Myocardial Tissue Regeneration Research Articles

Bridging the Gap: Advances and Challenges in Heart Regeneration from In Vitro to In Vivo Applications.

Cardiovascular diseases, particularly ischemic heart disease, area leading cause of morbidity and mortality worldwide. Myocardial infarction (MI) results in extensive cardiomyocyte loss, inflammation, extracellular matrix (ECM) degradation, fibrosis, and ultimately, adverse ventricular remodeling associated with impaired heart function. While heart transplantation is the only definitive treatment for end-stage heart failure, donor organ scarcity necessitates the development of alternative therapies. In such cases, methods to promote endogenous tissue regeneration by stimulating growth factor secretion and vascular formation alone are insufficient. Techniques for the creation and transplantation of viable tissues are therefore highly sought after. Approaches to cardiac regeneration range from stem cell injections to epicardial patches and interposition grafts. While numerous preclinical trials have demonstrated the positive effects of tissue transplantation on vasculogenesis and functional recovery, long-term graft survival in large animal models is rare. Adequate vascularization is essential for the survival of transplanted tissues, yet pre-formed microvasculature often fails to achieve sufficient engraftment. Recent studies report success in enhancing cell survival rates in vitro via tissue perfusion. However, the transition of these techniques to in vivo models remains challenging, especially in large animals. This review aims to highlight the evolution of cardiac patch and stem cell therapies for the treatment of cardiovascular disease, identify discrepancies between in vitro and in vivo studies, and discuss critical factors for establishing effective myocardial tissue regeneration in vivo.

A Whole-Course-Repair System Based on Stimulus-Responsive Multifunctional Hydrogels for Myocardial Tissue Regeneration.

Myocardial infarction (MI) has emerged as the predominant cause of cardiovascular morbidity globally. The pathogenesis of MI unfolds as a progressive process encompassing three pivotal phases: inflammation, proliferation, and remodeling. Smart stimulus-responsive hydrogels have garnered considerable attention for their capacity to deliver therapeutic drugs precisely and controllably at the MI site. Here, a smart stimulus-responsive hydrogel with a dual-crosslinked network structure is designed, which enables the precise and controlled release of therapeutic drugs in different pathological stages for the treatment of MI. The hydrogel can rapidly release curcumin (Cur)in the inflammatory phase of MI to exert anti-apoptotic/anti-inflammatory effects. Recombinant humanized collagen type III (rhCol III) is loaded in the hydrogel and released as the hydrogel swelled/degraded during the proliferative phase to promote neovascularization. RepSox (a selective TGF-β inhibitor) releases from Pluronic F-127 grafted with aldehyde nanoparticles (PF127-CHO@RepSox NPs) in the remodeling phase to against fibrosis. The results in vitro and in vivo suggest that the hydrogel improves cardiac function and alleviates cardiac remodeling by suppressing inflammation and apoptosis, promoting neovascularization, and inhibiting myocardial fibrosis. A whole-course-repair system, leveraging stimulus-responsive multifunctional hydrogels, demonstrates notable effectiveness in enhancing post-MI cardiac function and facilitating the restoration of damaged myocardial tissue.

Some Numerical Results on Chemotactic Phenomena in Stem Cell Therapy for Cardiac Regeneration

Biological models for cardiac regeneration and remodeling, along with the effects of cytokines or chemokines during the therapy with mesenchymal stem cells after a myocardial infarction, are of crucial importance for understanding the complex underlying mechanisms. This paper presents a mathematical model composed of three coupled partial differential equations that describes the dynamics of stem cells, nutrients and chemokines, highlighting the fundamental role of the chemokines during the myocardial tissue regeneration process. The system is solved numerically using mimetic difference operators and the MOLE library for MATLAB. The results show the tissue regeneration process in the necrotic part closest to the cell implantation area.

Targeted delivery of factors and cells for improving cardiac tissue regeneration and heart function following myocardial infarction

Following myocardial infarction (MI), cardiac tissue undergoes irreversible cellular alterations, with cardiomyocytes being replaced by fibrotic tissue. In order to improve tissue regeneration, a previously characterized chitosan-based cryogel, which was designed by our group, was used. The treatment regimen involved the sequential delivery of the cryogel loaded with specific cytokines and growth factors, followed by a separate injection of pre-differentiated cells. Initially, the cryogel loaded with interleukin-10 and transforming growth factor-β was injected into infarcted tissue immediately after MI induction, targeting the acute inflammatory response. On day four post-MI, a second injection was administered, this time utilizing cryogel loaded with vascular endothelial growth factor and fibroblast growth factor-2, aimed at promoting tissue regeneration and angiogenesis. Subsequently, on day six post-MI, the experimental group received cardiomyocyte-like cells, smooth muscle cells, and endothelial cells. The purpose of these cells, in synergy with cytokines and growth factors, was to repopulate the lost cellular populations, thereby enhancing myocardial repair. The treatment improved myocardial tissue regeneration, increased cardiac output, ejection fraction, and reduced fibrotic regions. Thus, the chitosan-based cryogel, enriched with anti-inflammatory and proangiogenic factors and supplemented with pre-differentiated cells, offers a promising platform for controlled release of therapeutics, promoting substantial tissue repair and regeneration following MI.

Mesenchymal Stem Cell Transplantation Has a Regenerative Effect in Ischemic Myocardium: An Experimental Rat Model Evaluated by SPECT-CT Assessment.

The regeneration of myocardial tissue and the improvement of myocardial activity after ischemia is one of the major areas of interest in cardiovascular research. We developed a novel experimental rat model and used it to examine the effect of mesenchymal stem cell transplantation (MSCT) on myocardial ischemia evaluated by SPECT-CT and immunohistochemistry. An open thoracotomy took place for forty adult female Wistar rats with (n = 30) or without (n = 10) surgical ligation of the left anterior descending coronary artery (LAD) in order to cause myocardial ischemia. Myocardial viability was evaluated via SPECT/CT 7 days before surgery, as well as at 7 and 14 days post-surgery. At day 0, 15 animals received homologous stem cells injected at the ischemic myocardium area. A SPECT/CT evaluation showed decreased activity of the myocardial cells in the left ventricle one week post-infarction. Regeneration of the ischemic myocardium fifteen days post-infarction was recorded only in animals subjected to stem cell transplantation. These findings were also confirmed by histology and immunohistochemical analysis, with the significantly higher expression of GATA4 and Nkx2.5. The positive effect of mesenchymal stem cell transplantation in the ischemic myocardium was recorded. The application of SPECT-CT allowed a clear evaluation of both the quality and quantity of the living myocardium post-infarction, leading to a new approach in the research of cardiovascular diseases. From a clinical perspective, MSCT may be beneficial when accompanied by myocardial revascularization procedures.

Bioscaffolds of graphene based-polymeric hybrid materials for myocardial tissue engineering.

Biomaterials currently utilized for the regeneration of myocardial tissue seem to associate with certain restrictions, including deficiency of electrical conductivity and sufficient mechanical strength. These two factors play an important role in cardiac tissue engineering and regeneration. The contractile property of cardiomyocytes depends on directed signal transmission over the electroconductive systems that happen inside the innate myocardium. Because of their distinctive electrical behavior, electroactive materials such as graphene might be used for the regeneration of cardiac tissue. In this review, we aim to provide deep insight into the applications of graphene and graphene derivative-based hybrid polymeric scaffolds in cardiomyogenic differentiation and cardiac tissue regeneration. Synthetic biodegradable polymers are considered as a platform because their degradation can be controlled over time and easily functionalized. Therefore, graphene-polymeric hybrid scaffolds with anisotropic electrical behavior can be utilized to produce organizational and efficient constructs for macroscopic cardiac tissue engineering. In cardiac tissue regeneration, natural polymer based-scaffolds such as chitosan, gelatin, and cellulose can provide a permissive setting significantly supporting the differentiation and growth of the human induced pluripotent stem cells -derived cardiomyocytes, in large part due to their negligible immunogenicity and suitable biodegradability. Cardiac tissue regeneration characteristically utilizes an extracellular matrix (scaffold), cells, and growth factors that enhance cell adhesion, growth, and cardiogenic differentiation. From the various evaluated electroactive polymeric scaffolds for cardiac tissue regeneration in the past decade, graphene and its derivatives-based materials can be utilized efficiently for cardiac tissue engineering.

Advances in Injectable Hydrogel Strategies for Heart Failure Treatment.

Heart failure (HF) affects 60 million people worldwide and has developed into a global public health problem surpassing cancer and urgently needs to be solved. According to the etiological spectrum, HF due to myocardial infarction (MI) has become the dominant cause of morbidity and mortality. Possible treatments include pharmacology, medical device implantation, and cardiac transplantation, which are limited in their ability to promote long-term functional stabilization of the heart. Injectable hydrogel therapy has emerged as a minimally invasive tissue engineering treatment approach. Hydrogels can provide the necessary mechanical support for the infarcted myocardium and serve as carriers of various drugs, bioactive factors and cells to improve the cellular microenvironment in the infarcted region and induce myocardial tissue regeneration. Herein, we explored the pathophysiological mechanism of HF and summarized injectable hydrogels as a potential solution for current clinical trials and applications. Specifically, mechanical support hydrogels, decellularized ECM hydrogels, a variety of biotherapeutic agent-loaded hydrogels and conductive hydrogels for cardiac repair were discussed, and the mechanism of action of these hydrogel-based therapies was emphasized. Finally, the limitations and future prospects of injectable hydrogel therapy for HF post MI were proposed to inspire novel therapeutic strategies. This article is protected by copyright. All rights reserved.

Biomaterials-Based Cell Therapy for Myocardial Tissue Regeneration.

Cardiovascular diseases (CVDs) have beenthe leading cause of death worldwide during the past several decades. Cell loss is the main problem that results in cardiac dysfunction and further mortality. Cell therapy aiming to replenish the lost cells is proposed to treat CVDs especially ischemic heart diseases which lead to a big portion of cell loss. Due to the direct injection's low cell retention and survival ratio, cell therapy using biomaterials as cell carriers has attracted more and more attention because of their promotion of cell delivery and maintenance at the aiming sites. In this review, the three main factors involved in cell therapy for myocardial tissue regeneration: cell sources (somatic cells, stem cells, and engineered cells), chemical components of cell carriers (natural materials, synthetic materials, and electroactive materials), and categories of cell delivery materials (patches, microspheres, injectable hydrogels, nanofiber and microneedles, etc.) are systematically summarized. An introduction of the methods including magnetic resonance/radionuclide/photoacoustic and fluorescence imaging for tracking the behavior of transplanted cells in vivo is also included. Current challenges of biomaterials-based cell therapy and their future directions are provided to give both beginners and professionals a clear view of the development and future trends in this area.

Preventive Effect of Bone Marrow Mononuclear Cell Transplantation on Acute Myocardial Infarction-Induced Heart Failure: A Meta-analysis of Randomized Controlled Trials.

Heart failure (HF) is a major complication of acute myocardial infarction (AMI). Transplantation of bone marrow mononuclear cells (BM-MNC) in the setting of AMI has been proposed as a means for myocardial tissue regeneration. Several trials have explored the outcomes of these cells on surrogate end points such as left ventricular ejection fraction (LVEF) in patients with AMI. However, the data regarding the clinical efficacy are infrequent. Here, we performed a meta-analysis investigating the effect of BM-MNCs injection on the rate of hospitalization for HF in the long-term follow-up period. PubMed, Scopus, and Cochrane databases were queried with various combinations of keywords through May 2, 2022. A random-effects meta-analysis was performed to calculate risk ratio (RR) and 95% confidence interval (CI) of hospitalization for HF, all-cause mortality, and stroke rate. Subgroup analyses for hospitalization based on time and cell dose were performed. A total of 2150 patients with AMI across 22 trials were included for quantitative synthesis. At long-term follow-up, AMI patients treated with an intracoronary injection of BM-MNCs were less likely to be hospitalized for heart failure compared to the control group receiving standard treatment (RR = 0.54, 95% CI = [0.37; 0.78], p = 0.002). There was no association between BM-MNC therapy and all-cause mortality (RR = 0.69, 95% CI = [0.47; 1.01], p = 0.05) and stroke (RR = 1.12, 95% CI= [0.24; 5.21], p = 0.85). Autologous injection of BM-MNC in the setting of AMI may be associated with decreased risk of hospitalization of heart failure in the long term. However, its effect on all-cause mortality and stroke rate is questionable.

The Progress of Stem Cell Therapy in Myocardial-Infarcted Heart Regeneration: Cell Sheet Technology.

Various tissues, including the heart, cornea, bone, esophagus, bladder and liver, have been vascularized using the cell sheet technique. It overcomes the limitations of existing techniques by allowing small layers of the cell sheet to generate capillaries on their own, and it can also be used to vascularize tissue-engineered transplants. Cell sheets eliminate the need for traditional tissue engineering procedures such as isolated cell injections and scaffold-based technologies, which have limited applicability. While cell sheet engineering can eliminate many of the drawbacks, there are still a few challenges that need to be addressed. The number of cell sheets that can be layered without triggering core ischemia or hypoxia is limited. Even when scaffold-based technologies are disregarded, strategies to tackle this problem remain a substantial impediment to the efficient regeneration of thick, living three-dimensional cell sheets. In this review, we summarize the cell sheet technology in myocardial infarcted tissue regeneration.

Isolation and Culture of Non-adherent Cells for Cell Reprogramming.

Coronary heart disease (CHD) is a leading cause of death globally, while its current management is limited to reducing the myocardial infarction area without actually replacing dead cardiomyocytes. Direct cell reprogramming is a method of cellular cardiomyoplasty which aims for myocardial tissue regeneration, and CD34+ cells are one of the potential sources due to their shared embryonic origin with cardiomyocytes. However, the isolation and culture of non-adherent CD34+ cells is crucial to obtain adequate cells for high-efficiency genetic modification. This study aimed to investigate the optimal method for isolation and culture of CD34+ peripheral blood cells using certain culture media. A peripheral blood sample was obtained from a healthy subject and underwent pre-enrichment, isolation, and expansion. The culture was subsequently observed for their viability, adherence, and confluence. Day 0 observation of the culture showed a healthy CD34+ cell with a round cell shape, without any adherent cells present yet. Day 4 of observation showed that CD34+ cells within the blood plasma medium became adherent, indicated by their transformations into spindle or oval morphologies. Meanwhile, CD34+ cells in vitronectin and fibronectin media showed no adherent cells and many of them died. Day 7 observation revealed more adherent CD34+ cells in blood plasma medium, and which had 75% of confluence. In conclusion, the CD34+ cells that were isolated using a combination of density and magnetic methods may be viable and adequately adhere in culture using blood plasma medium, but not in cultures using fibronectin and vitronectin.

Gelatin‐Lysozyme Nanofibrils Electrospun Patches with Improved Mechanical, Antioxidant, and Bioresorbability Properties for Myocardial Regeneration Applications

AbstractBiopolymeric patches show enormous potential for the regeneration of infarcted myocardium tissues. However, most of them usually lack appropriate mechanical performance, stability in water, and important functionalities; for instance, antioxidant activity. Protein nanofibrils, such as lysozyme nanofibrils (LNFs), are biocompatible nanostructures with excellent mechanical performance, water insolubility, and antioxidant activity exploited to fabricate materials for different biomedical applications. In this study, LNFs are used to produce gelatin electrospun nanocomposite cardiac patches with improved properties. The addition of the LNFs to the gelatin electrospun patches enhance their mechanical properties, increasing the patches Young's modulus from 3 to 6 MPa, in their wet state, which agrees with the requirements of myocardial contractility. Additionally, it is observed an increment of the antioxidant activity to 80%, by adding only 5% (w/w) of LNFs, and the bioresorbability rate is shortened to 30–35 d, compared to 45 d for the gelatin‐only patches, while maintaining their morphology, and biocompatibility toward cardiomyoblasts and fibroblasts. Furthermore, 15% of a model drug is burst released from the patches and preserved for 21 d. Overall, these results demonstrate that LNFs have a great potential as functional reinforcements to fabricate biopolymeric electrospun patches for myocardial infarcted tissue regeneration.

A 3D mathematical model of coupled stem cell-nutrient dynamics in myocardial regeneration therapy

Stem cell therapy is a promising treatment for the regeneration of myocardial tissue injured by an ischemic event. Mathematical modeling of myocardial regeneration via stem cell therapy is a challenging task, since the mechanisms underlying the processes involved in the treatment are not yet fully understood. Many aspects must be accounted for, such as the spread of stem cells and nutrients, chemoattraction, cell proliferation, stages of cell maturation, differentiation, angiogenesis, stochastic effects, just to name a few. In this paper we propose a 3D mathematical model with a free boundary that aims to provide a qualitative description of some main aspects of the stem cell regenerative therapy in a simplified scenario. The paper mainly focuses on the description of the shrinking of the necrotic core during treatment. The stem cell and nutrients dynamics are described through coupled reaction-diffusion problems. Proliferation, chemoattraction, tissue regeneration and nutrient consumption are included in the model.

Tunable biomaterials for myocardial tissue regeneration: promising new strategies for advanced biointerface control and improved therapeutic outcomes.

Following myocardial infarction (MI) and the natural healing process, the cardiac mechanostructure changes significantly leading to reduced contractile ability and resulting in additional pressure on the heart muscle thereby increasing the risk of heart failure (HF). The application of cardiac scaffolds in the form of epicardial patches or injectable hydrogels at the infarcted region of the myocardium helps to mechanically reinforce the ventricular walls and allows control over the various stages of the healing process, reducing pathological remodeling and fibrosis and eventually restoring cardiac function. Recent progress in the field of biomaterials engineering allows tuning of cardiac scaffold properties for more effective tissue-biomaterial interaction leading to improved therapeutic outcomes. Nanoscaffold characteristics required for myocardial tissue engineering (TE) including mechanical property, pore size/porosity, immunomodulation, bioactivity, electroconductivity, injectability (for hydrogels) and thickness (for cardiac patches) are herewith reviewed. Strategies for controlling each of these properties via blending, scaffold fabrication, degree of crosslinking, and incorporation of bioactive molecules, amongst others are also discussed. The mechanism of myocardial restoration via enhanced angiogenesis, stem cell homing and mechanical support is further detailed. Finally, key novel innovative strategies with high promise for clinical translation are presented; in particular, the use of extracellular vesicle-loaded scaffolds, integration of electronics within scaffolds for real time monitoring of the engineered tissue performance as well as the possibility of refilling scaffolds with drugs/cells/proteins via a subcutaneous port are highlighted.

Physical Exercise and Cardiac Repair: The Potential Role of Nitric Oxide in Boosting Stem Cell Regenerative Biology.

Over the years strong evidence has been accumulated showing that aerobic physical exercise exerts beneficial effects on the prevention and reduction of cardiovascular risk. Exercise in healthy subjects fosters physiological remodeling of the adult heart. Concurrently, physical training can significantly slow-down or even reverse the maladaptive pathologic cardiac remodeling in cardiac diseases, improving heart function. The underlying cellular and molecular mechanisms of the beneficial effects of physical exercise on the heart are still a subject of intensive study. Aerobic activity increases cardiovascular nitric oxide (NO) released mainly through nitric oxidase synthase 3 activity, promoting endothelium-dependent vasodilation, reducing vascular resistance, and lowering blood pressure. On the reverse, an imbalance between increasing free radical production and decreased NO generation characterizes pathologic remodeling, which has been termed the “nitroso-redox imbalance”. Besides these classical evidence on the role of NO in cardiac physiology and pathology, accumulating data show that NO regulate different aspects of stem cell biology, including survival, proliferation, migration, differentiation, and secretion of pro-regenerative factors. Concurrently, it has been shown that physical exercise generates physiological remodeling while antagonizes pathologic remodeling also by fostering cardiac regeneration, including new cardiomyocyte formation. This review is therefore focused on the possible link between physical exercise, NO, and stem cell biology in the cardiac regenerative/reparative response to physiological or pathological load. Cellular and molecular mechanisms that generate an exercise-induced cardioprotective phenotype are discussed in regards with myocardial repair and regeneration. Aerobic training can benefit cells implicated in cardiovascular homeostasis and response to damage by NO-mediated pathways that protect stem cells in the hostile environment, enhance their activation and differentiation and, in turn, translate to more efficient myocardial tissue regeneration. Moreover, stem cell preconditioning by and/or local potentiation of NO signaling can be envisioned as promising approaches to improve the post-transplantation stem cell survival and the efficacy of cardiac stem cell therapy.

The cardioprotective effect and mechanism of bioactive glass on myocardial reperfusion injury

Myocardial reperfusion treatment for ischemic infarction may cause lethal injury of cardiomyocytes, which is known as ischemia/reperfusion (I/R) injury. As a kind of prospective biomaterial with superior properties, the application of bioactive glasses (BGs) in myocardial tissue engineering have received great interests. In this study, the cardioprotective effect and relevant mechanism of BG on myocardial reperfusion injury were investigated in vitro. H9c2 cardiomyocytes were pretreated with BG extracts and then cultured in hypoxic environment for 30 min followed by reoxygenation for 1 h. The activity of released lactate dehydrogenase (LDH) and the content of malondialdehyde (MDA) in H9c2 cells were tested by assay kits. Cell viability was analyzed by Live/Dead staining assay and the number of living cells was detected by Cell Counting Kit-8 (CCK-8) assay. The cytoskeletal protein F-actin was stained and observed under inverted fluorescence microscope. Mitochondrial membrane potential (MMP) level, reactive oxygen species (ROS) production and apoptosis ratio were evaluated by fluorescent observation and flow cytometry simultaneously. The gene expressions relevant to apoptosis were detected by quantitative real time polymerase chain reaction (qRT-PCR) analysis. The results showed that BG extracts effectively inhibited hypoxia/reoxygenation (H/R)-induced cell injury by suppressing oxidative stress and mitochondrial permeability transition (MPT) within H9c2 cells. Meanwhile, apoptosis caused by H/R injury was alleviated and three classic apoptotic signaling pathways were proved to be regulated by BG extracts. Further analysis showed that phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signaling pathway was up-regulated in H/R-induced H9c2 cells by BG extracts, leading to relieved cellular apoptosis. These results indicated that BG might exert cardioprotective effect in reperfusion injury when applied in myocardial tissue regeneration and repair.

Fabrication and characterization of a thick, viable bi-layered stem cell-derived surrogate for future myocardial tissue regeneration

Cardiac tissue surrogates show promise for restoring mechanical and electrical function in infarcted left ventricular (LV) myocardium. For these cardiac surrogates to be useful in vivo, they are required to support synchronous and forceful contraction over the infarcted region. These design requirements necessitate a thickness sufficient to produce a useful contractile force, an area large enough to cover an infarcted region, and prevascularization to overcome diffusion limitations. Attempts to meet these requirements have been hampered by diffusion limits of oxygen and nutrients (100–200 µm) leading to necrotic regions. This study demonstrates a novel layer-by-layer (LbL) fabrication method used to produce tissue surrogates that meet these requirements and mimic normal myocardium in form and function. Thick (1.5–2 mm) LbL cardiac tissues created from human induced pluripotent stem cell-derived cardiomyocytes and endothelial cells were assessed, in vitro, over a 4-week period for viability (<5.6 ± 1.4% nectrotic cells), cell morphology, viscoelastic properties and functionality. Viscoelastic properties of the cardiac surrogates were determined via stress relaxation response modeling and compared to native murine LV tissue. Viscoelastic characterization showed that the generalized Maxwell model of order 4 described the samples well (0.7 < R 2 < 0.98). Functional performance assessment showed enhanced t-tubule network development, gap junction communication as well as conduction velocity (16.9 ± 2.3 cm s−1). These results demonstrate that LbL fabrication can be utilized successfully in creating complex, functional cardiac surrogates for potential therapeutic applications.

Conductive carbon nanofibers incorporated into collagen bio-scaffold assists myocardial injury repair

Currently, treatment of myocardial infarction considered as unmet clinical need. Nanomaterials have been used in the regeneration of tissues such as bone, dental and neural tissue in the body and have increased hope for revitalizing of damaged tissues. Conductive carbon base nanomaterials with its superior physicochemical properties have emerged as promising materials for cardiovascular application. In this study, we applied a biosynthetic collagen scaffold containing carbon nanofiber for regenerating of damaged heart tissue.The collagen-carbon nanofiber scaffold was fabricated and fully characterised. The scaffold was grafted on the affected area of myocardial ischemia, immediately after ligation of the left anterior descending artery in the wistar rat's model. After 4 weeks, histological analyses were performed for investigation of formation of immature cardio-myocytes, epicardial cells, and angiogenesis.Compared to untreated hearts, this scaffold significantly protects heart tissue against injury. This improvement is accompanied by a reduction in fibrosis and the increased formation of a blood vessel network and immature cardio-myocytes in the infarction heart. No toxicity detected with apoptotic and TUNEL assays. In conclusion, the mechanical support of the collagen scaffold with carbon nanofiber enhanced the regeneration of myocardial tissue.

Atorvastatin lipid nanocapsules and gold nanoparticles embedded in injectable thermo-gelling hydrogel scaffold containing adipose tissue extracellular matrix for myocardial tissue regeneration.

This study aimed to prepare, optimise, and characterise the novel hybrid hydrogel scaffold containing atorvastatin lipid nanocapsules (LNCs) and gold nanoparticles (NPs) to improve cardiomyoblasts proliferation and regeneration of myocardium. A thermo-responsive aminated guaran (AGG) hydrogel was prepared to encompass extracellular matrix (ECM) fetched from human adipose tissue. Emulsion phase-inversion technique was used to obtain LNCs. Biocompatibility, tensile strength, conductivity, and proliferation of human myocardial cells of the optimised formulation were studied. The LNCs have a spherical shape, and the optimised formulation showed a mean particle size of 18.79 nm, the zeta potential of - 11.4 mV, drug loading of 99.99%, and release efficiency percent over 72 h was 18.73%. The injectable thermo-sensitive hydrogel prepared using 1 w/v% of AGG, 35 w/w% of ECM, ∼0.5 mg/ml of gold NPs and atorvastatin loaded LNCs showed the best physical characteristics. The hybrid scaffold loaded with atorvastatin and gold NPs improved the proliferation of cardiomyoblasts more than sevenfold with enhanced cell attachment to the scaffold. The tensile strength and the conductivity of the scaffold were 300 kPa and 0.14 S/m, respectively. Injectable hybrid adipose tissue prepared by ECM and AGG hydrogel loaded with atorvastatin and gold NPs showed promising physical characteristics for myocardial tissue engineering.

Regulation of Cardiomyocyte Differentiation, Angiogenesis, and Inflammation by the Delta Opioid Signaling in Human Mesenchymal Stem Cells

Lack of angiogenesis, inflammation, and low differentiation of MSCs upon transplantation to ischemic site are major drawbacks in cell therapies for myocardial tissue regeneration. To overcome these problems, this study aimed to increase the angiogenesis, anti-inflammation, and differentiation of human umbilical cord MSCs (hMSCs) into cardiomyocytes by activating the delta opioid pathway by its agonist SNC80 with the combination of zebularine, activin A and oxytocin. Human umbilical cord MSCs were seeded on gelatin-coated plates by using alpha MEM. MSCs were treated with SNC80 and the combination of zebularine, activin A and oxytocin. Media and inducers were changed every 3 days once until 21 days. Spent media collected from day 7 and day 21 was used to estimate angiogenic (VEGF) and anti- or pro-inflammatory cytokines (IL-10, IL1b, IL-6) levels by ELISA. The effect of spent media on in vitro endothelial tube formation and anti-inflammatory effect on inflammation induced with LPS on macrophages was also studied along with cytokine levels. Proteins that were isolated from day 7 and day 21 were used to study for cardiomyocyte markers (GATA4, MEF2C, connexin 43, and KCNJ2) and NOTCH1 involved in cardiomyocyte differentiation using Western blot. Activation of DOR increases the VEGF secretion levels estimated by ELISA and increases the in vitro tube formation in terms of number of loops and total length. Delta opioid receptor (DOR)-activated conditioned media secreted anti-inflammatory cytokine IL-10, which could prevent the secretion of pro-inflammatory cytokines IL-1b and IL-6 from LPS induced macrophages. DOR activated MSCs upregulated the early and late cardiomyocytes markers (GATA4, MEF2C and connexin 43, KCNJ43) via NOTCH1 signaling. Activation of DOR on hMSCs plays a vital role in angiogenesis, anti-inflammation, and cardiomyocyte differentiation by regulating the NOTCH1 signaling pathway. Our results indicate that, upon activation of delta opioid receptors on human umbilical cord derived mesenchymal stem cells, they can differentiate into heart cells (by expressing specific markers GATA4, MEF2C, Connexin43), show enhanced formation of blood vessels and anti-inflammatory activity. This approach may help to treat pateints post heart attack.