Engineered myocardial tissues constructed in vivo using cardiomyocyte-like cells derived from bone marrow mesenchymal stem cells in rats

Supporting wound healing by mesenchymal stem cells (MSCs) therapy in combination with scaffold, hydrogel, and matrix; State of the art

Non-healing wounds impose a huge annual cost on the survival of different countries and large populations in the world. Wound healing is a complex and multi-step process, the speed and quality of which can be changed by various factors. To promote wound healing, compounds such as platelet-rich plasma, growth factors, platelet lysate, scaffolds, matrix, hydrogel, and cell therapy, in particular, with mesenchymal stem cells (MSCs) are suggested. Nowadays, the use of MSCs has attracted a lot of attention. These cells can induce their effect by direct effect and secretion of exosomes. On the other hand, scaffolds, matrix, and hydrogels provide suitable conditions for wound healing and the growth, proliferation, differentiation, and secretion of cells. In addition to generating suitable conditions for wound healing, the combination of biomaterials and MSCs increases the function of these cells at the site of injury by favoring their survival, proliferation, differentiation, and paracrine activity. In addition, other compounds such as glycol, sodium alginate/collagen hydrogel, chitosan, peptide, timolol, and poly(vinyl) alcohol can be used along with these treatments to increase the effectiveness of treatments in wound healing. In this review article, we take a glimpse into the merging scaffolds, hydrogels, and matrix application with MSCs therapy to favor wound healing.

In Vivo Cartilage Regeneration with Cell-Seeded Natural Biomaterial Scaffold Implants: 15-Year Study

Articular cartilage can be easily damaged from human's daily activities, leading to inflammation and to osteoarthritis, a situation that can diminish the patients' quality of life. For larger cartilage defects, scaffolds are employed to provide cells the appropriate three-dimensional environment to proliferate and differentiate into healthy cartilage tissue. Natural biomaterials used as scaffolds, attract researchers' interest because of their relative nontoxic nature, their abundance as natural products, their easy combination with other materials, and the relative easiness to establish Marketing Authorization. The last 15 years were chosen to review, document, and elucidate the developments on cell-seeded natural biomaterials for articular cartilage treatment in vivo. The parameters of the experimental designs and their results were all documented and presented. Considerations about the newly formed cartilage and the treatment of cartilage defects were discussed, along with difficulties arising when applying natural materials, research limitations, and tissue engineering approaches for hyaline cartilage regeneration.

Cardiogenic Differentiation of Murine Bone Marrow-Derived Mesenchymal Stem Cells by 5-Azacytidine: A Follow-up In vitro Study

Background:

Cell-based therapy is a promising tool in the management of myocardial infarction.

Aim of the Work:

The aim of this study is to examine the in vitro potential differentiation of murine bone marrow (BM)-derived stem cells into cardiomyocytes using 5-azacytidine after 1, 3, and 5 weeks and follow it up after 8 weeks.

Materials and Methods:

BM-derived mesenchymal stem cells (MSCs) were extracted from the bones of adult albino rats. MSCs were induced with 10 μM 5-azacytidine for 24 h. The cells were examined after 1, 3, 5, and 8 weeks. Cell characterization with immunocytochemistry for detection of CD105, desmin, and T-troponin and transmission electron microscopy was performed.

Results:

The 5-azacytidine-induced MSCs showed light and electron microscopic histological characteristics resembling cardiomyocytes and progressively expressed the cardiac muscle-specific markers over the 1^st, 3^rd, and 5^th weeks, yet by the 8^th week, these parameters were significantly downregulated.

Conclusion:

Prolonged survival of 5-azacytidine-induced MSCs in culture beyond the 8^th week resulted in loss of the newly acquired cardiomyocyte characteristics. It is not recommended to prolong the maintenance of 5-azacytidine-induced MSCs in culture on the hope of increasing its cardiogenic potentiality beyond 5 weeks.

Cardiomyocyte dedifferentiation and remodeling in 3D scaffolds to generate the cellular diversity of engineering cardiac tissues

The use of engineered cardiac tissues (ECTs) is a new strategy for the repair and replacement of cardiac tissues in patients with myocardial infarction, particularly at late stages. However, the mechanisms underlying the development of ECTs, including cell-scaffold interactions, are not fully understood, although they are closely related to their therapeutic effect. In the present study, we aimed to determine the cellular fate of cardiomyocytes in a 3D scaffold microenvironment, as well as their role in generating the cellular diversity of ECTs by single-cell sequencing analysis. Consistent with the observed plasticity of cardiomyocytes during cardiac regeneration, cardiomyocytes in 3D scaffolds appeared to dedifferentiate, showing an initial loss of normal cytoskeleton organization in the adaptive response to the new scaffold microenvironment. Cardiomyocytes undergoing this process regained their proliferation potential and gradually developed into myocardial cells at different developmental stages, generating heterogeneous regenerative ECTs. To better characterize the remodeled ECTs, high-throughput single-cell sequencing was performed. The ECTs contained a wide diversity of cells related to endogenous classes in the heart, including myocardial cells at different developmental stages and different kinds of interstitial cells. Non-cardiac cells seemed to play important roles in cardiac reconstruction, especially Cajal-like interstitial cells and macrophages. Altogether, our results showed for the first time that cells underwent adaptive dedifferentiation for survival in a 3D scaffold microenvironment to generate heterogeneous tissues. These findings provide an important basis for an improved understanding of the development and assembly of engineered tissues.

Construction of engineered myocardial tissues in vitro with cardiomyocyte‑like cells and a polylactic‑co‑glycolic acid polymer

The aim of the present study was to explore the feasibility of the construction of engineered myocardial tissues in vitro with cardiomyocyte‑like cells derived from bone marrow mesenchymal stem cells (BMMSCs) and a polylactic‑co‑glycolic acid (PLGA) polymer. The PLGA polymer was sheared into square pieces (10x10x1 mm), sterilized by Co60 irradiation, and hydrated in Dulbecco's modified Eagle's medium for 1 h. BMMSCs were isolated from the bone marrow of Sprague‑Dawley rats and the third passage cells were induced by 5‑azacytidine (5‑aza). Following successful induction, the cells were trypsinized and suspended at a density of 1x109/ml. Then, the cell suspension was added to the PLGA scaffold and cultured for 14 days. The morphological changes of BMMSCs were observed using phase contrast microscopy. Immunofluorescence staining was used to identify the cardiomyocyte‑like cells. Hematoxylin and eosin (H&E) and immunohistochemical staining were used to observe the morphology of the engineered myocardial tissues. The cell adhesion rates and scanning electron microscopy were used to observe the compatibility of the cardiomyocyte‑like cells and PLGA. Transmission electron microscopy was used to view the ultrastructure of the engineered myocardial tissues. BMMSCs in primary culture presented round or short spindle cell morphologies. Following induction by 5‑aza, the cells exhibited a long spindle shape and a parallel arrangement. Analysis of the cell adhesion rates demonstrated that the majority of the cardiomyocyte‑like cells had adhered to the PLGA scaffolds at 24 h. H&E staining suggested that the cardiomyocyte‑like cells with spindle nuclei were evenly distributed in the PLGA scaffold. Immunofluorescence staining revealed that the cardiomyocyte‑like cells were positive for cardiac troponin I. Scanning electron microscopy demonstrated that the inoculated cells were well attached to the PLGA scaffold. Transmission electron microscopy indicated that the engineered myocardial tissues contained well‑arranged myofilaments, desmosomes, gap junction and Z line‑like structures. The present study successfully constructed engineered myocardial tissues in vitro with a PLGA polymer and cardiomyocyte‑like cells derived from BMMSCs, which are likely to share various structural similarities with the original heart tissue.

Triiodo-L-Thyronine Promotes the Maturation of Cardiomyocytes Derived From Rat Bone Marrow Mesenchymal Stem Cells

Bone marrow mesenchymal stem cells (BMMSCs) can differentiate into cardiomyocytes and be used in cardiac tissue engineering for heart regeneration. However, the effective clinical application of cardiomyocytes derived from BMMSCs is limited because of their immature phenotype. The aim of this study was to investigate the potential of triiodo-L-thyronine (T3) to drive cardiomyocytes derived from BMMSCs to a more mature state. BMMSCs were divided into 3 groups: untreated controls, differentiated, and T3 treated. The differentiation potential was evaluated by immunofluorescence microscopy and flow cytometry. Data were represented as the numbers of cells positive for the troponin I (cTnI), α-actinin, GATA4, and the connexin-43 (Cx-43). The mRNA levels of these specific markers of cardiomyocytes were determined by quantitative real-time polymerase chain reaction. The levels of cardiomyocytes markers protein and octamer-binding transcription factor 4 (Oct-4) were determined by Western blot analyses. Our data demonstrate that T3 treatment leads to a significant increase in cells positive for cTnI, GATA4, Cx-43, and α-actinin. The mRNA and protein expression levels of these specific markers of cardiomyocytes were also increased after T3 treatment. At the same time, the protein expression level of Oct-4 was substantially downregulated in T3-treated cells. These results demonstrate that T3 treatment increases the differentiation of BMMSCs induced to cardiomyocytes and promotes their maturation.

Mesenchymal stem cells in cardiac regeneration: a detailed progress report of the last 6 years (2010-2015)

Mesenchymal stem cells have been used for cardiovascular regenerative therapy for decades. These cells have been established as one of the potential therapeutic agents, following several tests in animal models and clinical trials. In the process, various sources of mesenchymal stem cells have been identified which help in cardiac regeneration by either revitalizing the cardiac stem cells or revascularizing the arteries and veins of the heart. Although mesenchymal cell therapy has achieved considerable admiration, some challenges still remain that need to be overcome in order to establish it as a successful technique. This in-depth review is an attempt to summarize the major sources of mesenchymal stem cells involved in myocardial regeneration, the significant mechanisms involved in the process with a focus on studies (human and animal) conducted in the last 6 years and the challenges that remain to be addressed.

Fibrin, the preferred scaffold for cell transplantation after myocardial infarction? An old molecule with a new life

Fibrin is a topical haemostat, sealant and tissue glue, which consists of concentrated fibrinogen and thrombin. It has broad medical and research uses. Recently, several studies have shown that engineered patches comprising mixtures of biological or synthetic materials and progenitor cells showed therapeutic promise for regenerating damaged tissues. In that context, fibrin maintains cell adherence at the site of injury, where cells are required for tissue repair, and offers a nurturing environment that protects implanted cells without interfering with their expected benefit. Here we review the past, present and future uses of fibrin, with a focus on its use as a scaffold material for cardiac repair. Fibrin patches filled with regenerative cells can be placed over the scarring myocardium; this methodology avoids many of the drawbacks of conventional cell-infusion systems. Advantages of using fibrin also include extraction from the patient's blood, an easy readjustment and implantation procedure, increase in viability and early proliferation of delivered cells, and benefits even with the patch alone. In line with this, we discuss the numerous preclinical studies that have used fibrin-cell patches, the practical issues inherent in their generation, and the necessary process of scaling-up from animal models to patients. In the light of the data presented, fibrin stands out as a valuable biomaterial for delivering cells to damaged tissue and for promoting beneficial effects. However, before the fibrin scaffold can be translated from bench to bedside, many issues must be explored further, including suboptimal survival and limited migration of the implanted cells to underlying ischaemic myocardium. Copyright © 2016 John Wiley & Sons, Ltd.

Differentiation of Bone Marrow Mesenchymal Stem Cells to Cardiomyocyte-Like Cells Is Regulated by the Combined Low Dose Treatment of Transforming Growth Factor-β1 and 5-Azacytidine

Bone marrow mesenchymal stem cells (BMMSCs) are used in cardiac tissue engineering for the regeneration of diseased hearts. We examined the differentiation of rat BMMSCs into cardiomyocyte-like cells when induced with a combined low dose treatment of transforming growth factor-β1 (TGF-β1) and 5-azacytidine (5-AZA). Results showed that cell proliferation in the combined low dose treatment group of TGF-β1 and 5-AZA was increased compared with the TGF-β1 group or the 5-AZA group. The cell apoptosis was relieved by combined TGF-β1 and 5-AZA treatment compared to 5-AZA treatment alone. The number of cells positive for myosin heavy chain, connexin-43, α-actin, and troponin I in the combined treatment group was higher than those observed in the TGF-β1 group or the 5-AZA group. Moreover, the combined low dose treatment group of TGF-β1 and 5-AZA reveals the strongest expression of troponin I, α-actin, and phosphorylated extracellular signal-regulated protein kinases 1 and 2 (p-ErK1/2) among the treatment groups. These results suggest that the combined low dose treatment of TGF-β1 and 5-AZA can improve the differentiation potential of rat BMMSCs into cardiomyocyte-like cells and alleviate cell damage effects in vitro. The mechanism that is involved in influencing differentiation may be associated with p-ErK1/2.

In Vitro Evaluation of Scaffolds for the Delivery of Mesenchymal Stem Cells to Wounds

Mesenchymal stem cells (MSCs) have been shown to improve tissue regeneration in several preclinical and clinical trials. These cells have been used in combination with three-dimensional scaffolds as a promising approach in the field of regenerative medicine. We compare the behavior of human adipose-derived MSCs (AdMSCs) on four different biomaterials that are awaiting or have already received FDA approval to determine a suitable regenerative scaffold for delivering these cells to dermal wounds and increasing healing potential. AdMSCs were isolated, characterized, and seeded onto scaffolds based on chitosan, fibrin, bovine collagen, and decellularized porcine dermis. In vitro results demonstrated that the scaffolds strongly influence key parameters, such as seeding efficiency, cellular distribution, attachment, survival, metabolic activity, and paracrine release. Chick chorioallantoic membrane assays revealed that the scaffold composition similarly influences the angiogenic potential of AdMSCs in vivo. The wound healing potential of scaffolds increases by means of a synergistic relationship between AdMSCs and biomaterial resulting in the release of proangiogenic and cytokine factors, which is currently lacking when a scaffold alone is utilized. Furthermore, the methods used herein can be utilized to test other scaffold materials to increase their wound healing potential with AdMSCs.

Scaffolds and tissue regeneration: An overview of the functional properties of selected organic tissues

Tissue engineering plays a significant role both in the re-establishment of functions and regeneration of organic tissues. Success in manufacturing projects for biological scaffolds, for the purpose of tissue regeneration, is conditioned by the selection of parameters such as the biomaterial, the device architecture, and the specificities of the cells making up the organic tissue to create, in vivo, a microenvironment that preserves and further enhances the proliferation of a specific cell phenotype. To support this approach, we have screened scientific publications that show biomedical applications of scaffolds, biomechanical, morphological, biochemical, and hemodynamic characteristics of the target organic tissues, and the possible interactions between different cell matrices and biological scaffolds. This review article provides an overview on the biomedical application of scaffolds and on the characteristics of the (bio)materials commonly used for manufacturing these biological devices used in tissue engineering, taking into consideration the cellular specificity of the target tissue. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 1483-1494, 2016.

Postinfarction Functional Recovery Driven by a Three-Dimensional Engineered Fibrin Patch Composed of Human Umbilical Cord Blood-Derived Mesenchymal Stem Cells

Considerable research has been dedicated to restoring myocardial cell slippage and limiting ventricular remodeling after myocardial infarction (MI). We examined the ability of a three-dimensional (3D) engineered fibrin patch filled with human umbilical cord blood-derived mesenchymal stem cells (UCBMSCs) to induce recovery of cardiac function after MI. The UCBMSCs were modified to coexpress luciferase and fluorescent protein reporters, mixed with fibrin, and applied as an adhesive, viable construct (fibrin-cell patch) over the infarcted myocardium in mice (MI-UCBMSC group). The patch adhered well to the heart. Noninvasive bioluminescence imaging demonstrated early proliferation and differentiation of UCBMSCs within the construct in the postinfarct mice in the MI-UCBMSC group. The implanted cells also participated in the formation of new, functional microvasculature that connected the fibrin-cell patch to both the subjacent myocardial tissue and the host circulatory system. As revealed by echocardiography, the left ventricular ejection fraction and fractional shortening at sacrifice were improved in MI-UCBMSC mice and were markedly reduced in mice treated with fibrin alone and untreated postinfarction controls. In conclusion, a 3D engineered fibrin patch composed of UCBMSCs attenuated infarct-derived cardiac dysfunction when transplanted locally over a myocardial wound.

Hyaluronan and cardiac regeneration

Hyaluronan (HA) is abundantly expressed in several human tissues and a variety of roles for HA has been highlighted. Particularly relevant for tissue repair, HA is actively produced during tissue injury, as widely evidenced in wound healing investigations. In the heart HA is involved in physiological functions, such as cardiac development during embryogenesis, and in pathological conditions including atherosclerosis and myocardial infarction. Moreover, owing to its relevant biological properties, HA has been widely used as a biomaterial for heart regeneration after a myocardial infarction. Indeed, HA and its derivatives are biodegradable and biocompatible, promote faster healing of injured tissues, and support cells in relevant processes including survival, proliferation, and differentiation. Injectable HA-based therapies for cardiovascular disease are gaining growing attention because of the benefits obtained in preclinical models of myocardial infarction. HA-based hydrogels, especially as a vehicle for stem cells, have been demonstrated to improve the process of cardiac repair by stimulating angiogenesis, reducing inflammation, and supporting local and grafted cells in their reparative functions. Solid-state HA-based scaffolds have been also investigated to produce constructs hosting mesenchymal stem cells or endothelial progenitor cells to be transplanted onto the infarcted surface of the heart. Finally, applying an ex-vivo mechanical stretching, stem cells grown in HA-based 3D scaffolds can further increase extracellular matrix production and proneness to differentiate into muscle phenotypes, thus suggesting a potential strategy to create a suitable engineered myocardial tissue for cardiac regeneration.

Acetylcholine secretion by motor neuron-like cells from umbilical cord mesenchymal stem cells

Umbilical cord mesenchymal stem cells were isolated by a double enzyme digestion method. The third passage of umbilical cord mesenchymal stem cells was induced with heparin and/or basic fibroblast growth factor. Results confirmed that cell morphology did not change after induction with basic fibroblast growth factor alone. However, neuronal morphology was visible, and microtubule-associated protein-2 expression and acetylcholine levels increased following induction with heparin alone or heparin combined with basic fibroblast growth factor. Hb9 and choline acetyltransferase expression was high following inductive with heparin combined with basic fibroblast growth factor. Results indicate that the inductive effect of basic fibroblast growth factor alone was not obvious. Heparin combined with basic fibroblast growth factor noticeably promoted the differentiation of umbilical cord mesenchymal stem cells into motor neuron-like cells. Simultaneously, umbilical cord mesenchymal stem cells could secrete acetylcholine.

Nanopatterned muscle cell patches for enhanced myogenesis and dystrophin expression in a mouse model of muscular dystrophy

Skeletal muscle is a highly organized tissue in which the extracellular matrix (ECM) is composed of highly-aligned cables of collagen with nanoscale feature sizes, and provides structural and functional support to muscle fibers. As such, the transplantation of disorganized tissues or the direct injection of cells into muscles for regenerative therapy often results in suboptimal functional improvement due to a failure to integrate with native tissue properly. Here, we present a simple method in which biodegradable, biomimetic substrates with precisely controlled nanotopography were fabricated using solvent-assisted capillary force lithography (CFL) and were able to induce the proper development and differentiation of primary mononucleated cells to form mature muscle patches. Cells cultured on these nanopatterned substrates were highly-aligned and elongated, and formed more mature myotubes as evidenced by up-regulated expression of the myogenic regulatory factors Myf5, MyoD and myogenin (MyoG). When transplanted into mdx mice models for Duchenne muscular dystrophy (DMD), the proposed muscle patches led to the formation of a significantly greater number of dystrophin-positive muscle fibers, indicating that dystrophin replacement and myogenesis is achievable in vivo with this approach. These results demonstrate the feasibility of utilizing biomimetic substrates not only as platforms for studying the influences of the ECM on skeletal muscle function and maturation, but also to create transplantable muscle cell patches for the treatment of chronic and acute muscle diseases or injuries.

A combined synthetic-fibrin scaffold supports growth and cardiomyogenic commitment of human placental derived stem cells

AIMS

A potential therapy for myocardial infarction is to deliver isolated stem cells to the infarcted site. A key issue with this therapy is to have at one's disposal a suitable cell delivery system which, besides being able to support cell proliferation and differentiation, may also provide handling and elastic properties which do not affect cardiac contractile function. In this study an elastic scaffold, obtained combining a poly(ether)urethane-polydimethylsiloxane (PEtU-PDMS) semi-interpenetrating polymeric network (s-IPN) with fibrin, was used as a substrate for in vitro studies of human amniotic mesenchymal stromal cells (hAMSC) growth and differentiation.

METHODOLOGY/PRINCIPAL FINDINGS

After hAMSC seeding on the fibrin side of the scaffold, cell metabolic activity and proliferation were evaluated by WST-1 and bromodeoxyuridine assays. Morphological changes and mRNAs expression for cardiac differentiation markers in the hAMSCs were examined using immunofluorescence and RT-PCR analysis. The beginning of cardiomyogenic commitment of hAMSCs grown on the scaffold was induced, for the first time in this cell population, by a nitric oxide (NO) treatment. Following NO treatment hAMSCs show morphological changes, an increase of the messenger cardiac differentiation markers [troponin I (TnI) and NK2 transcription factor related locus 5 (Nkx2.5)] and a modulation of the endothelial markers [vascular endothelial growth factor (VEGF) and kinase insert domain receptor (KDR)].

CONCLUSIONS/SIGNIFICANCE

The results of this study suggest that the s-IPN PEtU-PDMS/fibrin combined scaffold allows a better proliferation and metabolic activity of hAMSCs cultured up to 14 days, compared to the ones grown on plastic dishes. In addition, the combined scaffold sustains the beginning of hAMSCs differentiation process towards a cardiomyogenic lineage.