Minimally invasive delivery of a hydrogel-based exosome patch to prevent heart failure

https://doi.org/10.1016/j.yjmcc.2022.04.020Get rights and content

Highlights

  • ExoGel is an injectable cardiac patch for delivering MSC exosomes to the heart.

  • Intrapericardial (iPC) injection is a minimally invasive delivery method to deliver ExoGel.

  • iPC injection has been safely performed in rodent and swine hearts in this study.

  • Aged rat model of heart failure was created in this study.

  • ExoGel plays a protective role in an aged rat model of heart failure.

Abstract

Coronary heart disease (CHD) has been the number one killer in the United States for decades and causes millions of deaths each year. Clinical treatment of heart ischemic injury relieves symptoms in the acute stage of CHD; however, patients with an infarcted heart muscle can develop heart failure (HF) due to chronic maladaptive remodeling. Regenerative therapy has been studied as a potential treatment option for myocardial infarction (MI) and HF. Cardiac patches have been designed and tested to increase therapeutic retention and integration. However, the delivery usually requires invasive surgical techniques, including open-chest surgeries and heart manipulation. Those procedures may cause chronic adhesions between the heart anterior wall and the chest wall. This study created and tested an injectable ExoGel by embedding mesenchymal stem cell (MSC) -derived exosomes into a hyaluronic acid (HA) hydrogel. ExoGel was injected into the pericardial cavity of rats with transverse aortic constriction (TAC) induced heart failure. ExoGel therapy reduced LV chamber size and preserved wall thickness. The feasibility and safety of ExoGel injection were further confirmed in a pig model.

Introduction

Coronary heart disease (CHD) generally presents a high prevalence in adults, and the risks of CHD increase with age in both genders [1]. Although treatment strategies have improved in the past several decades, the loss of functional myocardium cannot be restored due to the lack of regenerative capability in the adult human heart [2]. Eventually, the patients may suffer from chronic and recurrent heart failure (HF) that contributes to death through alternations in calcium homeostasis, action potential prolongation, and HF-related lung complications [3]. Stem cell therapy has been studied for decades. It has been reported as a robust strategy that can promote proliferation in infarcted myocardium through paracrine cargos such as proteins [4,5], RNA species [6,7], and extracellular vesicles [7,8]. Among those different cell types, mesenchymal stem cells (MSCs) [9] have been reported as a promising therapeutic agent restoring cardiac function by multifaceted mechanisms.

Direct cardiac delivery of MSCs suffers from low cell retention and survival. Also, potential risks of cell transplantation include immunogenicity and tumorgenicity [10,11]. Therefore, MSC-derived exosomes, or nanosized extracellular vesicles, have been studied as an alternative for MSC therapy. MSC exosomes share similar protein factors, lipid messengers, and regulatory microRNAs (miRNAs) with MSCs and induce their treatment effects mainly by triggering pro-regenerative and anti-fibrotic signaling pathways mediated by different cargo miRNAs [12]. Our previous study showed that miR-21-5p from MSC exosomes regulated PI3K signaling pathway through Akt kinase activity inhibition [13]. Additionally, MSC exosomes play an essential role in the modulation of immune reactions [14] and the reduction of cardiomyocyte apoptosis through miR-199a-3p [15]. Such mechanisms of MSCs include enhanced proliferation and reduced apoptosis of cardiomyocytes [16,17]. However, intravenously injected exosomes could be cleared rapidly from the blood and accumulate in organs such as the brain, lung, and liver rather than in the heart [18]. Even though direct intramyocardial injection of exosomes has shown promising results, it is an invasive technique with restricted application scenarios.

Various bioengineering techniques have been designed to deliver exosomes to the heart efficiently. For example, exosomes were conjugated with cardiac homing peptide or hybridized with platelet membrane to enhance the exosome homing ability after intravenous injection [19,20]. Exosomes were also loaded in cardiac patches made of natural or synthetic materials to generate higher cardiac retention than intramyocardial injection [21]. However, transplantation of cardiac patches typically requires traumatic surgery, which is not acceptable for patients with mild-to-moderate heart diseases. We designed an injectable hyaluronic acid (HA) hydrogel patch loaded with MSC-derived exosomes (ExoGel) in the present study. We tested the feasibility of delivering ExoGel into the pericardial space of rodent or porcine hearts via a thoracoscope-guided minimally invasive procedure. The acute retention and inflammatory response to ExoGel delivery were determined in rodent models, while the safety assessments were performed in healthy pigs as a translational effort.

Section snippets

Fabrication and characterization of an injectable ExoGel

Exosomes were isolated from MSCs and concentrated using the ultrafiltration method as previously described [22]. HA Hydrogel has excellent gelling properties due to its capability to bind water quickly [6]. It is suitable to be delivered into the pericardial fluid environment for sustained drug release. The safety and efficacy of HA hydrogel in heart repair have been established. ExoGel was fabricated by embedding MSC exosomes in HA hydrogel at 1 × 109 exosomes/ml (Fig. 1A). Before ExoGel

Discussion

Although exosomes may vary among different cell types, cell culture conditions, exosome isolation, and purification methods [25], researchers are still enthusiastic about applying exosomes as therapeutics. Two major theories attribute to the mechanism of exosomes: possession of proteomic potency and release of regulating miRNAs [26]. Therefore, many different biotechnologies regarding exosomes are created based on these mechanisms to increase the delivery efficiency and therapeutic potency. For

Isolation and characterization of MSC exosomes

The MSC conditioned media was concentrated via centrifugal filter units Amicon Ultra-15 (3-kDa cutoff) and washed with PBS once at the beginning of exosome isolation. Then, we used the Ultra-15 centrifugal filter units (100 kDa cutoff) to concentrate the exosomes, which were washed with PBS twice. After the wash, NanoSight LM10 (Malvern Instruments Ltd., UK) was used to examine the concentration of exosomes after a 1000-fold dilution.

Preparation of HA hydrogel and ExoGel

The HA hydrogel was prepared to test the effectiveness of

Declaration of Competing Interest

The authors declare no competing financial interests.

Acknowledgments

GC, KH, and TGC conceived and designed the research, GC and DZ performed experiments, analyzed the data, and drafted the paper with guidance from KH and TGC. All authors have reviewed the final version and approved the content in this manuscript. This work was supported by the American Heart Association (21CDA855570 to KH).

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