Cardiac Tissue Regeneration Research Articles

Beneficial effects of mesenchymal stem cells on adult porcine cardiomyocytes in non-contact co-culture.

Mesenchymal stem cells (MSCs) have been reported to improve survival of cardiomyocytes (CMCs) and overall regeneration of cardiac tissue. Despite promising preclinical results, interactions of MSCs and CMCs, both direct and indirect, remain unclear. In this study, porcine bone marrow MSCs and freshly isolated porcine primary adult CMCs were used for non-contact co-culture experiments. Morphology, viability and functional parameters of CMCs were measured over time and compared between CMCs cultured alone and CMCs co-cultured with MSCs. In non-contact co-culture, MSCs improved survival of CMCs. CMCs co-cultured with MSCs maintained CMCs morphology and viability in significantly higher percentage than CMCs cultured alone. In viable CMCs, mitochondrial respiration was preserved in both CMCs cultured alone and in CMCs co-cultured with MSCs. Comparison of cellular contractility and calcium handling, measured in single CMCs, revealed no significant differences between viable CMCs from co-culture and CMCs cultured alone. In conclusion, non-contact co-culture of porcine MSCs and CMCs improved survival of CMCs with a sufficient preservation of functional and mitochondrial parameters.

Polyurethane-Polycaprolactone Blend Patches: Scaffold Characterization and Cardiomyoblast Adhesion, Proliferation, and Function.

A remarkable challenge in myocardial tissue engineering is the development of biomimetic constructs that can potentially improve myocardial repair and regeneration. Polyurethane (PU) scaffolds are extensively utilized in the cardiovascular system. We have synthesized a new biodegradable poly(ester-ether urethane urea) (PEEUU) using a new and simple method. To enhance mechanical and physicochemical properties, the PEEUU was blended with polycaprolactone (PCL). We then fabricated a series of new PU-PCL scaffolds. The scaffolds were then characterized using SEM, porosity measurement, attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), DSC, water contact angle measurement, swelling measurement, in vitro degradation rate, and mechanical tests. Expression of the cardiac-specific proteins on the scaffolds was investigated using immunofluorescence staining and quantitative real-time PCR. The elasticity of blends increased with an increase of PEEUU. In the blend scaffolds, the size and interconnectivity of pores were in an appropriate range (142-170 μm) as reported in the literature. These blend scaffolds revealed high cell metabolic activity for cardiomyoblasts and also enabled cells to proliferate and express cardiac marker proteins at higher rates. Histological examination of subcutaneously transplanted scaffolds after two months revealed degradation in the blend scaffolds. It is demonstrated that functionality of cells is sensitive to the composition of biomaterials used, and the effective cell-biomaterial interactions are critical in order to create a functional tissue engineered product that allows seeded cells to develop their normal activity. The PEEUU-PCL blends could potentially provide a versatile platform to fabricate functional scaffolds with an effective cell-biomaterial interaction for cardiac tissue regeneration.

Effects of cardiosphere-derived cell transplantation on cardiac mitochondrial oxygen consumption after myocardial infarction in rats.

It is postulated that impaired mitochondrial energy-producing ability may lead to the development of chronic heart failure following an acute myocardial infarction. In this study, the effects of transplantation of cardiosphere-derived cells (CDCs) into the viable cardiac tissue after a myocardial infarction on the cardiac mitochondrial oxygen consumption rate (OCR) were examined. CDCs isolated from adult rat cardiac tissue fragments were cultured. Myocardial infarction was induced by ligation of the left ventricular coronary artery in rats. Immediately after coronary artery ligation (CAL), approximately 1 million CDCs were injected into the viable myocardium around the infarct area. Eight weeks after CAL, animals without transplantation showed signs of heart failure such as impaired cardiac pump function. Furthermore, the mitochondrial OCR of the viable cardiac tissue in rats with heart failure was reduced. In contrast, the cardiac pump function and mitochondrial OCR were preserved without a reduction in the infarct size in the animals with transplantation of CDCs. These results suggest that the transplantation of CDCs into the infarcted rat heart contributes to a preservation of mitochondrial function, leading to an improvement of cardiac contractile function without regeneration of cardiac tissues.

Cardiomyogenic differentiation of human bone marrow-derived mesenchymal stem cell spheroids within electrospun collagen nanofiber mats.

Collagen is the major structural protein in myocardium and contributes to tissue strength and integrity, cellular orientation, and cell-cell and cell-matrix interactions. Significant post-myocardial infarction related loss of cardiomyocytes and cardiac tissue, and their subsequent replacement with fibrous scar tissue, negatively impacts endogenous tissue repair and regeneration capabilities. To overcome such limitations, tissue engineers are working toward developing a 3D cardiac patch which not only mimics the structural, functional, and biological hierarchy of the native cardiac tissue, but also could deliver autologous stem cells and encourage their homing and differentiation. In this study, we examined the utility of electrospun, randomly-oriented, type-I collagen nanofiber (dia = 789 ± 162 nm) mats on the cardiomyogenic differentiation of human bone marrow-derived mesenchymal stem cells (BM-MSC) spheroids, in the presence or absence of 10 μM 5-azacytidine (aza). Results showed that these scaffolds are biocompatible and enable time-dependent evolution of early (GATA binding protein 4: GATA4), late (cardiac troponin I: cTnI), and mature (myosin heavy chain: MHC) cardiomyogenic markers, with a simultaneous reduction in CD90 (stemness) expression, independent of aza-treatment. Aza-exposure improved connexin-4 expression and sustained sarcomeric α-actin expression, but provided only transient improvement in cardiac troponin T (cTnT) expression. Cell orientation and alignment significantly improved in these nanofiber scaffolds over time and with aza-exposure. Although further quantitative in vitro and in vivo studies are needed to establish the clinical applicability of such stem-cell laden collagen nanofiber mats as cardiac patches for cardiac tissue regeneration, our results underscore the benefits of 3D milieu provided by electrospun collagen nanofiber mats, aza, and spheroids on the survival, cardiac differentiation and maturation of human BM-MSCs. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 3303-3312, 2018.

Meta-Analysis of Cell Therapy Studies in Heart Failure and Acute Myocardial Infarction.

Heart failure (HF) is one of the leading causes of death worldwide and has reached epidemic proportions in most industrialized nations. Despite major improvements in the treatment and management of the disease, the prognosis for patients with HF remains poor with approximately only half of patients surviving for 5 years or longer after diagnosis. The poor prognosis of HF patients is in part because of irreparable damage to cardiac tissue and concomitant maladaptive changes associated with the disease. Cell-based therapies may have the potential to transform the treatment and prognosis of HF through regeneration or repair of damaged cardiac tissue. Accordingly, numerous phase I and II randomized clinical trials have tested the clinical benefits of cell transplant, mostly autologous bone marrow-derived mononuclear cells, in patients with HF, ischemic heart disease, and acute myocardial infarction. Although many of these trials were relatively small, meta-analyses of cell-based therapies have attempted to apply rigorous statistical methodology to assess the potential clinical benefits of the intervention. As a prelude to larger phase III trials, meta-analyses, therefore, remain the obvious means of evaluating the available clinical evidence. Here, we review the different meta-analyses of randomized clinical trials that evaluate the safety and potential beneficial effect of cell therapies in HF and acute myocardial infarction spanning nearly 2 decades since the first pioneering trials were conducted.

Cardiomyocyte Proliferation for Therapeutic Regeneration.

Current pharmacologic treatments for cardiovascular disease do not correct the underlying cellular defect, the loss of cardiomyocytes. With recent advancements in cardiac regenerative approaches, the induction of endogenous mature cardiomyocyte proliferation has emerged as a new possibility. Here, we review progress made toward the regeneration of cardiac tissue in the mammalian heart through the stimulation of mature cardiomyocyte renewal. The targeting of several developmental and signaling pathways has been shown to stimulate cell cycle re-entry in mature cardiomyocytes. In animal models of cardiac regeneration, various strategies have been used to target these pathways to stimulate cardiomyocyte renewal and have relied on the delivery of signaling factors via systemic delivery, epicardial patches, or direct intramyocardial injection. Gene therapy techniques involving the viral delivery of transgenes by using adenoviral or adeno-associated viral vectors have been used to successfully target cardiac gene expression. The delivery of nucleic acids in the form of anti-microRNAs and microRNA mimetics has also been shown to be effective in stimulating cardiomyocyte renewal. As the field of cardiac regeneration continues to progress, an important ongoing challenge in developing clinically translatable therapies is limiting the stimulation of growth pathways in non-cardiomyocytes.

Phytochemical Incorporated Drug Delivery Scaffolds for Tissue Regeneration

Tissue-engineered scaffolds are platforms for drug delivery and potential candidates for skin, musculoskeletal, bone and cardiac tissue engineering. Though scaffolds incorporated with drugs, growth factors and cytokines are reported, research focusing on phytochemical-incorporated tissue-engineered scaffolds for tissue regeneration and repair are scarce. Phytochemicals used in traditional medicine are treasure houses which have a wide range of biochemical and functional activities that are yet to be explored and if tagged to innovative technologies can easily enable a new generation of tissue-engineered products. Moreover, well characterised and standardised phytochemicals are economic and non-toxic alternatives to synthetic growth factors and cytokines. This review brings into focus—(1) the potential phytochemical candidates for future tissue engineering applications and (2) the incorporation strategies that could be adopted for the synthesis of de novo phytochemical releasing biomaterials and tissue-engineered medical products (TEMP). Tissue-engineered scaffolds are platforms for drug delivery and have immense applications in skin, musculoskeletal, bone and cardiac tissue regeneration. Though such scaffolds incorporated with drugs and growth factors are available, research focusing on phytochemical-incorporated tissue-engineered scaffolds for stem cells and tissue regeneration are scarce. Phytochemicals in traditional medicine are treasure houses with varied biochemical and functional activities that are yet to be explored and this review highlights the gateway of the potential phytochemical candidates for future tissue engineering applications. Phytochemical incorporation strategies are also adopted for the new generation of drug releasing biomaterials and tissue-engineered medical products (TEMP). Future research aims at synthesising and developing biocompatible ceramic/polymeric scaffolds incorporated with easily available, economic and non-toxic formulation of phytochemicals which are effectively used in traditional medicine. Proof of burden studies for safety and efficacy of these scaffolds will be performed in suitable animal models to promote tissue regeneration and repair.

Strategic design of cardiac mimetic core-shell nanofibrous scaffold impregnated with Salvianolic acid B and Magnesium l-ascorbic acid 2 phosphate for myoblast differentiation

The major loss of myocardial tissue extracellular matrix after infarction is a serious complication that leads to heart failure. Regeneration and integration of damaged cardiac tissue is challenging since the functional restoration of the injured myocardium is an incredible task. The injured micro environment of myocardium fails to regenerate spontaneously. The emergence of nano-biomaterials would be a promising approach to regenerate such a damaged cardiomyocytes tissue. Here, we have fabricated a dual bioactive embedded nanofibrous cardiac patch via coaxial electrospinning technique, to mimic the topographical and chemical cues of the natural cardiac tissue. The proportion and the concentration of the polymers were optimized for tailored delivery of bioactives from a spatio-temporally designed scaffold. The functionalization of polymeric core shell nanofibrous scaffold with dual bioactives enhanced the physico-chemical and bio-mechanical properties of the scaffolds that has resulted in a 3-dimensional topography mimicking the natural cardiac like extracellular matrix. The sustained delivery of bioactive signals, improved cell adhesion, proliferation, migration and differentiation could be attributed to its highly interconnected nanofibrous matrix with good extended morphology. Further, the expression of cardiac specific markers were found to increase on investigation of mRNA by real time PCR studies and proteins by immunofluorescence and western blotting techniques, confirming cell - biomaterial interactions. Flow cytometry analysis authenticated a potent mitochondrial membrane potential of cells treated with nanocomposite. In addition, in ovo studies in chicken chorioallantoic membrane assay confirm the efficacy of the developed scaffold in inducing angiogenesis required for maintaining its viability after transplantation onto the infarcted zone. These promising results demonstrate the potential of the composite nanofibrous scaffold as an effective biomaterial substrate for cardiac regeneration providing cues for development of novel cardiac therapeutics.

3D printing for cardiovascular tissue engineering: a review

Although the current medical treatments have been successful in reducing the coronary heart disease related mortality rate, however there still exist various challenges in cardiac tissue engineering due to the hierarchical property of native myocardium and branched structure of blood vessels. The regeneration of progenitor cells, replacement infarcted cardiac tissues and the tissue-engineered constructs are the demand of the current era. In this contrast, 3D printing of scaffold for cardiac tissue engineering plays a crucial role. 3D printing techniques are used to generate patient-specific foundation that mimics the milieu of biological tissue. Various studies are under investigation to regenerate the cardiac tissues. Lack of regeneration capacity is a major hunt in cardiac tissue engineering. This review will provide an overview of 3D bioprinting techniques for cardiovascular tissue engineering. First, it summarises the background about bioprinting (working principles) followed by various bioink materials for cardiac tissue engineering. Recent approaches for the 3D printing of cardiac scaffolds for the regeneration of cardiac tissues are discussed.

Cardiac progenitor reprogramming for heart regeneration.

Myocardial infarction leads to the loss of a huge number of cardiomyocytes and the reparatory response to this phenomenon is scar tissue formation, which impairs heart function. Direct reprogramming technology offers an alternative strategy for the generation of functional cardiomyocytes not only in vitro, but also in vivo in the site of injury. Results have demonstrated cardiac tissue regeneration and improvement in heart function after myocardial infarction following local injection of vectors encoding reprogramming transcription factors or miRNAs. This shows the great potential of cardiac reprogramming technology for heart regeneration. However, in addition to cardiomyocytes, other cell types, including endothelial cells and smooth muscle cells are also required to be generated in the damaged area in order to achieve complete cardiac tissue regeneration. To this aim induced proliferative/expandable cardiovascular progenitor cells (iCPCs) appear to be an appropriate cell source, which is capable of differentiation into three cardiovascular lineages both in vitro and in vivo. In this regard, this study goes over in vitro and in vivo cardiac reprogramming technology and specifically deals with cardiac progenitor reprogramming and its potential for heart regeneration.

A Mini-Review on the Bioactive Glass-Based Composites in Soft Tissue Repair

As a third-generation biomaterial, the bioactive glass (BG) has gained the attention of various research groups who have started to employ it for enhancing tissue regeneration. Most of these applications focus on bone tissue engineering based on either BG alone or BG-based composites, where the properties of the other components can improve those of the BG. Moreover, recently, the BG has become one of the important materials with ability to improve the regeneration of soft tissues. This review highlights the up-to-date advances in the different BG-based composites which have been studied in the treatment of various soft tissue injuries. These include the neuronal, muscle, lung and cardiac tissue regeneration, as well as cornea treatment. In addition, the enhancement in tissue repair due to the composite structure is discussed with comparing to the individual component structures.

EComment. Platelet-rich plasma and cardiac tissue regeneration.

eComment. Platelet-rich plasma and cardiac tissue regeneration.

Cardiac tissue regeneration: A preliminary study on carbon-based nanotubes gelatin scaffold.

The aim of this study was set-up and test of gelatin and carbon nanotubes scaffolds. Gelatin-based (5%) genipin cross-linked (0.2%) scaffolds embedding single-walled carbon nanotubes (SWCNTs, 0.3, 0.5, 0.7, 0.9, and 1.3% w/w) were prepared and mechanically/electrically characterized. For biological evaluation, H9c2 cell line was cultured for 10 days. Cytotoxicity, cell growth and differentiation, immunohistochemistry, and real-time PCR analysis were performed. Myoblast and cardiac differentiation were obtained by serum reduction to 1% (C1% ) and stimulation with 50 nM all trans-retinoic acid (CRA ), respectively. Immunohistochemistry showed elongated myotubes in C1% while round and multinucleated cells in CRA with also a significantly increased expression of natriuretic peptides (NP) and ET-1 receptors in parallel with a decreased ET-1. On scaffolds, cell viability was similar for Gel-SWCNT0.3%/0.9% ; NP and ET systems expression decreased in both concentrations with respect to control and CX-43, mainly due to a lacking of complete differentiation in cardiac phenotype during that time. Although further analyses on novel biomaterials are necessary, these results represent a useful starting point to develop new biomaterial-based scaffolds. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2750-2762, 2018.

Heart regeneration in adult Xenopus tropicalis after apical resection

BackgroundMyocardium regeneration in adult mammals is very limited, but has enormous therapeutic potentials. However, we are far from complete understanding the cellular and molecular mechanisms by which heart tissue can regenerate. The full functional ability of amphibians to regenerate makes them powerful animal models for elucidating how damaged mature organs are naturally reconstituted in an adult organism. Like other amphibians, such as newts and axolotls, adult Xenopus displays high regenerative capacity such as retina. So far, whether the adult frog heart processes regenerative capacity after injury has not been well delineated.ResultsWe examined the regeneration of adult cardiac tissues of Xenopus tropicalis after resection of heart apex. We showed, for the first time, that the adult X. tropicalis heart can regenerate perfectly in a nearly scar-free manner approximately 30 days after injury via apical resection. We observed that the injured heart was sealed through coagulation immediately after resection, which was followed by transient fibrous tissue production. Finally, the amputated area was regenerated by cardiomyocytes. During the regeneration process, the cardiomyocytes in the border area of the myocardium adjacent to the wound exhibited high proliferation after injury, thus contribute the newly formed heart tissue.ConclusionsEstablishing a cardiac regeneration model in adult X. tropicalis provides a powerful tool for recapitulating a perfect regeneration phenomenon and elucidating the underlying molecular mechanisms of cardiac regeneration in an adult heart, and findings from this model may be applicable in mammals.

Collagen scaffold enhances the regenerative properties of mesenchymal stromal cells.

MSCs are widely applied to regenerate heart tissue in myocardial diseases but when grown in standard two-dimensional (2D) cultures exhibit limited potential for cardiac repair and develop fibrogenic features with increasing culture time. MSCs can undergo partial cardiomyogenic differentiation, which improves their cardiac repair capacity. When applied to collagen patches they may improve cardiac tissue regeneration but the mechanisms remain elusive. Here, we investigated the regenerative properties of MSCs grown in a collagen scaffold as a three-dimensional (3D) culture system, and performed functional analysis using an engineered heart tissue (EHT) model. We showed that the expression of cardiomyocyte-specific proteins by MSCs co-cultured with rat neonatal cardiomyocytes was increased in collagen patches versus conventional cultures. MSCs in 3D collagen patches were less fibrogenic, secreted more cardiotrophic factors, retained anti-apoptotic and immunomodulatory function, and responded less to TLR4 ligand lipopolysaccharide (LPS) stimulation. EHT analysis showed no effects by MSCs on cardiomyocyte function, whereas control dermal fibroblasts abrogated the beating of cardiac tissue constructs. We conclude that 3D collagen scaffold improves the cardioprotective effects of MSCs by enhancing the production of trophic factors and modifying their immune modulatory and fibrogenic phenotype. The improvement in myocardial function by MSCs after acquisition of a partial cardiac cell-like phenotype is not due to enhanced MSC contractility. A better understanding of the mechanisms of MSC-mediated tissue repair will help to further enhance the therapeutic potency of MSCs.

Enhancement of Intercellular Electrical Synchronization by Conductive Materials in Cardiac Tissue Engineering.

cardiac tissue regeneration for the treatment of cardiovascular diseases has been of great research interest. Under the hypothesis that electrical synchronization of cardiac cells can be aided by conductive materials, electrically conductive scaffolds have been frequently used to improve cardiac tissue regeneration. However, theoretical analysis is presently absent in examining the underlying mechanism and rationally guiding the design of these conductive scaffolds. here, equivalent-circuit models are proposed, in which two adjacent groups of cardiomyocytes are grown either on a bulk conductive substrate or around conductive nanostructures. When one group of cells leads with action potentials, the membrane depolarization of the following group is investigated. this study reveals that membrane depolarization of the following group is most sensitive to seal resistance to the substrate while surface roughness and conductivity of the material have less influence. In addition, it is found that a multiple-cell group is easier to be depolarized by its adjacent beating cardiomyocytes. For nanostructure-bridged cardiac cells, substantial depolarization occurs only with a seal resistance larger than 1013Ω/sqr, which is contradictory to many reported estimations. this work theoretically confirms the positive role of conductive scaffolds and nanostructures in aiding electrical synchronization of cardiac cells and reveals that its performance mainly relies on the cell-device interface. this work provides a theoretical basis for the rational design of electroactive scaffolds for enhanced cardiac tissue engineering.

Relationship between structure and physical strength of silk fibroin nanofiber sheet depending on insolubilization treatment

ABSTRACTMaterials such as expanded polytetrafluoroethylene and glutaraldehyde‐fixed bovine pericardium are currently used for cardiac tissue regeneration. However, patches made from these materials remain permanently without being absorbed by the body and must be replaced overtime because of degeneration or lack of growth. To improve the long‐term outcomes for cardiac tissue regeneration, biocompatible and biodegradable materials must be used. In this study, we used two biocompatible polymers, silk fibroin (SF), which is biodegradable and segmented polyurethane, to prepare nonwoven sheets that were then insolubilized by water vapor or methanol treatment. The tensile stress increased significantly on adding segmented polyurethane to pure SF and the water vapor processed sheets showed higher extension on strain than the methanol‐processed sheets. The different insolubilization treatments also resulted in different SF structures. Our results show that it is possible to obtain the physical properties required for cardiac tissue repair patch by varying the insolubilization treatment. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45560.

P1573The left atrial appendagea -biological band aid for cardiac tissue regeneration

P1573The left atrial appendagea -biological band aid for cardiac tissue regeneration

Hydrogels for Cardiac Tissue Repair and Regeneration

The main cause of death in the world continues to be cardiovascular disease, which affects annually over 900,000 people and in the entire word approximately 50% of the people suffering myocardial infarction (MI) die within 5 years. MI causes a number of cardiac pathologies like hypertension, blocked coronary arteries and valvular heart diseases resulting ischemic cardiac injury. In the last years, cardiac tissue engineering has made considerable progress, because this progress have been made towards developing injectable hydrogels for the purpose of cardiac repair and/or regeneration. This study aims to provide an updated survey of the major progress in the flied of injectable cardiac tissue engineering, including biomaterials (natural, synthetic or hybrid hydrogels), their advantages or disadvantages and the main seeding cell sources. Also, this review focuses on the progress made in the field of hydrogels for cardiac tissue repair and/or regeneration for MI over the last years.

Abstract 200: Nanofibrous Microsphere Mediated High Engraftment of hESC Derived Cardiomyocytes Improves Rat Heart Function After Infarction

Cell-based therapy is a promising strategy to regenerate the injured heart after myocardial infarction. However, the current strategies only show modest therapeutic benefits largely due to the low engraftment and poor regeneration of functional cardiac muscle tissue. To address these critical issues in heart regeneration, we applied poly (L-lactic acid) nanofibrous hollow microspheres (NF-HMS) as cell carriers to transplant human embryonic stem cell (hESC) derived cardiomyocytes (CMs) into infarcted rat hearts. Our studies showed that, 28 days after cell transplantation, graft size of the CM+NF-HMS group (1.85 ± 0.72 mm 2 ) was significantly higher than that of the CM only group (0.49 ± 0.34 mm 2 ) (P<0.01), resulting in a 3.78 fold increase of CM engraftment by application of NF-HMS. Consequently, the reduction of infarct size in CM+NF-HMS group was significantly greater than that of the CM only group (42.58% versus 12.07% reduction). Furthermore, the grafted cells could couple with host cells as indicated by connexin 43 connections between grafted and host cells. Functionally, the left ventricular ejection fraction and fractional shortening in CM+NF-HMS group was significantly improved compared with CM only and PBS control groups. The increased engraftment of CMs in CM+NF-HMS group also promoted a higher density of vasculature in the infarction border zone. Thus, the highly engrafted transplantation of CMs using NF-HMS as a cell carrier resulted in significant improvement of CM engraftment, revascularization, and functional performance, providing an exciting strategy for heart regeneration.