Induction of myogenic differentiation of human mesenchymal stem cells cultured on Notch agonist (Jagged-1) modified biodegradable scaffold surface

GANT61 exerts anticancer cell and anticancer stem cell capacity in colorectal cancer by blocking the Wnt/β‑catenin and Notch signalling pathways

The present study aimed to assess the anticancer cell and anticancer stem cell (CSC) effects of GANT61, and its regulatory influence on the Wnt/β-catenin and Notch signalling pathways in colorectal cancer (CRC). HT-29 and HCT-116 cells were treated with 0, 2.5, 5, 10, 20 or 40 µM GANT61, after which relative cell viability and the expression of Gli1, β-catenin and Notch1, as well as the percentage of CD133⁺ cells, were detected. Subsequently, HT-29/HCT-116 cells and CSCs were treated with 20 µM GANT61, 10 mM of the Wnt/β-catenin pathway agonist HLY78, and 30 mM of the Notch pathway agonist JAG1 (alone or in combination), which was followed by the assessment of cell viability and apoptosis. In both cell lines, GANT61 reduced relative cell viability in a time- and dose-dependent manner, inhibited Gli1, β-catenin and Notch1 expression, and decreased the percentage of CD133⁺ cells in a dose-dependent manner. Furthermore, HLY78 and JAG1 were both found to improve the relative viability, while downregulating the apoptosis of untreated and GANT61-treated HT-29 and HCT-116 cells. Moreover, Wnt/β-catenin and Notch signalling pathway activity were upregulated in CSCs isolated from HT-29 and HCT-116 cells, compared with the associated control groups. GANT61 also reduced the viability of HT-29 and HCT-116 cells and increased apoptosis, whereas HLY78 and JAG1 treatment resulted in the opposite effect. Moreover, both HLY78 and JAG1 attenuated the effects of GANT61 on cellular viability and apoptosis. In conclusion, GANT61 was found to effectively eliminate cancer cells and CSCs by blocking the Wnt/β-catenin and Notch signalling pathways in CRC.

Computational analysis of the role of mechanosensitive Notch signaling in arterial adaptation to hypertension

Arteries grow and remodel in response to mechanical stimuli. Hypertension, for example, results in arterial wall thickening. Cell-cell Notch signaling between vascular smooth muscle cells (VSMCs) is known to be involved in this process, but the underlying mechanisms are still unclear. Here, we investigated whether Notch mechanosensitivity to strain may regulate arterial thickening in hypertension. We developed a multiscale computational framework by coupling a finite element model of arterial mechanics, including residual stress, to an agent-based model of mechanosensitive Notch signaling, to predict VSMC phenotypes as an indicator of growth and remodeling. Our simulations revealed that the sensitivity of Notch to strain at mean blood pressure may be a key mediator of arterial thickening in hypertensive arteries. Further simulations showed that loss of residual stress can have synergistic effects with hypertension, and that changes in the expression of Notch receptors, but not Jagged ligands, may be used to control arterial growth and remodeling and to intensify or counteract hypertensive thickening. Overall, we identify Notch mechanosensitivity as a potential mediator of vascular adaptation, and we present a computational framework that can facilitate the testing of new therapeutic and regenerative strategies.

Engineering tissue morphogenesis: taking it up a Notch

Recreating functional tissues through bioengineering strategies requires steering of complex cell fate decisions. Notch, a juxtacrine signaling pathway, regulates cell fate and controls cellular organization with local precision. The engineering-friendly characteristics of the Notch pathway provide handles for engineering tissue patterning and morphogenesis. We discuss the physiological significance and mechanisms of Notch signaling with an emphasis on its potential use for engineering complex tissues. We highlight the current state of the art of Notch activation and provide a view on the design aspects, opportunities, and challenges in modulating Notch for tissue-engineering strategies. We propose that finely tuned control of Notch contributes to the generation of tissues with accurate form and functionality.

Mechano-regulated cell-cell signaling in the context of cardiovascular tissue engineering

Cardiovascular tissue engineering (CVTE) aims to create living tissues, with the ability to grow and remodel, as replacements for diseased blood vessels and heart valves. Despite promising results, the (long-term) functionality of these engineered tissues still needs improvement to reach broad clinical application. The functionality of native tissues is ensured by their specific mechanical properties directly arising from tissue organization. We therefore hypothesize that establishing a native-like tissue organization is vital to overcome the limitations of current CVTE approaches. To achieve this aim, a better understanding of the growth and remodeling (G&R) mechanisms of cardiovascular tissues is necessary. Cells are the main mediators of tissue G&R, and their behavior is strongly influenced by both mechanical stimuli and cell-cell signaling. An increasing number of signaling pathways has also been identified as mechanosensitive. As such, they may have a key underlying role in regulating the G&R of tissues in response to mechanical stimuli. A more detailed understanding of mechano-regulated cell-cell signaling may thus be crucial to advance CVTE, as it could inspire new methods to control tissue G&R and improve the organization and functionality of engineered tissues, thereby accelerating clinical translation. In this review, we discuss the organization and biomechanics of native cardiovascular tissues; recent CVTE studies emphasizing the obtained engineered tissue organization; and the interplay between mechanical stimuli, cell behavior, and cell-cell signaling. In addition, we review past contributions of computational models in understanding and predicting mechano-regulated tissue G&R and cell-cell signaling to highlight their potential role in future CVTE strategies.

Designing Biomaterials to Modulate Notch Signaling in Tissue Engineering and Regenerative Medicine

The design of cell-instructive biomaterials for tissue engineering and regenerative medicine is at a crossroads. Although the conventional tissue engineering approach is top-down (cells seeded to macroporous scaffolds and mature to form tissues), bottom-up tissue engineering strategies are becoming appealing. With such developments, we can study cell signaling events, thus enabling functional tissue assembly in physiologic and diseased models. Among many important signaling pathways, the Notch signaling pathway is the most diverse in its influence during tissue morphogenesis and repair following injury. Although Notch signaling is extensively studied in developmental biology and cancer biology, our knowledge of designing biomaterial-based Notch signaling platforms and incorporating Notch signaling components into engineered tissue systems is limited. By incorporating Notch signaling to tissue engineering scaffolds, we can direct cell-specific responses and improve engineered tissue maturation. This review will discuss recent progress in the development of Notch signaling biomaterials as a promising target to control cellular fate decisions, including the influences of ligand identity, biophysical material cues, ligand presentation strategies, and mechanotransduction. Notch signaling is consequently of interest to direct, control, and reprogram cellular behavior on a biomaterial surface. We anticipate that discussions in this article will allow for enhanced knowledge and insight into designing Notch targeted biomaterials for various tissue engineering and cell fate determinations. Impact statement Notch signaling is recognized as an important pathway in tissue engineering and regenerative medicine; however, there is no systematic review on this topic. The comprehensive review and perspectives presented here provide an in-depth discussion on ligand presentation strategies both in 2D and in 3D cell culture environments involving biomaterials/scaffolds. In addition, this review article provides insight into the challenges in designing cell surrogate biomaterials capable of providing Notch signals. To the best of the authors' knowledge, this is the first review relevant to the fields of tissue engineering.

Bacterial cellulose membrane conjugated with plant-derived osteopontin: Preparation and its potential for bone tissue regeneration

Bacterial cellulose membrane (BCM) has been recently recognized as a new generation of carbohydrate-based nanomaterial that possesses a great potential in tissue engineering applications. This research aims to develop an active non-resorbable guided tissue regeneration (GTR) membrane from BCM by conjugating with plant-derived recombinant human osteopontin (p-rhOPN), an economically produced and RGD-containing biomolecule. The BCM was initially grafted with poly(acrylic acid) (PAA) brushes to form poly(acrylic acid)-grafted BCM. Multiple carboxyl groups introduced to the BCM by PAA can serve as active anchoring points for p-rhOPN conjugation and yielded p-rhOPN-BCM. All chemically modified BCMs were characterized by attenuated total reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, while their surface morphology was evaluated by field emission-scanning electron microscopy and atomic force microscopy analyses. The amount of p-rhOPN adhered on the membrane was quantified by enzyme-linked immunosorbent assay. The immunocytochemistry, two-stage quantitative real-time reverse transcriptase polymerase chain reaction and in vitro mineralization analyses strongly suggested that p-rhOPN-BCM could elicit biological functions leading to the enhancement of osteogenic differentiation of human periodontal ligament stem cells as effective as BCM conjugated with commercially available rhOPN from mammalian cells (rhOPN-BCM), suggesting its potential to be used as GTR membrane to promote bone tissue regeneration.

Influence of the Assembly State on the Functionality of a Supramolecular Jagged1-Mimicking Peptide Additive

Expanding the bioactivation toolbox of supramolecular materials is of utmost relevance for their broad applicability in regenerative medicines. This study explores the functionality of a peptide mimic of the Notch ligand Jagged1 in a supramolecular system that is based on hydrogen bonding ureido-pyrimidinone (UPy) units. The functionality of the peptide is studied when formulated as an additive in a supramolecular solid material and as a self-assembled system in solution. UPy conjugation of the DSLJAG1 peptide sequence allows for the supramolecular functionalization of UPy-modified polycaprolactone, an elastomeric material, with UPy-DSLJAG1. Surface presentation of the UPy-DSLJAG1 peptide was confirmed by atomic force microscopy and X-ray photoelectron spectroscopy analyses, but no enhancement of Notch activity was detected in cells presenting Notch1 and Notch3 receptors. Nevertheless, a significant increase in Notch-signaling activity was observed when DSLJAG1 peptides were administered in the soluble form, indicating that the activity of DSLJAG1 is preserved after UPy functionalization but not after immobilization on a supramolecular solid material. Interestingly, an enhanced activity in solution of the UPy conjugate was detected compared with the unconjugated DSLJAG1 peptide, suggesting that the self-assembly of supramolecular aggregates in solution ameliorates the functionality of the molecules in a biological context.

Micropatterned Cell Orientation of Cyanobacterial Liquid-Crystalline Hydrogels

Control of cell extension direction is crucial for the regeneration of tissues, which are generally composed of oriented molecules. The scaffolds of highly oriented liquid crystalline polymer chains were fabricated by casting cyanobacterial mega-saccharides, sacran, on parallel-aligned micrometer bars of polystyrene (PS). Polarized microscopy revealed that the orientation was in transverse direction to the longitudinal axes of the PS bars. Swelling behavior of the micropatterned hydrogels was dependent on the distance between the PS bars. The mechanical properties of these scaffolds were dependent on the structural orientation; additionally, the Young's moduli in the transverse direction were higher than those in the parallel direction to the major axes of the PS bars. Further, fibroblast L929 cells were cultivated on the oriented scaffolds to be aligned along the orientation axis. L929 cells cultured on these scaffolds exhibited uniaxial elongation.

Surface-immobilized plant-derived osteopontin as an effective platform to promote osteoblast adhesion and differentiation

In this report, recombinant human osteopontin synthesized in tobacco plants (p-rhOPN) is introduced as a potential bioactive molecule that can promote osteoblast adhesion and differentiation. A glass substrate (SiO₂/Si-OH) grafted with poly(acrylic acid) (SiO₂/Si-PAA) was prepared by surface-initiated reversible addition-fragmentation chain transfer polymerization and used as a carboxyl-rich platform for the chemical conjugation of p-rhOPN. The PAA grafting and subsequent p-rhOPN immobilization were confirmed by water contact angle, Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy analyses. Indirect ELISA quantification revealed that the p-rhOPN immobilization efficiency was above 95% and the surface coverage was a function of the p-rhOPN concentration. MC-3T3-E1 cells cultured on the SiO₂/Si-PAA substrate immobilized with various concentrations (0.6-30 ng/mL) of p-rhOPN (SiO₂/Si-p-rhOPN) exhibited superior cell spreading compared to those cultured on SiO₂/Si-OH or gelatin-modified glass substrate (SiO₂/Si-gelatin). Polymerase chain reaction analysis indicated that the SiO₂/Si-p-rhOPN substrates with high level of immobilized p-rhOPN promoted MC-3T3-E1 cell differentiation, as demonstrated by the higher transcript expression levels of the osteogenic differentiation regulatory gene, Runt-related transcription factor 2, compared to cells cultured on SiO₂/Si-OH or SiO₂/Si-gelatin. Given that p-rhOPN can be more economically produced than the commercially available OPN derived from human or mammalian sources, then, together with its well-preserved biological function in spite of being chemically conjugated to the substrates, it is likely that p-rhOPN could be more broadly applied for the development of materials for bone tissue engineering with a promising medical and commercial value.

Surface-modified polymers for cardiac tissue engineering

Cardiovascular disease (CVD), leading to myocardial infarction and heart failure, is one of the major causes of death worldwide. The physiological system cannot significantly regenerate the capabilities of a damaged heart. The current treatment involves pharmacological and surgical interventions; however, less invasive and more cost-effective approaches are sought. Such new approaches are developed to induce tissue regeneration following injury. Hence, regenerative medicine plays a key role in treating CVD. Recently, the extrinsic stimulation of cardiac regeneration has involved the use of potential polymers to stimulate stem cells toward the differentiation of cardiomyocytes as a new therapeutic intervention in cardiac tissue engineering (CTE). The therapeutic potentiality of natural or synthetic polymers and cell surface interactive factors/polymer surface modifications for cardiac repair has been demonstrated in vitro and in vivo. This review will discuss the recent advances in CTE using polymers and cell surface interactive factors that interact strongly with stem cells to trigger the molecular aspects of the differentiation or formulation of cardiomyocytes for the functional repair of heart injuries or cardiac defects.

Materials-Directed Differentiation of Mesenchymal Stem Cells for Tissue Engineering and Regeneration

Cell-based therapies are a promising alternative to grafts and organ transplantation for treating tissue loss or damage due to trauma, malfunction, or disease. Over the past two decades, mesenchymal stem cells (MSCs) have attracted much attention as a potential cell population for use in regenerative medicine. While the proliferative capacity and multilineage potential of MSCs provide an opportunity to generate clinically relevant numbers of transplantable cells, their use in tissue regenerative applications has met with relatively limited success to date apart from secreting paracrine-acting factors to modulate the defect microenvironment. Presently, there is significant effort to engineer the biophysical properties of biomaterials to direct MSC differentiation and further expand on the potential of MSCs in tissue engineering, regeneration, and repair. Biomaterials can dictate MSC differentiation by modulating features of the substrate including composition, mechanical properties, porosity, and topography. The purpose of this review is to highlight recent approaches for guiding MSC fate using biomaterials and provide a description of the underlying characteristics that promote differentiation toward a desired phenotype.

The effects of bi-functional anti-adhesion scaffolds on flexor tendon healing in a rabbit model

Progressive tendon adhesion is a major challenge in flexor tendon repair. The authors developed a bifunctional anti-adhesion scaffold and hypothesized that its application would reduce adhesion formation and deliver mesenchymal stem cells (MSCs) to enhance tendon healing. The scaffold was fabricated by an electrospinning machine before surface modification. The flexor tendons of 29 New Zealand rabbits underwent surgical repair and randomized to control, scaffold and scaffold loaded with MSC group. At 3 and 8 weeks post-surgery, range of motion (ROM), biomechanical properties, and histology were examined. There was no significant increase in ROM and biomechanical properties between the three groups. The histology showed successful delivery of MSCs but no significant difference in nuclear morphometry. This barrier delivers and retains MSCs within the tendon repair site. However, its sheet form and wrapping around the repair site may not be optimal for tendon healing. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2605-2614, 2018.

Consequences of MEGF10 deficiency on myoblast function and Notch1 interactions

Mutations in MEGF10 cause early onset myopathy, areflexia, respiratory distress, and dysphagia (EMARDD), a rare congenital muscle disease, but the pathogenic mechanisms remain largely unknown. We demonstrate that short hairpin RNA (shRNA)-mediated knockdown of Megf10, as well as overexpression of the pathogenic human p.C774R mutation, leads to impaired proliferation and migration of C2C12 cells. Myoblasts from Megf10-/- mice and Megf10-/-/mdx double knockout (dko) mice also show impaired proliferation and migration compared to myoblasts from wild type and mdx mice, whereas the dko mice show histological abnormalities that are not observed in either single mutant mouse. Cell proliferation and migration are known to be regulated by the Notch receptor, which plays an essential role in myogenesis. Reciprocal co-immunoprecipitation studies show that Megf10 and Notch1 interact via their respective intracellular domains. These interactions are impaired by the pathogenic p.C774R mutation. Megf10 regulation of myoblast function appears to be mediated at least in part via interactions with key components of the Notch signaling pathway, and defects in these interactions may contribute to the pathogenesis of EMARDD.

Effects of Functional Groups of Materials on Nonspecific Adhesion and Chondrogenic Induction of Mesenchymal Stem Cells on Free and Micropatterned Surfaces

Functional groups of materials are known to affect cell behaviors, yet the corresponding effect on stem cell differentiation is always coupled with that of cell spreading; it is thus unclear whether the chemical groups influence cell differentiation directly or via cell spreading indirectly. Herein we used a unique surface patterning technique to decouple the corresponding effects. Mesenchymal stem cells (MSCs) derived from bone marrow were seeded on surfaces coated with alkanethiols with one of four functional end groups (-CH₃, -OH, -COOH, and -NH₂) and underwent 9 days of chondrogenic induction. The measurements of quartz crystal microbalance with dissipation confirmed less proteins adsorbed from the cell culture media on the neutral -CH₃ and -OH surfaces than on the charged -COOH and -NH₂ surfaces. The neutral surfaces exhibited less cell spreading and higher extents of chondrogenic differentiation than the charged surfaces, according to the characterizations of immunofluorescence staining and quantitative real-time polymerase chain reaction. We further used a transfer lithography technique to prepare patterned surfaces on nonfouling poly(ethylene glycol) hydrogels to localize single MSCs on microislands with self-assembly monolayers of different alkanethiols, under given microisland areas and thus well-defined spreading areas of cells. While small microislands were always beneficial for chondrogenic induction, we found that the type of functional groups had no significant effect on chondrogenic induction under the given cell spreading areas, implying that the chemical groups influence cell differentiation only indirectly. Our results hence illustrate that functional groups regulate stem cell differentiation via tuning protein adsorption and then nonspecific cell adhesion and thus cell spreading.

Binary colloidal crystals (BCCs) as a feeder-free system to generate human induced pluripotent stem cells (hiPSCs)

Human induced pluripotent stem cells (hiPSCs) are capable of differentiating into any cell type and provide significant advances to cell therapy and regenerative medicine. However, the current protocol for hiPSC generation is relatively inefficient and often results in many partially reprogrammed colonies, which increases the cost and reduces the applicability of hiPSCs. Biophysical stimulation, in particular from tuning cell-surface interactions, can trigger specific cellular responses that could in turn promote the reprogramming process. In this study, human fibroblasts were reprogrammed into hiPSCs using a feeder-free system and episomal vectors using novel substrates based on binary colloidal crystals (BCCs). BCCs are made from two different spherical particle materials (Si and PMMA) ranging in size from nanometers to micrometers that self-assemble into hexagonal close-packed arrays. Our results show that the BCCs, particularly those made from a crystal of 2 μm Si and 0.11 μm PMMA particles (2SiPM) facilitate the reprogramming process and increase the proportion of fully reprogrammed hiPSC colonies, even without a vitronectin coating. Subsequent isolation of clonal hiPSC lines demonstrates that they express pluripotent markers (OCT4 and TRA-1-60). This proof-of-concept study demonstrates that cell reprogramming can be improved on substrates where surface properties are tailored to the application.

Micropatterning Extracellular Matrix Proteins on Electrospun Fibrous Substrate Promote Human Mesenchymal Stem Cell Differentiation Toward Neurogenic Lineage

In this study, hybrid micropatterned grafts constructed via a combination of microcontact printing and electrospinning techniques process were utilized to investigate the influencing of patterning directions on human mesenchymal stem cells (hMSCs) differentiation to desired phenotypes. We found that the stem cells could align and elongate along the direction of the micropattern, where they randomly distributed on nonmicropatterned surfaces. Concomitant with patterning effect of component on stem cell alignment, a commensurate increase on the expression of neural lineage commitment markers, such as microtubule associated protein 2 (MAP2), Nestin, NeuroD1, and Class III β-Tubulin, were revealed from mRNA expression by quantitative Real Time PCR (qRT-PCR) and MAP2 expression by immunostaining. In addition, the effect of electrospun fiber orientation on cell behaviors was further examined. An angle of 45° between the direction of micropatterning and orientation of aligned fibers was verified to greatly prompt the outgrowth of filopodia and neurogenesis of hMSCs. This study demonstrates that the significance of hybrid components and electrospun fiber alignment in modulating cellular behavior and neurogenic lineage commitment of hMSCs, suggesting promising application of porous scaffolds with smart component and topography engineering in clinical regenerative medicine.