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When science contradicts people’s experiences, they often deny the science. Psychological science may be particularly prone to denialism because of its relatively high relevance to people’s lives. In two sets of studies ( N = 637 from university students and Mechanical Turk workers), we tested whether perceived and actual incongruence between one’s personality and scientific findings predict psychological discomfort and science denialism. Participants rated the incongruence (subjective incongruence) between their own personality responses and science, as well as their comfort and denial of the science. Those who experienced more subjective incongruence experienced greater discomfort and reported more science denialism. Those whose personality characteristics were objectively incongruent with the science also experienced greater subjective incongruence (all studies), discomfort (Studies 1A, 1B, and 1C), and science denialism (Studies 1A, 1C, and 2B) compared with those with congruent characteristics. Implications regarding denialism of psychological science, and science more broadly, are discussed.

A combination of ultrahigh-speed optical imaging (5 × 106 frames/s), B-mode ultrasound and passive cavitation detection was used to study the vaporization process and determine both the acoustic droplet vaporization (ADV) and inertial cavitation (IC) thresholds of phospholipid-coated perfluorobutane nanodroplets (PFB NDs, diameter = 237 ± 16 nm). PFB NDs have not previously been studied with ultrahigh-speed imaging and were observed to form individual microbubbles (1–10 μm) within two to three cycles and subsequently larger bubble clusters (10–50 μm). The ADV and IC thresholds did not statistically significantly differ and decreased with increasing pulse length (20–20,000 cycles), pulse repetition frequency (1–100 Hz), concentration (108–1010 NDs/mL), temperature (20°C–45°C) and decreasing frequency (1.5–0.5 MHz). Overall, the results indicate that at frequencies of 0.5, 1.0 and 1.5 MHz, PFB NDs can be vaporized at moderate peak negative pressures (

Nostalgia is an emotion that confers psychological benefits. The literature has neglected romantic nostalgia—that is, nostalgia specifically for past experiences shared with one’s partner—and its potential advantages for relationships. We examined romantic nostalgia in one correlational study, two experiments, and one daily diary study ( N = 638). Romantic nostalgia was positively associated with greater relationship commitment, satisfaction, and closeness (Study 1). Additionally, inducing romantic nostalgia via a writing task (Study 2) or music (Study 3) strengthened relational benefits. Finally, participants reported more positive relationship-specific experiences on days when they felt greater romantic nostalgia (Study 4). We discuss contributions to the nostalgia and relationships literatures.

Synthetic clays are promising biomaterials for delivery of therapeutic molecules in regenerative medicine. However, before their use can be translated into clinical applications, their safety must be assessed in human volunteers. The aim of this study was to test the hypothesis that a synthetic nanoclay (LAPONITE) does not cause irritation to the human skin. To achieve this, a nanoclay gel at two different concentrations (1.5 and 3% w/v) was applied on the forearm of healthy volunteers for 24 h. 1% sodium lauryl sulfate (SLS) and 3% (w/v) polyacrylic acid were used as the positive and negative controls, respectively. The compromise in the skin barrier function was measured by trans-epidermal water loss (TEWL), erythema by spectroscopic measurements, and skin inflammatory biomarkers (IL-1α and IL-1RA) by the enzyme-linked immunosorbent assay. We found that the nanoclay caused no prolonged increase in TEWL, erythema, or induction of inflammatory cytokines. This was in contrast to 1% SLS, a known irritant, which induced significant increases in both skin erythema and TEWL. We conclude that the nanoclay is not an irritant and is thus suitable for therapeutic interventions at the skin surface.

People often reflect nostalgicallyon the momentous occasions of their relationships. Experiencing romantic nostalgia-nostalgia for shared experiences with one's current romantic partner-likely confers relationship-specific benefits. Indeed, prior research indirectly hints at this assumed outcome by looking at relationship narratives. More recent work provides direct evidence that romantic nostalgia is both positively correlated with and causally enhances relationship-specific benefits. We describe such research and discuss avenues for future investigations that address mechanisms and potential downsides of romantic nostalgia while exploring translational possibilities.

Abstract. Empathy and perspective taking play important roles in interpersonal functioning. As prior research has linked metaphor use to emotional understanding, it is likely that metaphor use is also involved in empathy and perspective taking. In two daily diary studies ( N = 225; Obs. = 1,849), we predicted that on days in which empathy and perspective taking were high, participants would also report higher metaphor use. In Study 1, we found support for our hypotheses, such that daily metaphor use was positively associated with daily empathy and perspective taking. In Study 2, we replicated these results. We place this work within the current literature and discuss the promise of an interpersonal function of metaphor use.

LAPONITE® clay nanoparticles are known to exert osteogenic effects on human bone marrow stromal cells (HBMSCs), most characteristically, an upregulation in alkaline phosphatase activity and increased calcium deposition. The specific properties of LAPONITE® that impart its bioactivity are not known. In this study the role of lithium, a LAPONITE® degradation product, was investigated through the use of lithium salts and lithium modified LAPONITE® formulations. In contrast to intact particles, lithium ions applied at concentrations equivalent to that present in LAPONITE®, failed to induce any significant increase in alkaline phosphatase (ALP) activity. Furthermore, no significant differences were observed in ALP activity with modified clay structures and the positive effect on osteogenic gene expression did not correlate with the lithium content of modified clays. These results suggest that other properties of LAPONITE® nanoparticles, and not their lithium content, are responsible for their bioactivity.

Organoids can shed light on the dynamic interplay between complex tissues and rare cell types within a controlled microenvironment. Here, we develop gut organoid cocultures with type-1 innate lymphoid cells (ILC1) to dissect the impact of their accumulation in inflamed intestines. We demonstrate that murine and human ILC1 secrete transforming growth factor β1, driving expansion of CD44v6 + epithelial crypts. ILC1 additionally express MMP9 and drive gene signatures indicative of extracellular matrix remodelling. We therefore encapsulated human epithelial–mesenchymal intestinal organoids in MMP-sensitive, synthetic hydrogels designed to form efficient networks at low polymer concentrations. Harnessing this defined system, we demonstrate that ILC1 drive matrix softening and stiffening, which we suggest occurs through balanced matrix degradation and deposition. Our platform enabled us to elucidate previously undescribed interactions between ILC1 and their microenvironment, which suggest that they may exacerbate fibrosis and tumour growth when enriched in inflamed patient tissues.

Melioidosis caused by the facultative intracellular pathogen Burkholderia pseudomallei is difficult to treat due to poor intracellular bioavailability of antibiotics and antibiotic resistance. In the absence of novel compounds, polymersome (PM)-encapsulation may increase the efficacy of existing antibiotics and reduce antibiotic resistance by promoting targeted, infection-specific intracellular uptake. In this study we developed PMs composed of widely available polyethylene oxide-polycaprolactone (PEO-PCL) block co-polymers and demonstrated their delivery to intracellular B. thailandensis infection using multispectral imaging flow cytometry (IFC) and coherent anti-Stokes Raman scattering (CARS) microscopy. Antibiotics were tightly sequestered in PMs and did not inhibit the growth of free-living B. thailandensis. However, on uptake of antibiotic-loaded PMs by infected macrophages, IFC demonstrated PM co-localisation with intracellular B. thailandensis and a significant inhibition of their growth. We conclude that PMs are a viable approach for the targeted antibiotic treatment of persistent intracellular Burkholderia infection.

Highlights • Increasing the volumetric concentration of PFP led to an increase in the size of lipid-coated PFP NDs. • Increasing sonication intensity and time led to a decrease in ND size. • The ND coating layer can be labelled with lipophilic fluorophores without affecting the overall ND size. • NDs were stable at 4 °C for one week, and at 37 °C for 110 min. • Ultrasound (0.5 MHz, 2–4 MPa) caused vaporisation of NDs within a tissue-mimicking phantom., Liquid perfluorocarbon nanodroplets (NDs) are an attractive alternative to microbubbles (MBs) for ultrasound-mediated therapeutic and diagnostic applications. ND size and size distribution have a strong influence on their behaviour in vivo, including extravasation efficiency, circulation time, and response to ultrasound stimulation. Thus, it is desirable to identify ways to tailor the ND size and size distribution during manufacturing. In this study phospholipid-coated NDs, comprising a perfluoro-n-pentane (PFP) core stabilised by a DSPC/PEG40s (1,2-distearoyl-sn-glycero-3-phosphocholine and polyoxyethylene(40)stearate, 9:1 molar ratio) shell, were produced in phosphate-buffered saline (PBS) by sonication. The effect of the following production-related parameters on ND size was investigated: PFP concentration, power and duration of sonication, and incorporation of a lipophilic fluorescent dye. ND stability was also assessed at both 4 °C and 37 °C. When a sonication pulse of 6 s and 15% duty cycle was employed, increasing the volumetric concentration of PFP from 5% to 15% v/v in PBS resulted in an increase in ND diameter from 215.8 ± 16.8 nm to 408.9 ± 171.2 nm. An increase in the intensity of sonication from 48 to 72 W (with 10% PFP v/v in PBS) led to a decrease in ND size from 354.6 ± 127.2 nm to 315.0 ± 100.5 nm. Increasing the sonication time from 20 s to 40 s (using a pulsed sonication with 30% duty cycle) did not result in a significant change in ND size (in the range 278–314 nm); however, when it was increased to 60 s, the average ND diameter reduced to 249.7 ± 9.7 nm, which also presented a significantly lower standard deviation compared to the other experimental conditions investigated (i.e., 9.7 nm vs. > 49.4 nm). The addition of the fluorescent dye DiI at different molar ratios did not affect the ND size distribution. NDs were stable at 4 °C for up to 6 days and at 37 °C for up to 110 min; however, some evidence of ND-to-MB phase transition was observed after 40 min at 37 °C. Finally, phase transition of NDs into MBs was demonstrated using a tissue-mimicking flow phantom under therapeutic ultrasound exposure conditions (ultrasound frequency: 0.5 MHz, acoustic pressure: 2–4 MPa, and pulse repetition frequency: 100 Hz).

A holographic model of chiral symmetry breaking is used to study the dynamics plus the meson and baryon spectrum of the underlying strong dynamics in composite Higgs models. The model is inspired by top-down D-brane constructions. We introduce this model by applying it to $N_f=2$ QCD. We compute meson masses, decay constants and the nucleon mass. The spectrum is improved by including higher dimensional operators to reflect the UV physics of QCD. Moving to composite Higgs models, we impose perturbative running for the anomalous dimension of the quark condensate in a variety of theories with varying number of colors and flavours. We compare our results in detail to lattice simulations for the following theories: $SU(2)$ gauge theory with two Dirac fundamentals; $Sp(4)$ gauge theory with fundamental and sextet matter; and $SU(4)$ gauge theory with fundamental and sextet quarks. In each case, the holographic results are encouraging since they are close to lattice results for masses and decay constants. Moreover, our models allow us to compute additional observables not yet computed on the lattice, to relax the quenched approximation and move to the precise fermion content of more realistic composite Higgs models not possible on the lattice. We also provide a new holographic description of the top partners including their masses and structure functions. With the addition of higher dimension operators, we show the top Yukawa coupling can be made of order one, to generate the observed top mass. Finally, we predict the spectrum for the full set of models with top partners proposed by Ferretti and Karateev., 57 pages + 5 pages (appendices), 20 figures, 12 tables; v2: minor additions, added references

Physical attraction is an important dimension of both romantic and companionate relationship of partners. This article presents a comprehensive cross-cultural validation of the short version of the Physical Attraction Scale (PAS-S) scale — the first and only multidimensional measure of physical attraction available for research and practice. The initial development of the scale was completed in a multisite study conducted with a large sample of university students, largely from the midwest and southeast of the United States. Results demonstrated a two-dimensional factor structure, excellent reliability, and evidence of content, convergent and discriminant validity. The following cross-cultural studies, which used the PAS-S, confirmed its robust factor structure, validity and reliability in the samples from 10 cultural regions in six countries. Therefore, this short version of the PAS-S can be recommended for cross-cultural practice and research. The versions of the scale in English, French, Portuguese, Russian and Georgian are provided in appendices. Based on the results of cross-cultural validation, authors recommend the PAS-S for research purposes and practical use in counselling and therapy. The scale provides a short and informative measure of (1) how a person feels attraction to their partner in close relationships and (2) which aspects of attraction are problematic.

Poly(N-isopropylacrylamide) (PNIPAm) is widely used to fabricate cell sheet surfaces for cell culturing, however copolymer and interpenetrated polymer networks based on PNIPAm have been rarely explored in the context of tissue engineering. Many complex and expensive techniques have been employed to produce PNIPAm-based films for cell culturing. Among them, spin coating has demonstrated to be a rapid fabrication process of thin layers with high reproducibility and uniformity. In this study, we introduce an innovative approach to produce anchored smart thin films both thermo- and electro-responsive, with the aim to integrate them in electronic devices and better control or mimic different environments for cells in vitro. Thin films were obtained by spin coating of colloidal solutions made by PNIPAm and PAAc nanogels. Anchoring the films to the substrates was obtained through heat treatment in the presence of dithiol molecules. From analyses carried out with AFM and XPS, the final samples exhibited a flat morphology and high stability to water washing. Viability tests with cells were finally carried out to demonstrate that this approach may represent a promising route to integrate those hydrogels films in electronic platforms for cell culture applications.

Nostalgizing confers social, existential, and self-oriented psychological benefits or functions. But how does the experience of nostalgia conduce to these functions? We propose that it does so, in part, through mental transportation, which involves mentally leaving one’s current space and transporting oneself into a past event. We addressed the role of mental transportation in one daily diary study and two experiments (N = 514). By assessing daily experiences of nostalgia in Study 1, we found that, on days in which participants felt more nostalgic, they were more likely to experience mental transportation. Following a narrative induction of nostalgia, we assessed mental transportation (Studies 2 and 3) and the three putative nostalgia functions: social, existential, self-oriented (Study 3). Nostalgic (vs. control) participants reported greater mental transportation (Studies 2 and 3), which in turn was associated with stronger functions (Study 3). The findings portray mental transportation as a key mechanism underlying the psychological benefits of nostalgia.

People use numerous metaphors to describe God. God is seen as a bearded man, light, and love. Based on metaphor theories, the metaphors people use to refer to God reflect how people think about God and could, in turn, reflect their worldview. However, little work has explored the common metaphors for God. This was the purpose of the current investigation. Four trained raters coded open-ended responses from predominantly Christian U.S. undergraduates (N = 2,923) describing God for the presence or absence of numerous metaphoric categories. We then assessed the frequency of each of the metaphor categories. We identified 16 metaphor categories that were present in more than 1% of the responses. The top categories were “GOD IS POWER,” “GOD IS HUMAN,” and “GOD IS MALE.” These findings were similar across religious affiliations. We attempted to support our coding analysis using top-down and bottom-up automated language analysis. Results from these analyses provided added confidence to our conclusions. We discuss the implications of our findings and the potential for future studies investigating important psychological and behavioral outcomes of using different metaphors for God.

The retention and sustained activity of therapeutic proteins at delivery sites are goals of regenerative medicine. Vascular endothelial growth factor (VEGF) has significant potential in promoting the growth and regeneration of blood vessels but is intrinsically labile. This is exacerbated by the inflammatory microenvironments at sites requiring regeneration. For VEGF to be efficacious, it may require a carrier that stabilises it, protects it from degradation and retains it at the site of interest. In this study, we tested the hypothesis that injectable nanoclay gels comprising Laponite™ XLG (a synthetic hectorite clay) can stabilise VEGF and retain it in the active form for therapeutic delivery. To achieve this, VEGF was incorporated in Laponite gels and its activity tested at a range of concentrations using in vitro cell culture tubulogenesis assays and in vivo angiogenesis assays. We found that VEGF-Laponite gels enhanced tubulogenesis in a dose-dependent manner in vitro. When administered subcutaneously in vivo, Laponite was retained at the injection site for up to a period of three weeks and promoted a 4-fold increase in blood vessel formation compared with that of alginate or vehicle controls as confirmed by CD31 staining. Notably, as compared to alginate, Laponite gels did not release VEGF, indicating a strong interaction between the growth factor and the nanoclay and suggesting that Laponite enhancement of VEGF efficacy is due to its retention at the implantation site for a prolonged period. Our approach provides a robust method for the delivery of bioactive recombinant VEGF without the necessity for complex hydrogel or protein engineering. STATEMENT OF SIGNIFICANCE: In medicine, it is important to deliver drugs to a particular location in the body. Often, however, the drugs are quickly broken down and carried away in the blood before they can exert their effect. In this study, we used a type of synthetic clay, called Laponite™, to preserve a molecule, named VEGF, that stimulates the growth of blood vessels. Previously, we have been able to bind VEGF to the surface of clays, but the clay is not effective when injected or applied as a gel. Herein, we show that we can mix VEGF with the clay and that it strongly stimulates blood vessel growth. We speculate that this would be a useful material for skin wound healing.

Activation of the canonical Wnt signaling pathway is an attractive anabolic therapeutic strategy for bone. Emerging data suggest that activation of the Wnt signaling pathway promotes bone mineral accrual in osteoporotic patients. The effect of Wnt stimulation in fracture healing is less clear as Wnt signaling has both stimulatory and inhibitory effects on osteogenesis. Here, we tested the hypothesis that transient Wnt stimulation promotes the expansion and osteogenesis of a Wnt-responsive stem cell population present in human bone marrow. Bone marrow mononuclear cells (BMMNCs) were isolated from patients undergoing hip arthroplasty and exposed to Wnt3A protein. The effect of Wnt pathway stimulation was determined by measuring the frequency of stem cells within the BMMNC populations by fluorescence-activated cell sorting and colony forming unit fibroblast (CFU-F) assays, before determining their osteogenic capacity in in vitro differentiation experiments. We found that putative skeletal stem cells in BMMNC isolates exhibited elevated Wnt pathway activity compared with the population as whole. Wnt stimulation resulted in an increase in the frequency of skeletal stem cells marked by the STRO-1bright/Glycophorin A− phenotype. Osteogenesis was elevated in stromal cell populations arising from BMMNCs transiently stimulated by Wnt3A protein, but sustained stimulation inhibited osteogenesis in a concentration-dependent manner. These results demonstrate that Wnt stimulation could be used as a therapeutic approach by transient targeting of stem cell populations during early fracture healing, but that inappropriate stimulation may prevent osteogenesis. Video Highlight: https://youtu.be/Wcs-crLvXbQ

Traditionally used as an angiogenic assay, the chorioallantoic membrane (CAM) assay of the chick embryo offers significant potential as an in vivo model for xenograft organ culture. Viable human bone can be cultivated on the CAM and increases in bone volume are evident; however, it remains unclear by what mechanism this change occurs and whether this reflects the physiological process of bone remodelling. In this study we tested the hypothesis that CAM-induced bone remodelling is a consequence of host and graft mediated processes. Bone cylinders harvested from femoral heads post surgery were placed on the CAM of green fluorescent protein (GFP)-chick embryos for 9 days, followed by micro computed tomography (μCT) and histological analysis. Three-dimensional registration of consecutive μCT-scans showed newly mineralised tissue in CAM-implanted bone cylinders, as well as new osteoid deposition histologically. Immunohistochemistry demonstrated the presence of bone resorption and formation markers (Cathepsin K, SOX9 and RUNX2) co-localising with GFP staining, expressed by avian cells only. To investigate the role of the human cells in the process of bone formation, decellularised bone cylinders were implanted on the CAM and comparable increases in bone volume were observed, indicating that avian cells were responsible for the bone mineralisation process. Finally, CAM-implantation of acellular collagen sponges, containing bone morphogenetic protein 2, resulted in the deposition of extracellular matrix and tissue mineralisation. These studies indicate that the CAM can respond to osteogenic stimuli and support formation or resorption of implanted human bone, providing a humanised CAM model for regenerative medicine research and a novel short-term in vivo model for tissue engineering and biomaterial testing.

Extracellular matrix stiffness has a profound effect on the behavior of many cell types. Adherent cells apply contractile forces to the material on which they adhere and sense the resistance of the material to deformation-its stiffness. This is dependent on both the elastic modulus and the thickness of the material, with the corollary that single cells are able to sense underlying stiff materials through soft hydrogel materials at low (

Clay nanoparticles, composites and hydrogels are emerging as a new class of biomaterial with exciting potential for tissue engineering and regenerative medicine applications. Clay particles have been extensively explored in polymeric nanocomposites for self-assembly and enhanced mechanical properties as well as for their potential as drug delivery modifiers. In recent years, a cluster of studies have explored cellular interactions with clay nanoparticles alone or in combination with polymeric matrices. These pioneering studies have suggested new and unforeseen utility for certain clays as bioactive additives able to enhance cellular functions including adhesion, proliferation and differentiation, most notably for osteogenesis. This review examines the recent literature describing the potential effects of clay-based nanomaterials on cell function and examines the potential role of key clay physicochemical properties in influencing such interactions and their exciting possibilities for regenerative medicine.

Spatiotemporal control of drug delivery is important for a number of medical applications and may be achieved using polymersome nanoparticles (PMs). Wnt signalling is a molecular pathway activated in various physiological processes, including bone repair, that requires precise control of activation. Here, we hypothesise that PMs can be stably loaded with a small molecule Wnt agonist, 6-bromoindirubin-3′-oxime (BIO), and activate Wnt signalling promoting the osteogenic differentiation in human primary bone marrow stromal cells (BMSCs). We showed that BIO-PMs induced a 40% increase in Wnt signaling activation in reporter cell lines without cytotoxicity induced by free BIO. BMSCs incubated with BIO-PMs showed a significant up-regulation of the Wnt target gene AXIN2 (14 ± 4 fold increase, P < 0.001) and a prolonged activation of the osteogenic gene RUNX2. We conclude that BIO-PMs could represent an innovative approach for the controlled activation of Wnt signaling for promoting bone regeneration after fracture.

Wnt proteins are secreted, hydrophobic, lipidated proteins found in all animals that play essential roles in development and disease. Lipid modification is thought to facilitate the interaction of the protein with its receptor, Frizzled, but may also regulate the transport of Wnt protein and its localization at the cell membrane. Here, by employing single-molecule fluorescence techniques, we show that Wnt proteins associate with and diffuse on the plasma membranes of living cells in the absence of any receptor binding. We find that labeled Wnt3A transiently and dynamically associates with the membranes of Drosophila Schneider 2 cells, diffuses with Brownian kinetics on flattened membranes and on cellular protrusions, and does not transfer between cells in close contact. In S2 receptor-plus (S2R+) cells, which express Frizzled receptors, membrane diffusion rate is reduced and membrane residency time is increased. These results provide direct evidence of Wnt3A interaction with living cell membranes, and represent, to our knowledge, a new system for investigating the dynamics of Wnt transport.

To fabricate PEGylated liposomes which preserve the activity of hydrophobic Wnt3A protein, and to demonstrate their efficacy in promoting expansion of osteoprogenitors from human bone marrow.PEGylated liposomes composed of several synthetic lipids were tested for their ability to preserve Wnt3A activity in reporter and differentiation assays. Single-molecule microspectroscopy was used to test for direct association of protein with liposomes.Labeled Wnt3A protein directly associated with all tested liposome preparations. However, Wnt3A activity was preserved or enhanced in PEGylated 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) liposomes but not in PEGylated 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) liposomes. PEGylated Wnt3A liposomes associated with skeletal stem cell populations in human bone marrow and promoted osteogenesis.Active Wnt protein-containing PEGylated liposomes may have utility for systemic administration for bone repair.

This chapter presents the summary of research that employed the TIARA method and provides an overview of the results on interpersonal reliability and validity obtained in the series of five studies. It also describes the implications of these results, methodology, and procedure for such analysis.

This chapter provides guides on how to use the TIARA method, including software requirements, instructions on preparation, and the procedures for administration, compiling, recording, and preparing data for analysis.

This chapter provides instructions for coding and scoring data collected with the TIARA method. This includes prescreening the data to identify outliers as well as suggestions for analyzing the reaction time distribution and transforming reaction time data to standard Likert-type scores.

This chapter presents the theory of dual-mode information processing as well as reviews various measures of implicit attitudes that have shaped the current research on this topic. Given this theoretical discussion and review of prior implicit measures, the chapter introduces a new method: the Test of Implicit Associations in Relationship Attitudes (TIARA).

This chapter presents methodology and results of the analyses of TIARA’s intrapersonal reliability and validity. It describes the methods for analysis and possible interpretations of individual cases in research and practice.

Impaired fracture healing is a major financial burden for healthcare services; 5%–10% of bone fractures result in non-unions, and there is no clinically approved systemic therapy. This study characterises acoustically stimulated microbubbles (MBs) and nanodroplets (NDs) as non-invasive ultrasound responsive vehicles for the targeted delivery of osteogenic compounds. A microscope-compatible water-tank incorporating a passive cavitation detector was developed to study the acoustic behaviour of MBs and NDs within physical models of bone fractures (gap: 3.5–5.5 mm, angles: 0 deg and 90 deg). The device was designed using COMSOL Multiphysics (Burlington, MA) and tested in-vitro. The bone was simulated using a material with comparable acoustic impedance (Sawbones, WA). Numerical simulations showed that the developed experimental set-up generated a relatively uniform acoustic field at a target plane. It could be operated at either 1 or 2 MHz US frequency, at an acoustic pressure in the range 0–1 MPa. The inclusion of a fracture model caused perturbations to the acoustic field, which were dependent on the architecture of the fracture (i.e., relative to the incident US field). Ongoing studies are investigating how these perturbations affect ND/MB response in-vitro. Further studies will investigate the relationship between MB/ND acoustic response and the release of biologically active compounds.Impaired fracture healing is a major financial burden for healthcare services; 5%–10% of bone fractures result in non-unions, and there is no clinically approved systemic therapy. This study characterises acoustically stimulated microbubbles (MBs) and nanodroplets (NDs) as non-invasive ultrasound responsive vehicles for the targeted delivery of osteogenic compounds. A microscope-compatible water-tank incorporating a passive cavitation detector was developed to study the acoustic behaviour of MBs and NDs within physical models of bone fractures (gap: 3.5–5.5 mm, angles: 0 deg and 90 deg). The device was designed using COMSOL Multiphysics (Burlington, MA) and tested in-vitro. The bone was simulated using a material with comparable acoustic impedance (Sawbones, WA). Numerical simulations showed that the developed experimental set-up generated a relatively uniform acoustic field at a target plane. It could be operated at either 1 or 2 MHz US frequency, at an acoustic pressure in the range 0–1 MPa. The inclusi...

Skin wound healing is a vital process that is important for re-establishing the epithelial barrier following disease or injury. Aberrant or delayed skin wound healing increases the risk of infection, causes patient morbidity, and may lead to the formation of scar tissue. One of the most important events in wound healing is coverage of the wound with a new epithelial layer. This occurs when keratinocytes at the wound periphery divide and migrate to re-populate the wound bed. Many approaches are under investigation to promote and expedite this process, including the topical application of growth factors and the addition of autologous and allogeneic tissue or cell grafts. The mechanical environment of the wound site is also of fundamental importance for the rate and quality of wound healing. It is known that mechanical stress can influence wound healing by affecting the behaviour of cells within the dermis, but it remains unclear how mechanical forces affect the healing epidermis. Tensile forces are known to affect the behaviour of cells within epithelia, however, and the material properties of extracellular matrices, such as substrate stiffness, have been shown to affect the morphology, proliferation, differentiation and migration of many different cell types. In this review we will introduce the structure of the skin and the process of wound healing. We will then discuss the evidence for the effect of tissue mechanics in re-epithelialisation and, in particular, on stem cell behaviour in the wound microenvironment and in intact skin. We will discuss how the elasticity, mechanical heterogeneity and topography of the wound extracellular matrix impact the rate and quality of wound healing, and how we may exploit this knowledge to expedite wound healing and mitigate scarring.

Biomaterial development for tissue engineering applications is rapidly increasing but necessitates efficacy and safety testing prior to clinical application. Current in vitro and in vivo models hold a number of limitations, including expense, lack of correlation between animal models and human outcomes and the need to perform invasive procedures on animals; hence requiring new predictive screening methods. In the present study we tested the hypothesis that the chick embryo chorioallantoic membrane (CAM) can be used as a bioreactor to culture and study the regeneration of human living bone. We extracted bone cylinders from human femoral heads, simulated an injury using a drill-hole defect, and implanted the bone on CAM or in vitro control-culture. Micro-computed tomography (?CT) was used to quantify the magnitude and location of bone volume changes followed by histological analyses to assess bone repair. CAM blood vessels were observed to infiltrate the human bone cylinder and maintain human cell viability. Histological evaluation revealed extensive extracellular matrix deposition in proximity to endochondral condensations (Sox9+) on the CAM-implanted bone cylinders, correlating with a significant increase in bone volume by ?CT analysis (p?0.01). This human-avian system offers a simple refinement model for animal research and a step towards a humanized in vivo model for tissue engineering.

Mature beta-cells and nerve cells share many functional similarities despite originating from different embryonic germ layers. The aim of this study was to investigate the potential of neural stem cells (NSCs), isolated from foetal rat brain, as a starting material from which to generate functionally responsive, insulin-containing cells. Our results demonstrated that NSCs can be significantly expanded in vitro and can be induced to express increased preproinsulin mRNA levels. In addition, these NSC-derived cells expressed transcriptional and functional elements associated with a mature beta-cell phenotype. The differentiated cells showed functional responses typical of pancreatic beta-cells, including glucose-dependent increases in metabolism and rapid elevations in intracellular Ca(2+) in response to the sulphonylurea tolbutamide or to increased glucose concentration. These results suggest that NSCs may have potential as a starting material from which to generate beta-cell surrogates for the treatment of patients with Type 1 diabetes mellitus.

A direct observation and an in-depth characterization of the steps by which bone mineral nucleates and grows in the extracellular matrix during the earliest stages of maturation, using relevant biomineralization models as they grow into mature bone mineral, is an important research goal. To better understand the process of bone mineralization in the extracellular matrix, we used nano-analytical electron microscopy techniques to examine an in vitro model of bone formation. This study demonstrates the presence of three dominant CaP structures in the mineralizing osteoblast cultures

Polymersome nanoparticles (PMs) are attractive candidates for spatio-temporal controlled delivery of therapeutic agents. Although many studies have addressed cellular uptake of solid nanoparticles, there is very little data available on intracellular release of molecules encapsulated in membranous carriers, such as polymersomes. Here, we addressed this by developing a quantitative assay based on the hydrophilic dye, fluorescein. Fluorescein was encapsulated stably in PMs of mean diameter 85 nm, with minimal leakage after sustained dialysis. No fluorescence was detectable from fluorescein PMs, indicating quenching. Following incubation of L929 cells with fluorescein PMs, there was a gradual increase in intracellular fluorescence, indicating PM disruption and cytosolic release of fluorescein. By combining absorbance measurements with flow cytometry, we quantified the real-time intracellular release of a fluorescein at a single-cell resolution. We found that 173 ± 38 polymersomes released their payload per cell, with significant heterogeneity in uptake, despite controlled synchronisation of cell cycle. This novel method for quantification of the release of compounds from nanoparticles provides fundamental information on cellular uptake of nanoparticle-encapsulated compounds. It also illustrates the stochastic nature of population distribution in homogeneous cell populations, a factor that must be taken into account in clinical use of this technology.

Biomaterial development for tissue engineering applications is rapidly increasing but necessitates efficacy and safety testing prior to clinical application. Current in vitro and in vivo models hold a number of limitations, including expense, lack of correlation between animal models and human outcomes and the need to perform invasive procedures on animals; hence requiring new predictive screening methods. In the present study we tested the hypothesis that the chick embryo chorioallantoic membrane (CAM) can be used as a bioreactor to culture and study the regeneration of human living bone. We extracted bone cylinders from human femoral heads, simulated an injury using a drill-hole defect, and implanted the bone on CAM or in vitro control-culture. Micro-computed tomography (μCT) was used to quantify the magnitude and location of bone volume changes followed by histological analyses to assess bone repair. CAM blood vessels were observed to infiltrate the human bone cylinder and maintain human cell viability. Histological evaluation revealed extensive extracellular matrix deposition in proximity to endochondral condensations (Sox9+) on the CAM-implanted bone cylinders, correlating with a significant increase in bone volume by μCT analysis (p

The use of materials properties to guide cell behaviour is an attractive option for regenerative medicine, where controlling stem cell behaviour is important for the establishment of a functioning cell population. A wide range of materials properties have been shown to influence many types of cells but little is known about the effects of topography on embryonic stem cells (ESCs). In order to advance this knowledge, we synthesised and characterised substrates formed of silica colloidal crystal (SCC) microspheres to present highly ordered and reproducible topographical features from 120-600 nm in diameter. We found that, compared to cells cultured on flat glass, cells cultured on the SCC substrates retained transcription of stem cell (Dppa5a, Nanog, and Pou5f1) and endoderm (Afp, Gata4, Sox17, and Foxa2) markers more similar to undifferentiated ESCs, suggesting the substrates are restricting differentiation, particularly towards the endoderm lineage. Additionally, five days after seeding, we observed strikingly different colony morphology, with cells on the SCC substrates growing in spherical colonies approximately ten cells thick, while cells on glass were growing in flat monolayers. Colonies on the SCC substrates developed a central pit, which was never observed in cells cultured on glass, and expressed proteins related to epithelialisation. Together, these data demonstrate the potential of using topographical cues to control stem cell behaviour in vitro.

Mammalian bone marrow is a complex organ responsible for a variety of critical homeostatic functions, including haematopoiesis. To achieve these functions, it has evolved to provide an environment for the habitation of stem cells—the bone marrow ‘stem cell niche’. In addition to haematopoetic stem cells, which are responsible for generating all cell lineages of the mammalian blood, recent evidence suggests that this same niche may provide an environment for the putative skeletal stem cell, responsible for forming the connective tissues of the skeleton—bone, cartilage and fat. In this chapter, we review recent research on the importance of skeletal stem cells and bone marrow stromal cells and their spatial localisation within the bone marrow. We discuss their role in providing a supportive microenvironment for the maintenance of haematopoetic stem cells, and some of their key molecular interactions via cell surface ligands, secreted growth factors, extracellular matrix and other physiocochemical means. We also discuss some of the pathologies that might arise from dysregulation of the niche, particularly with regard to ageing. Finally, we review recent attempts to recreate the bone marrow microenvironment in vitro.

There is an urgent need to develop technology for continuous in vivo glucose monitoring in subjects with diabetes mellitus. Problems with existing devices based on electrochemistry have encouraged alternative approaches to glucose sensing in recent years, and those based on fluorescence intensity and lifetime have special advantages, including sensitivity and the potential for non-invasive measurement when near-infrared light is used. Several receptors have been employed to detect glucose in fluorescence sensors, and these include the lectin concanavalin A (Con A), enzymes such as glucose oxidase, glucose dehydrogenase and hexokinase/glucokinase, bacterial glucose-binding protein, and boronic acid derivatives (which bind the diols of sugars). Techniques include measuring changes in fluorescence resonance energy transfer (FRET) between a fluorescent donor and an acceptor either within a protein which undergoes glucose-induced changes in conformation or because of competitive displacement; measurement of glucose-induced changes in intrinsic fluorescence of enzymes (e.g. due to tryptophan residues in hexokinase) or extrinsic fluorophores (e.g. using environmentally sensitive fluorophores to signal protein conformation). Non-invasive glucose monitoring can be accomplished by measurement of cell autofluorescence due to NAD(P)H, and fluorescent markers of mitochondrial metabolism can signal changes in extracellular glucose concentration. Here we review the principles of operation, context and current status of the various approaches to fluorescence-based glucose sensing.