Direct Cardiac Epigenetic Reprogramming through Codelivery of 5'Azacytidine and miR-133a Nanoformulation.

Direct reprogramming of cardiac fibroblasts to induced cardiomyocytes (iCMs) is a promising approach to cardiac regeneration. However, the low yield of reprogrammed cells and the underlying epigenetic barriers limit its potential. Epigenetic control of gene regulation is a primary factor in maintaining cellular identities. For instance, DNA methylation controls cell differentiation in adults, establishing that epigenetic factors are crucial for sustaining altered gene expression patterns with subsequent rounds of cell division. This study attempts to demonstrate that 5'AZA and miR-133a encapsulated in PLGA-PEI nanocarriers induce direct epigenetic reprogramming of cardiac fibroblasts to cardiomyocyte-like cells. The results present a cardiomyocyte-like phenotype following seven days of the co-delivery of 5'AZA and miR-133a nanoformulation into human cardiac fibroblasts. Further evaluation of the global DNA methylation showed a decreased global 5-methylcytosine (5-medCyd) levels in the 5'AZA and 5'AZA/miR-133a treatment group compared to the untreated group and cells with void nanocarriers. These results suggest that the co-delivery of 5'AZA and miR-133a nanoformulation can induce the direct reprogramming of cardiac fibroblasts to cardiomyocyte-like cells in-vitro, in addition to demonstrating the influence of miR-133a and 5'AZA as epigenetic regulators in dictating cell fate.

Biotechnological advances and applications of human pluripotent stem cell-derived heart models.

In recent years, significant biotechnological advancements have been made in engineering human cardiac tissues and organ-like models. This field of research is crucial for both basic and translational research due to cardiovascular disease being the leading cause of death in the developed world. Additionally, drug-associated cardiotoxicity poses a major challenge for drug development in the pharmaceutical and biotechnological industries. Progress in three-dimensional cell culture and microfluidic devices has enabled the generation of human cardiac models that faithfully recapitulate key aspects of human physiology. In this review, we will discuss 3D pluripotent stem cell (PSC)-models of the human heart, such as engineered heart tissues and organoids, and their applications in disease modeling and drug screening.

A patterned human primitive heart organoid model generated by pluripotent stem cell self-organization.

Pluripotent stem cell-derived organoids can recapitulate significant features of organ development in vitro. We hypothesized that creating human heart organoids by mimicking aspects of in utero gestation (e.g., addition of metabolic and hormonal factors) would lead to higher physiological and anatomical relevance. We find that heart organoids produced using this self-organization-driven developmental induction strategy are remarkably similar transcriptionally and morphologically to age-matched human embryonic hearts. We also show that they recapitulate several aspects of cardiac development, including large atrial and ventricular chambers, proepicardial organ formation, and retinoic acid-mediated anterior-posterior patterning, mimicking the developmental processes found in the post-heart tube stage primitive heart. Moreover, we provide proof-of-concept demonstration of the value of this system for disease modeling by exploring the effects of ondansetron, a drug administered to pregnant women and associated with congenital heart defects. These findings constitute a significant technical advance for synthetic heart development and provide a powerful tool for cardiac disease modeling.

Scaffold mediated delivery of dual miRNAs to transdifferentiate cardiac fibroblasts.

The standard scaffold-mediated delivery of drugs/biomolecules has been successful due to the unique attributes of scaffolds, specifically the electrospun polymeric scaffolds that mimic ECM are well suited for advanced regenerative applications. Cardiac tissue engineering includes the interpretation of cellular and molecular mechanisms concerning heart regeneration and identifying an efficient reprogramming strategy to overcome the limitation of delivery systems and enhance the reprogramming efficiency. This study is a step towards developing a functional scaffold through a parallel interpretation of electrospun PLLA scaffolds with two distinct topologies to achieve sustained delivery of two muscle-specific microRNAs (miR-1 and miR-133a) to directly reprogram the adult human cardiac fibroblasts into cardiomyocyte-like cells. Polyethyleneimine was used to form stable PEI-miRNA complexes through electrostatic interactions. These complexes were immobilized on the electrospun smooth and porous scaffolds, where a loading efficiency of ~96% for the fibronectin modified and ~38% for unmodified surfaces was observed, regardless of their surface topology. The in-vitro release experiment exhibited a biphasic release pattern of PEI-miRNA polyplexes from the scaffolds. These dual miRNA scaffold systems proved to be an excellent formulation since their combinatorial effect involving the topographic cues of electrospun fibers, and dual miRNAs helped control the cardiac fibroblast cell fate precisely.

Direct Cardiac Reprogramming with Engineered miRNA Scaffolds.

Ischemic heart disease is a predominant cause of death worldwide. The loss or death of cardiomyocytes due to restricted blood flow often results in a cardiac injury. Myofibroblasts replace these injured cardiomyocytes to preserve structural integrity. However, the depleted cardiomyocytes lead to cardiac dysfunction such as pathological cardiac dilation, reduced cardiac contraction, and fibrosis. Repair and regeneration of myocardium are the best possible therapy for end-stage heart failure patients because the current cardiomyocytes restoration therapies are limited to heart transplantation only. The emergence of interests to directly reprogram a mammalian heart with minimal regenerative capacity holds a promising future in the field of cardiovascular regenerative medicine. Repair and regeneration become the two crucial factors in the field of cardiovascular regenerative medicine since heart muscles have no substitutes, like heart valves or blood vessels. Cardiac regeneration includes strategies to reprogram with diverse factors like small molecules, genetic and epigenetic regulators. However, there are some constraints like low efficacy, immunogenic problems, and unsafe delivery systems that pose a daunting challenge in human trial translations. Hence, there is a need for a holistic nanoscale approach in regulating cell fate effectively and efficiently with a safer delivery and a suitable microenvironment that mimics the extracellular matrix. In this review, we have discussed the current state-of-the-art techniques, challenges in direct reprogramming of fibroblasts to cardiac muscle, and prospects of biomaterials in miRNA delivery and cardiac regeneration predominantly during the past decade (2008-2019).

ECM Mimetic Electrospun Porous Poly (L-lactic acid) (PLLA) Scaffolds as Potential Substrates for Cardiac Tissue Engineering.

Cardiac tissue engineering (CTE) aims to generate potential scaffolds to mimic extracellular matrix (ECM) for recreating the injured myocardium. Highly porous scaffolds with properties that aid cell adhesion, migration and proliferation are critical in CTE. In this study, electrospun porous poly (l-lactic acid) (PLLA) porous scaffolds were fabricated and modified with different ECM derived proteins such as collagen, gelatin, fibronectin and poly-L-lysine. Subsequently, adult human cardiac fibroblasts (AHCF) were cultured on the protein modified and unmodified fibers to study the cell behavior and guidance. Further, the cytotoxicity and reactive oxygen species (ROS) assessments of the respective fibers were performed to determine their biocompatibility. Excellent cell adhesion and proliferation of the cardiac fibroblasts was observed on the PLLA porous fibers regardless of the surface modifications. The metabolic rate of cells was on par with the conventional cell culture ware while the proliferation rate surpassed the latter by nearly two-folds. Proteome profiling revealed that apart from being an anchorage platform for cells, the surface topography has modulated significant expression of the cellular proteome with many crucial proteins responsible for cardiac fibroblast growth and proliferation.

Vesicular systems employing natural substances as promising drug candidates for MMP inhibition in glioblastoma: A nanotechnological approach.

Glioblastoma multiforme (GBM), one of the most lethal Brain tumors, characterized by its high invasive nature and increased mortality rates forms a major bottleneck in transport of therapeutics across the Blood Brain Barrier (BBB). Matrix metalloproteinases (MMPs) are classified as enzymes, which are found to be up regulated in the Glioma tumor microenvironment and thus can be considered as a target for inhibition for curbing GBM. Many chemotherapeutics and techniques have been employed for inhibiting MMPs till now but all of them failed miserably and were withdrawn in clinical trials due to their inability in restricting the tumor growth or increasing the overall survival rates. Thus, the quest for finding the suitable MMP inhibitor is still on and there is a critical need for identification of novel compounds which can alter the BBB permeability, restrain tumor growth and prevent tumor recurrence. Currently, naturally derived substances are gaining widespread attention as tumor inhibitors and many studies have been reported by far highlighting their importance in restricting MMP expression thus serving as chemotherapeutics for cancer due to their minimal toxicity. These substances may serve as probable candidates for inhibiting MMP expression in GBM. However, targeting and delivering the inhibitor to its target site is an issue that needs to be overcome in order to attain maximum specificity and sustained release. The birth of nanotechnology served as a boon in delivering drugs to the most complicated areas thus paving way for Nano drug delivery. An efficient Nano carrier with ability to cross the BBB and competently kill the Glioma cells forms the prerequisite for GBM chemotherapy. Vesicular drug delivery systems are one such class of carriers, which have the capacity to release the drug at a predetermined rate at the target site thus minimizing any undesirable side effects. Exploiting vesicular systems as promising Nano drug carriers to formulate naturally derived substances, that can bypass the BBB and act as an inhibitor against MMPs in GBM is the main theme of this review.