Ischemic cardiac tissue conditioned media induced differentiation of human mesenchymal stem cells into early stage cardiomyocytes

Histone Deacetylase Inhibitor Suberoylanilide Hydroxamic Acid Improves Energetic Status and Cardiomyogenic Differentiation of Human Dilated Myocardium-Derived Primary Mesenchymal Cells

Background. In this study the effect of histone deacetylase (HDAC) inhibitor suberoylanilide hydroxamic acid (SAHA) on the energetic status and cardiomyogenic differentiation of human healthy and dilated myocardium-derived mesenchymal stromal cells (hmMSC) have been investigated. Methods. The hmMSC were isolated from the healthy and dilated post-operation heart biopsies by explant outgrowth method. Cell proliferation, HDAC activity, mitochondrial membrane potential, and level of adenosine triphosphate (ATP) were evaluated. The effect of SAHA on mitochondrial parameters has been investigated also by Seahorse XF analyzer and cardiomyogenic differentiation was confirmed by the expression of transcription factor NK2 Homeobox 5 (Nkx2.5), cardiac troponin T and alpha cardiac actin at gene and protein levels. Results. Dilated myocardium-derived hmMSC had almost 1.5 folds higher HDAC activity compared to the healthy cells and significantly lower mitochondrial membrane potential and ATP level. HDAC class I and II inhibitor SAHA improved energetic status of mitochondria in dilated myocardium-isolated hmMSC and increased expression of cardiac specific proteins during 14 days of exposure of cells to SAHA. Conclusions. HDAC inhibitor SAHA can be a promising therapeutic for dilated cardiomyopathy (DCM). Dilated hmMSC exposed to SAHA improved energetic status and, subsequently, cardiomyogenic differentiation. Data suggest that human dilated myocardium-derived MSC still have cardio tissue regenerative potential, which might be stimulated by HDAC inhibitors.

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.

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.

Cardiosphere Conditioned Media Influence the Plasticity of Human Mediastinal Adipose Tissue-Derived Mesenchymal Stem Cells

Nowadays, cardiac regenerative medicine is facing many limitations because of the complexity to find the most suitable stem cell source and to understand the regenerative mechanisms involved. Mesenchymal stem cells (MSCs) have shown great regenerative potential due to their intrinsic properties and ability to restore cardiac functionality, directly by transdifferentiation and indirectly by paracrine effects. Yet, how MSCs could respond to definite cardiac-committing microenvironments, such as that created by resident cardiac progenitor cells in the form of cardiospheres (CSs), has never been addressed. Recently, a putative MSC pool has been described in the mediastinal fat (hmADMSCs), but both its biology and function remain hitherto unexplored. Accordingly, we investigated the potential of hmADMSCs to be committed toward a cardiovascular lineage after preconditioning with CS-conditioned media (CCM). Results indicated that CCM affects cell proliferation. Gene expression levels of multiple cardiovascular and stemness markers (MHC, KDR, Nkx2.5, Thy-1, c-kit, SMA) are significantly modulated, and the percentage of hmADMSCs preconditioned with CCM and positive for Nkx2.5, MHC, and KDR is significantly higher relative to FBS and explant-derived cell conditioned media (EDCM, the unselected stage before CS formation). Growth factor-specific and survival signaling pathways (i.e., Erk1/2, Akt, p38, mTOR, p53) present in CCM are all equally regulated. Nonetheless, earlier BAD phosphorylation (Ser112) occurs associated with the CS microenvironment (and to a lesser extent to EDCM), whereas faster phosphorylation of PRAS40 in FBS, and of Akt (Ser473) in EDCM and 5-azacytidine occurs compared to CCM. For the first time, we demonstrated that the MSC pool held in the mediastinal fat is adequately plastic to partially differentiate in vitro toward a cardiac-like lineage. Besides, we have provided novel evidence of the potent inductive niche-like microenvironment that the CS structure can reproduce in vitro. hmADMSCs can represent an interesting tool in order to exploit their possible role in cardiovascular diseases and treatment.

5-azacytidine promotes terminal differentiation of hepatic progenitor cells

5-azacytidine (5-azaC) is known to induce cardiomyocyte differentiation. However, its function in hepatocyte differentiation is unclear. The present study investigated the in vitro capability of 5-azaC to promote maturation and differentiation of mouse embryonic hepatic progenitor cells, with the aim of developing an approach for improving hepatic differentiation. Mouse embryonic hepatic progenitor cells (HP14.5 cells) were treated with 5-azaC at concentrations from 0 to 20 μmol/l, in addition to hepatocyte induction culture medium. Hepatocyte induction medium induces HP14.5 cell differentiation. 5-azaC may enhance the albumin promotor-driven Gaussia luciferase (ALB-GLuc) activity in induced HP14.5 cells. In the present study 2 μmol/l was found to be the optimum concentration with which to achieve this. The expression of hepatocyte-associated factors was not significantly different between the group treated with 5-azaC alone and the control group. The mRNA levels of ALB; cytokeratin 18 (CK18); tyrosine aminotransferase (TAT); and cytochrome p450, family 1, member A1 (CYP1A1); in addition to the protein levels of ALB, CK18 and uridine diphosphate glucuronyltransferase 1A (UGT1A) in the induced group with 5-azaC, were higher than those in the induced group without 5-azaC, although no significant differences were detected in expression of the hepatic stem cell markers, DLK and α-fetoprotein, between the two groups. Treatment with 5-azaC alone did not affect glycogen synthesis or indocyanine green (ICG) metabolic function in HP14.5 cells, although it significantly increased ICG uptake and periodic acid-Schiff-positive cell numbers amongst HP14.5 cells. Therefore, the present study demonstrated that treatment with 5-azaC alone exerted no effects on the maturation and differentiation of HP14.5 cells. However, 5-azaC exhibited a synergistic effect on the terminal differentiation of induced hepatic progenitor cells in association with a hepatic induction medium.

Potential of 5-azacytidine induction decidual stromal cells from maternal human term placenta towards cardiomyocyte-like cells in serum-free medium

Decidual stromal cells (DSCs) from maternal term placenta represent a potential source of cells for the treatment of cardiovascular and graft-versus-host diseases. However, it is not clear whether DSCs could be induced towards cardiomyocyte-like differentiation. We chose the placentas which should bred male new-baby. We isolated DSCs from placenta by tissue adherence. The morphology, immunophenotype, and multi-lineage potential were analyzed. Karyotype analysis (G-band) was performed to determine the source and karyotype stability of DSCs. DSCs were induced by 5-azacytidine. Expression of Myf5, α-cardiac actin, Cardiac troponin T (cTnT) and GAPDH was assessed by PCR, and cTnT expression was also analyzed by immunofluorescence. Karyotype analyses indicated that cells were derived from the maternal matrix. After induction with 5-azacytidine, DSCs expressed the cardiac-specific markers Myf5, myogenin and cTnT, indicating differentiation towards cardiomyocyte-like cells.

Bone marrow-derived multipotent stromal cells promote myocardial fibrosis and reverse remodeling of the left ventricle

Cell therapy is increasingly recognized as a beneficial practice in various cardiac conditions, but its fundamentals remain largely unclear. The fates of transplanted multipotent stromal cells in postinfarction cardiac microenvironments are particularly understudied. To address this issue, labeled multipotent stromal cells were infused into rat myocardium at day 30 after myocardial infarction, against the background of postinfarction cardiosclerosis. Therapeutic effects of the transplantation were assessed by an exercise tolerance test. Histological examination at 14 or 30 days after the transplantation was conducted by means of immunostaining and quantitative image analysis. An improvement in the functional status of the cardiovascular system was observed after both the autologous and the allogeneic transplantations. Location of the label-positive cells within the heart was restricted to the affected part of myocardium. The transplanted cells could give rise to fibroblasts or myofibroblasts but not to cardiac myocytes or blood vessel cells. Both types of transplantation positively influenced scarring processes, and no expansion of fibrosis to border myocardium was observed. Left ventricular wall thickening associated with reduced dilatation index was promoted by transplantation of the autologous cells. According to the results, multipotent stromal cell transplantation prevents adverse remodeling and stimulates left ventricular reverse remodeling.

Mesenchymal stem cell delivery strategies to promote cardiac regeneration following ischemic injury

Myocardial infarction (MI) is one of the leading causes of mortality worldwide and is associated with irreversible cardiomyocyte death and pathological remodeling of cardiac tissue. In the past 15 years, several animal models have been developed for pre-clinical testing to assess the potential of stem cells for functional tissue regeneration and the attenuation of left ventricular remodeling. The promising results obtained in terms of improved cardiac function, neo-angiogenesis and reduction in infarct size have motivated the initiation of clinical trials in humans. Despite the potential, the results of these studies have highlighted that the effective delivery and retention of viable cells within the heart remain significant challenges that have limited the therapeutic efficacy of cell-based therapies for treating the ischemic myocardium. In this review, we discuss key elements for designing clinically translatable cell-delivery approaches to promote myocardial regeneration. Key topics addressed include cell selection, with a focus on mesenchymal stem cells derived from the bone marrow (bMSCs) and adipose tissue (ASCs), including a discussion of their potential mechanisms of action. Natural and synthetic biomaterials that have been investigated as injectable cell delivery vehicles for cardiac applications are critically reviewed, including an analysis of the role of the biomaterials themselves in the therapeutic scheme.

Nanofiber-reinforced myocardial tissue-construct as ventricular assist device

OBJECTIVES

This study aimed to create a myocardial tissue construct by tissue engineering to repair, replace, and regenerate damaged cardiac tissue.

METHODS AND RESULTS

Human cardiac muscles harvested from a homograft heart retrieval system were decellularized followed by coating with electrospun nanofibers to make them amenable to scaffolding. These processed cardiac tissues were nourished in modified media having ischemic cardiac tissue conditioned media in 6 separate experimental variants, and cord blood mononuclear cells were injected into 4 of them. On the 17th day of culture, the nanofiber-coated scaffolds injected with mononuclear cells and/or reinforced by electrical and mechanical forces, started contracting spontaneously at varying rates, while the control remain noncontractile. Histological staining confirmed the pre-culture acellularity as well as post-culture stem cell viability, and revealed expression of troponin I and cardiac myosin. The acellular processed scaffold when implanted into sheep ischemic myocardial apex revealed transformation into sheep myocardium after 4 months of implantation.

CONCLUSION

These results provide direct evidence for the re-cellularization of decellularized cardiac tissue grafts reinforced with a polymer nanofiber coating, by human mononuclear cells injection, leading to generation of a tissue-engineered myocardial construct.

Innate immunity and cardiomyocytes in ischemic heart disease

Myocardial ischemia/reperfusion (I/R) is the most common cause of myocardial inflammation, which is primarily a manifestation of the innate immune responses. Innate immunity is activated when pattern recognition receptors (PRRs) respond to molecular patterns common to microbes and to danger signals expressed by injured or infected cells, so called pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). The expression of various PRRs in cardiomyocytes and the release of DAMPs from cardiomyocytes subjected to I/R injury, through active mechanisms as well as passive processes, enable cardiomyocytes to generate innate immune responses. Studies in isolated heart and cardiomyocytes have confirmed the inflammatory and functional effects of cardiac PRRs especially Toll-like receptors in response to I/R-derived DAMPs, such as heat shock proteins. This review addresses the active role of cardiomyocytes in mediating innate inflammatory responses to myocardial I/R. We propose that cardiomyocytes act as innate immune cells in myocardial I/R injury.

Enhanced differentiation potential of human amniotic mesenchymal stromal cells by using three-dimensional culturing

The therapeutic potential of human amniotic mesenchymal stromal cells (hAMSCs) remains limited because of their differentiation towards mesenchymal stem cells (MSCs) following adherence. The aim of this study was to develop a three-dimensional (3-D) culture system that would permit hAMSCs to differentiate into cardiomyocyte-like cells. hAMSCs were isolated from human amnions of full-term births collected after Cesarean section. Immunocytochemistry, immunofluorescence and flow cytometry analyses were undertaken to examine hAMSC marker expression for differentiation status after adherence. Membrane currents were determined by patch clamp analysis of hAMSCs grown with or without cardiac lysates. Freshly isolated hAMSCs were positive for human embryonic stem-cell-related markers but their marker profile significantly shifted towards that of MSCs following adherence. hAMSCs cultured in the 3-D culture system in the presence of cardiac lysate expressed cardiomyocyte-specific markers, in contrast to those maintained in standard adherent cultures or those in 3-D cultures without cardiac lysate. hAMSCs cultured in 3-D with cardiac lysate displayed a cardiomyocyte-like phenotype as observed by membrane currents, including a calcium-activated potassium current, a delayed rectifier potassium current and a Ca(2+)-resistant transient outward K(+) current. Thus, although adherence limits the potential of hAMSCs to differentiate into cardiomyocyte-like cells, the 3-D culture of hAMSCs represents a more effective method of their culture for use in regenerative medicine.