Development of target-specific liposomes for delivering small molecule drugs after reperfused myocardial infarction

Puerarin-Loaded Liposomes Co-Modified by Ischemic Myocardium-Targeting Peptide and Triphenylphosphonium Cations Ameliorate Myocardial Ischemia-Reperfusion Injury

Purpose

Mitochondrial damage may lead to uncontrolled oxidative stress and massive apoptosis, and thus plays a pivotal role in the pathological processes of myocardial ischemia-reperfusion (I/R) injury. However, it is difficult for the drugs such as puerarin (PUE) to reach the mitochondrial lesion due to lack of targeting ability, which seriously affects the expected efficacy of drug therapy for myocardial I/R injury.

Methods

We prepared triphenylphosphonium (TPP) cations and ischemic myocardium-targeting peptide (IMTP) co-modified puerarin-loaded liposomes (PUE@T/I-L), which effectively deliver the drug to mitochondria and improve the effectiveness of PUE in reducing myocardial I/R injury.

Results

In vitro test results showed that PUE@T/I-L had sustained release and excellent hemocompatibility. Fluorescence test results showed that TPP cations and IMTP double-modified liposomes (T/I-L) enhanced the intracellular uptake, escaped lysosomal capture and promoted drug targeting into the mitochondria. Notably, PUE@T/I-L inhibited the opening of the mitochondrial permeability transition pore, reduced intracellular reactive oxygen species (ROS) levels and increased superoxide dismutase (SOD) levels, thereby decreasing the percentage of Hoechst-positive cells and improving the survival of hypoxia-reoxygenated (H/R)-injured H9c2 cells. In a mouse myocardial I/R injury model, PUE@T/I-L showed a significant myocardial protective effect against myocardial I/R injury by protecting mitochondrial integrity, reducing myocardial apoptosis and decreasing infarct size.

Conclusion

This drug delivery system exhibited excellent mitochondrial targeting and reduction of myocardial apoptosis, which endowed it with good potential extension value in the precise treatment of myocardial I/R injury.

Phage Display as a Medium for Target Therapy Based Drug Discovery, Review and Update

Phage libraries are now amongst the most prominent approaches for the identification of high-affinity antibodies/peptides from billions of displayed phages in a specific library through the biopanning process. Due to its ability to discover potential therapeutic candidates that bind specifically to targets, phage display has gained considerable attention in targeted therapy. Using this approach, peptides with high-affinity and specificity can be identified for potential therapeutic or diagnostic use. Furthermore, phage libraries can be used to rapidly screen and identify novel antibodies to develop immunotherapeutics. The Food and Drug Administration (FDA) has approved several phage display-derived peptides and antibodies for the treatment of different diseases. In the current review, we provided a comprehensive insight into the role of phage display-derived peptides and antibodies in the treatment of different diseases including cancers, infectious diseases and neurological disorders. We also explored the applications of phage display in targeted drug delivery, gene therapy, and CAR T-cell.

Journey into tomorrow: cardiovascular wellbeing transformed by nano-scale innovations

Worldwide, cardiovascular diseases (CVDs) account for the vast majority of deaths and place enormous financial strains on healthcare systems. Gold nanoparticles, quantum dots, polymeric nanoparticles, carbon nanotubes, and lipids are innovative nanomaterials promising in tackling CVDs. In the setting of CVDs, these nanomaterials actively impact cellular responses due to their distinctive properties, including surface energy and topographies. Opportunities to more precisely target CVDs have arisen due to recent developments in nanomaterial science, which have introduced fresh approaches. An in-depth familiarity with the illness and its targeted mechanisms is necessary to use nanomaterials in CVDs effectively. We support the academic community's efforts to prioritize Nano-technological techniques in addressing risk factors linked with cardiovascular diseases, acknowledging the far-reaching effects of these conditions. The significant impact of nanotechnology on the early detection and treatment of cardiovascular diseases highlights the critical need for novel approaches to this pressing health problem, which is affecting people worldwide.

Small non-coding RNA therapeutics for cardiovascular disease

Novel bio-therapeutic agents that harness the properties of small, non-coding nucleic acids hold great promise for clinical applications. These include antisense oligonucleotides that inhibit messenger RNAs, microRNAs (miRNAs), or long non-coding RNAs; positive effectors of the miRNA pathway (short interfering RNAs and miRNA mimics); or small RNAs that target proteins (i.e. aptamers). These new therapies also offer exciting opportunities for cardiovascular diseases and promise to move the field towards more precise approaches based on disease mechanisms. There have been substantial advances in developing chemical modifications to improve the in vivo pharmacological properties of antisense oligonucleotides and reduce their immunogenicity. Carrier methods (e.g. RNA conjugates, polymers, and lipoplexes) that enhance cellular uptake of RNA therapeutics and stability against degradation by intracellular nucleases are also transforming the field. A number of small non-coding RNA therapies for cardiovascular indications are now approved. Moreover, there is a large pipeline of therapies in clinical development and an even larger list of putative therapies emerging from pre-clinical studies. Progress in this area is reviewed herein along with the hurdles that need to be overcome to allow a broader clinical translation.

Advanced Drug Delivery Micro- and Nanosystems for Cardiovascular Diseases

Advanced drug delivery micro- and nanosystems have been widely explored due to their appealing specificity/selectivity, biodegradability, biocompatibility, and low toxicity. They can be applied for the targeted delivery of pharmaceuticals, with the benefits of good biocompatibility/stability, non-immunogenicity, large surface area, high drug loading capacity, and low leakage of drugs. Cardiovascular diseases, as one of the primary mortalities cause worldwide with significant impacts on the quality of patients’ life, comprise a variety of heart and circulatory system pathologies, such as peripheral vascular diseases, myocardial infarction, heart failure, and coronary artery diseases. Designing novel micro- and nanosystems with suitable targeting properties and smart release behaviors can help circumvent crucial challenges of the tolerability, low stability, high toxicity, and possible side- and off-target effects of conventional drug delivery routes. To overcome different challenging issues, namely physiological barriers, low efficiency of drugs, and possible adverse side effects, various biomaterials-mediated drug delivery systems have been formulated with reduced toxicity, improved pharmacokinetics, high bioavailability, sustained release behavior, and enhanced therapeutic efficacy for targeted therapy of cardiovascular diseases. Despite the existing drug delivery systems encompassing a variety of biomaterials for treating cardiovascular diseases, the number of formulations currently approved for clinical use is limited due to the regulatory and experimental obstacles. Herein, the most recent advancements in drug delivery micro- and nanosystems designed from different biomaterials for the treatment of cardiovascular diseases are deliberated, with a focus on the important challenges and future perspectives.

Nanomaterials-Mediated Therapeutics and Diagnosis Strategies for Myocardial Infarction

The alarming mortality and morbidity rate of myocardial infarction (MI) is becoming an important impetus in the development of early diagnosis and appropriate therapeutic approaches, which are critical for saving patients' lives and improving post-infarction prognosis. Despite several advances that have been made in the treatment of MI, current strategies are still far from satisfactory. Nanomaterials devote considerable contribution to tackling the drawbacks of conventional therapy of MI by improving the homeostasis in the cardiac microenvironment via targeting, immune modulation, and repairment. This review emphasizes the strategies of nanomaterials-based MI treatment, including cardiac targeting drug delivery, immune-modulation strategy, antioxidants and antiapoptosis strategy, nanomaterials-mediated stem cell therapy, and cardiac tissue engineering. Furthermore, nanomaterials-based diagnosis strategies for MI was presented in term of nanomaterials-based immunoassay and nano-enhanced cardiac imaging. Taken together, although nanomaterials-based strategies for the therapeutics and diagnosis of MI are both promising and challenging, such a strategy still explores the immense potential in the development of the next generation of MI treatment.

Optimization and Characterization of a Liposomal Azithromycin Formulation for Alternative Macrophage Activation

Liposomal azithromycin (L-AZM) promotes macrophage polarization toward an M2-like phenotype in the context of myocardial infarction that results in improved cardiovascular outcomes in mice. To improve upon this formulation, we sought to identify optimized formulation, stability, and biological activity parameters necessary to enhance the immunomodulatory activity and efficacy of L-AZM. While our parent formulation contains a mixture of long-chain saturated phosphatidylcholine and phosphatidylglycerol lipids, we evaluated a series of formulations with different amounts of unsaturated lipids and cholesterol with the goal of improving the loading capacity and stability of the formulations. We also introduce fusogenic lipids to improve the cytosolic delivery to enhance the immune modulatory properties of the drug. To achieve these goals, we initially prepared a library of 24 formulations using thin film hydration and assessed the resultant liposomes for size and polydispersity. Five lead formulations were identified based on low polydispersity (<0.3) and stability over time. The lead formulations were then evaluated for stability in serum using dialysis and macrophage polarization activity in vitro as measured by decreased IL-12 expression. Collectively, our data indicate that the formulation components drive the balance between encapsulation efficiency and stability and that all the lead liposomal formulations improve in vitro alternative macrophage activation as compared to free AZM.

Mechanochemical preparation of triptolide-loaded self-micelle solid dispersion with enhanced oral bioavailability and improved anti-tumor activity

Triptolide (TP), a compound isolated from a Chinese medicinal herb, possesses potent anti-tumor, immunosuppressive, and anti-inflammatory properties, but was clinically limited due to its poor solubility, bioavailability, and toxicity. Considering the environment-friendly, low-cost mechanochemical techniques and potential dissolution enhancement ability of Na₂GA, an amorphous solid dispersion (Na₂GA&TP-BM) consisting of TP and Na₂GA were well-prepared to address these issues. The performance of Na₂GA&TP-BM was improved through ball milling, such as from crystalline state to an amorphous solid dispersion, suitable nano micelle size and surface potential, and increased solubility. This change had a significant improvement of pharmacokinetic behavior in mice and could be able to extend the blood circulation time of the antitumor drug. Moreover, in vitro and in vivo anti-tumor study showed that Na₂GA&TP-BM displayed more potent cytotoxicity to tumor cells. The work illustrated an environment-friendly and safe preparation of the TP formulation, which was promising to enhance the oral bioavailability and antitumor ability of TP, might be considered for efficient anticancer therapy.

Nanocarrier-Based Targeted Therapies for Myocardial Infarction

Myocardial infarction is a major cause of morbidity and mortality worldwide. Due to poor inherent regeneration of the adult mammalian myocardium and challenges with effective drug delivery, there has been little progress in regenerative therapies. Nanocarriers, including liposomes, nanoparticles, and exosomes, offer many potential advantages for the therapy of myocardial infarction, including improved delivery, retention, and prolonged activity of therapeutics. However, there are many challenges that have prevented the widespread clinical use of these technologies. This review aims to summarize significant principles and developments in the field, with a focus on nanocarriers using ligand-based or cell mimicry-based targeting. Lastly, a discussion of limitations and potential future direction is provided.

Nanomaterials: A Promising Therapeutic Approach for Cardiovascular Diseases

Cardiovascular diseases (CVDs) are a primary cause of death globally. A few classic and hybrid treatments exist to treat CVDs. However, they lack in both safety and effectiveness. Thus, innovative nanomaterials for disease diagnosis and treatment are urgently required. The tiny size of nanomaterials allows them to reach more areas of the heart and arteries, making them ideal for CVDs. Atherosclerosis causes arterial stenosis and reduced blood flow. The most common treatment is medication and surgery to stabilize the disease. Nanotechnologies are crucial in treating vascular disease. Nanomaterials may be able to deliver medications to lesion sites after being infused into the circulation. Newer point-of-care devices have also been considered together with nanomaterials. For example, this study will look at the use of nanomaterials in imaging, diagnosing, and treating CVDs.

Novel Techniques Targeting Fibroblasts after Ischemic Heart Injury

The great plasticity of cardiac fibroblasts allows them to respond quickly to myocardial injury and to contribute to the subsequent cardiac remodeling. Being the most abundant cell type (in numbers) in the heart, and a key participant in the several phases of tissue healing, the cardiac fibroblast is an excellent target for treating cardiac diseases. The development of cardiac fibroblast-specific approaches have, however, been difficult due to the lack of cellular specific markers. The development of genetic lineage tracing tools and Cre-recombinant transgenics has led to a huge acceleration in cardiac fibroblast research. Additionally, the use of novel targeted delivery approaches like nanoparticles and modified adenoviruses, has allowed researchers to define the developmental origin of cardiac fibroblasts, elucidate their differentiation pathways, and functional mechanisms in cardiac injury and disease. In this review, we will first characterize the roles of fibroblasts in the different stages of cardiac repair and then examine novel techniques targeting fibroblasts post-ischemic heart injury.

Red Blood Cell Extracellular Vesicle-Based Drug Delivery: Challenges and Opportunities

Recently, red blood cell-derived extracellular vesicles (RBCEVs) have attracted attention for clinical applications because of their safety and biocompatibility. RBCEVs can escape macrophages through the binding of CD47 to inhibitory receptor signal regulatory protein α. Furthermore, genetic materials such as siRNA, miRNA, mRNA, or single-stranded RNA can be encapsulated within RBCEVs and then released into target cells for precise treatment. However, their side effects, half-lives, target cell specificity, and limited large-scale production under good manufacturing practice remain challenging. In this review, we summarized the biogenesis and composition of RBCEVs, discussed the advantages and disadvantages of RBCEVs for drug delivery compared with synthetic nanovesicles and non-red blood cell-derived EVs, and provided perspectives for overcoming current limitations to the use of RBCEVs for clinical applications.

Late-Stage Amination of Drug-Like Benzoic Acids: Access to Anilines and Drug Conjugates through Directed Iridium-Catalyzed C-H Activation

The functionalization of C-H bonds, ubiquitous in drugs and drug-like molecules, represents an important synthetic strategy with the potential to streamline the drug-discovery process. Late-stage aromatic C-N bond-forming reactions are highly desirable, but despite their significance, accessing aminated analogues through direct and selective amination of C-H bonds remains a challenging goal. The method presented herein enables the amination of a wide array of benzoic acids with high selectivity. The robustness of the system is manifested by the large number of functional groups tolerated, which allowed the amination of a diverse array of marketed drugs and drug-like molecules. Furthermore, the introduction of a synthetic handle enabled expeditious access to targeted drug-delivery conjugates, PROTACs, and probes for chemical biology. This rapid access to valuable analogues, combined with operational simplicity and applicability to high-throughput experimentation has the potential to aid and considerably accelerate drug discovery.

Non-Viral Gene Delivery Systems for Treatment of Myocardial Infarction: Targeting Strategies and Cardiac Cell Modulation

Cardiovascular diseases (CVD) are the leading cause of morbidity and mortality worldwide. Conventional therapies involving surgery or pharmacological strategies have shown limited therapeutic effects due to a lack of cardiac tissue repair. Gene therapy has opened an avenue for the treatment of cardiac diseases through manipulating the underlying gene mechanics. Several gene therapies for cardiac diseases have been assessed in clinical trials, while the clinical translation greatly depends on the delivery technologies. Non-viral vectors are attracting much attention due to their safety and facile production compared to viral vectors. In this review, we discuss the recent progress of non-viral gene therapies for the treatment of cardiovascular diseases, with a particular focus on myocardial infarction (MI). Through a summary of delivery strategies with which to target cardiac tissue and different cardiac cells for MI treatment, this review aims to inspire new insights into the design/exploitation of non-viral delivery systems for gene cargos to promote cardiac repair/regeneration.

Identification of Novel Ligands for Targeted Antifibrotic Therapy of Chronic Pancreatitis

PURPOSE

Chronic pancreatitis (CP) is an inflammatory disorder of the pancreas that leads to impaired pancreatic function. The limited therapeutic options and the lack of molecular targeting ligands or non-serum-based biomarkers hinder the development of target-specific drugs. Thus, there is a need for an unbiased, comprehensive discovery and evaluation of pancreatitis-specific ligands.

METHODS

This study utilized a computational-guided in vivo phage display approach to select peptide ligands selective for cellular components in the caerulein-induced mouse model of CP. The identified peptides were conjugated to pegylated DOPC liposomes via the reverse-phase evaporation method, and the in vivo specificity and pharmacokinetics were determined. As proof of concept, CP-targeted liposomes were used to deliver an antifibrotic small molecular drug, apigenin. Antifibrotic effects determined by pancreatic histology, fibronectin expression, and collagen deposition were evaluated.

RESULTS

We have identified five peptides specific for chronic pancreatitis and demonstrated selectivity to activated pancreatic stellate cells, acinar cells, macrophages, and extracellular matrix, respectively. MDLSLKP-conjugated liposomes demonstrated an increased particle accumulation by 1.3-fold in the inflamed pancreas compared to the control liposomes. We also observed that targeted delivery of apigenin resulted in improved acini preservation, a 37.2% and 33.1% respective reduction in collagen and fibronectin expression compared to mice receiving the free drug, and reduced oxidative stress in the liver.

CONCLUSION

In summary, we have developed a systematic approach to profile peptide ligands selective for cellular components of complex disease models and demonstrated the biomedical applications of the identified peptides to improve tissue remodeling in the inflamed pancreas.

Targeting fibrosis in the failing heart with nanoparticles

Heart failure (HF) is a clinical syndrome characterized by typical symptoms and signs caused by a structural and/or functional cardiac abnormality, resulting in a reduced cardiac output and/or elevated intracardiac pressures at rest or during stress. Due to increasing incidence, prevalence and, most importantly mortality, HF is a healthcare burden worldwide, despite the improvement of treatment options and effectiveness. Acute and chronic cardiac injuries trigger the activation of neurohormonal, inflammatory, and mechanical pathways ultimately leading to fibrosis, which plays a key role in the development of cardiac dysfunction and HF. The use of nanoparticles for targeted drug delivery would greatly improve therapeutic options to identify, prevent and treat cardiac fibrosis. In this review we will highlight the mechanisms of cardiac fibrosis development to depict the pathophysiological features for passive and active targeting of acute and chronic cardiac fibrosis with nanoparticles. Then we will discuss how cardiomyocytes, immune and inflammatory cells, fibroblasts and extracellular matrix can be targeted with nanoparticles to prevent or restore cardiac dysfunction and to improve the molecular imaging of cardiac fibrosis.

Release of vascular agonists from liposome-microbubble conjugate by ultrasound-mediated microbubble destruction: effect on vascular function

The endothelium is a single cell layer of the vessel wall and a key regulator of blood flow in vascular beds. Local and systemic pathologies have been associated with alterations in endothelial function. However, targeting the endothelium with vasoconstrictor or vasodilator drugs is often accompanied by systemic effects. Here, we evaluated a liposome-microbubble delivery system as a vascular hydrophilic agonist carrier. Phenylephrine (Phe) or acetylcholine (Ach)-loaded liposomes were conjugated to microbubbles. The drug release was triggered by ultrasound (US), and the vascular response was assessed in rat aortic rings using an isolated organ chamber. Aortic rings incubated with Phe-liposome-microbubble conjugate, exposed to US showed a marked contractile response (0.79 ± 0.04 g) compared to empty liposomes conjugated to microbubbles, aortic rings exposed only to US, and Phe-liposome-microbubble conjugate without US exposure that elicited a minimal or no response. Expressed as %, contractile responses were 85.24 ± 4.31% and 12.62 ± 3.23% for Phe-Chol-liposome-microbubble conjugate and empty Chol-liposome-microbubble conjugate exposed to US, respectively. Addition of 1 × 10^-5 M Ach to pre-contracted aortic rings decreased the contraction response from 1 to 0.21 g. The addition of Ach-liposome conjugate and exposure to US decreased the contraction response to 0.32 g. Additionally, the ED50 values for Phe and Ach released by US from liposome-microbubble conjugates were 3.6 × 10^-8 M ± 2.8 × 10^-9 M for Phe and 2.0 × 10^-8 M ± 1.8 × 10^-9 M. In conclusion, we evaluated a hybrid delivery system that consisted of loaded liposomes conjugated to microbubbles to deliver and release vascular agonists using UMMD.

Nanodiagnosis and Nanotreatment of Cardiovascular Diseases: An Overview

Cardiovascular diseases (CVDs) are the world’s leading cause of mortality and represent a large contributor to the costs of medical care. Although tremendous progress has been made for the diagnosis of CVDs, there is an important need for more effective early diagnosis and the design of novel diagnostic methods. The diagnosis of CVDs generally relies on signs and symptoms depending on molecular imaging (MI) or on CVD-associated biomarkers. For early-stage CVDs, however, the reliability, specificity, and accuracy of the analysis is still problematic. Because of their unique chemical and physical properties, nanomaterial systems have been recognized as potential candidates to enhance the functional use of diagnostic instruments. Nanomaterials such as gold nanoparticles, carbon nanotubes, quantum dots, lipids, and polymeric nanoparticles represent novel sources to target CVDs. The special properties of nanomaterials including surface energy and topographies actively enhance the cellular response within CVDs. The availability of newly advanced techniques in nanomaterial science opens new avenues for the targeting of CVDs. The successful application of nanomaterials for CVDs needs a detailed understanding of both the disease and targeting moieties.

Triptolide delivery: Nanotechnology-based carrier systems to enhance efficacy and limit toxicity

Triptolide (TP) possesses a wide range of biological and pharmacological activities involved in the treatment of various diseases. However, widespread usages of TP raise the urgent issues of the severe toxicity, which hugely limits its further clinical application. The novel functional nanostructured delivery system, which is of great significance in enhancing the efficacy, reducing side effects and improving bioavailability, could improve the enrichment, penetration and controlled release of drugs in the lesion location. Over the past decades, considerable efforts have been dedicated to designing and developing a variety of TP delivery systems with the intention of alleviating the adverse toxicity effects and enhancing the bioavailability. In this review, we briefly summarized and discussed the recent functionalized nano-TP delivery systems for the momentous purpose of guiding further development of novel TP delivery systems and providing perspectives for future clinical applications.

Nanostructured Polymeric, Liposomal and Other Materials to Control the Drug Delivery for Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the leading cause of death globally, taking an estimated 17.9 million lives each year, representing one third of global mortality. As existing therapies still have limited success, due to the inability to control the biodistribution of the currently approved drugs, the quality of life of these patients is modest. The advent of nanomedicine has brought new insights in innovative treatment strategies. For this reason, several novel nanotechnologies have been developed for both targeted and prolonged delivery of therapeutics to the cardiovascular system tο minimize side effects. In this regard, nanoparticles made of natural and/or synthetic nanomaterials, like liposomes, polymers or inorganic materials, are emerging alternatives for the encapsulation of already approved drugs to control their delivery in a targeted way. Therefore, nanomedicine has attracted the attention of the scientific community as a potential platform to deliver therapeutics to the injured heart. In this review, we discuss the current types of biomaterials that have been investigated as potential therapeutic interventions for CVDs as they open up a host of possibilities for more targeted and effective therapies, as well as minimally invasive treatments.

Targeted miR-21 loaded liposomes for acute myocardial infarction

Acute and persistent myocardial ischemia is the main cause of acute myocardial infarction (AMI) and heart failure. MicroRNA-21(miR-21) contributes to the pathophysiological consequences of acute myocardial infarction by targeting downstream crucial regulators. Thus, miR-21 mimics are a promising strategy for the treatment of AMI. However, their poor stability and insufficient cellular uptake are the major challenges. Herein, we encapsulated miR-21 mimics into liposomes modified with the cardiac troponin T (cTnT) antibody for targeted delivery of miR-21(cT-21-LIPs) to the ischemic myocardium. The cT-21-LIPs exhibited enhanced targeting efficiency to hypoxia primary cardiomyocytes in vitro and improved accumulation in the ischemic heart of AMI rats after injection via the tail vein due to the specifical target to overexpressed troponin. The cT-21-LIPs could significantly improve the cardiac function and decrease the infarct size after AMI, while maintaining the viability of cardiomyocytes. This design provides a novel strategy for delivering small nucleotide drugs specifically to the infarcted heart, which may find great potential in clinics.

Liposomal delivery of azithromycin enhances its immunotherapeutic efficacy and reduces toxicity in myocardial infarction

A growing body of evidence shows that altering the inflammatory response by alternative macrophage polarization is protective against complications related to acute myocardial infarction (MI). We have previously shown that oral azithromycin (AZM), initiated prior to MI, reduces inflammation and its negative sequelae on the myocardium. Here, we investigated the immunomodulatory role of a liposomal AZM formulation (L-AZM) in a clinically relevant model to enhance its therapeutic potency and avoid off-target effects. L-AZM (40 or 10 mg/kg, IV) was administered immediately post-MI and compared to free AZM (F-AZM). L-AZM reduced cardiac toxicity and associated mortality by 50% in mice. We observed a significant shift favoring reparatory/anti-inflammatory macrophages with L-AZM formulation. L-AZM use resulted in a remarkable decrease in cardiac inflammatory neutrophils and the infiltration of inflammatory monocytes. Immune cell modulation was associated with the downregulation of pro-inflammatory genes and the upregulation of anti-inflammatory genes. The immunomodulatory effects of L-AZM were associated with a reduction in cardiac cell death and scar size as well as enhanced angiogenesis. Overall, L-AZM use enhanced cardiac recovery and survival after MI. Importantly, L-AZM was protective from F-AZM cardiac off-target effects. We demonstrate that the liposomal formulation of AZM enhances the drug’s efficacy and safety in an animal model of acute myocardial injury. This is the first study to establish the immunomodulatory properties of liposomal AZM formulations. Our findings strongly support clinical trials using L-AZM as a novel and clinically relevant therapeutic target to improve cardiac recovery and reduce heart failure post-MI in humans.

Challenges in the development of nanoparticle-based imaging agents: Characterization and biology

Despite imaging agents being some of the earliest nanomedicines in clinical use, the vast majority of current research and translational activities in the nanomedicine field involves therapeutics, while imaging agents are severely underrepresented. The reasons for this lack of representation are several fold, including difficulties in synthesis and scale-up, biocompatibility issues, lack of suitable tissue/disease selective targeting ligands and receptors, and a high bar for regulatory approval. The recent focus on immunotherapies and personalized medicine, and development of nanoparticle constructs with better tissue distribution and selectivity, provide new opportunities for nanomedicine imaging agent development. This manuscript will provide an overview of trends in imaging nanomedicine characterization and biocompatibility, and new horizons for future development. This article is categorized under: Diagnostic Tools > in vivo Nanodiagnostics and Imaging Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine.

Potential application of liposomal nanodevices for non-cancer diseases: an update on design, characterization and biopharmaceutical evaluation

Liposomes, lipid-based vesicular systems, have attracted major interest as a means to improve drug delivery to various organs and tissues in the human body. Recent literature highlights the benefits of liposomes for use as drug delivery systems, including encapsulating of both hydrophobic and hydrophilic cargos, passive and active targeting, enhanced drug bioavailability and therapeutic effects, reduced systemic side effects, improved cargo penetration into the target tissue and triggered contents release. Pioneering work of liposomes researchers led to introduction of long-circulating, ligand-targeted and triggered release liposomes, as well as, liposomes containing nucleic acids and vesicles containing combination of cargos. Altogether, these findings have led to widespread application of liposomes in a plethora of areas from cancer to conditions such as cardiovascular, neurologic, respiratory, skin, autoimmune and eye disorders. There are numerous review articles on the application of liposomes in treatment of cancer, which seems the primary focus, whereas other diseases also benefit from liposome-mediated treatments. Therefore, this article provides an illustrated detailed overview of liposomal formulations, in vitro characterization and their applications in different disorders other than cancer. Challenges and future directions, which must be considered to obtain the most benefit from applications of liposomes in these disorders, are discussed.

Photosensitive nanocarriers for specific delivery of cargo into cells

Nanoencapsulation is a rapidly expanding technology to enclose cargo into inert material at the nanoscale size, which protects cargo from degradation, improves bioavailability and allows for controlled release. Encapsulation of drugs into functional nanocarriers enhances their specificity, targeting ability, efficiency, and effectiveness. Functionality may come from cell targeting biomolecules that direct nanocarriers to a specific cell or tissue. Delivery is usually mediated by diffusion and erosion mechanisms, but in some cases, this is not sufficient to reach the expected therapeutic effects. This work reports on the development of a new photoresponsive polymeric nanocarrier (PNc)-based nanobioconjugate (NBc) for specific photo-delivery of cargo into target cells. We readily synthesized the PNcs by modification of chitosan with ultraviolet (UV)-photosensitive azobenzene molecules, with Nile red and dofetilide as cargo models to prove the encapsulation/release concept. The PNcs were further functionalized with the cardiac targeting transmembrane peptide and efficiently internalized into cardiomyocytes, as a cell line model. Intracellular cargo-release was dramatically accelerated upon a very short UV-light irradiation time. Delivering cargo in a time-space controlled fashion by means of NBcs is a promising strategy to increase the intracellular cargo concentration, to decrease dose and cargo side effects, thereby improving the effectiveness of a therapeutic regime.

Nanoparticle delivery of cardioprotective therapies

Acute myocardial infarction (AMI), and the heart failure (HF) that often follows, are leading causes of death and disability worldwide. Crucially, there are currently no effective treatments, other than myocardial reperfusion, for reducing myocardial infarct (MI) size and preventing HF following AMI. Thus, there is an unmet need to discover novel cardioprotective therapies to reduce MI size, and prevent HF in AMI patients. Although a large number of therapies have been shown to reduce MI size in experimental studies, the majority have failed to benefit AMI patients. Failure to deliver cardioprotective therapy to the ischemic heart in sufficient concentrations following AMI is a major factor for the lack of success observed in previous clinical cardioprotection studies. Therefore, new strategies are needed to improve the delivery of cardioprotective therapies to the ischemic heart following AMI. In this regard, nanoparticles have emerged as drug delivery systems for improving the bioavailability, delivery, and release of cardioprotective therapies, and should result in improved efficacy in terms of reducing MI size and preventing HF. In this article, we provide a review of currently available nanoparticles, some of which have been FDA-approved, in terms of their use as drug delivery systems in cardiovascular disease and cardioprotection.

Importance of thorough tissue and cellular level characterization of targeted drugs in the evaluation of pharmacodynamic effects

Targeted nanoparticle delivery is a promising strategy for increasing efficacy and limiting side effects of therapeutics. When designing a targeted liposomal formulation, the in vivo biodistribution of the particles must be characterized to determine the value of the targeting approach. Peroxisome proliferator-activated receptor (PPAR) agonists effectively treat metabolic syndrome by decreasing dyslipidemia and insulin resistance but side effects have limited their use, making them a class of compounds that could benefit from targeted liposomal delivery. The adipose targeting sequence peptide (ATS) could fit this role, as it has been shown to bind to adipose tissue endothelium and induce weight loss when delivered conjugated to a pro-apoptotic peptide. To date, however, a full assessment of ATS in vivo biodistribution has not been reported, leaving important unanswered questions regarding the exact mechanisms whereby ATS targeting enhances therapeutic efficacy. We designed this study to evaluate the biodistribution of ATS-conjugated liposomes loaded with the PPARα/γ dual agonist tesaglitazar in leptin-deficient ob/ob mice. The ATS-liposome biodistribution in adipose tissue and other organs was examined at the cellular and tissue level using microscopy, flow cytometry, and fluorescent molecular tomography. Changes in metabolic parameters and gene expression were measured by target and off-target tissue responses to the treatment. Unexpectedly, ATS targeting did not increase liposomal uptake in adipose relative to other tissues, but did increase uptake in the kidneys. Targeting also did not significantly alter metabolic parameters. Analysis of the liposome cellular distribution in the stromal vascular fraction with flow cytometry revealed high uptake by multiple cell types. Our findings highlight the need for thorough study of in vivo biodistribution when evaluating a targeted therapy.

Nanoparticle-mediated delivery of siRNA into zebrafish heart: a cell-level investigation on the biodistribution and gene silencing effects

Nanomaterials hold promise for the delivery of nucleic acids to facilitate gene therapy in cardiac diseases. However, as much of the in vivo study of nanomaterials was conducted via the "trial and error" method, the understanding of the nanomaterial-mediated delivery in cardiac tissue was limited to the gross efficiency in manipulating the gene expression while little was known about the delivery process and mechanism in particular at the cell level. In this study, small interfering RNA (siRNA) nanoparticles formulated with a polyamidoamine (PAMAM) nanomaterial were applied to the injured heart of zebrafish. The distribution of nanoparticles in cardiomyocytes, endothelial cells, macrophages and leukocytes was quantitatively analyzed with precision at the cell level by using transgenic models. Based on the distribution characteristics, gene silencing effects in a specific group of cells were analyzed to illustrate how siRNA nanoparticles could get potent gene silencing in different cells in vivo. The results elucidated the heterogeneous distribution of siRNA nanoparticles and how nanoparticles could be efficient despite the significant difference in cellular uptake efficiency in different cells. It demonstrated a paradigm and the need to decouple cellular processes to understand nanoparticle-mediated delivery in complex tissue and the investigation/methodology may lead to important information to guide the design of advanced targeted drug-delivery systems in heart.

Therapy for myocardial infarction: In vitro and in vivo evaluation of puerarin-prodrug and tanshinone co-loaded lipid nanoparticulate system

Myocardial infarction (MI) is the leading cause of morbidity and mortality worldwide. Nanoparticle systems carrying drugs have already been developed to treat MI. To improve the efficiency of tanshinone (TAN), and to achieve the synergistic effect of TAN and puerarin (PUE), PUE-prodrug and TAN co-loaded solid lipid nanoparticles (SLN) was structured and utilized for MI treatment in the present research. PUE-prodrug was synthesized by an esterification reaction. PUE-prodrug and TAN co-loaded SLN (PUEp/TAN-SLN) were prepared by a single emulsification followed by a solvent evaporation method. The physicochemical properties of SLN were characterized and the in vivo infarct therapy effects were evaluated in MI rats. PUE-prodrug and TAN contained SLN showed a size of 112.6 ± 3.1 nm. The SLN encapsulation reduced the cytotoxicity of drugs and was a safer system. PUEp-SLN exhibited a 1.7-fold increase in comparison to PUE-SLN (21.2 ± 2.1 versus 12.5 ± 1.5 mg/L), in the mean time a 3.4-fold increase compared with free PUE in heart drug concentration (21.2 ± 2.1 versus 6.3 ± 0.9 mg/L). In vivo infarct therapy efficiency of double drugs loaded PUEp/TAN-SLN (17 ± 1.9%) was significantly better than the single drug loaded PUEp-SLN (31 ± 1.6%) and TAN-SLN (40 ± 2.2%). PUE-prodrug contained, double drugs co-loaded SLN can be utilized as promising candidate delivery system for cardioprotective drugs in treatment of myocardial infarction.

Biologics and Cardiovascular Disease

The advent of biologic therapy has enhanced our ability to augment disease in an increasingly targeted manner. The use of biologics in cardiovascular disease (CVD) has steadily increased over the past several decades. Much of the early data on biologics and CVD were derived from their use in rheumatologic populations. Atherosclerosis, myocardial infarction, and heart failure have been closely linked to the inflammatory response. Accordingly, cytokines such as tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 have been targeted. Noninflammatory mediators, such as proprotein convertase subtilisin kexin type 9 (PCSK9), have been selected for therapeutic intervention as well. Furthermore, RNA interference (RNAi) therapy has emerged and may serve as another targeted therapeutic mechanism. Herein, we will review the history, obstacles, and advances in using biologic therapy for CVD.

Bacteriophage-based biomaterials for tissue regeneration

Bacteriophage, also called phage, is a human-safe bacteria-specific virus. It is a monodisperse biological nanostructure made of proteins (forming the outside surface) and nucleic acids (encased in the protein capsid). Among different types of phages, filamentous phages have received great attention in tissue regeneration research due to their unique nanofiber-like morphology. They can be produced in an error-free format, self-assemble into ordered scaffolds, display multiple signaling peptides site-specifically, and serve as a platform for identifying novel signaling or homing peptides. They can direct stem cell differentiation into specific cell types when they are organized into proper patterns or display suitable peptides. These unusual features have allowed scientists to employ them to regenerate a variety of tissues, including bone, nerves, cartilage, skin, and heart. This review will summarize the progress in the field of phage-based tissue regeneration and the future directions in this field.

Plectin-targeted liposomes enhance the therapeutic efficacy of a PARP inhibitor in the treatment of ovarian cancer

Advances in genomics and proteomics drive precision medicine by providing actionable genetic alterations and molecularly targeted therapies, respectively. While genomic analysis and medicinal chemistry have advanced patient stratification with treatments tailored to the genetic profile of a patient's tumor, proteomic targeting has the potential to enhance the therapeutic index of drugs like poly(ADP-ribose) polymerase (PARP) inhibitors. PARP inhibitors in breast and ovarian cancer patients with BRCA1/2 mutations have shown promise. About 10% of the patients who received Olaparib (PARP inhibitor) showed adverse side effects including neutropenia, thrombocytopenia and in some cases resulted in myelodysplastic syndrome, indicating that off-target effects were substantial in these patients. Through proteomic analysis, our lab previously identified plectin, a cytolinker protein that mislocalized onto the cell surface during malignant transformation of healthy ovarian tissue. This cancer specific phenotype allowed us to image pancreatic cancer successfully using plectin targeted peptide (PTP) conjugated to nanoparticles or displayed on capsid protein of adeno-associated virus (AAV) particles. Objective: The goal of this study was to integrate the available pharmacogenomics and proteomic data to develop effective anti-tumor therapies using a targeted drug delivery approach. Methods: Plectin expression and localization in human ovarian tumor specimens were analyzed followed by in vitro confirmation of cell surface plectin localization in healthy and ovarian cancer cell lines. PTP-conjugated liposomes were prepared and their specificity for plectin+ cells was determined in vitro and in vivo. A remote loading method was employed to encapsulate a PARP inhibitor (AZ7379) into liposomes. An ideal buffer exchange method and remote loading conditions were determined based on the amount of lipid and drug recovered at the end of a remote loading process. Finally, in vivo tumor growth studies were performed to determine the efficacy of PTP liposomes in preventing PARP activity in mice bearing OVCAR8 (high grade epithelial ovarian cancer (EOC)) tumors. Results: PTP liposomal AZ7379 delivery not only enhanced PARP inhibition but also resulted in decelerated tumor growth in mice bearing subcutaneous and intraperitoneal OVCAR8 tumors. In mice bearing subcutaneous or intraperitoneal tumors, treatment with PTP liposomes resulted in a 3- and 1.7-fold decrease in tumor volume, respectively, compared to systemic drug treatment. Conclusion: Targeted drug delivery assisted by genomic and proteomic data provides an adaptable model system that can be extended to effectively treat other cancers and diseases.

Cell-Based Drug Delivery and Use of Nano-and Microcarriers for Cell Functionalization

Cell functionalization with recently developed various nano- and microcarriers for therapeutics has significantly expanded the application of cell therapy and targeted drug delivery for the effective treatment of a number of diseases. The aim of this progress report is to review the most recent advances in cell-based drug vehicles designed as biological transporter platforms for the targeted delivery of different drugs. For the design of cell-based drug vehicles, different pathways of cell functionalization, such as covalent and noncovalent surface modifications, internalization of carriers are considered in greater detail together with approaches for cell visualization in vivo. In addition, several animal models for the study of cell-assisted drug delivery are discussed. Finally, possible future developments and applications of cell-assisted drug vehicles toward targeted transport of drugs to a designated location with no or minimal immune response and toxicity are addressed in light of new pathways in the field of nanomedicine.

Ultra-Low-Dose Ultrasound Molecular Imaging for the Detection of Angiogenesis in a Mouse Murine Tumor Model: How Little Can We See?

OBJECTIVES

The objective of this study was to evaluate the minimum microbubble dose for ultrasound molecular imaging to achieve statistically significant detection of angiogenesis in a mouse model.

MATERIALS AND METHODS

The preburst minus postburst method was implemented on a Verasonics ultrasound research scanner using a multiframe compounding pulse inversion imaging sequence. Biotinylated lipid (distearoyl phosphatidylcholine-based) microbubbles that were conjugated with antivascular endothelial growth factor 2 (VEGFR2) antibody (MBVEGFR2) or isotype control antibody (MBControl) were injected into mice carrying adenocarcinoma xenografts. Different injection doses ranging from 5 × 10 to 1 × 10 microbubbles per mouse were evaluated to determine the minimum diagnostically effective dose.

RESULTS

The proposed imaging sequence was able to achieve statistically significant detection (P < 0.05, n = 5) of VEGFR2 in tumors with a minimum MBVEGFR2 injection dose of only 5 × 10 microbubbles per mouse (distearoyl phosphatidylcholine at 0.053 ng/g mouse body mass). Nonspecific adhesion of MBControl at the same injection dose was negligible. In addition, the targeted contrast ultrasound signal of MBVEGFR2 decreased with lower microbubble doses, whereas nonspecific adhesion of MBControl increased with higher microbubble doses.

CONCLUSIONS

The dose of 5 × 10 microbubbles per animal is now the lowest injection dose on record for ultrasound molecular imaging to achieve statistically significant detection of molecular targets in vivo. Findings in this study provide us with further guidance for future developments of clinically translatable ultrasound molecular imaging applications using a lower dose of microbubbles.

PCM and TAT co-modified liposome with improved myocardium delivery: in vitro and in vivo evaluations

In this study, PCM and TAT co-modified liposome was developed as a novel drug carrier for myocardium delivery with evaluation of its in vitro and in vivo properties. Liposomes containing fluorescent probe coumarin-6 were prepared by thin-film hydration. The PCM ligands specifically bind to the PCM receptors in the extracellular connective tissue of primary myocardium cells (MCs), while the TAT ligands functioned as a classical cell penetrating peptide to make liposomes internalized by MCs. The unmodified liposome (L), PCM-modified liposome (PL), TAT-modified liposome (TL) and PCM and TAT co-modified liposome (PTL) were prepared and characterized. The cellular uptake and intracellular distribution of various liposomes by MCs demonstrated that PTL had the best delivery capability. Peptide inhibition assay indicated that the uptake of PL could be inhibited by PCM. However, TAT could almost not suppress the uptake of TL. In addition, the CCK-8 experiments showed that liposomes had low cytotoxicity. In vivo fluorescent images of frozen sections and HPLC-fluorescence analysis further demonstrated that PTL had highest myocardium distribution. The results of this study demonstrated that PCM and TAT co-modifying could improve the myocardial targeting ability of liposome.

Dynamic, heterogeneous endothelial Tie2 expression and capillary blood flow during microvascular remodeling

Microvascular endothelial cell heterogeneity and its relationship to hemodynamics remains poorly understood due to a lack of sufficient methods to examine these parameters in vivo at high resolution throughout an angiogenic network. The availability of surrogate markers for functional vascular proteins, such as green fluorescent protein, enables expression in individual cells to be followed over time using confocal microscopy, while photoacoustic microscopy enables dynamic measurement of blood flow across the network with capillary-level resolution. We combined these two non-invasive imaging modalities in order to spatially and temporally analyze biochemical and biomechanical drivers of angiogenesis in murine corneal neovessels. By stimulating corneal angiogenesis with an alkali burn in Tie2-GFP fluorescent-reporter mice, we evaluated how onset of blood flow and surgically-altered blood flow affects Tie2-GFP expression. Our study establishes a novel platform for analyzing heterogeneous blood flow and fluorescent reporter protein expression across a dynamic microvascular network in an adult mammal.

Evaluation of pharmacokinetic and pharmacodynamic profiles of liposomes for the cell type-specific delivery of small molecule drugs

Liposome-based drug formulations represent an exciting avenue of research as they increase efficacy to toxicity ratios. Current formulations rely on passive accumulation to the disease site where drug is taken up by the cells. Ligand mediated targeting increases the net accumulation of liposomes, however, an unexplored benefit is to potentially refine pharmacodynamics (PD) of a drug specifically to different cell types within diseased tissue. As a model system, we engineered cardiomyocyte- (I-1) and endothelial-targeted (B-40) liposomes to carry a VEGFR2 inhibitor (PTK787), and examined the effect of cell type-specific delivery on both pharmacokinetics (PK) and PD. Neovascularization in post-myocardial infarction was significantly reduced by B-40 liposomes loaded with PTK787 as compared to animals injected with I-1 liposomes, and profoundly more as compared to free PTK787. This study thus shows that the intraorgan targeting of drugs through cell type-specific delivery holds substantial promise towards lowering the minimal efficacious dose administered systemically.

Liposomes as a Putative Tool to Investigate NAADP Signaling in Vasculogenesis

Nicotinic acid adenine dinucleotide phosphate (NAADP) is the newest discovered intracellular second messengers, which is able to release Ca²⁺ stored within endolysosomal (EL) vesicles. NAADP-induced Ca²⁺ signals mediate a growing number of cellular functions, ranging from proliferation to muscle contraction and differentiation. Recently, NAADP has recently been shown to regulate angiogenesis by promoting endothelial cell growth. It is, however, still unknown whether NAADP stimulates proliferation also in endothelial progenitor cells, which are mobilized in circulation after an ischemic insult to induce tissue revascularization. Herein, we described a novel approach to prepare NAADP-containing liposomes, which are highly cell membrane permeable and are therefore amenable for stimulating cell activity. Accordingly, NAADP-containing liposomes evoked an increase in intracellular Ca²⁺ concentration, which was inhibited by NED-19, a selective inhibitor of NAADP-induced Ca²⁺ release. Furthermore, NAADP-containing liposomes promoted EPC proliferation, a process which was inhibited by NED-19 and BAPTA, a membrane permeable intracellular Ca²⁺ buffer. Therefore, NAADP-containing liposomes stand out as a promising tool to promote revascularization of hypoxic/ischemic tissues by favoring EPC proliferation. J. Cell. Biochem. 118: 3722-3729, 2017. © 2017 Wiley Periodicals, Inc.

Targeting and modulating infarct macrophages with hemin formulated in designed lipid-based particles improves cardiac remodeling and function

Uncontrolled activation of pro-inflammatory macrophages after myocardial infarction (MI) accelerates adverse left ventricular (LV) remodeling and dysfunction. Hemin, an iron-containing porphyrin, activates heme oxygenase-1 (HO-1), an enzyme with anti-inflammatory and cytoprotective properties. We sought to determine the effects of hemin formulated in a macrophage-targeted lipid-based carrier (denoted HA-LP) on LV remodeling and function after MI. Hemin encapsulation efficiency was ~100% at therapeutic dose levels. In vitro, hemin/HA-LP abolished TNF-α secretion from macrophages, whereas the same doses of free hemin and drug free HA-LP had no effect. Hemin/HA-LP polarized peritoneal and splenic macrophages toward M2 anti-inflammatory phenotype. We next induced MI in mice and allocated them to IV treatment with hemin/HA-LP (10mg/kg), drug free HA-LP, free hemin (10mg/kg) or saline, one day after MI. Active in vivo targeting to infarct macrophages was confirmed with HA-LP doped with PE-rhodamine. LV remodeling and function were assessed by echocardiography before, 7, and 30days after treatment. Significantly, hemin/HA-LP effectively and specifically targets infarct macrophages, switches infarct macrophages toward M2 anti-inflammatory phenotype, improves angiogenesis, reduces scar expansion and improves infarct-related regional function. In conclusion, macrophage-targeted lipid-based drug carriers with hemin switch macrophages into an anti-inflammatory phenotype, and improve infarct healing and repair. Our approach presents a novel strategy to modulate inflammation and improve infarct repair.

Controlled actuation of therapeutic nanoparticles: an update on recent progress

A primary envisioned use for nanoparticles (NPs) in a cellular context is for controlled drug delivery where the full benefit of NP attributes (small size, large drug cargo loading capacity) can improve the pharmacokinetics of the drug cargo. This requires the ability to controllably manipulate the release of the drug cargo from the NP vehicle or ‘controlled actuation’. In this review, we highlight new developments in this field from 2013 to 2015. The number and breadth of reports are a testament to the significant advancements made in this field over this time period. We conclude with a perspective of how we envision this field to continue to develop in the years to come.

The potential for nanotechnology to improve delivery of therapy to the acute ischemic heart

Treatment of acute cardiac ischemia remains an area in which there are opportunities for therapeutic improvement. Despite significant advances, many patients still progress to cardiac hypertrophy and heart failure. Timely reperfusion is critical in rescuing vulnerable ischemic tissue and is directly related to patient outcome, but reperfusion of the ischemic myocardium also contributes to damage. Overproduction of reactive oxygen species, initiation of an inflammatory response and deregulation of calcium homeostasis all contribute to injury, and difficulties in delivering a sufficient quantity of drug to the affected tissue in a controlled manner is a limitation of current therapies. Nanotechnology may offer significant improvements in this respect. Here, we review recent examples of how nanoparticles can be used to improve delivery to the ischemic myocardium, and suggest some approaches that may lead to improved therapies for acute cardiac ischemia.

Micromanaging cardiac regeneration: Targeted delivery of microRNAs for cardiac repair and regeneration

The loss of cardiomyocytes during injury and disease can result in heart failure and sudden death, while the adult heart has a limited capacity for endogenous regeneration and repair. Current stem cell-based regenerative medicine approaches modestly improve cardiomyocyte survival, but offer neglectable cardiomyogenesis. This has prompted the need for methodological developments that crease de novo cardiomyocytes. Current insights in cardiac development on the processes and regulatory mechanisms in embryonic cardiomyocyte differentiation provide a basis to therapeutically induce these pathways to generate new cardiomyocytes. Here, we discuss the current knowledge on embryonic cardiomyocyte differentiation and the implementation of this knowledge in state-of-the-art protocols to the direct reprogramming of cardiac fibroblasts into de novo cardiomyocytes in vitro and in vivo with an emphasis on microRNA-mediated reprogramming. Additionally, we discuss current advances on state-of-the-art targeted drug delivery systems that can be employed to deliver these microRNAs to the damaged cardiac tissue. Together, the advances in our understanding of cardiac development, recent advances in microRNA-based therapeutics, and innovative drug delivery systems, highlight exciting opportunities for effective therapies for myocardial infarction and heart failure.