases (CVDs) have become an active research field with substantial value and potential. Nevertheless, there are few bibliometric studies in this field. We aimed to visualize the research hotspots and trends of exosomes in CVDs using a bibliometric analysis to help understand the future development of basic and clinical research.

Methods: The articles and reviews regarding exosomes in the CVDs were culled from the Web of Science Core Collection, and knowledge maps were generated using CiteSpace and VOSviewer software.

Results: A total of 1,039 articles were included. The number of exosome articles in the CVDs increased yearly. These publications came from 60 countries/regions, led by the US and China. The primary research institutions were Shanghai Jiao Tong University and Nanjing Medical University. Circulation Research was the journal and co-cited journal with the most studies. We identified 473 authors among which Lucio Barile had the most significant number of articles and Thery C was co-cited most often. After analysis, the most common keywords are myocardium infarction, microRNA and mesenchymal stem cells. Ischemic heart disease, pathogenesis, regeneration, stem cells, targeted therapy, biomarkers, cardiac protection, and others are current and developing areas of study.

Conclusion: We identified the research hotspots and trends of exosomes in CVDs using bibliometric and visual methods. Research on exosomes is flourishing in the cardiovascular medicine. Regenerative medicine, exosome engineering, delivery vehicles, and biomarkers will likely become the focus of future research.

Hypoxia-driven secretion of extracellular matrix proteins in the exosomes reflects the asymptomatic pathology of rotator cuff tendinopathies

The major hallmark of rotator cuff tendinopathies (RCT) is the disorganization of the tendon extracellular matrix (ECM), which is due to a decrease in the ratio of collagen I to collagen III. In addition, the pathology of the tendon matrisome remains asymptomatic, and hypoxia has been identified to be the priming signal to initiate the molecular pathology of RCT. Also, the secretome content of hypoxia-challenged tendon cells (tenocytes) reflects the pathological status of RCT. With this background, the present study was designed to establish the expression status and molecular crosstalk of the ECM component proteins contained in the exosomes of the hypoxia-challenged swine tenocytes. The mass spectrometry analysis revealed the upregulation of COL1A2, P4HA1, PRDX2, P3H1, COL6A1, PPIB, LCN1, and COL3A1 and the downregulation of COLA12, PDIA4, COLG, FN1, CTSK, and TNC in the exosomes of hypoxic tenocytes. These proteins interact with diverse proteins and operate multiple pathways associated with ECM homeostasis and repair as determined by NetworkAnalyst. The functional analysis of these proteins reflects the pathology of tendon ECM, which is correlated with the asymptomatic phase of RCT. Understanding the signaling mediated by these proteins would reveal the underlying molecular pathology and offers translational significance in the diagnosis and management of RCT.

Similarities and Differences in Extracellular Vesicle Profiles between Ischaemic Stroke and Myocardial Infarction

Extracellular vesicles (EVs) are involved in intercellular signalling through the transfer of molecules during physiological and pathological conditions, such as ischaemic disease. EVs might therefore play a role in ischaemic stroke (IS) and myocardial infarction (MI). In the present study, we analysed the similarities and differences in the content of circulating EVs in patients with IS and MI. This prospective observational study enrolled 140 participants (81 patients with IS, 37 with MI and 22 healthy controls [HCs]). We analysed the protein and microRNA content from EVs using proteomics and reverse transcription quantitative real-time polymerase chain reaction and compared it between the groups. In the patients with IS and MI, we identified 14 common proteins. When comparing IS and MI, we found differences in the protein profiles (apolipoprotein B, alpha-2-macroglobulin, fibronectin). We also found lower levels of miR-340 and miR-424 and higher levels of miR-29b in the patients with IS and MI compared with the HCs. Lastly, we found higher miR-340 levels in IS than in MI. In conclusion, proteomic and miRNA analyses suggest a relationship between circulating EV content and the patient’s disease state. Although IS and MI affect different organs (brain and heart) with distinct histological characteristics, certain EV proteins and miRNAs appear to participate in both diseases, while others are present only in patients with IS.

The potential diagnostic and therapeutic applications of exosomes in drug-induced liver injury

Drug-induced liver injury (DILI) has gradually become a global public medical problem, which can be caused by more than 1000 currently available drugs. Unfortunately, the diagnosis and treatment of DILI are limited and imperfect. Exosomes can be secreted by a variety of cells and tissues in the body, rich in cell-type specific proteins, nucleic acids and lipids, which has been widely studied as an important intercellular communication vehicle in liver diseases. Emerging data suggest that circulating exosomes and their cargos can be used as minimally-invasive sources of potential molecular biomarkers for the early detection, monitoring and evaluation of DILI. Exosomes in the urine were also found to contain proteins or RNAs that were indicative of DILI. In addition, exosomes derived from mesenchymal stem cell or hepatocyte are considered potential therapeutic agents to promote liver regenerative responses, modulate inflammatory response and deduce hepatocytes apoptosis. Based on the current findings, we suggest the potential applications of exosomes as biomarkers and therapeutics for DILI.

In vitro controlled release of extracellular vesicles for cardiac repair from poly(glycerol sebacate) acrylate-based polymers

Cell therapy to restore cardiac function in chronic heart failure has been extensively studied. However, its therapeutic value is limited due to poor cell engraftment and survival and the therapeutic outcomes have been attributed to paracrine secretions such as extracellular vesicles (EV). The direct use of EV is an attractive therapeutic strategy and it has been shown that the kinetics of delivery of the EV to the targeted tissue may impact the outcomes. However, there are currently no technologies to deliver EV to the heart in a controlled and tunable manner. The objective of this study was to design a controlled release system, based on a photocurable adhesive polymer, to locally deliver EV to the cardiac tissue. We have first demonstrated that the adhesive polymer, PGSA-g-EG, did not impact the EV bioactivity in vitro and was biocompatible in vivo when tested in a rat model. Importantly, the polymer remained attached to the heart surface for at least 1 month. We have then evaluated and optimized the in vitro release kinetics of the EV from the PGSA-g-EG polymer. Freeze-dried EV formulations were developed to tune the release kinetics and maximize the loading in the polymeric material. Moreover, despite the instability of the EV in aqueous medium at 37°C, the PGSA-g-EG polymer was able to release bioactive EV for at least 14 days. Overall, these results suggest that the PGSA-g-EG is a suitable material to promote the controlled delivery of bioactive EV over an extended period of time. STATEMENT OF SIGNIFICANCE: Extracellular vesicles (EV) are an investigational class of therapeutics that has shown promise to restore cardiac function following an ischemic event. Furthermore, its translation to the clinics is expected to pose less regulatory challenges than cell-based therapies. However, EV therapeutic outcomes are likely to be impacted by the route of administration and the kinetics of delivery to the target tissue. Therefore, there is a need for biomaterial-based technologies to deliver, in a controlled and tunable manner, EV to the heart. The present study describes the use of PGSA-g-EG polymer as an adhesive cardiac patch with potential to enable the controlled delivery of bioactive EV over an extended period of time to the cardiac tissue.