Regulating the stemness of mesenchymal stem cells by tuning micropattern features

Topological defects induced intra-tissue heterogeneity of mesenchymal stem cell via regulatory self-organization and differentiation

Currently, in vitro fabrication of intra-tissue heterogeneity remains a critical challenge in development of adult stem cell based tissue engineering. Interestingly, as a typical structure in symmetry-breaking phase transitions, topological defects are extensively presented in biological substances. These topological defects are commonly observed within cell monolayer in vitro and demonstrated to be effective in induction of intra-tissue heterogeneity by regulating cell migration. Nevertheless, their impacts on the behavior of mesenchymal stem cells (MSCs) remain elusive. In this study, micro-grooved substrates were utilized to explore the role of topological defects in regulation of MSCs' self-organization and osteogenic differentiation. The results indicated that topological defects could induce the central aggregates of MSCs at central region of +1 and +1/2 topological defects by modulating centripetal migration. On the contrast, negatively charged topological were able to induce centrifugal migration and further inducing heterogeneous distribution of MSCs. Subsequently, these heterogeneously distributed MSCs were capable of inducing intra-tissue heterogeneity in terms of proliferation, stemness maintenance and osteogenic differentiation via regulatory morphogenesis.

Machine learning-assisted ratiometric fluorescence sensor array for recognition of multiple quinolones antibiotics

Developing analytical methods for simultaneous detection of multiple antibiotic residues is crucial for environmental protection and human health. In this study, a dual lanthanide fluorescence probe (GDP-Eu-Tb) based on nucleotides has been designed. The addition of quinolone antibiotics (QNs) quench the Eu3+ fluorescence signal through the inner filter effect (IFE) and exhibit characteristic peaks, enabling ratio fluorescence detection of levofloxacin (LVLX), gatifloxacin (GTLX), and moxifloxacin (MXLX). A ratiometric fluorescence sensor array is constructed using a single sensor element (GDP-Eu-Tb), combined with principal component analysis (PCA) and decision tree (DT) algorithms to model the relationship between fluorescence intensity ratios (I450/I616, I460/I616, I463/I616, I468/I616) and QNs. The performance of the DT model is evaluated using accuracy, precision, recall, and F1 score, with stability and generalizability confirmed by stratified ten-fold cross-validation. This approach demonstrates high sensitivity, selectivity and applicability and provides an effective solution for antibiotic residue detection.

Lighthouses illuminating tumor metastasis: The application of fluorescent probes in the localization and imaging metastatic lymph nodes across various tumors

The significance of metastatic lymph nodes in tumor diagnosis and prognosis is self-evident. With the deepening of research on the lymphatic system and the advancement of imaging technology, an increasing number of near-infrared fluorescent probes targeting tumor metastatic lymph nodes have been developed. These probes can identify tumors while further detecting lymph nodes (LNs), showcasing great potential in image-guided surgery. In this review, we comprehensively outline the design strategies and applications of near-infrared fluorescent probes for cancers with a high propensity for lymph node metastasis during disease progression. Particular emphasis is placed on two targeting mechanisms: tumor-directed probes capable of identifying metastatic lymph nodes and lymph node-specific probes utilizing passive targeting of metastatic lymph nodes or active targeting of lymph nodes directly. Additionally, we discuss current issues and future prospects in this field, which will facilitate the development of new fluorescent probes and their further clinical translation.

Orchestrating Macrophage and Bone Mesenchymal Stem Cells to Promote Bone Regeneration via Modulation of the Internal Surface Morphology inside 3D Printed Scaffolds

Surface morphology has been widely used to orchestrate multicellular function. However, most studies are mainly based on two-dimensional (2D) surface morphology. Therefore, a new scaffold that could be used to design and obtain controllable internal surface morphology was fabricated to explore the effect of a micropatterned scaffold on bone repair. In this study, through the combination of three-dimensional (2D) printing and soft lithography, a controllable micropatterned poly(ε-caprolactone) scaffold was obtained, which realized the transformation from 2D micropattern research to 3D research. Pit micropatterns with morphology sizes of 0, 25, and 45 μm (Flat, P25, and P45) were constructed. In vitro, the results showed that the P25 micropattern had a better effect on the promotion of M2 polarization, inhibition of the M1 polarization of RAW264.7 cells, and promotion of the osteogenic differentiation of bone marrow stromal stem cells (BMSCs). Direct and indirect coculture models of macrophages and BMSCs were constructed to study the bone immunomodulation of the pit micropatterns. Compared with the Flat and P45 groups, the P25 group could promote the secretion of M2 markers, inhibit the secretion of M1 markers, and immunomodulate the promotion of osteogenic differentiation of BMSCs. In vivo, the results also showed that the P25 group had a lower proinflammatory effect and better performance than scaffolds without micropatterned surfaces and a bigger morphology size (the P45 group), which could regulate the immune function of macrophages, reduce the inflammatory response, and accelerate bone regeneration and repair. This work provides a new strategy for the preparation of scaffolds for bone defect regeneration.

Phototherapeutic activity of polypyridyl ruthenium(II) complexes through synergistic action of nitric oxide and singlet oxygen

In recent years, photodynamic therapy (PDT) and gas therapy (GT) have emerged as research hotspots due to their excellent cancer treatment efficacy. By combining the advantages of both, the simultaneous and controllable release of reactive oxygen species (ROS) and nitric oxide (NO) has become a possibility. This paper describes the design of two Ru(II) complexes, [Ru(bpy)2(NFIP)](PF6)2 (Ru1, bpy = 2,2'-bipyridine, NFIP = 4-nitro-3-trifluoromethylaniline-1H-imidazo[4,5-f][1,10]phenanthroline) and [Ru(phen)2(NFIP)](PF6)2 (Ru2, phen = 1,10-phenanthroline), through the integration of the polypyridyl ruthenium structure and a photoresponsive NO donor. The structures and purity of the complexes were confirmed by several methods, including 1H NMR, mass spectrometry, elemental analysis, high performance liquid chromatography (HPLC) and UV-Vis absorption spectra. Both complexes were demonstrated to efficiently generate singlet oxygen (1O2) (ΦΔ = 0.40 and 0.44 in phosphate buffered saline (PBS) for Ru1 and Ru2, respectively) and release NO under visible light irradiation. Upon light exposure, Ru2 exhibited significant phototoxicity against human cervical cancer HeLa cells. In vitro experiments indicated that Ru2 elevated the levels of ROS and NO in HeLa cells when exposed to light, resulting in mitochondrial impairment and caspase-mediated cell death. Overall, Ru2 proves to be a potent phototherapeutic compound, capable of producing ROS and NO, thus providing precision in cancer phototherapy.

Inside out: Exploring edible biocatalytic biosensors for health monitoring

Edible biosensors can measure a wide range of physiological and biochemical parameters, including temperature, pH, gases, gastrointestinal biomarkers, enzymes, hormones, glucose, and drug levels, providing real-time data. Edible biocatalytic biosensors represent a new frontier within healthcare technology available for remote medical diagnosis. The main challenges to develop edible biosensors are: i) finding edible materials (i.e. redox mediators, conductive materials, binders and biorecognition elements such as enzymes) complying with Food and Drug Administration (FDA), European Food Safety Authority (EFSA) and European Medicines Agency (EMEA) regulations; ii) developing bioelectronics able to operate in extreme working conditions such as low pH (∼pH 1.5 gastric fluids etc.), body temperature (between 37 °C and 40 °C) and highly viscous bodily fluids that may cause surface biofouling issues. Nowadays, advanced printing techniques can revolutionize the design and manufacturing of edible biocatalytic biosensors. This review outlines recent research on biomaterials suitable for creating edible biocatalytic biosensors, focusing on their electrochemical properties such as electrical conductivity and redox potential. It also examines biomaterials as substrates for printing and discusses various printing methods, highlighting challenges and perspectives for edible biocatalytic biosensors.

A xenogenic-free culture medium for cell micro-patterning systems as cell-instructive biomaterials for potential clinical applications

Cell micro-patterning controls cell fate and function and has potential for generating therapeutically usable mesenchymal stromal cell (MSC) populations with precise functions. However, to date, the micro-patterning of human cells in a translational context has been impossible because only ruminant media supplements, e.g. fetal bovine serum (FBS), are established for use with micro-patterns (MPs). Thus, there are currently no good manufacturing practice (GMP)-compliant media available for MPs. This study tested a xenogenic-free human plasma and platelet lysate (hP + PL) medium supplement to determine its compatibility with MPs. Unfiltered hP + PL medium resulted in significant protein deposition, creating a 'carpet-like' layer that rendered MPs ineffective. Filtration (3×/5×) eliminated this effect. Importantly, quantitative comparison using droplet digital PCR revealed that human MSCs in all media types exhibited similar profiles with strong myogenic Calponin 1/Transgelin 2 (TAGLN2) and weaker osteogenic alkaline phosphatase/Runt-related transcription factor 2 marker expression, and much weaker adipogenic (lipoprotein lipase/peroxisome proliferator-activated receptor gamma) and chondrogenic (collagen type II/aggrecan) expression, with profiles being dominated by myogenic markers. Within these similar profiles, an even stronger induction of the myogenic marker TAGLN2 by all hP + PL- compared to FBS-containing media. Overall, this suggested that FBS can be replaced with hP + PL without altering differentiation profiles. However, assessing individual MSC responses to various MP types with defined categories revealed that unfiltered hP + PL medium was unusable. Importantly, FBS- and 3× filtered hP + PL media were comparable in each differentiation category. Summarized, this study recommends 3× filtered hP + PL as a xenogenic-free and potentially GMP-compliant alternative to FBS as a culture medium supplement for micro-patterning cell populations in both basic and translational research that will ensure consistent and reliable MSC micro-patterning for therapeutic use.

Biofunctionalized patterned platform as microarray biochip to supervise delivery and expression of pDNA nanolipoplexes in stem cells via mechanotransduction

Biochips are widely applied to manipulate the geometrical morphology of stem cells in recent years. Patterned antenna-like pseudopodia are also probed to explore the influence of pseudopodia formation on gene delivery and expression on biochips. However, how the antenna-like pseudopodia affect gene transfection is unsettled and the underlying trafficking mechanism of exogenous genes in engineered single cells is not announced. Therefore, the engineered microarray biochips were conceptualized and prepared by the synthesized photointelligent biopolymer to precisely manage geometric topological structures (cell size and antenna-like protrusion) of stem cells on biochips. The cytoskeleton could be regulated in engineered cells and large cells with more antennas assembled well-organized actin filaments to affect cell tension distribution. The stiffness and adhesion force were measured by atomic force microscope to reveal cell nanomechanics on microarray biochips. Cytoskeleton-mediated nanomechanics could be adjusted by actin filaments. Gene transfection efficiency was enhanced with increasing cell nanomechanics, which was also confirmed by the evaluation of cell internalization capacity of nanoparticles and DNA synthesis ability. This work will provide a new strategy to study functional biomaterials, microarray chips and internal mechanism of gene transfection in patterned stem cells on biochips.

A novel dual-site fluorescent probe for the one-step detection of Cys and SO2 in living cells

BACKGROUND

Cysteine (Cys) is the major intracellular thiol and plays a key role in human pathology. Furthermore, endogenous sulfur dioxide (SO2) is produced in mammals. Abnormal levels of SO2 are commonly associated with a variety of respiratory, cardiovascular, and neurological diseases. Therefore, given their important role in life activities, it is significant to construct a fluorescent probe that can detection between Cys and SO2.

RESULTS

We have designed and synthesized a two-site fluorescent probe CUM with coumarin derivative and benzaldehyde molecules, which can detect and differentiate between Cys and SO2 through dual excitation wavelengths. Its carbon-carbon double bond reacts with Cys and undergoes a nucleophilic reaction, emitting green fluorescence at 520 nm, while SO32- reacts with benzaldehyde molecules in the probe CUM and undergoes a blue fluorescence at 460 nm. SO32- reacts with the benzaldehyde molecule of probe CUM and fluoresces blue at 460 nm. Thus, the probe CUM with two reaction sites can distinguish between Cys and SO2 and shows good selectivity and fast reaction speed. In addition, we successfully utilized probe CUM to image Cys and SO2 in human breast cancer cells (MDA-MB-231).

SIGNIFICANCE

This work provides an effective method for the molecular design of coumarin-based fluorescent probes. Probe CUM as a promising and reliable tool for the meticulous discrimination and quantification of Cys and SO2 in diverse biological matrices, thereby opening up new avenues for various biological systems.

The Myofibroblast Fate of Therapeutic Mesenchymal Stromal Cells: Regeneration, Repair, or Despair?

Mesenchymal stromal cells (MSCs) can be isolated from various tissues of healthy or patient donors to be retransplanted in cell therapies. Because the number of MSCs obtained from biopsies is typically too low for direct clinical application, MSC expansion in cell culture is required. However, ex vivo amplification often reduces the desired MSC regenerative potential and enhances undesired traits, such as activation into fibrogenic myofibroblasts. Transiently activated myofibroblasts restore tissue integrity after organ injury by producing and contracting extracellular matrix into scar tissue. In contrast, persistent myofibroblasts cause excessive scarring-called fibrosis-that destroys organ function. In this review, we focus on the relevance and molecular mechanisms of myofibroblast activation upon contact with stiff cell culture plastic or recipient scar tissue, such as hypertrophic scars of large skin burns. We discuss cell mechanoperception mechanisms such as integrins and stretch-activated channels, mechanotransduction through the contractile actin cytoskeleton, and conversion of mechanical signals into transcriptional programs via mechanosensitive co-transcription factors, such as YAP, TAZ, and MRTF. We further elaborate how prolonged mechanical stress can create persistent myofibroblast memory by direct mechanotransduction to the nucleus that can evoke lasting epigenetic modifications at the DNA level, such as histone methylation and acetylation. We conclude by projecting how cell culture mechanics can be modulated to generate MSCs, which epigenetically protected against myofibroblast activation and transport desired regeneration potential to the recipient tissue environment in clinical therapies.

Focal adhesion and actin orientation regulated by cellular geometry determine stem cell differentiation via mechanotransduction

Tuning cell adhesion geometry can affect cytoskeleton organization and the distribution of cytoskeleton forces, which play critical roles in controlling cell functions. To elucidate the geometrical relationship with cytoskeleton force distribution, it is necessary to control cell morphology. In this study, a series of dextral vortex micropatterns were prepared to precisely control cell morphology for investigating the influence of the curvature degree of adhesion curves on intracellular force distribution and stem cell differentiation at a sub-cellular level. Peripherial actin filaments of micropatterned cells were assembled along the adhesion curves and showed different orientations, filament thicknesses and densities. Focal adhesion and cytoskeleton force distribution were dependent on the curvature degree. Intracellular force distribution was also regulated by adhesion curves. The cytoskeleton and force distribution affected the osteogenic differentiation of mesenchymal stem cells through a YAP/TAZ-mediated mechanotransduction process. Thus, regulation of cell adhesion curvature, especially at cytoskeletal filament level, is critical for cell function manipulation. STATEMENT OF SIGNIFICANCE: In this study, a series of dextral micro-vortexes were prepared and used for the culture of human mesenchymal stem cells (hMSCs) to precisely control adhesive curvatures (0°, 30°, 60°, and 90°). The single MSCs on the micropatterns had the same size and shape but showed distinct focal adhesion (FA) and cytoskeleton orientations. Cellular nanomechanics were observed to be correlated with the curvature degrees, subsequently influencing nuclear morphological features. As a consequence, the localization of the mechanotransduction sensor and activator-YAP/TAZ was affected, influencing osteogenic differentiation. The results revealed the pivotal role of adhesive curvatures in the manipulation of stem cell differentiation via the machanotransduction process, which has rarely been investigated.

Tannic acid modified keratin/sodium alginate/carboxymethyl chitosan biocomposite hydrogels with good mechanical properties and swelling behavior

Natural polymer-based hydrogels have demonstrated great potential as wound-healing dressings. They help to maintain a moist wound environment as well as promote faster healing. In this work, a multifunctional hydrogel was prepared using keratin, sodium alginate, and carboxymethyl chitosan with tannic acid modification. Micro-morphology of hydrogels has been performed by scanning electron microscopy. Fourier Transform Infrared Spectroscopy reveals the presence of hydrogen bonding. The mechanical properties of the hydrogels were examined using a universal testing machine. Furthermore, we investigated several properties of the modified hydrogel. These properties include swelling rate, water retention, anti-freezing properties, antimicrobial and antioxidant properties, hemocompatibility evaluation and cell viability test in vitro. The modified hydrogel has a three-dimensional microporous structure, the swelling rate was 1541.7%, the elastic modulus was 589.74 kPa, the toughness was 211.74 kJ/m3, and the elongation at break was 75.39%, which was similar to the human skin modulus. The modified hydrogel also showed inhibition of S. aureus and E. coli, as well as a DPPH scavenging rate of 95%. In addition, the modified hydrogels have good biological characteristics. Based on these findings, the K/SA/CCS hydrogel holds promise for applications in biomedical engineering.

A novel dual-function fluorescent probe for the detection of cysteine and its applications in vitro

A fluorescent probe of both colorimetric and ratiometric type for highly selective and sensitive detection of Cys (cysteine) is very important in biological analysis. In this work, a new colorimetric and ratiometric fluorescent probe ((E)-2-(2-(5-(4-(acryloyloxy)phenyl)furan-2-yl)vinyl)-3-methylbenzo[d]thiazol-3-ium iodide, LP-1) was designed and synthesized for the detection of Cys. The reaction mechanism of LP-1 toward Cys involves a conjugate addition reaction between Cys and the α,β-unsaturated carbonyl group, leading to the formation of an intermediate thioether, followed by intramolecular cyclization to produce the desired compounds LP-1-OH. At this point, the ICT process is activated, significantly increasing the fluorescence intensity of the molecules. Meanwhile, LP-1 is highly selective and sensitive to Cys identification under optimized experimental conditions. LP-1 shows a good linear relationship in the range of Cys concentration from 0.40 μM to 40 μM (R2 = 0.9942) and the limit of detection (LOD) of Cys is 0.19 μM. In addition, we have developed a simple, portable and low-cost smartphone-based high-sensitivity Cys detection method based on naked eye obvious color detection. LP-1 also has low cell toxicity and can be successfully used for biological imaging of Cys, suggesting that it is a promising biological application tool for Cys detection.

Hierarchical Surface Pattern on Ni-Free Ti-Based Bulk Metallic Glass to Control Cell Interactions

Ni-free Ti-based bulk metallic glasses (BMGs) are exciting materials for biomedical applications because of their outstanding biocompatibility and advantageous mechanical properties. The glassy nature of BMGs allows them to be shaped and patterned via thermoplastic forming (TPF). This work demonstrates the versatility of the TPF technique to create micro- and nano-patterns and hierarchical structures on Ti40Zr10Cu34Pd14Sn2 BMG. Particularly, a hierarchical structure fabricated by a two-step TPF process integrates 400 nm hexagonal close-packed protrusions on 2.5 µm square protuberances while preserving the advantageous mechanical properties from the as-cast material state. The correlations between thermal history, structure, and mechanical properties are explored. Regarding biocompatibility, Ti40Zr10Cu34Pd14Sn2 BMGs with four surface topographies (flat, micro-patterned, nano-patterned, and hierarchical-structured surfaces) are investigated using Saos-2 cell lines. Alamar Blue assay and live/dead analysis show that all tested surfaces have good cell proliferation and viability. Patterned surfaces are observed to promote the formation of longer filopodia on the edge of the cytoskeleton, leading to star-shaped and dendritic cell morphologies compared with the flat surface. In addition to potential implant applications, TPF-patterned Ti-BMGs enable a high level of order and design flexibility on the surface topography, expanding the available toolbox for studying cell behavior on rigid and ordered surfaces.

Engineering protein nanoparticles for drug delivery

Protein nanoparticles offer a highly tunable platform for engineering multifunctional drug delivery vehicles that can improve drug efficacy and reduce off-target effects. While many protein nanoparticles have demonstrated the ability to tolerate genetic and posttranslational modifications for drug delivery applications, this review will focus on three protein nanoparticles of increasing size. Each protein nanoparticle possesses distinct properties such as highly tunable stability, capacity for splitting or fusing subunits for modular surface decoration, and well-characterized conformational changes with impressive capacity for large protein cargos. While many of the genetic and posttranslational modifications leverage these protein nanoparticle's properties, the shared techniques highlight engineering approaches that have been generalized across many protein nanoparticle platforms.

Surface micropatterning of 3D printed PCL scaffolds promotes osteogenic differentiation of BMSCs and regulates macrophage M2 polarization

Micropatterned structures on the surface of materials possessing biomimetic properties to mimic the extracellular matrix and induce cellular behaviors have been widely studied. However, it is still a major challenge to obtain internally stable and controllable micropatterned 3D scaffolds for bone repair and regeneration. In this study, 3D scaffolds with regular grating arrays using polycaprolactone (PCL) as a matrix material were prepared by combining 3D printing and soft lithography, and the effects of grating micropatterning on osteogenic differentiation of BMSCs and M1/M2 polarization of macrophages were investigated. The results showed that compared with the planar group and the 30um grating spacing group, PCL with a grating spacing of 20um significantly promoted the osteogenic differentiation of BMSCs, induced the polarization of RAW264.7 cells toward M2 type, and suppressed the expression of M1-type pro-inflammatory genes and markers. In conclusion, we successfully constructed PCL-based three-dimensional scaffolds with stable and controllable micrographs (grating arrays) inside, which possess excellent osteogenic properties and promote the formation of an immune microenvironment conducive to osteogenesis. This study is a step forward to the exploration of bone-filling materials affecting cell behavior, and makes a new contribution to the provision of high-quality materials.

Antimicrobial Hydrogels: Potential Materials for Medical Application

Microbial infections based on drug-resistant pathogenic organisms following surgery or trauma and uncontrolled bleeding are the main causes of increased mortality from trauma worldwide. The prevalence of drug-resistant pathogens has led to a significant increase in medical costs and poses a great threat to the normal life of people. This is an important issue in the field of biomedicine, and the emergence of new antimicrobial materials hydrogels holds great promise for solving this problem. Hydrogel is an important material with good biocompatibility, water absorption, oxygen permeability, adhesion, degradation, self-healing, corrosion resistance, and controlled release of drugs as well as structural diversity. Bacteria-disturbing hydrogels have important applications in the direction of surgical treatment, wound dressing, medical device coating, and tissue engineering. This paper reviews the classification of antimicrobial hydrogels, the current status of research, and the potential of antimicrobial hydrogels for one application in biomedicine, and analyzes the current research of hydrogels in biomedical applications from five aspects: metal-loaded hydrogels, drug-loaded hydrogels, carbon-material-loaded hydrogels, hydrogels with fixed antimicrobial activity and biological antimicrobial hydrogels, and provides an outlook on the high antimicrobial activity, biodegradability, biocompatibility, injectability, clinical applicability and future development prospects of hydrogels in this field.

Role of the mechanical microenvironment on CD-44 expression of breast adenocarcinoma in response to radiotherapy

The biological effects of ionizing radiation are exploited in the clinical practice of radiotherapy to destroy tumour cells while sparing the surrounding normal tissue. While most of the radiotherapy research focused on DNA damage and repair, recently a great attention is going to cells' interactions with the mechanical microenvironment of both malignant and healthy tissues after exposure. In fact, the stiffness of the extracellular matrix can modify cells' motility and spreading through the modulation of transmembrane proteins and surface receptors' expression, such as CD-44. CD-44 receptor has held much interest also in targeted-therapy due to its affinity with hyaluronic acid, which can be used to functionalize biodegradable nanoparticles loaded with chemotherapy drugs for targeted therapy. We evaluated changes in CD-44 expression in two mammary carcinoma cell lines (MCF10A and MDA-MB-231) after exposure to X-ray (2 or 10 Gy). To explore the role of the mechanical microenvironment, we mimicked tissues' stiffness with polyacrylamide's substrates producing two different elastic modulus values (0.5 and 15 kPa). We measured a dose dependent increase in CD-44 relative expression in tumour cells cultured in a stiffer microenvironment. These findings highlight a crucial connection between the mechanical properties of the cell's surroundings and the post-radiotherapy expression of surface receptors.

Recent design strategies and applications of organic fluorescent probes for food freshness detection

Food spoilage poses a significant risk to human health, making the assessment of food freshness essential for ensuring food safety and quality. In recent years, there has been rapid progress in the development of fast detection technologies for food freshness. Among them, organic fluorescent probes have garnered significant attention in the field of food safety and sensing due to their easy functionalization, high sensitivity, and user-friendly nature. To comprehensively examine the latest advancements in organic fluorescent probes for food freshness detection, this review summarized their applications within the past five years. Initially, the fundamental detection principles of organic fluorescent probes are outlined. Subsequently, the recent research progress in utilizing organic fluorescent probes to detect various chemical indicators of freshness are discussed. Finally, the challenges and future directions for organic fluorescent probes in food freshness detection are elaborated upon. While, organic fluorescent probes have demonstrated their effectiveness in evaluating food freshness and possess great potential for practical applications, further research is still needed to enable their widespread commercial utilization. With continued advancements in synthesis and functionalization techniques, organic fluorescent probes will contribute to enhancing the efficiency of food safety detection.

Cyclic stretch modulates the cell morphology transition under geometrical confinement by covalently immobilized gelatin

Fibroblasts geometrically confined by photo-immobilized gelatin micropatterns were subjected to cyclic stretch on the silicone elastomer. By using covalently micropatterned surfaces, the cell morphologies such as cell area and length were quantitatively investigated under a cyclic stretch for 20 hours. The mechanical forces did not affect the cell growth but significantly altered the cellular morphology on both non-patterned and micropatterned surfaces. It was found that cells on non-patterns showed increasing cell length and decreasing cell area under the stretch. The width of the strip micropatterns provided a different extent of contact guidance for fibroblasts. The highly extended cells on the 10 μm pattern under static conditions would perform a contraction behavior once treated by cyclic stretch. In contrast, cells with a low extension on the 2 μm pattern kept elongating according to the micropattern under the cyclic stretch. The vertical stretch induced an increase in cell area and length more than the parallel stretch in both the 10 μm and 2 μm patterns. These results provided new insights into cell behaviors under geometrical confinement in a dynamic biomechanical environment and may guide biomaterial design for tissue engineering in the future.

How Hydrogel Stiffness Affects Adipogenic Differentiation of Mesenchymal Stem Cells under Controlled Morphology

Matrix stiffness has been disclosed as an essential regulator of cell fate. However, it is barely studied how the matrix stiffness affects stem cell functions when cell morphology changes. Thus, in this study, the effect of hydrogel stiffness on adipogenic differentiation of human bone-marrow-derived mesenchymal stem cells (hMSCs) with controlled morphology was investigated. Micropatterns of different size and elongation were prepared by a photolithographical micropatterning technique. The hMSCs were cultured on the micropatterns and showed a different spreading area and elongation following the geometry of the underlying micropatterns. The cells with controlled morphology were embedded in agarose hydrogels of different stiffnesses. The cells showed a different level of adipogenic differentiation that was dependent on both hydrogel stiffness and cell morphology. Adipogenic differentiation became strong when the cell spreading area decreased and hydrogel stiffness increased. Adipogenic differentiation did not change with cell elongation. Therefore, cell spreading area and hydrogel stiffness could synergistically affect adipogenic differentiation of hMSCs, while cell elongation did not affect adipogenic differentiation. A change of cell morphology and hydrogel stiffness was accompanied by actin filament alignment that was strongly related to adipogenic differentiation. The results indicated that cell morphology could affect cellular sensitivity to hydrogel stiffness. The results will provide useful information for the elucidation of the interaction of stem cells and their microenvironmental biomechanical cues.

Microwave-Excited, Antibacterial Core-Shell BaSO4/BaTi5O11@PPy Heterostructures for Rapid Treatment of S. aureus-Infected Osteomyelitis

Owing to its deep penetration capability, microwave (MW) therapy has emerged as a promising method to eradicate deep-seated acute bone infection diseases such as osteomyelitis. However, the MW thermal effect still needs to be enhanced to achieve rapid and efficient treatment of deep focal infected areas. In this work, the multi-interfacial core-shell structure barium sulfate/barium polytitanates@polypyrrole (BaSO₄/BaTi₅O₁₁@PPy) was prepared, which exhibited enhanced MW thermal response via the well-designed multi-interfacial structure. To be specific, BaSO₄/BaTi₅O₁₁@PPy achieved rapid temperature increases in a short period and efficient clearance of Staphylococcus aureus (S. aureus) infections under MW irradiation. After 15 min MW irradiation, the antibacterial efficacy of BaSO₄/BaTi₅O₁₁@PPy can reach up to 99.61 ± 0.22%. Their desirable thermal production capabilities originated from enhanced dielectric loss including multiple interfacial polarization and conductivity loss. Additionally, in vitro analysis illuminated that the underlying antimicrobial mechanism was attributed to the noticeable MW thermal effect and changes in energy metabolic pathways on bacterial membrane instigated by BaSO₄/BaTi₅O₁₁@PPy under MW irradiation. Considering remarkable antibacterial efficiency and acceptable biosafety, we envision that it has significant value in broadening the pool of desirable candidates to fight against S. aureus-infected osteomyelitis. STATEMENT OF SIGNIFICANCE: : The treatment of deep bacterial infection remains challenging due to the ineffectiveness of antibiotic treatment and the susceptibility to bacterial resistance. Microwave (MW) thermal therapy (MTT) is a promising approach with remarkable penetration to centrally heat up the infected area. This study proposes to utilize the core-shell structure BaSO₄/BaTi₅O₁₁@PPy as an MW absorber to achieve localized heating under MW radiation for MTT. In vitro experiments demonstrated that the disrupted bacterial membrane is primarily due to the localized high temperature and interrupted electron transfer chain. As a consequence, its antibacterial rate is as high as 99.61% under MW irradiation. It is shown that the BaSO₄/BaTi₅O₁₁@PPy is a promising candidate for eliminating bacterial infection in deep-seated tissues.

Fabrication of CO-releasing surface to enhance the blood compatibility and endothelialization of TiO2 nanotubes on titanium surface

Although the construction of nanotube arrays with the micro-nano structures on the titanium surfaces has demonstrated a great promise in the field of blood-contacting materials and devices, the limited surface hemocompatibility and delayed endothelial healing should be further improved. Carbon monoxide (CO) gas signaling molecule within the physiological concentrations has excellent anticoagulation and the ability to promote endothelial growth, exhibiting the great potential for the blood-contact biomaterials, especially the cardiovascular devices. In this study, the regular titanium dioxide nanotube arrays were firstly prepared in situ on the titanium surface by anodic oxidation, followed by the immobilization of the complex of sodium alginate/carboxymethyl chitosan (SA/CS) on the self-assembled modified nanotube surface, the CO-releasing molecule (CORM-401) was finally grafted onto the surface to create a CO-releasing bioactive surface to enhance the biocompatibility. The results of scanning electron microscopy (SEM), X-ray energy dispersion spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS) revealed that the CO-releasing molecules were successfully immobilized on the surface. The modified nanotube arrays not only exhibited excellent hydrophilicity but also could slowly release CO gas molecules, and the amount of CO release increased when cysteine was added. Furthermore, the nanotube array can promote albumin adsorption while inhibit fibrinogen adsorption to some extent, demonstrating its selective albumin adsorption; although this effect was somewhat reduced by the introduction of CORM-401, it can be significantly enhanced by the catalytic release of CO. The results of hemocompatibility and endothelial cell growth behaviors showed that, as compared with the CORM-401 modified sample, although the SA/CS-modified sample had better biocompatibility, in the case of cysteine-catalyzed CO release, the released CO could not only reduce the platelet adhesion and activation as well as hemolysis rate, but also promote endothelial cell adhesion and proliferation as well as vascular endothelial growth factor (VEGF) and nitric oxide (NO) expression. As a result, the research of the present study demonstrated that the releasing CO from TiO₂ nanotubes can simultaneously enhance the surface hemocompatibility and endothelialization, which could open a new route to enhance the biocompatibility of the blood-contacting materials and devices, such as the artificial heart valve and cardiovascular stents.

Exploiting the Biophysical Cues toward Dual Differentiation of hMSC's within Geometrical Patterns

A wide variety of cues from the extracellular matrix (ECM) have been known to affect the differentiation of stem cells in vivo. In particular, the biophysical cues and cell shape have been known to affect the stem cell function, yet very little is known about the interplay between how these cues control differentiation. For the first time, by using photolithography to pattern poly(ethylene glycol) (PEG), patterns of square and triangular geometries were created, and the effect of these structures and the biophysical cues arising were utilized to differentiate cells into multiple lineages inside a same pattern without the use of any adhered protein or growth factors. The data from these studies showed that the cells present at the edges were well elongated, exhibit high aspect ratios, and differentiated into osteogenic lineage, whereas the cells present at the center exhibit lower aspect ratio and were primarily adipogenic lineage regardless of the geometry. This was correlated to the higher expression of focal adhesion proteins at the edges, the expression of which have been known to affect the osteogenic differentiation. By showing MSC lineage commitment relationships due to physical signals, this study highlights the importance of these cues and cell shape in further understanding stem cell behavior for tissue engineering applications.

Structure modification: a successful tool for prodrug design

Prodrug strategy is critical for innovative drug development. Structural modification is the most straightforward and effective method to develop prodrugs. Improving drug defects and optimizing the physical and chemical properties of a drug, such as lipophilicity and water solubility, changing the way of administration can be achieved through specific structural modification. Designing prodrugs by linking microenvironment-responsive groups to the prototype drugs is of great help in enhancing drug targeting. In the meantime, making connections between prodrugs and suitable drug delivery systems could realize drug loading increases, greater stability, bioavailability and drug release control. In this paper, lipidic, water-soluble, pH-responsive, redox-sensitive and enzyme-activatable prodrugs are reviewed on the basis of structural modification.

Extracellular Cues Govern Shape and Cytoskeletal Organization in Giant Unilamellar Lipid Vesicles

Spontaneous and induced front-rear polarization and a subsequent asymmetric actin cytoskeleton is a crucial event leading to cell migration, a key process involved in a variety of physiological and pathological conditions such as tissue development, wound healing, and cancer. Migration of adherent cells relies on the balance between adhesion to the underlying matrix and cytoskeleton-driven front protrusion and rear retraction. A current challenge is to uncouple the effect of adhesion and shape from the contribution of the cytoskeleton in regulating the onset of front-rear polarization. Here, we present a minimal model system that introduces an asymmetric actin cytoskeleton in synthetic cells, which are resembled by giant unilamellar lipid vesicles (GUVs) adhering onto symmetric and asymmetric micropatterned surfaces. Surface micropatterning of streptavidin-coated regions with varying adhesion shape and area was achieved by maskless UV photopatterning. To further study the effects of GUV shape on the cytoskeletal organization, actin filaments were polymerized together with bundling proteins inside the GUVs. The micropatterns induce synthetic cell deformation upon adhesion to the surface, with the cell shape adapting to the pattern shape and size. As expected, asymmetric patterns induce an asymmetric deformation in adherent synthetic cells. Actin filaments orient along the long axis of the deformed GUV, when having a length similar to the size of the major axis, whereas short filaments exhibit random orientation. With this bottom-up approach we have laid the first steps to identify the relationship between cell front-rear polarization and cytoskeleton organization in the future. Such a minimal system will allow us to further study the major components needed to create a polarized cytoskeleton at the onset of migration.

Stemness potency and structural characteristics of thyroid cancer cell lines

BACKGROUND

Thyroid cancer is the most frequent type of endocrine malignancy. Thyroid carcinomas are derived from the follicular epithelium and classified as papillary (PTC) (85%), follicular (FTC) (12%), and anaplastic (ATC) (<3%). Thyroid cancer could arise from thyroid cancer stem-like cells (CSCs). CSCs are cancer cells that feature stem-like properties. Kruppel-like factor (KLF4) and Stage-spesific embryonic antigen 1 (SSEA-1) are types of stem cell markers. Filamentous actin (F-actin) is an essential part of the cellular cytoskeleton. The purpose of this study was to evaluate the stem cell potency and the spatial distribution of the cytoskeletal element F-actin in PTC, FTC, and ATC cell lines.

MATERIALS AND METHODS

Normal thyroid cell line (NTC) Nthy-ori-3-1, PTC cell line BCPAP, FTC cell line FTC-133 and ATC cell line 8505c were stained with SSEA-1 and KLF4 for stem cell potency and F-actin for cytoskeleton. The morphological properties of cells were assessed by a scanning electron microscope (SEM) and elemental ratios were compared with EDS.

RESULTS

PTCs had greater percentages of SSEA-1 and KLF4 protein intensity (0.32% and 0.49%, respectively) than NTCs. ATCs had a greater proportion of KLF4 expression (0.8%) than NTCs. NTCs and FTCs had increased F-actin intensity across the cell, but PTCs had the lowest among these four cell lines. NTCs and PTCs, as well as NTCs and FTCs, have statistically identical aspect ratios and round values. These values, however, were statistically different in ATCs.

CONCLUSION

The study of stem cell markers and the cytoskeletal element F-actin in cancer and normal thyroid cell lines may assist in the identification of new therapeutic targets and contribute in the understanding of treatment resistance mechanisms.

Therapeutic potential of Curcuma oil and its terpenoids in gynecological cancers

BACKGROUND

Gynecological cancers encompass all uncontrolled and aberrant cell growth in the female reproductive system, therapeutic interventions are constantly evolving, but there is still a high death rate, significant side effects and medication resistance, making the task of treatment challenging and complex. The essential oil extracted from the rhizome of Curcuma longa is a promising natural drug, which has excellent biological activity on cancer cells and is to be developed as a new type of anti-gynecological tumor therapeutic agent.

PURPOSE

To systematically summarize the available evidence for the efficacy of Curcuma oil and its terpenoids (β-elemene, curcumol, furanodiene, and germacrone) in gynecological cancers, primarily malignancies of the reproductive system, involving ovarian, cervical, and endometrial cancers, explain the underlying mechanisms of preventing and treating gynecological cancers, and assess the shortcomings of existing work.

RESULTS

Through several signaling channels, Curcuma oil and its terpenoids can not only stop the growth of ovarian cancer, cervical cancer, and endometrial cancer cells, limit the formation of tumors, but also raise the effectiveness of chemotherapy drugs and improve the quality of life for patients.

CONCLUSION

It provides a preclinical basis for the efficacy of Curcuma oil as a broad-spectrum anti-tumor agent for the prevention and treatment of gynecological cancers. Even so, further efforts are still needed to improve the bioavailability of Curcuma oil and upgrade related experiments.

Amphiphilic sodium alginate-polylysine hydrogel with high antibacterial efficiency in a wide pH range

Bacterial infection is a major pathological factor leading to persistent wounds. With the aging of population, wound infection has gradually become a global health-issue. The wound site environment is complicated, and the pH changes dynamically during healing. Therefore, there is an urgent need for new antibacterial materials that can adapt to a wide pH range. To achieve this goal, we developed a thymol-oligomeric tannic acid/amphiphilic sodium alginate-polylysine hydrogel film, which exhibited excellent antibacterial efficacy in the pH range from 4 to 9, achieving the highest achievable 99.993 % (4.2 log units) and 99.62 % (2.4 log units) against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli, respectively. The hydrogel films exhibited excellent cytocompatibility, suggesting that the materials are promising as a novel wound healing material without the concern of biosafety.

Peroxidase-like MoS2/Ag nanosheets with synergistically enhanced NIR-responsive antibacterial activities

Pathogenic microbial infections have been threatening public health all over the world, which makes it highly desirable to develop an antibiotics-free material for bacterial infection. In this paper, molybdenum disulfide (MoS₂) nanosheets loaded with silver nanoparticles (Ag NPs) were constructed to inactive bacteria rapidly and efficiently in a short period under a near infrared (NIR) laser (660 nm) in the presence of H₂O₂. The designed material presented favorable features of peroxidase-like ability and photodynamic property, which endowed it with fascinating antimicrobial capacity. Compared with free MoS₂ nanosheets, the MoS₂/Ag nanosheets (denoted as MoS₂/Ag NSs) exhibited better antibacterial performance against Staphylococcus aureus by the generated reactive oxygen species (ROS) from both peroxidase-like catalysis and photodynamic, and the antibacterial efficiency of MoS₂/Ag NSs could be further improved by increasing the amount of Ag. Results from cell culture tests proved that MoS₂/Ag3 nanosheets had a negligible impact on cell growth. This work provided new insight into a promising method for eliminating bacteria without using antibiotics, and could serve as a candidate strategy for efficient disinfection to treat other bacterial infections.

Convergence of Biofabrication Technologies and Cell Therapies for Wound Healing

BACKGROUND

Cell therapy holds great promise for cutaneous wound treatment but presents practical and clinical challenges, mainly related to the lack of a supportive and inductive microenvironment for cells after transplantation. Main: This review delineates the challenges and opportunities in cell therapies for acute and chronic wounds and highlights the contribution of biofabricated matrices to skin reconstruction. The complexity of the wound healing process necessitates the development of matrices with properties comparable to the extracellular matrix in the skin for their structure and composition. Over recent years, emerging biofabrication technologies have shown a capacity for creating complex matrices. In cell therapy, multifunctional material-based matrices have benefits in enhancing cell retention and survival, reducing healing time, and preventing infection and cell transplant rejection. Additionally, they can improve the efficacy of cell therapy, owing to their potential to modulate cell behaviors and regulate spatiotemporal patterns of wound healing.

CONCLUSION

The ongoing development of biofabrication technologies promises to deliver material-based matrices that are rich in supportive, phenotype patterning cell niches and are robust enough to provide physical protection for the cells during implantation.

Topographical biointerface regulating cellular functions for bone tissue engineering

The physiochemical properties of the implant interface significantly influence cell growth, differentiation, cellular matrix deposition, and mineralisation, and eventually, determine the bone regeneration efficiency. Cells directly sense and respond to the physical, chemical, and mechanical cues of the implant surface, and it is increasingly recognized that surface topography can evoke specific cellular responses, conferring biological functions on substrate materials and regulating tissue regeneration. Current progress towards the fundamental understanding of the interplay between the cell and topographical surface has been made by combined advance in fabrication technologies and cell biology. Particularly, the precise fabrication and control of nano/microscale topographies can provide the fundamental knowledge of the mechanotransduction process that governs the cellular response as well as the knowledge of how the specific features drive cells towards a defined differentiation outcome. In this review, we first introduce common techniques and substrate materials for designing and fabricating micro/nano‐topographical surfaces for bone regeneration. We then illustrate the intrinsic relationship of topological cues, cellular signal transduction, and cell functions and fates in osteogenic differentiation. Finally, we discuss the challenges and the future of using topological cues as a cell therapy to direct bone tissue regeneration.

Quantitative analysis of biomolecule release from polystyrene-block-polyethylene oxide thin films

Block copolymers have garnered recent attention due to their ability to contain molecular cargo within nanoscale domains and release said cargo in aqueous environments. However, the release kinetics of cargo from these thin-films has not yet been reported. Knowledge of the release quantities and release profiles of these systems is paramount for applications of these systems. Here, Polystyrene-block-poly(ethylene oxide) (PS-b-PEO) was co-assembled with fluorescein isothiocyanate isomer I-lysozyme (FITC-LZ) and fluorescein isothiocyanate isomer I-TAT (FITC-TAT), such that these molecular cargos arrange within the PEO domains of the thin films. We show that high loading ratios of cargo/PS-b-PEO do not significantly impact the nanostructure of the films; however, a loading limit appears to be present with aggregates of protein forming at the microscale with higher loading ratios. The presence of lysozyme (LZ) within the films was confirmed qualitatively after aqueous exposure through photo-induced force microscopy (PiFM) imaging at the Amide I characteristic peak (∼1650 cm^-1). Furthermore, we demonstrate that LZ maintains activity and structure after exposure to the polymer solvent (benzene/methanol/water mix). Finally, we demonstrate quantitatively 20-80 ng cm^-2 of cargo is released from these films, depending on the cargo incorporated. We show that the larger molecule lysozyme is released over a longer time than the smaller TAT peptide. Finally, we demonstrate the ability to tune the quantity of cargo released by altering the thickness of the PS-b-PEO thin-films during fabrication.

Micro-patterned cell populations as advanced pharmaceutical drugs with precise functional control

Human cells are both advanced pharmaceutical drugs and 'drug deliverers'. However, functional control prior to or after cell implantation remains challenging. Micro-patterning cells through geometrically defined adhesion sites allows controlling morphogenesis, polarity, cellular mechanics, proliferation, migration, differentiation, stemness, cell-cell interactions, collective cell behavior, and likely immuno-modulatory properties. Consequently, generating micro-patterned therapeutic cells is a promising idea that has not yet been realized and few if any steps have been undertaken in this direction. This review highlights potential therapeutic applications, summarizes comprehensively the many cell functions that have been successfully controlled through micro-patterning, details the established micro-pattern designs, introduces the available fabrication technologies to the non-specialized reader, and suggests a quality evaluation score. Such a broad review is not yet available but would facilitate the manufacturing of therapeutically patterned cell populations using micro-patterned cell-instructive biomaterials for improved functional control as drug delivery systems in the context of cells as pharmaceutical products.

Scaffold Pore Curvature Influences ΜSC Fate through Differential Cellular Organization and YAP/TAZ Activity

Tissue engineering aims to repair, restore, and/or replace tissues in the human body as an alternative to grafts and prostheses. Biomaterial scaffolds can be utilized to provide a three-dimensional microenvironment to facilitate tissue regeneration. Previously, we reported that scaffold pore size influences vascularization and extracellular matrix composition both in vivo and in vitro, to ultimately influence tissue phenotype for regenerating cranial suture and bone tissues, which have markedly different tissue properties despite similar multipotent stem cell populations. To rationally design biomaterials for specific cell and tissue fate specification, it is critical to understand the molecular processes governed by cell-biomaterial interactions, which guide cell fate specification. Building on our previous work, in this report we investigated the hypothesis that scaffold pore curvature, the direct consequence of pore size, modulates the differentiation trajectory of mesenchymal stem cells (MSCs) through alterations in the cytoskeleton. First, we demonstrated that sufficiently small pores facilitate cell clustering in subcutaneous explants cultured in vivo, which we previously reported to demonstrate stem tissue phenotype both in vivo and in vitro. Based on this observation, we cultured cell-scaffold constructs in vitro to assess early time point interactions between cells and the matrix as a function of pore size. We demonstrate that principle curvature directly influences nuclear aspect and cell aggregation in vitro. Scaffold pores with a sufficiently low degree of principle curvature enables cell differentiation; pharmacologic inhibition of actin cytoskeleton polymerization in these scaffolds decreased differentiation, indicating a critical role of the cytoskeleton in transducing cues from the scaffold pore microenvironment to the cell nucleus. We fabricated a macropore model, which allows for three-dimensional confocal imaging and demonstrates that a higher principle curvature facilitates cell aggregation and the formation of a potentially protective niche within scaffold macropores which prevents MSC differentiation and retains their stemness. Sufficiently high principle curvature upregulates yes-associated protein (YAP) phosphorylation while decreased principle curvature downregulates YAP phosphorylation and increases YAP nuclear translocation with subsequent transcriptional activation towards an osteogenic differentiation fate. Finally, we demonstrate that the inhibition of the YAP/TAZ pathway causes a defect in differentiation, while YAP/TAZ activation causes premature differentiation in a curvature-dependent way when modulated by verteporfin (VP) and 1-oleyl-lysophosphatidic acid (LPA), respectively, confirming the critical role of biomaterials-mediated YAP/TAZ signaling in cell differentiation and fate specification. Our data support that the principle curvature of scaffold macropores is a critical design criterion which guides the differentiation trajectory of mesenchymal stem cells' scaffolds. Biomaterial-mediated regulation of YAP/TAZ may significantly contribute to influencing the regenerative outcomes of biomaterials-based tissue engineering strategies through their specific pore design.

Nitrogen-doped carbon dots as a fluorescent probe for folic acid detection and live cell imaging

The folic acid (FA) level in human body can be used as an indicator for body's normal physiological activities and offer insight into the growth and reproduction of the body's cells. But the abnormal level of FA can cause some diseases. Herein, we designed a simple and convenient approach to prepare fluorescent N-doped carbon dots (N-CDs) for the FA detection. These N-CDs have excellent hydrophilicity, high photostability, and outstanding biocompatibility, as well as excitation-independent emission behavior with typical excitation/emission peaks at 295 nm/412 nm. Upon the existence of FA, the fluorescence emission spectrum of N-CDs was significantly quenched through the synergy of static quenching mechanism and internal filtering effect (IFE). Under optimal conditions, the limit of detection was 28.0 nM (S/N = 3) within the FA concentration range of 0-200.0 μM. In addition, N-CDs were successfully employed to detect FA in real samples such as urine and fetal bovine serum (FBS), with a recovery rate of 99.6%-100.7% for quantitative addition. Furthermore, cell experiments confirmed the low toxicity and the cell imaging performance of these N-CDs, indicating that the obtained N-CDs could be served as a credible quantitative probe for FA analysis in the field of biosensing.

The crescendo pulse frequency of shear stress stimulates the endothelialization of bone marrow mesenchymal stem cells on the luminal surface of decellularized scaffold in the bioreactor

A completely confluent endothelial cell (EC) monolayer is required to maintain proper vascular function in small diameter tissue-engineered vascular graft (TEVG). However, the most effective method for EC attachment to the luminal surface and formation of an entire endothelium layer that works in vitro remains a complicated challenge that requires urgent resolution. Although pulsatile flow has been shown to be better suited for the generation of functional endothelium, the optimal frequency setting is unknown. Several pulsatile flow frequencies were used to implant rat bone mesenchymal stem cells (MSC) into the lumen of decellularized porcine carotid arteries. The endothelium's integrity and cell activity were investigated in order to determine the best pulse frequency settings. The results showed that MSC were maximally preserved and exhibited maximal morphological changes with improved endothelialization performance in response to increased pulse stimulation frequency. Increased pulse frequency stimulation stimulates the expression of mechanoreceptor markers, cytoskeleton reorganization in the direction of blood flow, denser skeletal proteins fibronectin, and stronger intercellular connections when compared to constant pulse frequency stimulation. MSC eventually develops an intact endothelial layer with anti-thrombotic properties on the inner wall of the decellularized tubular lumen. Conclusion: The decellularized vessels retain the three-dimensional structure of the vasculature, have a surface topography suitable for MSC growth, and have good mechanical properties. By increasing the frequency of pulsed stimulation, MSC endothelialize the lumen of the decellularized vasculature. It is expected to have anti-thrombotic and anti-neointimal hyperplasia properties after implantation, ultimately improving the patency of TEVG.

Pillar-Based Mechanical Induction of an Aggressive Tumorigenic Lung Cancer Cell Model

Tissue microarchitecture imposes physical constraints to the migration of individual cells. Especially in cancer metastasis, three-dimensional structural barriers within the extracellular matrix are known to affect the migratory behavior of cells, regulating the pathological state of the cells. Here, we employed a culture platform with micropillar arrays of 2 μm diameter and 16 μm pitch (2.16 micropillar) as a mechanical stimulant. Using this platform, we investigated how a long-term culture of A549 human lung carcinoma cells on the (2.16) micropillar-embossed dishes would influence the pathological state of the cell. A549 cells grown on the (2.16) micropillar array with 10 μm height exhibited a significantly elongated morphology and enhanced migration even after the detachment and reattachment, as evidenced in the conventional wound-healing assay, single-cell tracking analysis, and in vivo tumor colonization assays. Moreover, the pillar-induced morphological deformation in nuclei was accompanied by cell-cycle arrest in the S phase, leading to suppressed proliferation. While these marked traits of morphology-migration-proliferation support more aggressive characteristics of metastatic cancer cells, typical indices of epithelial-mesenchymal transition were not found, but instead, remarkable traces of amoeboidal transition were confirmed. Our study also emphasizes the importance of mechanical stimuli from the microenvironment during pathogenesis and how gained traits can be passed onto subsequent generations, ultimately affecting their pathophysiological behavior. Furthermore, this study highlights the potential use of pillar-based mechanical stimuli as an in vitro cell culture strategy to induce more aggressive tumorigenic cancer cell models.

A Cell Culture Chip with Transparent, Micropillar-Decorated Bottom for Live Cell Imaging and Screening of Breast Cancer Cells

In the recent years, microfabrication technologies have been widely used in cell biology, tissue engineering, and regenerative medicine studies. Today, the implementation of microfabricated devices in cancer research is frequent and advantageous because it enables the study of cancer cells in controlled microenvironments provided by the microchips. Breast cancer is one of the most common cancers in women, and the way breast cancer cells interact with their physical microenvironment is still under investigation. In this study, we developed a transparent cell culture chip (Ch-Pattern) with a micropillar-decorated bottom that makes live imaging and monitoring of the metabolic, proliferative, apoptotic, and morphological behavior of breast cancer cells possible. The reason for the use of micropatterned surfaces is because cancer cells deform and lose their shape and acto-myosin integrity on micropatterned substrates, and this allows the quantification of the changes in morphology and through that identification of the cancerous cells. In the last decade, cancer cells were studied on micropatterned substrates of varying sizes and with a variety of biomaterials. These studies were conducted using conventional cell culture plates carrying patterned films. In the present study, cell culture protocols were conducted in the clear-bottom micropatterned chip. This approach adds significantly to the current knowledge and applications by enabling low-volume and high-throughput processing of the cell behavior, especially the cell–micropattern interactions. In this study, two different breast cancer cell lines, MDA-MB-231 and MCF-7, were used. MDA-MB-231 cells are invasive and metastatic, while MCF-7 cells are not metastatic. The nuclei of these two cell types deformed to distinctly different levels on the micropatterns, had different metabolic and proliferation rates, and their cell cycles were affected. The Ch-Pattern chips developed in this study proved to have significant advantages when used in the biological analysis of live cells and highly beneficial in the study of screening breast cancer cell–substrate interactions in vitro.

Review on material parameters to enhance bone cell function in vitro and in vivo

Bone plays critical roles in support, protection, movement, and metabolism. Although bone has an innate capacity for regeneration, this capacity is limited, and many bone injuries and diseases require intervention. Biomaterials are a critical component of many treatments to restore bone function and include non-resorbable implants to augment bone and resorbable materials to guide regeneration. Biomaterials can vary considerably in their biocompatibility and bioactivity, which are functions of specific material parameters. The success of biomaterials in bone augmentation and regeneration is based on their effects on the function of bone cells. Such functions include adhesion, migration, inflammation, proliferation, communication, differentiation, resorption, and vascularization. This review will focus on how different material parameters can enhance bone cell function both in vitro and in vivo.

Hepatitis B virus infection modeling using multi-cellular organoids derived from human induced pluripotent stem cells

Chronic infection with hepatitis B virus (HBV) remains a global health concern despite the availability of vaccines. To date, the development of effective treatments has been severely hampered by the lack of reliable, reproducible, and scalable in vitro modeling systems that precisely recapitulate the virus life cycle and represent virus-host interactions. With the progressive understanding of liver organogenesis mechanisms, the development of human induced pluripotent stem cell (iPSC)-derived hepatic sources and stromal cellular compositions provides novel strategies for personalized modeling and treatment of liver disease. Further, advancements in three-dimensional culture of self-organized liver-like organoids considerably promote in vitro modeling of intact human liver tissue, in terms of both hepatic function and other physiological characteristics. Combined with our experiences in the investigation of HBV infections using liver organoids, we have summarized the advances in modeling reported thus far and discussed the limitations and ongoing challenges in the application of liver organoids, particularly those with multi-cellular components derived from human iPSCs. This review provides general guidelines for establishing clinical-grade iPSC-derived multi-cellular organoids in modeling personalized hepatitis virus infection and other liver diseases, as well as drug testing and transplantation therapy.

Fluid Flow Mechanical Stimulation-Assisted Cartridge Device for the Osteogenic Differentiation of Human Mesenchymal Stem Cells

Human mesenchymal stem cells (hMSCs) have the potential to differentiate into different types of mesodermal tissues. In vitro proliferation and differentiation of hMSCs are necessary for bone regeneration in tissue engineering. The present study aimed to design and develop a fluid flow mechanically-assisted cartridge device to enhance the osteogenic differentiation of hMSCs. We used the fluorescence-activated cell-sorting method to analyze the multipotent properties of hMSCs and found that the cultured cells retained their stemness potential. We also evaluated the cell viabilities of the cultured cells via water-soluble tetrazolium salt 1 (WST-1) assay under different rates of flow (0.035, 0.21, and 0.35 mL/min) and static conditions and found that the cell growth rate was approximately 12% higher in the 0.035 mL/min flow condition than the other conditions. Moreover, the cultured cells were healthy and adhered properly to the culture substrate. Enhanced mineralization and alkaline phosphatase activity were also observed under different perfusion conditions compared to the static conditions, indicating that the applied conditions play important roles in the proliferation and differentiation of hMSCs. Furthermore, we determined the expression levels of osteogenesis-related genes, including the runt-related protein 2 (Runx2), collagen type I (Col1), osteopontin (OPN), and osteocalcin (OCN), under various perfusion vis-à-vis static conditions and found that they were significantly affected by the applied conditions. Furthermore, the fluorescence intensities of OCN and OPN osteogenic gene markers were found to be enhanced in the 0.035 mL/min flow condition compared to the control, indicating that it was a suitable condition for osteogenic differentiation. Taken together, the findings of this study reveal that the developed cartridge device promotes the proliferation and differentiation of hMSCs and can potentially be used in the field of tissue engineering.

A bio-inspired self-recoverable polyampholyte hydrogel with low temperature sensing

Hydrogel-based flexible sensors have been extensively investigated, but inevitably, some hydrogels will not work properly at low temperature or recover their original property after deformation. In this work, a polyampholyte hydrogel was successfully prepared by introducing zwitterionic monomers with hydrophobic association. The electrostatic interaction based on polyelectrolyte provides excellent stretchability, fatigue resistance and self-recovery. It was important that the hydrogel, as an excellent strain sensor, exhibited a high electrical conductivity of 0.041 S cm-1, a low temperature resistance of -31.7 °C, and a high sensitivity in the strain range of 0-500%. The hydrogel sensor is used for human motion detection, including joint movement, vocalization, and walking. Predictably, the hydrogel will provide stable performance in a complex temperature environment and exhibited a wide range of applications in physiological signal monitoring, electronic skin and soft robots.

Regulating the uptake of poly(N-(2-hydroxypropyl) methacrylamide)-based micelles in cells cultured on micropatterned surfaces

Cellular uptake of nanoparticles plays a crucial role in cell-targeted biomedical applications. Despite abundant studies trying to understand the interaction between nanoparticles and cells, the influence of cell geometry traits such as cell spreading area and cell shape on the uptake of nanoparticles remains unclear. In this study, poly(vinyl alcohol) is micropatterned on polystyrene cell culture plates using ultraviolet photolithography to control the spreading area and shape of individual cells. The effects of these factors on the cellular uptake of poly(N-(2-hydroxypropyl)methacrylamide)-based micelles were investigated at a single-cell level. Human carcinoma MCF-7 and A549 cells as well as normal Hs-27 and MRC-5 fibroblasts were cultured on micropatterned surfaces. MCF-7 and A549 cells, both with larger sizes, had a higher total micelle uptake. However, the uptake of Hs-27 and MRC-5 cells decreased with increasing spreading area. In terms of cell shapes, MCF-7 and A549 cells with round shapes showed a higher micelle uptake, while those with a square shape had a lower cellular uptake. On the other hand, Hs-27 and MRC-5 cells showed opposite behaviors. The results indicate that the geometry of cells can influence the nanoparticle uptake and may shed light on the design of functional nanoparticles.

Adhesion and Growth of Neuralized Mouse Embryonic Stem Cells on Parylene-C/SiO2 Substrates

Neuronal patterning on microfabricated architectures has developed rapidly over the past few years, together with the emergence of soft biocompatible materials and tissue engineering scaffolds. Previously, we introduced a patterning technique based on serum and the biopolymer parylene-C, achieving highly compliant growth of primary neurons and astrocytes on different geometries. Here, we expanded this technique and illustrated that neuralized cells derived from mouse embryonic stem cells (mESCs) followed stripes of variable widths with conformity equal to or higher than that of primary neurons and astrocytes. Our results indicate the presence of undifferentiated mESCs, which also conformed to the underlying patterns to a high degree. This is an exciting and unexpected outcome, as molecular mechanisms governing cell and ECM protein interactions are different in stem cells and primary cells. Our study enables further investigations into the development and electrophysiology of differentiating patterned neural stem cells.

Synergistic Effect of Biomaterial and Stem Cell for Skin Tissue Engineering in Cutaneous Wound Healing: A Concise Review

Skin tissue engineering has made remarkable progress in wound healing treatment with the advent of newer fabrication strategies using natural/synthetic polymers and stem cells. Stem cell therapy is used to treat a wide range of injuries and degenerative diseases of the skin. Nevertheless, many related studies demonstrated modest improvement in organ functions due to the low survival rate of transplanted cells at the targeted injured area. Thus, incorporating stem cells into biomaterial offer niches to transplanted stem cells, enhancing their delivery and therapeutic effects. Currently, through the skin tissue engineering approach, many attempts have employed biomaterials as a platform to improve the engraftment of implanted cells and facilitate the function of exogenous cells by mimicking the tissue microenvironment. This review aims to identify the limitations of stem cell therapy in wound healing treatment and potentially highlight how the use of various biomaterials can enhance the therapeutic efficiency of stem cells in tissue regeneration post-implantation. Moreover, the review discusses the combined effects of stem cells and biomaterials in in vitro and in vivo settings followed by identifying the key factors contributing to the treatment outcomes. Apart from stem cells and biomaterials, the role of growth factors and other cellular substitutes used in effective wound healing treatment has been mentioned. In conclusion, the synergistic effect of biomaterials and stem cells provided significant effectiveness in therapeutic outcomes mainly in wound healing improvement.