Cell-to-cell contact induces mesenchymal stem cell to differentiate into cardiomyocyte and smooth muscle cell

ContactBlot: Microfluidic Control and Measurement of the Cell-Cell Contact State to Assess Contact-Inhibited ERK Signaling

Extracellular signal-regulated kinase (ERK) signaling is essential to regulated cell behaviors, including cell proliferation, differentiation, and apoptosis. The influence of cell-cell contacts on ERK signaling is central to epithelial cells, yet few studies have sought to understand the same in cancer cells, particularly with single-cell resolution. To acquire same-cell measurements of both phenotypic (cell-contact state) and targeted-protein (ERK phosphorylation) profiles, we prepend high-content, whole-cell imaging prior to end-point cellular-resolution Western blot analyses for each of hundreds of individual HeLa cancer cells cultured on that same chip, which we call contactBlot. By indexing the phosphorylation level of ERK in each cell or cell cluster to the imaged cell-contact state, we compare the ERK signaling between isolated and in-contact cells. We observe attenuated (∼2×) ERK signaling in HeLa cells that are in-contact versus isolated. Attenuation is sustained when the HeLa cells are challenged with hyperosmotic stress. Our findings show the impact of cell-cell contacts on ERK activation with isolated and in-contact cells while introducing a multi-omics tool for control and scrutiny of cell-cell interactions.

Contact Blot: Microfluidic Control and Measurement of Cell-Cell Contact State to Assess Contact-Inhibited ERK Signaling

Extracellular signal-regulated kinase (ERK) signaling is essential to regulated cell behaviors, including cell proliferation, differentiation, and apoptosis. The influence of cell-cell contacts on ERK signaling is central to epithelial cells, yet few studies have sought to understand the same in cancer cells, particularly with single-cell resolution. To acquire same-cell measurements of both phenotypic (cell-contact state) and targeted-protein profile (ERK phosphorylation), we prepend high-content, whole-cell imaging prior to endpoint cellular-resolution western blot analyses for each of hundreds of individual HeLa cancer cells cultured on that same chip, which we call contact Blot. By indexing the phosphorylation level of ERK in each cell or cell-cluster to the imaged cell-contact state, we compare ERK signaling between isolated and in-contact cells. We observe attenuated (~2×) ERK signaling in HeLa cells which are in-contact versus isolated. Attenuation is sustained when the HeLa cells are challenged with hyperosmotic stress. Our findings show the impact of cell-cell contacts on ERK activation with isolated and in-contact cells, while introducing a multi omics tool for control and scrutiny of cell-cell interactions.

Direct contact with endothelial cells drives dental pulp stem cells toward smooth muscle cells differentiation via TGF-β1 secretion

AIM

Prevascularization is vital to accelerate functional blood circulation establishment in transplanted engineered tissue constructs. Mesenchymal stem cells (MSCs) or mural cells could promote the survival of implanted endothelial cells (ECs) and enhance the stabilization of newly formed blood vessels. However, the dynamic cell-cell interactions between MSCs, mural cells and ECs in the angiogenic processes remain unclear. This study aimed to explore the interactions of human umbilical vein ECs (HUVECs) and dental pulp stem cells (DPSCs) in an in vitro cell coculture model.

METHODOLOGY

Human umbilical vascular ECs and DPSCs were directly cocultured or indirectly cocultured with transwell inserts in endothelial basal media-2 (EBM-2) supplemented with 5% FBS for 6 days. Expression of SMC-specific markers in DPSCs monoculture and HUVEC+DPSC cocultures was assessed by western blot and immunofluorescence. Activin A and transforming growth factor-beta 1 (TGF-β1) in conditioned media (CM) of HUVECs monoculture (E-CM), DPSCs monoculture (D-CM) and HUVEC+DPSC cocultures (E+D-CM) were analysed by enzyme-linked immunosorbent assay. TGF-β RI kinase inhibitor VI, SB431542, was used to block TGF-β1/ALK5 signalling in DPSCs.

RESULTS

The expression of SMC-specific markers, α-SMA, SM22α and Calponin, were markedly increased in HUVEC+DPSC direct cocultures compared to that in DPSCs monoculture, while no differences were demonstrated between HUVEC+DPSC indirect cocultures and DPSCs monoculture. E+D-CM significantly upregulated the expression of SMC-specific markers in DPSCs compared to E-CM and D-CM. Activin A and TGF-β1 were considerably higher in E+D-CM than that in D-CM, with upregulated Smad2 phosphorylation in HUVEC+DPSC cocultures. Treatment with activin A did not change the expression of SMC-specific markers in DPSCs, while treatment with TGF-β1 significantly enhanced these markers' expression in DPSCs. In addition, blocking TGF-β1/ALK5 signalling inhibited the expression of α-SMA, SM22α and Calponin in DPSCs.

CONCLUSIONS

TGF-β1 was responsible for DPSC differentiation into SMCs in HUVEC+DPSC cocultures, and TGF-β1/ALK5 signalling pathway played a vital role in this process.

Volumetric Printing Across Melt Electrowritten Scaffolds Fabricates Multi-Material Living Constructs with Tunable Architecture and Mechanics

Major challenges in biofabrication revolve around capturing the complex, hierarchical composition of native tissues. However, individual 3D printing techniques have limited capacity to produce composite biomaterials with multi-scale resolution. Volumetric bioprinting recently emerged as a paradigm-shift in biofabrication. This ultrafast, light-based technique sculpts cell-laden hydrogel bioresins into 3D structures in a layerless fashion, providing enhanced design freedom over conventional bioprinting. However, it yields prints with low mechanical stability, since soft, cell-friendly hydrogels are used. Herein, the possibility to converge volumetric bioprinting with melt electrowriting, which excels at patterning microfibers, is shown for the fabrication of tubular hydrogel-based composites with enhanced mechanical behavior. Despite including non-transparent melt electrowritten scaffolds in the volumetric printing process, high-resolution bioprinted structures are successfully achieved. Tensile, burst, and bending mechanical properties of printed tubes are tuned altering the electrowritten mesh design, resulting in complex, multi-material tubular constructs with customizable, anisotropic geometries that better mimic intricate biological tubular structures. As a proof-of-concept, engineered tubular structures are obtained by building trilayered cell-laden vessels, and features (valves, branches, fenestrations) that can be rapidly printed using this hybrid approach. This multi-technology convergence offers a new toolbox for manufacturing hierarchical and mechanically tunable multi-material living structures.

Fibrotic remodeling and tissue regeneration mechanisms define the therapeutic potential of human muscular progenitors

Fibrosis is an intrinsic biological reaction toward the challenges of tissue injury that is implicated in the wound-healing process. Although it is useful to efficiently mitigate the damage, progression of fibrosis is responsible for the morbidity and mortality occurring in a variety of diseases. Because of lacking effective treatments, there is an emerging need for exploring antifibrotic strategies. Cell therapy based on stem/progenitor cells is regarded as a promising approach for treating fibrotic diseases. Appropriate selection of cellular sources is required for beneficial results. Muscle precursor cells (MPCs) are specialized progenitors harvested from skeletal muscle for conducting muscle regeneration. Whether they are also effective in regulating fibrosis has seldom been explored and merits further investigation. MPCs were successfully harvested from all human samples regardless of demographic backgrounds. The extracellular matrices remodeling was enhanced through the paracrine effects mediated by MPCs. The suppression effects on fibrosis were confirmed in vivo when MPCs were transplanted into the diseased animals with oral submucous fibrosis. The data shown here revealed the potential of MPCs to be employed to simultaneously regulate both processes of fibrosis and tissue regeneration, supporting them as the promising cell candidates for development of the cell therapy for antifibrosis and tissue regeneration.

Decellularized fish swim bladder patch loaded with mesenchymal stem cells inhibits neointimal hyperplasia

We previously showed decellularized fish swim bladder can be used as vascular patch and tube graft in rats, mesenchymal stem cells (MSCs) have showed the capability to inhibit neointimal hyperplasia in different animal models. We hypothesized that decellularized fish swim bladder patch loaded with MSCs (bioinspired patch) can inhibit neointimal hyperplasia in a rat aortic patch angioplasty model. Rat MSCs were grown in vitro and flow cytometry was used to confirm their quality. 3.6 × 10⁵ MSCs were mixed into 100 μl of sodium alginate (SA)/hyaluronic acid (HA) hydrogel, two layers of fish swim bladders (5 mm × 5 mm) were sutured together, bioinspired patch was created by injection of hydrogel with MSCs into the space between two layers of fish swim bladder patches. Decellularized rat thoracic aorta patch was used as control. Patches were harvested at days 1 and 14 after implantation. Samples were examined by histology, immunohistochemistry, and immunofluorescence. The decellularized rat thoracic aorta patch and the fish swim bladder patch had a similar healing process after implantation. The bioinspired patch had a similar structure like native aorta. Bioinspired patch showed a decreased neointimal thickness (p = .0053), fewer macrophages infiltration (p = .0090), and lower proliferation rate (p = .0291) compared to the double layers fish swim bladder patch group. Decellularized fish swim bladder patch loaded with MSCs can inhibit neointimal hyperplasia effectively. Although this is a preliminary animal study, it may have a potential application in large animals or clinical research.

Potential applications of mesenchymal stem cells and their derived exosomes in regenerative medicine

INTRODUCTION

Regenerative medicine involves the replacement of damaged cells, tissues, or organs to restore normal function. Mesenchymal stem cells (MSCs) and exosomes secreted by MSCs have unique advantages that make them a suitable candidate in the field of regenerative medicine.

AREAS COVERED

This article provides a comprehensive overview of regenerative medicine, focusing on the use of MSCs and their exosomes as potential therapies for replacing damaged cells, tissues, or organs. This article discusses the distinct advantages of both MSCs and their secreted exosomes, including their immunomodulatory effects, lack of immunogenicity, and recruitment to damaged areas. While both MSCs and exosomes have these advantages, MSCs also have the unique ability to self-renew and differentiate. This article also assesses the current challenges associated with the application of MSCs and their secreted exosomes in therapy. We have reviewed proposed solutions for improving MSC or exosome therapy, including ex-vivo preconditioning strategies, genetic modification, and encapsulation. Literature search was conducted using Google Scholar and PubMed databases.

EXPERT OPINION

Providing insight into the future development of MSC and exosome-based therapies and to encourage the scientific community to focus on the identified gaps, develop appropriate guidelines, and enhance the clinical application of these therapies.

[Regenerative medicine for the corneal epithelium : Cell therapy from bench to bedside]

In the case of thermal or caustic burns of the ocular surface, loss of limbal epithelial stem cells leads to compromised self-renewal of the corneal epithelium. This results in permanent loss of vision. In these situations, transplantation of cultured limbal epithelial cells on an amniotic membrane or fibrin gel as substrate (Holoclar®) can help to regenerate the corneal surface. The required cells are obtained from the healthy partner eye, if available. Adult stem cells from other parts of the body potentially serve as alternative cell sources: hair follicles, oral mucosa, mesenchymal stromal cells, or induced pluripotent stem cells (originally, e.g., skin fibroblasts). The reprogramming of such cells can be achieved with the help of transcription factors. In addition, work is being done on biosynthetic or synthetic matrices, which not only serve as substrate material for the transplantation but also support the functional properties of these cells (self-renewal, corneal epithelial-typical phenotype).

Surface Functionalized Polyaniline Nanofibers:Chitosan Nanocomposite for Promoting Neuronal-like Differentiation of Primary Adipose Derived Mesenchymal Stem Cells and Urease Activity

Bioscaffolds having electrically conducting polymers (CPs) have become increasingly relevant in tissue engineering (TE) because of their ability to regulate conductivity and promote biological function. With this in mind, the current study shows a conducting polyaniline nanofibers (PNFs) dispersed chitosan (Ch) nanocomposites scaffold with a simple one-step surface functionalization approach using glutaraldehyde for potential neural regeneration applications. According to the findings, 4 wt % PNFs dispersion in Ch matrix is an optimal concentration for achieving desirable biological functions while maintaining required physicochemical properties as evidenced by SEM, XRD, current-voltage (I-V) measurement, mechanical strength test, and in vitro biodegradability test. Surface chemical compositional analysis using XPS and ATR FT-IR confirms the incorporation of aldehyde functionality after functionalization, which is corroborated by surface energy calculations following the Van Oss-Chaudhury-Good method. Surface functionalization induced enhancement in surface hydrophilicity in terms of the polar component of surface energy (γ_i^AB) from 6.35 to 12.54 mN m^-1 along with an increase in surface polarity from 13.61 to 22.54%. Functionalized PNF:Ch scaffolds demonstrated improvement in enzyme activity from 67 to 94% and better enzyme kinetics with a reduction of Michaelis constants (K_m) from 21.55 to 13.81 mM, indicating favorable protein-biomaterial interactions and establishing them as biologically perceptible materials. Surface functionalization mediated improved cell-biomaterial interactions led to improved viability, adhesion, and spreading of primary adipose derived mesenchymal stem cells (ADMSCs) as well as improved immunocompatibility. Cytoskeletal architecture assessment under differentiating media containing 10 ng/mL of each basic fibroblast growth factor (bFGF) and epidermal growth factor (EGF) revealed significant actin remodeling with neurite-like projections on the functionalized scaffolds after 14 days. Immunocytochemistry results showed that more than 85% of cells expressed early neuron specific β III tubulin protein on the functionalized scaffolds, whereas glial fibrillary acidic protein (GFAP) expression was limited to approximately 40% of cells. The findings point to the functionalized nanocomposites' potential as a smart scaffold for electrically stimulated neural regeneration, as they are flexible enough to be designed into microchanneled or conduit-like structures that mimic the microstructures and mechanical properties of peripheral nerves.

Tunneling nanotubes: Reshaping connectivity

Tunneling nanotubes (TNTs), open membranous channels between connected cells, represent a novel direct way of communication between distant cells for the diffusion of various cellular material, including survival or death signals, genetic material, organelles, and pathogens. Their discovery prompted us to review our understanding of many physiological and pathological processes involving cellular communication but also allowed us to discover new mechanisms of communication at a distance. While this has enriched the field, it has also generated some confusion, as different TNT-like protrusions have been described, and it is not clear whether they have the same structure-function. Most studies have been based on low-resolution imaging methods, and one of the major problems is the inconsistency in demonstrating the capacity of these various connections to transfer material between cells belonging to different populations. This brief review examines the fundamental properties of TNTs. In adult tissues, TNTs are stimulated by different diseases, stresses, and inflammatory signals. 'Moreover', based on the similarity of the processes of development of synaptic spines and TNT formation, we argue that TNTs in the brain predate synaptic transmission, being instrumental in the orchestration of the immature neuronal circuit.

Biomimetic Culture Strategies for the Clinical Expansion of Mesenchymal Stromal Cells

Mesenchymal stromal/stem cells (MSCs) typically require significant ex vivo expansion to achieve the high cell numbers required for research and clinical applications. However, conventional MSC culture on planar (2D) plastic surfaces has been shown to induce MSC senescence and decrease cell functionality over long-term proliferation, and usually, it has a high labor requirement, a high usage of reagents, and therefore, a high cost. In this Review, we describe current MSC-based therapeutic strategies and outline the important factors that need to be considered when developing next-generation cell expansion platforms. To retain the functional value of expanded MSCs, ex vivo culture systems should ideally recapitulate the components of the native stem cell microenvironment, which include soluble cues, resident cells, and the extracellular matrix substrate. We review the interplay between these stem cell niche components and their biological roles in governing MSC phenotype and functionality. We discuss current biomimetic strategies of incorporating biochemical and biophysical cues in MSC culture platforms to grow clinically relevant cell numbers while preserving cell potency and stemness. This Review summarizes the current state of MSC expansion technologies and the challenges that still need to be overcome for MSC clinical applications to be feasible and sustainable.

Characterization and therapeutic applications of mesenchymal stem cells for regenerative medicine

BACKGROUND

Mesenchymal stem cells (MSCs) are multipotent, genomic stable, self-renewable, and culturally expandable adult stem cells. MSCs facilitate tissue development, maintenance and repair, and produce secretory factors that support engraftment and trophic functions, marking them an attractive option in cell therapy, regenerative medicine and tissue engineering.

METHOD

In this review, we summarize the recent researches regarding the isolation and characterization of MSCs, therapeutic applications and advanced engineering techniques. We also discuss the advantages and limitations that remain to be overcome for MSCs based therapy.

RESULTS

It has been demonstrated that MSCs are able to modulate endogenous tissue and immune cells. Preclinical studies and early phase clinical trials have shown their great potential for tissue engineering of bone, cartilage, marrow stroma, muscle, fat, and other connective tissues.

CONCLUSIONS

MSC-based therapy show considerable promise to rebuild damaged or diseased tissues, which could be a promising therapeutic method for regeneration medicine.

Fine intercellular connections in development: TNTs, cytonemes, or intercellular bridges?

Intercellular communication is a fundamental property of multicellular organisms, necessary for their adequate responses to changing environment. Tunneling nanotubes (TNTs) represent a novel means of intercellular communication being a long cell-to-cell conduit. TNTs are actively formed under a broad range of stresses and are also proposed to exist under physiological conditions. Development is a physiological condition of particular interest, as it requires fine coordination. Here we discuss whether protrusions shown to exist during embryonic development of different species could be TNTs or if they represent other types of cell structure, like cytonemes or intercellular bridges, that are suggested to play an important role in development.

In vitro and in vivo effects of insulin-producing cells generated by xeno-antigen free 3D culture with RCP piece

To establish widespread cell therapy for type 1 diabetes mellitus, we aimed to develop an effective protocol for generating insulin-producing cells (IPCs) from adipose-derived stem cells (ADSCs). We established a 3D culture using a human recombinant peptide (RCP) petaloid μ-piece with xeno-antigen free reagents. Briefly, we employed our two-step protocol to differentiate ADSCs in 96-well dishes and cultured cells in xeno-antigen free reagents with 0.1 mg/mL RCP μ-piece for 7 days (step 1), followed by addition of histone deacetylase inhibitor for 14 days (step 2). Generated IPCs were strongly stained with dithizone, anti-insulin antibody at day 21, and microstructures resembling insulin secretory granules were detected by electron microscopy. Glucose stimulation index (maximum value, 4.9) and MAFA mRNA expression were significantly higher in 3D cultured cells compared with conventionally cultured cells (P < 0.01 and P < 0.05, respectively). The hyperglycaemic state of streptozotocin-induced diabetic nude mice converted to normoglycaemic state around 14 days after transplantation of 96 IPCs under kidney capsule or intra-mesentery. Histological evaluation revealed that insulin and C-peptide positive structures existed at day 120. Our established xeno-antigen free and RCP petaloid μ-piece 3D culture method for generating IPCs may be suitable for clinical application, due to the proven effectiveness in vitro and in vivo.

Generation of bioartificial hearts using decellularized scaffolds and mixed cells

BACKGROUND

Patients with end-stage heart failure must receive treatment to recover cardiac function, and the current primary therapy, heart transplantation, is plagued by the limited supply of donor hearts. Bioengineered artificial hearts generated by seeding of cells on decellularized scaffolds have been suggested as an alternative source for transplantation. This study aimed to develop a tissue-engineered heart with lower immunogenicity and functional similarity to a physiological heart that can be used for heart transplantation.

MATERIALS AND METHODS

We used sodium dodecyl sulfate (SDS) to decellularize cardiac tissue to obtain a decellularized scaffold. Mesenchymal stem cells (MSCs) were isolated from rat bone marrow and identified by flow cytometric labeling of their surface markers. At the same time, the multi-directional differentiation of MSCs was analyzed. The MSCs, endothelial cells, and cardiomyocytes were allowed to adhere to the decellularized scaffold during perfusion, and the function of tissue-engineered heart was analyzed by immunohistochemistry and electrocardiogram.

RESULTS

MSCs, isolated from rats differentiated into cardiomyocytes, were seeded along with primary rat cardiomyocytes and endothelial cells onto decellularized rat heart scaffolds. We first confirmed the pluripotency of the MSCs, performed immunostaining against cardiac markers expressed by MSC-derived cardiomyocytes, and completed surface antigen profiling of MSC-derived endothelial cells. After cell seeding and culture, we analyzed the performance of the bioartificial heart by electrocardiography but found that the bioartificial heart exhibited abnormal electrical activity. The results indicated that the tissue-engineered heart lacked some cells necessary for the conduction of electrical current, causing deficient conduction function compared to the normal heart.

CONCLUSION

Our study suggests that MSCs derived from rats may be useful in the generation of a bioartificial heart, although technical challenges remain with regard to generating a fully functional bioartificial heart.

Extracellular vesicles from regenerative human cardiac cells act as potent immune modulators by priming monocytes

BACKGROUND

Nano-sized vesicles, so called extracellular vesicles (EVs), from regenerative cardiac cells represent a promising new therapeutic approach to treat cardiovascular diseases. However, it is not yet sufficiently understood how cardiac-derived EVs facilitate their protective effects. Therefore, we investigated the immune modulating capabilities of EVs from human cardiac-derived adherent proliferating (CardAP) cells, which are a unique cell type with proven cardioprotective features.

RESULTS

Differential centrifugation was used to isolate EVs from conditioned medium of unstimulated or cytokine-stimulated (IFNγ, TNFα, IL-1β) CardAP cells. The derived EVs exhibited typical EV-enriched proteins, such as tetraspanins, and diameters mostly of exosomes (< 100 nm). The cytokine stimulation caused CardAP cells to release smaller EVs with a lower integrin ß1 surface expression, while the concentration between both CardAP-EV variants was unaffected. An exposure of either CardAP-EV variant to unstimulated human peripheral blood mononuclear cells (PBMCs) did not induce any T cell proliferation, which indicates a general low immunogenicity. In order to evaluate immune modulating properties, PBMC cultures were stimulated with either Phytohemagglutin or anti-CD3. The treatment of those PBMC cultures with either CardAP-EV variant led to a significant reduction of T cell proliferation, pro-inflammatory cytokine release (IFNγ, TNFα) and increased levels of active TGFβ. Further investigations identified CD14+ cells as major recipient cell subset of CardAP-EVs. This interaction caused a significant lower surface expression of HLA-DR, CD86, and increased expression levels of CD206 and PD-L1. Additionally, EV-primed CD14+ cells released significantly more IL-1RA. Notably, CardAP-EVs failed to modulate anti-CD3 triggered T cell proliferation and pro-inflammatory cytokine release in monocultures of purified CD3+ T cells. Subsequently, the immunosuppressive feature of CardAP-EVs was restored when anti-CD3 stimulated purified CD3+ T cells were co-cultured with EV-primed CD14+ cells. Beside attenuated T cell proliferation, those cultures also exhibited a significant increased proportion of regulatory T cells.

CONCLUSIONS

CardAP-EVs have useful characteristics that could contribute to enhanced regeneration in damaged cardiac tissue by limiting unwanted inflammatory processes. It was shown that the priming of CD14+ immune cells by CardAP-EVs towards a regulatory type is an essential step to attenuate significantly T cell proliferation and pro-inflammatory cytokine release in vitro.

The chaperone ERp29 is required for tunneling nanotube formation by stabilizing MSec

Tunneling nanotubes (TNTs) are membrane conduits that mediate long-distance intercellular cross-talk in several organisms and play vital roles during development, pathogenic transmission, and cancer metastasis. However, the molecular mechanisms of TNT formation and function remain poorly understood. The protein MSec (also known as TNFα-induced protein 2 (TNFAIP2) and B94) is essential for TNT formation in multiple cell types. Here, using affinity protein purification, mass spectrometric identification, and confocal immunofluorescence microscopy assays, we found that MSec interacts with the endoplasmic reticulum (ER) chaperone ERp29. siRNA-mediated ERp29 depletion in mammalian cells significantly reduces TNT formation, whereas its overexpression induces TNT formation, but in a strictly MSec-dependent manner. ERp29 stabilized MSec protein levels, but not its mRNA levels, and the chaperone activity of ERp29 was required for maintaining MSec protein stability. Subcellular ER fractionation and subsequent limited proteolytic treatment suggested that MSec is associated with the outer surface of the ER. The ERp29-MSec interaction appeared to require the presence of other bridging protein(s), perhaps triggered by post-translational modification of ERp29. Our study implicates MSec as a target of ERp29 and reveals an indispensable role for the ER in TNT formation, suggesting new modalities for regulating TNT numbers in cells and tissues.

Regeneration of esophagus using a scaffold-free biomimetic structure created with bio-three-dimensional printing

Various strategies have been attempted to replace esophageal defects with natural or artificial substitutes using tissue engineering. However, these methods have not yet reached clinical application because of the high risks related to their immunogenicity or insufficient biocompatibility. In this study, we developed a scaffold-free structure with a mixture of cell types using bio-three-dimensional (3D) printing technology and assessed its characteristics in vitro and in vivo after transplantation into rats. Normal human dermal fibroblasts, human esophageal smooth muscle cells, human bone marrow-derived mesenchymal stem cells, and human umbilical vein endothelial cells were purchased and used as a cell source. After the preparation of multicellular spheroids, esophageal-like tube structures were prepared by bio-3D printing. The structures were matured in a bioreactor and transplanted into 10-12-week-old F344 male rats as esophageal grafts under general anesthesia. Mechanical and histochemical assessment of the structures were performed. Among 4 types of structures evaluated, those with the larger proportion of mesenchymal stem cells tended to show greater strength and expansion on mechanical testing and highly expressed α-smooth muscle actin and vascular endothelial growth factor on immunohistochemistry. Therefore, the structure with the larger proportion of mesenchymal stem cells was selected for transplantation. The scaffold-free structures had sufficient strength for transplantation between the esophagus and stomach using silicon stents. The structures were maintained in vivo for 30 days after transplantation. Smooth muscle cells were maintained, and flat epithelium extended and covered the inner surface of the lumen. Food had also passed through the structure. These results suggested that the esophagus-like scaffold-free tubular structures created using bio-3D printing could hold promise as a substitute for the repair of esophageal defects.

Cardiotrophic Growth Factor-Driven Induction of Human Muse Cells Into Cardiomyocyte-Like Phenotype

Multilineage-differentiating stress-enduring (Muse) cells are endogenous nontumorigenic stem cells collectable as stage-specific embryonic antigen 3 (SSEA-3) + from various organs including the bone marrow and are pluripotent-like. The potential of human bone marrow-derived Muse cells to commit to cardiac lineage cells was evaluated. We found that (1) initial treatment of Muse cells with 5'-azacytidine in suspension culture successfully accelerated demethylation of cardiac marker Nkx2.5 promoter; (2) then transferring the cells onto adherent culture and treatment with early cardiac differentiation factors including wingless-int (Wnt)-3a, bone morphogenetic proteins (BMP)-2/4, and transforming growth factor (TGF) β1; and (3) further treatment with late cardiac differentiation cytokines including cardiotrophin-1 converted Muse cells into cardiomyocyte-like cells that expressed α-actinin and troponin-I with a striation-like pattern. MLC2a expression in the final step suggested differentiation of the cells into an atrial subtype. MLC2v, a marker for a mature ventricular subtype, was expressed when cells were treated with Dickkopf-related protein 1 (DKK-1) and Noggin, inhibitors of Wnt3a and BMP-4, respectively, between steps (2) and (3). None of the steps included exogenous gene transfection, making induced cells feasible for future clinical application.

Mesenchymal stem cells as the near future of cardiology medicine - truth or wish?

Cardiac damage is one of major cause of worldwide morbidity and mortality. Despite the development in pharmacotherapy, cardiosurgery and interventional cardiology, many patients remain at increased risk of developing adverse cardiac remodeling. An alternative treatment approach is the application of stem cells. Mesenchymal stem cells are among the most promising cell types usable for cardiac regeneration. Their homing to the damaged area, differentiation into cardiomyocytes, paracrine and/or immunomodulatory effect on cardiac tissue was investigated extensively. Despite promising preclinical reports, clinical trials on human patients are not convincing. Meta-analyses of these trials open many questions and show that routine clinical application of mesenchymal stem cells as a cardiac treatment may be not as helpful as expected. This review summarizes contemporary knowledge about mesenchymal stem cells role in cardiac tissue repair and discusses the problems and perspectives of this experimental therapeutical approach.

Tissue Engineering at the Blood-Contacting Surface: A Review of Challenges and Strategies in Vascular Graft Development

Tissue engineered vascular grafts (TEVGs) are beginning to achieve clinical success and hold promise as a source of grafting material when donor grafts are unsuitable or unavailable. Significant technological advances have generated small-diameter TEVGs that are mechanically stable and promote functional remodeling by regenerating host cells. However, developing a biocompatible blood-contacting surface remains a major challenge. The TEVG luminal surface must avoid negative inflammatory responses and thrombogenesis immediately upon implantation and promote endothelialization. The surface has therefore become a primary focus for research and development efforts. The current state of TEVGs is herein reviewed with an emphasis on the blood-contacting surface. General vascular physiology and developmental challenges and strategies are briefly described, followed by an overview of the materials currently employed in TEVGs. The use of biodegradable materials and stem cells requires careful control of graft composition, degradation behavior, and cell recruitment ability to ensure that a physiologically relevant vessel structure is ultimately achieved. The establishment of a stable monolayer of endothelial cells and the quiescence of smooth muscle cells are critical to the maintenance of patency. Several strategies to modify blood-contacting surfaces to resist thrombosis and control cellular recruitment are reviewed, including coatings of biomimetic peptides and heparin.

Reduction of marginal mass required for successful islet transplantation in a diabetic rat model using adipose tissue-derived mesenchymal stromal cells

BACKGROUND AIMS

Adipose tissue-derived mesenchymal stromal cells (AT-MSCs), widely known as multipotent progenitors, release several cytokines that support cell survival and repair. There are in vitro and in vivo studies reporting the regenerative role of AT-MSCs possibly mediated by their protective effects on functional islet cells as well as their capacity to differentiate into insulin-producing cells (IPCs).

METHODS

On such a basis, our goal in the present study was to use three different models including direct and indirect co-cultures and islet-derived conditioned medium (CM) to differentiate AT-MSCs into IPCs and to illuminate the molecular mechanisms of the beneficial impact of AT-MSCs on pancreatic islet functionality. Furthermore, we combined in vitro co-culture of islets and AT-MSCs with in vivo assessment of islet graft function to assess whether co-transplantation of islets with AT-MSCs can reduce marginal mass required for successful islet transplantation and prolong graft function in a diabetic rat model.

RESULTS

Our findings demonstrated that AT-MSCs are suitable for creating a microenvironment favorable for the repair and longevity of the pancreas β cells through the improvement of islet survival and maintenance of cell morphology and insulin secretion due to their potent properties in differentiation. Most importantly, hybrid transplantation of islets with AT-MSCs significantly promoted survival, engraftment and insulin-producing function of the graft and reduced the islet mass required for reversal of diabetes.

CONCLUSIONS

This strategy might be of therapeutic potential solving the problem of donor islet material loss that currently limits the application of allogeneic islet transplantation as a more widespread therapy for type 1 diabetes.

A Contact-Based Method for Differentiation of Human Mesenchymal Stem Cells into an Endothelial Cell-Phenotype

Adult stem cells such as mesenchymal stem cells (MSC) are known to possess the ability to augment neovascularization processes and are thus widely popular as an autologous source of progenitor cells. However there is a huge gap in our current knowledge of mechanisms involved in differentiating MSC into endothelial cells (EC), essential for lining engineered blood vessels. To fill up this gap, we attempted to differentiate human MSC into EC, by culturing the former onto chemically fixed layers of EC or its ECM, respectively. We expected direct contact of MSC when cultured atop fixed EC or its ECM, would coax the former to differentiate into EC. Results showed that human MSC cultured atop chemically fixed EC or its ECM using EC-medium showed enhanced expression of CD31, a marker for EC, compared to other cases. Further in all human MSC cultured using EC-medium, typically characteristic cobble stone shaped morphologies were noted in comparison to cells cultured using MSC medium, implying that the differentiated cells were sensitive to soluble VEGF supplementation present in the EC-medium. Results will enhance and affect therapies utilizing autologous MSC as a cell source for generating vascular cells to be used in a variety of tissue engineering applications.

miR‑149 promotes the myocardial differentiation of mouse bone marrow stem cells by targeting Dab2

To investigate the role of microRNA (miR)‑149 in the cardiac differentiation of mouse bone marrow mesenchymal stem cells (MSCs) in vitro, MSCs were infected with a lentivirus overexpressing miR‑149 and the effect on cardiac differentiation was determined. The quantitative polymerase chain reaction results demonstrated that miR‑149 promoted the expression of cardiac‑specific markers in MSCs. Western blotting and a luciferase activity assay demonstrated that disabled homolog 2 (Dab2) was a direct target of miR‑149. Dab2 ectopic expression and Wnt/β‑catenin signaling pathway inhibition was able to reverse the increased expression of cardiac‑specific markers induced by miR‑149. In conclusion, miR‑149 was able to target Dab2 and promote the cardiac differentiation of mouse MSCs in vitro, which depended upon the Wnt/β‑catenin signaling pathway.

Human Adipose-Derived and Amniotic Fluid-Derived Stem Cells: A Preliminary In Vitro Study Comparing Myogenic Differentiation Capability

Background

Around the world, disabilities due to musculoskeletal disorders have increased and are a major health problem worldwide. In recent years, stem cells have been considered to be powerful tools for musculoskeletal tissue engineering. Human adipose-derived stem cells (hADSCs) and amniotic fluid-derived stem cells (hAFSCs) undergo typical differentiation process into cells of mesodermal origin and can be used to treat muscular system diseases. The aim of the present study was to compare the biological characteristic of stem cells isolated from different human tissues (adipose tissue and amniotic fluid) with respect to myogenic capacity and skeletal and smooth muscle differentiation under the same conditions.

Material/Methods

hAFSCs and hADSCs were isolated during standard medical procedures and widely characterized by specific markers expression and differentiation potential. Both cell types were induced toward smooth and striated muscles differentiation, which was assessed with the use of molecular techniques.

Results

For phenotypic characterization, both stem cell types were assessed for the expression of OCT-4, SOX2, CD34, CD44, CD45, and CD90. Muscle-specific markers appeared in both stem cell types, but the proportion of positive cells showed differences depending on the experimental conditions used and the source from which the stem cells were isolated.

Conclusions

In this study, we demonstrated that hADSCs and hAFSCs have different capability of differentiation toward both muscle types. However, hADSCs seem to be a better source for myogenic protocols and can promote skeletal and smooth muscle regeneration through either direct muscle differentiation or by paracrine mechanism.

Mesenchymal Stem Cells in Cardiology

Cardiovascular disease (CVD) accounts for more deaths globally than any other single disease. There are on average 1.5 million episodes of myocardial infarction (heart attack) each year in the United States alone with roughly one-third resulting in death. There is therefore a major need for developing new and effective strategies to promote cardiac repair. Intramyocardial transplantation of mesenchymal stem cells (MSCs) has emerged as a leading contender in the pursuit of clinical intervention and therapy. MSCs are potent mediators of cardiac repair and are therefore an attractive tool in the development of preclinical and clinical trials. MSCs are capable of secreting a large array of soluble factors, which have had demonstrated effects on pathogenic cardiac remolding, fibrosis, immune activation, and cardiac stem cell proliferation within the damaged heart. MSCs are also capable of differentiation into cardiomyocytes, endothelial cells, and vascular smooth muscle cells, although the relative contribution of trilineage differentiation and paracrine effectors on cardiac repair remains the subject of active investigation.

Treatment of Myocardial Infarction with Gene-modified Mesenchymal Stem Cells in a Small Molecular Hydrogel

The effect of transplanted rat mesenchymal stem cells (MSCs) can be reduced by extracellular microenvironment in myocardial infarction (MI). We tested a novel small-molecular hydrogel (SMH) on whether it could provide a scaffold for hepatocyte growth factor (HGF)-modified MSCs and alleviate ventricular remodeling while preserving cardiac function after MI. Overexpression of HGF in MSCs increased Bcl-2 and reduced Bax and caspase-3 levels in response to hypoxia in vitro. Immunocytochemistry demonstrated that cardiac troponin (cTnT), desmin and connexin 43 expression were significantly enhanced in the 5-azacytidine (5-aza) with SMH group compared with the 5-aza only group in vitro and in vivo. Bioluminescent imaging indicated that retention and survival of transplanted cells was highest when MSCs transfected with adenovirus (ad-HGF) were injected with SMH. Heart function and structure improvement were confirmed by echocardiography and histology in the Ad-HGF-SMHs-MSCs group compared to other groups. Our study showed that: HGF alleviated cell apoptosis and promoted MSC growth. SMHs improved stem cell adhesion, survival and myocardial cell differentiation after MSC transplantation. SMHs combined with modified MSCs significantly decreased the scar area and improved cardiac function.

Stem cell-based peripheral vascular regeneration

Chronic critical limb ischemia (CLI) represents an end-stage manifestation of peripheral arterial disease (PAD). CLI patients are at very high risk of amputation and cardiovascular complications, leading to severe morbidity and mortality. Because many patients with CLI are ineligible for conventional revascularization procedures, it is urgently needed to explore alternative strategies to improve blood supply in the ischemic tissue. Although researchers initially focused on gene/protein therapy using proangiogenic growth factors/cytokines, recent discovery of somatic stem/progenitor cells including bone marrow (BM)-derived endothelial progenitor cells (EPCs) and mesenchymal stem cells (MSCs) has drastically developed the field of therapeutic angiogenesis for CLI. Overall, early phase clinical trials demonstrated that stem/progenitor cell therapies may be safe, feasible and potentially effective. However, only few late-phase clinical trials have been conducted. This review provides an overview of the preclinical and clinical reports to demonstrate the usefulness and the current limitations of the cell-based therapies.

Mechanisms of stem cell based cardiac repair-gap junctional signaling promotes the cardiac lineage specification of mesenchymal stem cells

Different subtypes of bone marrow-derived stem cells are characterized by varying functionality and activity after transplantation into the infarcted heart. Improvement of stem cell therapeutics requires deep knowledge about the mechanisms that mediate the benefits of stem cell treatment. Here, we demonstrated that co-transplantation of mesenchymal stem cells (MSCs) and hematopoietic stem cells (HSCs) led to enhanced synergistic effects on cardiac remodeling. While HSCs were associated with blood vessel formation, MSCs were found to possess transdifferentiation capacity. This cardiomyogenic plasticity of MSCs was strongly promoted by a gap junction-dependent crosstalk between myocytes and stem cells. The inhibition of cell-cell coupling significantly reduced the expression of the cardiac specific transcription factors NKX2.5 and GATA4. Interestingly, we observed that small non-coding RNAs are exchanged between MSCs and cardiomyocytes in a GJ-dependent manner that might contribute to the transdifferentiation process of MSCs within a cardiac environment. Our results suggest that the predominant mechanism of HSCs contribution to cardiac regeneration is based on their ability to regulate angiogenesis. In contrast, transplanted MSCs have the capability for intercellular communication with surrounding cardiomyocytes, which triggers the intrinsic program of cardiogenic lineage specification of MSCs by providing cardiomyocyte-derived cues.

Deriving vascular smooth muscle cells from mesenchymal stromal cells: Evolving differentiation strategies and current understanding of their mechanisms

Vascular smooth muscle cells (VSMCs) play essential roles in regulating blood vessel form and function. Regeneration of functional vascular smooth muscle tissue to repair vascular diseases is an area of intense research in tissue engineering and regenerative medicine. For functional vascular smooth muscle tissue regeneration to become a practical therapy over the next decade, the field will need to have access to VSMC sources that are effective, robust and safe. While pluripotent stem cells hold good future promise to this end, more immediate translation is expected to come from approaches that generate functional VSMCs from adult sources of multipotent adipose-derived and bone marrow-derived mesenchymal stromal cells (ASCs and BMSCs). The research to this end is extensive and is dominated by studies relating to classical biochemical signalling molecules used to induce differentiation of ASCs and BMSCs. However, prolonged use of the biochemical induction factors is costly and can cause potential endotoxin contamination in the culture. Over recent years several non-traditional differentiation approaches have been devised to mimic defined aspects of the native micro-environment in which VSMCs reside to contribute to the differentiation of VSMC-like cells from ASCs and BMSCs. In this review, the promises and limitations of several non-traditional culture approaches (e.g., co-culture, biomechanical, and biomaterial stimuli) targeting VSMC differentiation are discussed. The extensive crosstalk between the underlying signalling cascades are delineated and put into a translational context. It is expected that this review will not only provide significant insight into VSMC differentiation strategies for vascular smooth muscle tissue engineering applications, but will also highlight the fundamental importance of engineering the cellular microenvironment on multiple scales (with consideration of different combinatorial pathways) in order to direct cell differentiation fate and obtain cells of a desired and stable phenotype. These strategies may ultimately be applied to different sources of stem cells in the future for a range of biomaterial and tissue engineering disciplines.

Stretchable Piezoelectric Substrate Providing Pulsatile Mechanoelectric Cues for Cardiomyogenic Differentiation of Mesenchymal Stem Cells

Ex vivo induction of cardiomyogenic differentiation of mesenchymal stem cells (MSCs) before implantation would potentiate therapeutic efficacy of stem cell therapies for ischemic heart diseases because MSCs rarely undergo cardiomyogenic differentiation following implantation. In cardiac microenvironments, electric pulse and cyclic mechanical strain are sequentially produced. However, no study has applied the pulsatile mechanoelectric cues (PMEC) to stimulate cardiomyogenic differentiation of MSCs ex vivo. In this study, we developed a stretchable piezoelectric substrate (SPS) that can provide PMEC to human MSCs (hMSCs) for cardiomyogenic differentiation ex vivo. Our data showed that hMSCs subjected to PMEC by SPS underwent promoted cardiac phenotype development: cell alignment and the expression of cardiac markers (i.e., cardiac transcription factors, structural proteins, ion channel proteins, and gap junction proteins). The enhanced cardiac phenotype development was mediated by the upregulation of cardiomyogenic differentiation-related autocrine factor expression, focal adhesion kinase, and extracellular signal-regulated kinases signaling pathways. Thus, SPS providing electrical and mechanical regulation of stem cells may be utilized to potentiate hMSC therapies for myocardial infarction and provide a tool for the study of stem cell biology.

A novel approach for fabricating highly tunable and fluffy bioinspired 3D poly(vinyl alcohol) (PVA) fiber scaffolds

The excellent biocompatibility, biodegradability and chemo-thermal stability of poly(vinyl alcohol) (PVA) have been harnessed in diverse practical applications. These properties have motivated the fabrication of high performance PVA based nanofibers with adequate control over the micro and nano-architectures and surface chemical interactions. However, the high water solubility and hydrophilicity of the PVA polymer limits the application of the electrospun PVA nanofibers in aqueous environments owing to instantaneous dissolution. In this work, we report a novel yet facile concept for fabricating extremely light, fluffy, insoluble and stable three dimensional (3D) PVA fibrous scaffolds with/without coating for multifunctional purposes. While the solubility, morphology, fiber density and mechanical properties of nanofibers could be tuned by optimizing the cross-linking conditions, the surface chemical reactivity could be readily enhanced by coating with a polydopamine (pDA) bioinspired polymer without compromising the stability and innate properties of the native PVA fiber. The 3D pDA-PVA scaffolds exhibited super dye adsorption and constructive synergistic cell-material interactions by promoting healthy adhesion and viability of the human mesenchymal stem cells (hMSCs) within 3D micro-niches. We foresee the application of tunable PVA 3D as a highly adsorbent material and a scaffold material for tissue regeneration and drug delivery with close consideration of realistic in vivo parameters.

Coculture effects on the osteogenic differentiation of human mesenchymal stromal cells

Cell-based bone regeneration is generally pursued based on single cell type approaches, for which human adipose tissue-derived mesenchymal stromal cells (AT-MSCs) are frequently used, owing to their easy accessibility and relatively large yield. In view of multiple cell types involved in physiological bone regeneration, this study aimed to evaluate the osteogenic differentiation of AT-MSCs upon co-culture with endothelial cells or macrophages in a direct or indirect in vitro co-culture set-up. Our hypotheses were that 1) endothelial cells and macrophages stimulate AT-MSCs proliferation and osteogenic differentiation and that 2) these two cell types will more profoundly affect osteogenic differentiation of AT-MSCs in a direct compared to an indirect co-culture set-up, because of the possibility for both cell-cell interactions and effects of secreted soluble factors in the former. Osteogenic differentiation of AT-MSCs was stimulated by endothelial cells, particularly in direct co-cultures. Although initial numbers of AT-MSCs in co-culture with endothelial cells were 50% compared to monoculture controls, equal levels of mineralization were achieved. Macrophages showed a variable effect on AT-MSCs behavior for indirect co-cultures and a negative effect on osteogenic differentiation of AT-MSCs in direct co-cultures, the latter likely due to species differences of the cell types used. The results of this study demonstrate potential for cell combination strategies in bone regenerative therapies.

Mesenchymal Stem Cells Derived from Human Exocrine Pancreas Spontaneously Express Pancreas Progenitor-Cell Markers in a Cell-Passage-Dependent Manner

Mesenchymal stem cells (MSCs) derived from bone marrow, adipose tissue, and most connective tissues have been recognized as promising sources for cell-based therapies. MSCs have also been detected in human pancreatic tissue, including endocrine and exocrine cells. These adult human pancreas-derived MSCs have generated a great deal of interest owing to their potential use in the differentiation of insulin-producing cells for diabetes treatment. In the present study, we isolated MSCs from the adult human exocrine pancreas to determine whether isolated MSCs have the potential to differentiate into pancreatic endocrine cells and, therefore, whether they can be used in stem cell-based therapies. Pancreatic tissue was digested by collagenase and an enriched exocrine-cell fraction was obtained by density-gradient separation. Crude exocrine cells were methodically cultured in suspension and then in adherent culture. We expanded the human pancreatic exocrine-derived MSCs (hpMSCs) by cell passaging in culture and confirmed by flow cytometry that >90% expressed human classic surface markers of MSCs. Interestingly, these cells expressed pancreatic transcription factors, such as Pdx1, Ngn3, and MafA, similar to pancreatic progenitor cells. These results indicated that hpMSCs can be used for the differentiation of pancreatic endocrine cells and may be used in type 1 diabetes treatment.

Daunorubicin Down-Regulates the Expression of Stem Cell Markers and Factors Involved in Stem Cell Migration and Homing in Rat Heart in Subchronic but not Acute Cardiomyopathy

We tested the hypothesis that daunorubicin (DAU) cardiotoxicity alters expression of cytokines involved in stem cell migration and homing. Male Wistar rats were treated with daunorubicin to induce acute DAU cardiomyopathy (6 × 3 mg/kg, i.p., every 48 hr, DAU-A) or subchronic DAU cardiomyopathy (15 mg/kg, i.v., DAU-C). The left ventricle was catheterized. The animals were killed 48 hr (DAU-A) and 8 weeks (DAU-C) after the last dose of DAU. Expression of foetal genes (Nppa, Nppb), isomyosins (Myh6, Myh7), sources of oxidative stress (Abcb8, gp91phox), cytokines (Sdf-1, Cxcr4, Scf, Vegf, Hgf, Igf-1), markers of cardiac progenitor (c-kit, Atnx-1), endothelial progenitor (CD34, CD133) and mesenchymal (CD44, CD105) stem cells were determined by qRT-PCR in left ventricular tissue. Reduced body-weight, decreased left ventricular weight and function, and elevated Nppa, Nppb, Myh7 were observed in both models. Myh6 decreased only in DAU-C, which had a 35% mortality. Up-regulated gp91phox and down-regulated Abcb8 in DAU were present only in DAU-C where we observed markedly decreased expressions of Scf and Vegf as well as expressions of stem cell markers. Down-regulation of cytokines and stem cell markers may reflect impaired chemotaxis, migration and homing of stem cells and tissue repair in the heart in subchronic but not acute model of DAU cardiomyopathy.

Shox2 influences mesenchymal stem cell fate in a co-culture model in vitro

Sinoatrial node (SAN) dysfunction is a common cardiovascular problem, and the development of a cell sourced biological pacemaker has been the focus of cardiac electrophysiology research. The aim of biological pacemaker therapy is to produce SAN-like cells, which exhibit spontaneous activity characteristic of the SAN. Short stature homeobox 2 (Shox2) is an early cardiac transcription factor and is crucial in the formation and differentiation of the sinoatrial node (SAN). The present study aimed to improve pacemaker function by overexpression of Shox2 in canine mesenchymal stem cells (cMSCs) to induce a phenotype similar to native pacemaker cells. To achieve this objective, the cMSCs were transfected with lentiviral pLentis-mShox2-red fluorescent protein, and then co-cultured with rat neonatal cardiomyocytes (RNCMs) in vitro for 5–7 days. The feasibility of regulating the differentiation of cMSCs into pacemaker-like cells by Shox2 overexpression was investigated. Reverse transcription-quantitative polymerase chain reaction and western blotting showed that Shox2-transfected cMSCs expressed high levels of T box 3, hyperpolarization-activated cyclic nucleotide-gated cation channel and Connexin 45 genes, which participate in SAN development, and low levels of working myocardium genes, Nkx2.5 and Connexin 43. In addition, Shox2-transfected cMSCs were able to pace RNCMs with a rate faster than the control cells. In conclusion, these data indicate that overexpression of Shox2 in cMSCs can greatly enhance the pacemaker phenotype in a co-culture model in vitro.

Comparative evaluation of cardiac markers in differentiated cells from menstrual blood and bone marrow-derived stem cells in vitro

In recent years, menstrual blood-derived stem cells (MenSCs) have been introduced as easily accessible and refreshing stem cell source without ethical considerations in the field of regenerative medicine. The aim of this study was to investigate in vitro cardiac differentiation capacity of MenSCs compared to bone marrow-derived stem cells (BMSCs) under two protocols using 5-aza-2'-deoxycytidine (5-aza) and basic fibroblast growth factor (bFGF). Our data revealed that differentiated MenSCs and BMSCs acquired some features of cardiomyocytes; however, degree of differentiation was dependent on the protocol. In a similar manner with BMSCs, differentiated MenSCs showed upper levels of mRNA/protein of late-stage cardiac markers under 5-aza stimulation and continuous treatment with bFGF (protocol 2) compared to those induced by 5-aza alone (protocol 1) evidencing the key role of bFGF in cardiac development of stem cells. Compared to corresponding undifferentiated cells differentiated MenSCs under protocol 2 showed remarkable expression of connexin-43 and TNNT2 at both gene and protein levels, whereas developed BMSCs under the same condition only expressed connextin-43 at the higher level. Superiority of protocol 2 over protocol 1 was confirmed by assessment of LDH and cTnI production by differentiated cells. Based on the accumulative data, our study provided convincing evidence that MenSCs have relatively higher capability to be differentiated toward cardiomyocyte compared with BMSCs. Furthermore, usage of bFGF and 5-aza to induce in vitro cardiac differentiation of MenSCs is highly recommended.

Tetramethylpyrazine induces differentiation of human umbilical cord-derived mesenchymal stem cells into neuron-like cells in vitro

The present study evaluated the ability and optimal concentration of tetramethylpyrazine (TMP) to induce human umbilical cord-derived mesenchymal stem cells (hUMSCs) to differentiate into neuron-like cells in vitro. Human umbilical cords from full-term caesarean section patients were used to obtain hUMSCs by collagenase digestion after removal of the umbilical artery and vein. The surface antigen expression profile of cultured hUMSCs was monitored by flow cytometry. After amplification, cells of the 5th passage were divided into experimental groups A–C treated with TMP at 4.67, 2.34 and 1.17 mg/ml, respectively, in low glucose-Dulbecco's Modified Eagle's Medium (L-DMEM) (induction medium), while group D (control) was exposed to L-DMEM culture medium only. Differentiation of hUMSCs into neuron-like cells and morphological changes were observed every 0.5 h with an inverted phase contrast microscope for 6 h. After the 6-h induction period, proportions of cells expressing neuronal markers neuron-specific enolase (NSE), neurofilament protein (NF-H) and glial fibrillary acidic protein (GFAP) were detected by immunohistochemistry. The optimal concentration of TMP was selected on the basis of neuron-like cell positive rate. Western blotting and RT-polymerase chain reaction were applied to detect the expression of NSE, NF-H, and GFAP of the group of optimal concentration in each point-in-time. Results showed that most primary cells were adherent 12 h after seeding and first appeared as diamond or polygon shapes. Thereafter, they gradually grew into long spindle-shaped cells and finally in a radiating or swirling pattern. The cells maintained a strong proliferative capacity after continuous passage. Flow cytometry analysis of cultured hUMSCs at the 3rd, 5th and 10th passages expressed CD73, CD90 and CD105, but not CD11b, CD19, CD34, CD45 or human leukocyte antigen-DR. After 6 h of TMP treatment, typical neuron-like cells with many protrusions connected into a net-like pattern were observed in all experimental groups. These neuron-like cells were positive for NSE and NF-H, but negative for GFAP. Among the tested treatment groups, group A with TMP at 4.67 mg/ml had the highest expression of NSE and NF-H. By contrast, no change was found after induction in the control group. The mRNA expression of cells expressing neuronal markers as well as GAPDH was observed, with the relative NSE transcript levels of 0, 1.303±0.031, 1.558±0.025, 1.927±0.019 and 2.415±0.033 after 0, 1, 2, 4 and 6 h of treatment, respectively; the mRNA expression of NH-F was 0, 1.429±0.025, 1.551±0.024, 1.930±0.042 and 1.398±0.014 after 0, 1, 2, 4 and 6 h of treatment, respectively. There was no expression of GFAP before or after induction and all the groups showed high expression of GAPDH at each time point. Protein expression was also observed on cells expressing neuronal markers as well as GAPDH at each time point. The protein expression of NSE was 0, 0.717±0.097, 0.919±0.056, 1.097±0.143 and 1.157±0.055 in proper order; the protein expression of NH-F was 0, 0.780±0.103, 0.973±0.150, 1.053±0.107 and 0.753±0.094 in proper order. There was no expression of GFAP before or after induction, and all the groups showed high expression of GAPDH at each tested time point. Our results demonstrated that TMP can induce hUMSCs to differentiate into neuron-like cells effectively with the optimal concentration of 4.67 mg/ml. After induction, the NSE and NF-H of the neuron-like cells were positive, but the GFAP-2 was negative.

A practical guide for the isolation and maintenance of stem cells from tendon

Stem cells are unspecialized cells that can self-renew and have the ability to develop into cells of highly specialized functions. The study of stem cells holds enormous promise in the medical field ranging from their uses in cell therapies to their uses for greater understanding of tissue development and disease pathologies. Stem cells have been isolated from tendon tissue recently. These tendon-derived stem cells (TDSCs) are particularly relevant for tendon repair and the study of the potential roles of stem cells in tendon pathology as they are isolated from tendon tissues. This paper aims to describe the step-by-step protocol and the practical tips for the isolation and verification of stem cell characteristics of TDSCs. The cell seeding density and hence cell-cell contact has a significant impact on the isolation and expansion of TDSCs. Hence, I also describe our established protocol for the determination of the optimal seeding density for TDSC isolation and culture.

Vascular Wall-Resident Multipotent Stem Cells of Mesenchymal Nature within the Process of Vascular Remodeling: Cellular Basis, Clinical Relevance, and Implications for Stem Cell Therapy

Until some years ago, the bone marrow and the endothelial cell compartment lining the vessel lumen (subendothelial space) were thought to be the only sources providing vascular progenitor cells. Now, the vessel wall, in particular, the vascular adventitia, has been established as a niche for different types of stem and progenitor cells with the capacity to differentiate into both vascular and nonvascular cells. Herein, vascular wall-resident multipotent stem cells of mesenchymal nature (VW-MPSCs) have gained importance because of their large range of differentiation in combination with their distribution throughout the postnatal organism which is related to their existence in the adventitial niche, respectively. In general, mesenchymal stem cells, also designated as mesenchymal stromal cells (MSCs), contribute to the maintenance of organ integrity by their ability to replace defunct cells or secrete cytokines locally and thus support repair and healing processes of the affected tissues. This review will focus on the central role of VW-MPSCs within vascular reconstructing processes (vascular remodeling) which are absolute prerequisite to preserve the sensitive relationship between resilience and stability of the vessel wall. Further, a particular advantage for the therapeutic application of VW-MPSCs for improving vascular function or preventing vascular damage will be discussed.

Mesenchymal stromal cells from bone marrow treated with bovine tendon extract acquire the phenotype of mature tenocytes

Objective

This study evaluated in vitro differentiation of mesenchymal stromal cells isolated from bone marrow, in tenocytes after treatment with bovine tendon extract.

Methods

Bovine tendons were used for preparation of the extract and were stored at −80 °C. Mesenchymal stromal cells from the bone marrow of three donors were used for cytotoxicity tests by means of MTT and cell differentiation by means of qPCR.

Results

The data showed that mesenchymal stromal cells from bone marrow treated for up to 21 days in the presence of bovine tendon extract diluted at diminishing concentrations (1:10, 1:50 and 1:250) promoted activation of biglycan, collagen type I and fibromodulin expression.

Conclusion

Our results show that bovine tendon extract is capable of promoting differentiation of bone marrow stromal cells in tenocytes.

Bone marrow-derived mesenchymal stem cells for the treatment of heart failure

Heart failure remains a major cause of death and disability, requiring rapid development of new therapies. Bone marrow-derived mesenchymal stem cell (MSC)-based therapy is an emerging approach for the treatment of both acute and chronic heart failure. Following successful experimental studies in a range of models, more than 40 clinical trials of MSC-based therapy for heart failure have now been registered, and the results of completed clinical trials so far have shown feasibility and safety of this approach with therapeutic potential suggested (though preliminarily). However, there appear to be several critical issues to be solved before this treatment could become a widespread standard therapy for heart failure. In this review, we comprehensively and systemically summarize a total of 73 preclinical studies and 11 clinical trial reports published to date. By analyzing the data in these reports, (1) improvement in the cell delivery method to the heart in order to enhance donor cell engraftment, (2) elucidation of mechanisms underpinning the therapeutic effects of the treatment differentiation and/or treatment secretion, and (3) validation of the utility of allogeneic MSCs which could enhance the efficacy and expand the application/indication of this therapeutic approach are highlighted as future perspectives. These important respects are further discussed in this review article with referencing latest scientific and clinical information.

Emerging physiological and pathological implications of tunneling nanotubes formation between cells

Cell-to-cell communication is a critical requirement to coordinate behaviors of the cells in a community and thereby achieve tissue homeostasis and conservation of the multicellular organisms. Tunneling nanotubes (TNTs), as a cell-to-cell communication over long distance, allow for bi- or uni-directional transfer of cellular components between cells. Identification of inducing agents and the cell and molecular mechanism underling the formation of TNTs and their structural and functional features may lead to finding new important roles for these intercellular bridges in vivo and in vitro. During the last decade, research has shown TNTs have different structural and functional properties, varying between and within cell systems. In this review, we will focus on TNTs and their cell and molecular mechanism of formation. Moreover, the latest findings into their functional roles in physiological and pathological processes, such as signal transduction, micro and nano-particles delivery, immune responses, embryogenesis, cellular reprogramming, apoptosis, cancer, and neurodegenerative diseases initiation and progression and pathogens transfer, will be discussed.

Transplantation of autologous bone marrow-derived mesenchymal stem cells for traumatic brain injury

Results from the present study demonstrated that transplantation of autologous bone marrow-derived mesenchymal stem cells into the lesion site in rat brain significantly ameliorated brain tissue pathological changes and brain edema, attenuated glial cell proliferation, and increased brain-derived neurotrophic factor expression. In addition, the number of cells double-labeled for 5-bromodeoxyuridine/glial fibrillary acidic protein and cells expressing nestin increased. Finally, blood vessels were newly generated, and the rats exhibited improved motor and cognitive functions. These results suggested that transplantation of autologous bone marrow-derived mesenchymal stem cells promoted brain remodeling and improved neurological functions following traumatic brain injury.

Transplantation in end-stage pulmonary hypertension (Third International Right Heart Failure Summit, part 3)

The Third International Right Heart Summit was organized for the purpose of bringing an interdisciplinary group of expert physician-scientists together to promote dialogue involving emerging concepts in the unique pathophysiology, clinical manifestation, and therapies of pulmonary vascular disease (PVD) and right heart failure (RHF). This review summarizes key ideas addressed in the section of the seminar entitled "Transplantation in End-Stage Pulmonary Hypertension." The first segment focused on paradigms of recovery for the failing right ventricle (RV) within the context of lung-alone versus dual-organ heart-lung transplantation. The subsequent 2-part section was devoted to emerging concepts in RV salvage therapy. A presentation of evolving cell-based therapy for the reparation of diseased tissue was followed by a contemporary perspective on the role of mechanical circulatory support in the setting of RV failure. The final talk highlighted cutting-edge research models utilizing stem cell biology to repair diseased tissue in end-stage lung disease-a conceptual framework within which new therapies for PVD have potential to evolve. Together, these provocative talks provided a novel outlook on how the treatment of PVD and RHF can be approached.

Sodium butyrate promotes the differentiation of rat bone marrow mesenchymal stem cells to smooth muscle cells through histone acetylation

Establishing an effective method to improve stem cell differentiation is crucial in stem cell transplantation. Here we aimed to explore whether and how sodium butyrate (NaB) induces rat bone marrow mesenchymal stem cells (MSCs) to differentiate into bladder smooth muscle cells (SMCs). We found that NaB significantly suppressed MSC proliferation and promoted MSCs differentiation into SMCs, as evidenced by the enhanced expression of SMC specific genes in the MSCs. Co-culturing the MSCs with SMCs in a transwell system promoted the differentiation of MSCs into SMCs. NaB again promoted MSC differentiation in this system. Furthermore, NaB enhanced the acetylation of SMC gene-associated H3K9 and H4, and decreased the expression of HDAC2 and down-regulated the recruitment of HDAC2 to the promoter regions of SMC specific genes. Finally, we found that NaB significantly promoted MSC depolarization and increased the intracellular calcium level of MSCs upon carbachol stimulation. These results demonstrated that NaB effectively promotes MSC differentiation into SMCs, possibly by the marked inhibition of HDAC2 expression and disassociation of HDAC2 recruitment to SMC specific genes in MSCs, which further induces high levels of H3K9ace and H4ace and the enhanced expression of target genes, and this strategy could potentially be applied in clinical tissue engineering and cell transplantation.