RETRACTED: Recent advances in cardiac regeneration: Stem cell, biomaterial and growth factors

Injectable Hydrogel-Based Nanocomposites for Cardiovascular Diseases

Cardiovascular diseases (CVDs), including a series of pathological disorders, severely affect millions of people all over the world. To address this issue, several potential therapies have been developed for treating CVDs, including injectable hydrogels as a minimally invasive method. However, the utilization of injectable hydrogel is a bit restricted recently owing to some limitations, such as transporting the therapeutic agent more accurately to the target site and prolonging their retention locally. This review focuses on the advances in injectable hydrogels for CVD, detailing the types of injectable hydrogels (natural or synthetic), especially that complexed with stem cells, cytokines, nano-chemical particles, exosomes, genetic material including DNA or RNA, etc. Moreover, we summarized the mainly prominent mechanism, based on which injectable hydrogel present excellent treating effect of cardiovascular repair. All in all, it is hopefully that injectable hydrogel-based nanocomposites would be a potential candidate through cardiac repair in CVDs treatment.

Current Trends in Biomaterial Utilization for Cardiopulmonary System Regeneration

The cardiopulmonary system is made up of the heart and the lungs, with the core function of one complementing the other. The unimpeded and optimal cycling of blood between these two systems is pivotal to the overall function of the entire human body. Although the function of the cardiopulmonary system appears uncomplicated, the tissues that make up this system are undoubtedly complex. Hence, damage to this system is undesirable as its capacity to self-regenerate is quite limited. The surge in the incidence and prevalence of cardiopulmonary diseases has reached a critical state for a top-notch response as it currently tops the mortality table. Several therapies currently being utilized can only sustain chronically ailing patients for a short period while they are awaiting a possible transplant, which is also not devoid of complications. Regenerative therapeutic techniques now appear to be a potential approach to solve this conundrum posed by these poorly self-regenerating tissues. Stem cell therapy alone appears not to be sufficient to provide the desired tissue regeneration and hence the drive for biomaterials that can support its transplantation and translation, providing not only physical support to seeded cells but also chemical and physiological cues to the cells to facilitate tissue regeneration. The cardiac and pulmonary systems, although literarily seen as just being functionally and spatially cooperative, as shown by their diverse and dissimilar adult cellular and tissue composition has been proven to share some common embryological codevelopment. However, necessitating their consideration for separate review is the immense adult architectural difference in these systems. This review also looks at details on new biological and synthetic biomaterials, tissue engineering, nanotechnology, and organ decellularization for cardiopulmonary regenerative therapies.

Extracellular matrix-derived extracellular vesicles promote cardiomyocyte growth and electrical activity in engineered cardiac atria

Extracellular matrix (ECM) plays a critical role in the provision of the necessary microenvironment for the proper regeneration of the cardiac tissue. However, specific mechanisms that lead to ECM-mediated cardiac regeneration are not well understood. To elucidate the potential mechanisms, we investigated ultra-structures of the cardiac ECM using electron microscopy. Intriguingly, we observed large quantities of micro-vesicles from decellularized right atria. RNA and protein analyses revealed that these contained exosomal proteins and microRNAs (miRNAs), which we referred to herein as ECM-derived extracellular vesicles (ECM-EVs). One particular miRNA from ECM-EVs, miR-199a-3p, promoted cell growth of isolated neonatal cardiomyocytes and sinus nodal cells by repressing homeodomain-only protein (HOPX) expression and increasing GATA-binding 4 (Gata4) acetylation. To determine the mechanisms, we knocked down Gata4 and showed that miR-199a-3p actions required Gata4 for cell proliferation in isolated neonatal cardiomyocytes and sinus nodal cells. To further explore the role of this miRNA, we isolated neonatal cardiac cells and recellularized into atrial ECM, referred here has engineered atria. Remarkably, miR-199a-3p mediated the enrichment of cardiomyocyte and sinus nodal cell population, and enhanced electrocardiographic signal activity of sinus nodal cells in the engineered atria. Importantly, antisense of miRNA (antagomir) against miR-199a-3p was capable of abolishing these actions of miR-199a-3p in the engineered atria. We further showed in Ang II-infused animal model of sinus nodal dysfunction that miR-199-3p-treated cardiac cells remarkably ameliorated and restored the electrical activity as shown by normalization of the ECG, in contrast to untreated cells, which did not show electrical recovery. In conclusion, these results provide clear evidence of the critical role of ECM, in not only providing a scaffold for cardiac tissue growth, but also in promoting atrial electrical function through ECM-derived miR-199a-3p.

Optimization of Human Myocardium Decellularization Method for the Construction of Implantable Patches

Cardiac tissue engineering by means of synthetic or natural scaffolds combined with stem/progenitor cells is emerging as the response to the unsatisfactory outcome of approaches based solely on the injection of cells. Parenchymal and supporting cells are surrounded, in vivo, by a specialized and tissue-specific microenvironment, consisting mainly of extracellular matrix (ECM) and soluble factors incorporated in the ECM. Since the naturally occurring ECM is the ideal platform for ensuring cell engraftment, survival, proliferation, and differentiation, the acellular native ECM appears by far the most promising and appealing substrate among all biomaterials tested so far. To obtain intact scaffold of human native cardiac ECM while preserving its composition, we compared the decellularized ECM (d-ECM) produced through five different protocols of decellularization (named Pr1, Pr2, Pr3, Pr4, and Pr5) in terms of efficiency of decellularization, composition, and three-dimensional architecture of d-ECM scaffolds and of their suitability for cell repopulation. The decellularization procedures proved substantially different. Specifically, only three, of the five protocols tested, proved effective in producing thoroughly acellular d-ECM. In addition, the d-ECM delivered differed in architecture and composition and, more importantly, in its ability to support engraftment, survival, and differentiation of cardiac primitive cells in vitro.

Stem cell, biomaterials and growth factors therapy for hepatocellular carcinoma

Hepatocellular carcinoma is an antecedent of liver illnesses, including viral hepatitis, alcohol abuse, or metabolic disease. Transforming growth factor-Beta (TGF-b) plays an important role in creating a favorable microenvironment for tumor cell growth via two major mechanisms: an intrinsic activity as an autocrine growth factor and an extrinsic activity by inducing microenvironment changes. Recently stem cell therapy as also been a promising and potential treatment for liver cancer and in addition signaling pathways like GF/GFR systems, SDF-1α/CXC4 ligand receptor interaction and PI3K/Akt signaling, and cytokines has been identified to regulate cell fate decisions, and can be utilized to positively influence cell therapy outcomes. Thus stem cell-based therapy, together with signaling pathways can become a practical option in regenerative processes for replacing dead hepatocytes cells. Targeted drug delivery systems (TDDS) via biomaterials are presently been explored for cancer therapeutics especially liver cancer as it allows the enhancement of drug concentration in the liver and decrease the dosage and side effects. This review is intended to give a comprehensive summary of available liver cancer therapy using stem cells, growth factor and biomaterials.