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Microbubbles (MB) are used as ultrasound (US) contrast agents in clinical settings because of their ability to oscillate upon exposure to acoustic pulses and generate nonlinear responses with a stable cavitation profile. Polymeric MB have recently attracted increasing attention as molecular imaging probes and drug delivery agents based on their tailorable acoustic responses, high drug loading capacity, and surface functionalization capabilities. While many of these applications require MB to be functionalized with biological ligands, the impact of bioconjugation on polymeric MB cavitation and acoustic properties remains poorly understood. Hence, we here evaluated the effects of MB shell hydrolysis and subsequent streptavidin conjugation on the acoustic behavior of poly(butyl cyanoacrylate) (PBCA) MB. We show that upon biofunctionaliza-tion, MB display higher acoustic stability, stronger stable cavitation, and enhanced second harmonic generation. Furthermore, functionalized MB preserve the binding capabilities of streptavidin conjugated on their surface. These findings provide insights into the effects of bioconjugation chemistry on polymeric MB acoustic properties, and they contribute to improving the performance of polymer-based US imaging and theranostic agents.

Metastasis is a complex and multifactorial process highly dependent on the interaction between disseminated tumor cells and the pre-metastatic niche. The metastatic sites detected in the bone of patients affected by neuroblastoma (NB), a malignancy of the developing sympathetic nervous system, are particularly aggressive. To improve our current knowledge of metastatic tumor cell biology and improve treatment success, appropriate in vitro and in vivo models that more closely resemble the native metastatic niche are needed. In this study, the impact of the geometry of synthetic β-tricalcium-phosphate (β-TCP) structures on the interaction of NB tumor cells with the stromal component has been examined. The tumor microenvironment is dynamically shaped by the stroma, which sustains the growth of NB cells inside the metastatic niche. The 3D growth conditions are a determining factor for the cell proliferation rate in β-TCP. With respect to planar counterparts, channeled 3D β-TCP structures stimulate more interleukin-6 and Fibronectin production and define Connexin 43 distribution inside the cells. Together, these results highlight how the biomechanical properties of the 3D microenvironment enable tumor cells to form spheroid-shaped arrangements. This, in turn, facilitates their pro-migratory and pro-invasive patterns and mimics the in vivo situation by translating realistic mechanobiological cues to the metastatic NB.

The anticoagulation treatment of cardiovascular patients, which is mandatory after implantation of heart valves or stents, has significantly adverse effects on life quality. This treatment can be reduced or even circumvented by developing novel antithrombogenic surfaces of blood-contacting implants. Thus, we aim to discover materials exhibiting outstanding hemocompatibility compared to other available synthetic materials. We present promising surficial characteristics of single crystalline alumina in terms of platelet activation inhibition. In order to elucidate the relation between its crystallographic properties including the plane orientation and blood cell behavior, we examined endothelialization, cytocompatibility, and platelet activation at the blood-alumina interfaces in a controlled experimental setup. We observed that the cell response is highly sensitive to the plane orientation and differs significantly for (0001) and (11-20) planes of Al2O3. Our results reveal for the first time the dependence of platelet activation on crystallographic orientation, which is assumed to be a critical condition controlling the thrombogenicity. Additionally, we used an endothelial cell monolayer as an internal control since endothelial cells have an impact on vessel integrity and implant acceptance. We successfully demonstrate that Al2O3(11-20) exhibits enhanced hemocompatibility in contrast to Al2O3(0001) and is comparable to the physiological endothelial monolayer in vitro.

Tissue-engineered constructs have great potential in many intervention strategies. In order for these constructs to function optimally, they should ideally mimic the cellular alignment and orientation found in the tissues to be treated. Here we present a simple and reproducible method for the production of cell-laden pure fibrin micro-fibers with longitudinal topography. The micro-fibers were produced using a molding technique and longitudinal topography was induced by a single initial stretch. Using this method, fibers up to 1 m in length and with diameters of 0.2-3 mm could be produced. The micro-fibers were generated with embedded endothelial cells, smooth muscle cell/fibroblasts or Schwann cells. Polarized light and scanning electron microscopy imaging showed that the initial stretch was sufficient to induce longitudinal topography in the fibrin gel. Cells in the unstretched control micro-fibers elongated randomly in both the floating and encapsulated environments, whereas the cells in the stretched micro-fibers responded to the introduced topography by adopting a similar orientation. Proof of concept bottom-up tissue engineering (TE) constructs are shown, all displaying various anisotropic organization of cells within. This simple, economical, versatile and scalable approach for the production of highly orientated and cell-laden micro-fibers is easily transferrable to any TE laboratory.

Advanced healthcare materials 2100812 (2021). doi:10.1002/adhm.202100812, Published by Wiley-VCH, Weinheim

Journal of biomedical materials research : JBMR 2020, 1-9 (2020). doi:10.1002/jbm.b.34559, Published by Wiley, New York, NY [u.a.]

Cytocompatibility and hemocompatibility are essential features for tissue- and blood-contacting implants such as artificial heart valves, vascular grafts and stents. Platelet activation as the main...

Significance Body reorganization in eels during gametogenesis can induce undesired side effects with possible pathological significance. This study provides analytical evidence for the maternal transfer of toxic metals from soft and hard tissues to the ovaries of mature females. By illustrating the metabolic fluxes and fate of mobilized minerals and metals in the fishes’ bodies during sexual development, we have identified a previously unreported aspect of anthropogenic impact on endangered anguillid eels. Furthermore, our findings suggest a physiologically connected interplay of energy metabolism and bone resorption in the reproductive strategy of eels. Consequently, we propose the eel as an interesting model organism for investigating the physiological pathways connecting lipid metabolism and mineral retention, known also to affect the health state of humans., During their once-in-a-lifetime transoceanic spawning migration, anguillid eels do not feed, instead rely on energy stores to fuel the demands of locomotion and reproduction while they reorganize their bodies by depleting body reserves and building up gonadal tissue. Here we show how the European eel (Anguilla anguilla) breaks down its skeleton to redistribute phosphorus and calcium from hard to soft tissues during its sexual development. Using multiple analytical and imaging techniques, we characterize the spatial and temporal degradation of the skeletal framework from initial to final gonadal maturation and use elemental mass ratios in bone, muscle, liver, and gonadal tissue to determine the fluxes and fates of selected minerals and metals in the eels’ bodies. We find that bone loss is more pronounced in females than in males and eventually may reach a point at which the mechanical stability of the skeleton is challenged. P and Ca are released and translocated from skeletal tissues to muscle and gonads, leaving both elements in constant proportion in remaining bone structures. The depletion of internal stores from hard and soft tissues during maturation-induced body reorganization is accompanied by the recirculation, translocation, and maternal transfer of potentially toxic metals from bone and muscle to the ovaries in gravid females, which may have direct deleterious effects on health and hinder the reproductive success of individuals of this critically endangered species.

Titanium niobium alloys exhibit a lower stiffness compared to Ti6Al4V, the 'gold standard' for load-bearing bone implants. Thus, the critical mismatch in stiffness between the implant and adjacent bone tissue could be addressed with TiNb alloys and thereby reduce stress shielding, which can result in bone resorption and subsequent implant loosening; however, the cellular response on the specific material is crucial for sufficient osseointegration. We therefore hypothesize that the response of human mesenchymal stromal cells (hMSC) and osteoblast-like cells on Ti45Nb surfaces can be improved by a novel nanoporous surface structure. For this purpose, an etching technique using hydrogen peroxide electrolyte solution was applied to Ti45Nb. The treated surfaces were characterized using SEM, LSM, AFM, nanoindentation, and contact angle measurements. Cell culture experiments using hMCS and MG-63 were conducted. The H2O2 treatment resulted in surface nanopores, an increase in surface wettability and a reduction in surface hardness. The proliferation of MG-63 was enhanced on TiNb45 compared to Ti6Al4V. MG-63 focal adhesion complexes were detected on all Ti45Nb surfaces, whereas the nanostructures notably increased the cell area and decreased cell solidity, indicating stimulated cell spreading and pseudopodia formation. Alizarin red stainings indicated that the nanoporous surfaces stimulated the osteogenic differentiation of hMSC. It can be concluded that the proposed surface treatment could potentially help to stimulate the osseointegration behaviour of the advantageous low stiff Ti45Nb alloy.

Several cytoskeleton-associated proteins and signaling pathways work in concert to regulate actin cytoskeleton remodeling, cell adhesion, and migration. Although the leukocyte-specific protein 1 (LSP1) has been shown to interact with the actin cytoskeleton, its function in the regulation of actin cytoskeleton dynamics is, as yet, not fully understood. We have recently demonstrated that the bimolecular complex between LSP1 and myosin1e controls actin cytoskeleton remodeling during phagocytosis. In this study, we show that LSP1 downregulation severely impairs cell migration, lamellipodia formation, and focal adhesion dynamics in macrophages. Inhibition of the interaction between LSP1 and myosin1e also impairs these processes resulting in poorly motile cells, which are characterized by few and small lamellipodia. Furthermore, cells in which LSP1-myosin1e interaction is inhibited are typically associated with inefficient focal adhesion turnover. Collectively, our findings show that the LSP1-myosin1e bimolecular complex plays a pivotal role in the regulation of actin cytoskeleton remodeling and focal adhesion dynamics required for cell migration.

Metastasis is a complex and multifactorial process highly dependent on the interaction between disseminated tumor cells and the pre-metastatic niche. The metastatic sites detected in the bone of patients affected by neuroblastoma (NB), a malignancy of the developing sympathetic nervous system, are particularly aggressive. To improve our current knowledge of metastatic tumor cell biology and improve treatment success, appropriate in vitro and in vivo models that more closely resemble the native metastatic niche are needed. In this study, the impact of the geometry of synthetic β-tricalcium-phosphate (β-TCP) structures on the interaction of NB tumor cells with the stromal component has been examined. The tumor microenvironment is dynamically shaped by the stroma, which sustains the growth of NB cells inside the metastatic niche. The 3D growth conditions are a determining factor for the cell proliferation rate in β-TCP. With respect to planar counterparts, channeled 3D β-TCP structures stimulate more interleukin-6 and Fibronectin production and define Connexin 43 distribution inside the cells. Together, these results highlight how the biomechanical properties of the 3D microenvironment enable tumor cells to form spheroid-shaped arrangements. This, in turn, facilitates their pro-migratory and pro-invasive patterns and mimics the in vivo situation by translating realistic mechanobiological cues to the metastatic NB.

PLOS ONE 16(9), e0257495 (2021). doi:10.1371/journal.pone.0257495, Published by PLOS, San Francisco, California, US

This study aimed to join the proven osteogenic properties of graphene oxide (GO) with bioinert zirconia implants. The dip-coating technique allows achieving this goal by forming a thin, homogenous, hydrolytically, and mechanically stable GO film onto silanized ceramic-substrates. SEM, AFM, XPS, and contact angle measurements confirmed the presence, transparency, integrity, and homogenous covering character of the GO film. The GO film is hydrolytically stable since it remained intact after a soaking period of 24 days in double-distilled water (ddH2O) and phosphate buffered saline and resisted a ten-minute sonication treatment for in ddH2O. This strong hydrolytic stability is due to the silanization with 3-amino-propyl-diisopropylethoxy-silane (APDS) enhancing the anchoring of GO flakes onto zirconia surfaces. Besides, the GO film disinfectable in 70% ethanol. Subsequently, we assessed our immobilized GO film as cytocompatible for L929 mouse fibroblast and human mesenchymal stem cells and propitious for the osteogenic differentiation demonstrated by a two times upregulation of the osteogenic transcription factor RunX2. The active hydroxyl and carboxyl groups of the GO film open new perspectives for the functionalization of ceramic implants by immobilization of biological agents, such as growth factors or antibiotics, and thus enhance the osseointegration.

Bionanoparticles based on filamentous phages or flexuous viruses are interesting candidates for meeting the challenges of tailoring biomineralization in hydrogel-based bone tissue substitutes. We hypothesized that hydroxyapatite crystal nucleation and matrix mineralization can be significantly increased by mineralization-inducing (MIP) and integrin binding motif (RGD) peptides presented on biomimetic nanoparticles. In this study, Potato virus X (PVX), a flexible rod-shaped plant virus was genetically engineered to present these functional peptides on its particle surface. Recombinant PVX-MIP/RGD particles were isolated from infected Nicotiana benthamiana plants and characterized by western blot, SEM, TEM, and TPLSM in MSC cultures. The presence of RGD was proven by cell attachment, spreading, and vinculin cluster analysis, and MIP by in vitro mineralization and osteogenic differentiation assays. Thus the tailored surface of genetically engineered PVX forms fibril-like nanostructures which enables enhanced focal adhesion-dependent cell adhesion, and matrix mineralization verified by Alizarin. Hydroxyapatite crystal nucleation is supported on recombinant PVX particles leading to a biomimetic network and bundle-like structures similar to mineralized collagen fibrils. In conclusion, the recombinant flexuous PVX nanoparticles exhibit properties with great potential for bone tissue substitutes. Statement of Significance A suitable biomaterial for tissue engineering should be able to mimic the endogenous extracellular matrix by presenting biochemical and biophysical cues. Novel hydrogel-based materials seek to meet the criteria of cytocompatibility, biodegradability, printability, and crosslinkability under mild conditions. However, a majority of existing hydrogels lack cell-interactive motifs, which are crucial to modulate cellular responses. The incorporation of the plant virus PVX to the hydrogel could improve functions like integrin-binding and mineralization due to peptide-presentation on the particle surface. The tailored surface of genetically engineered PVX forms fibril-like nanostructures which enables enhanced focal adhesion-dependent cell adhesion and matrix mineralization and offers great potential for the development of new hydrogel compositions for bone tissue substitutes.

Frontiers in Bioengineering and Biotechnology 7, 340 (2019). doi:10.3389/fbioe.2019.00340, Published by Frontiers Media, Lausanne

Poly(n-butyl cyanoacrylate) microbubbles (PBCA-MB) are extensively employed for functional and molecular ultrasound (US) imaging, as well as for US-mediated drug delivery. To facilitate the use of PBCA-MB as a commercial platform for biomedical applications, it is important to systematically study and improve their stability and shelf-life. In this context, lyophilization (freeze drying) is widely used to increase shelf-life and promote product development. Here, we set out to analyze the stability of standard and rhodamine-B loaded PBCA-MB at three different temperatures (4 &deg, C, 25 &deg, C, and 37 &deg, C), for a period of time of up to 20 weeks. In addition, using sucrose, glucose, polyvinylpyrrolidone (PVP), and polyethylene glycol (PEG) as cryoprotectants, we investigated if PBCA-MB can be lyophilized without affecting their size, concentration, US signal generation properties, and dye retention. Stability assessment showed that PBCA-MB remain largely intact for three and four weeks at 4 &deg, C and 25 &deg, C, respectively, while they disintegrate within one to two weeks at 37 &deg, C, thereby compromising their acoustic properties. Lyophilization analyses demonstrated that PBCA-MB can be efficiently freeze-dried with 5% sucrose and 5% PVP, without changing their size, concentration, and US signal generation properties. Experiments involving rhodamine-B loaded MB indicated that significant dye leakage from the polymeric shell takes place within two to four weeks in case of non-lyophilized PBCA-MB. Lyophilization of rhodamine-loaded PBCA-MB with sucrose and PVP showed that the presence of the dye does not affect the efficiency of freeze-drying, and that the dye is efficiently retained upon MB lyophilization. These findings contribute to the development of PBCA-MB as pharmaceutical products for preclinical and clinical applications.

Mechanical properties of hydrogels can be modified by the variation of structure and concentration of reactive building blocks. One promising biological source for the synthesis of biocompatible hydrogels is fibrinogen. Fibrinogen is a glycoprotein in blood, which can be transformed enzymatically to fibrin playing an important role in wound healing and clot formation. In the present work, it is demonstrated that hybrid hydrogels with their improved mechanical properties, tunable internal structure, and enhanced resistance to degradation can be synthesized by a combination of fibrinogen and reactive amphiphilic copolymers. Water-soluble amphiphilic copolymers with tunable molecular weight and controlled amounts of reactive epoxy side groups are used as reactive crosslinkers to reinforce fibrin hydrogels. In the present work, copolymers that can influence the mechanical properties of fibrin-based hydrogels are used. The reactive copolymers increase the storage modulus of the hydrogels from 600 Pa to 30 kPa. The thickness of fibrin fibers is regulated by the copolymer concentration. It could be demonstrated that the fibrin-based hydrogels are biocompatible and support cell proliferation. Their degradation rate is considerably slower than that of native fibrin gels. In conclusion, fibrin-based hydrogels with tunable elasticity and fiber thickness useful to direct cell responses like proliferation and differentiation are produced. �� 2020 The Authors. Published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Ceramics 2(2), 260 - 270 (2019). doi:10.3390/ceramics2020021, Published by MDPI, Basel

Elastic fibers are a fundamental requirement for tissue-engineered equivalents of physiologically elastic native tissues. Here, a simple one-step electrospinning approach is developed, combining i) catalyst-free click chemistry, ii) coaxial electrospinning, and iii) recombinant elastin-like polymers as a relevant class of biomaterials. Water-stable elastin-like fibers are obtained without the use of cross-linking agents, catalysts, or harmful organic solvents. The fibers can be directly exposed to an aqueous environment at physiological temperature and their morphology maintained for at least 3 months. The bioactivity of the fibers is demonstrated with human vascular cells and the potential of the process for vascular tissue engineering is shown by fabricating small-diameter tubular fibrous scaffolds. Moreover, highly porous fluffy 3D constructs are obtained without the use of specially designed collectors or sacrificial materials, further supporting their applicability in the biomedical field. Ultimately, the strategy that is developed here may be applied to other click systems, contributing to expanding their potential in medical technology.

Producción Científica, Elastin is a key extracellular matrix (ECM) protein that imparts functional elasticity to tissues and therefore an attractive candidate for bioengineering materials. Genetically engineered elastin-like recombinamers (ELRs) maintain inherent properties of the natural elastin (e.g. elastic behavior, bioactivity, low thrombogenicity, inverse temperature transition) while featuring precisely controlled composition, the possibility for biofunctionalization and non-animal origin. Recently the chemical modification of ELRs to enable their crosslinking via a catalyst-free click chemistry reaction, has further widened their applicability for tissue engineering. Despite these outstanding properties, the generation of macroporous click-ELR scaffolds with controlled, interconnected porosity has remained elusive so far. This significantly limits the potential of these materials as the porosity has a crucial role on cell infiltration, proliferation and ECM formation. In this study we propose a strategy to overcome this issue by adapting the salt leaching/gas foaming technique to click-ELRs. As result, macroporous hydrogels with tuned pore size and mechanical properties in the range of many native tissues were reproducibly obtained as demonstrated by rheological measurements and quantitative analysis of fluorescence, scanning electron and two-photon microscopy images. Additionally, the appropriate size and interconnectivity of the pores enabled smooth muscle cells to migrate into the click-ELR scaffolds and deposit extracellular matrix. The macroporous structure together with the elastic performance and bioactive character of ELRs, the specificity and non-toxic character of the catalyst-free click-chemistry reaction, make these scaffolds promising candidates for applications in tissue regeneration. This work expands the potential use of ELRs and click chemistry systems in general in different biomedical fields., Ministerio de Economía, Industria y Competitividad (Projects MAT2013-42473-R, MAT2015-68901-R, MAT2016- 78903-R), Junta de Castilla y León (programa de apoyo a proyectos de investigación - Ref. VA313U14, VA015U16 y PCIN-2015-010), gobierno federal y estatal de Alemania en el marco del Programa de Posición Rotacional i³tm (2014-R4-01) y del Programa START de la Facultad de Medicina de la Universidad de Aachen (proyecto nº 691713),el centro de imágenes del Centro Interdisciplinario de Investigación Clínica (IZKF) de la Facultad de Medicina de la Universidad de Aachen

Corneal endothelial dysfunction remains the most frequent indication for corneal transplantation, limited by donor material shortage, poor long-term graft survival, or allogeneic graft rejection. Therefore, tissue-engineered endothelial grafts (TEEG) represent a promising alternative to human donor tissue. In this study, we generated electro-spun scaffolds and tested these for their suitability for human corneal endothelial cell (hCEC) cultivation.The polymers poly(methyl-methacrylate) (PMMA), poly(lactic-co-glycolic acid) (PLGA), and polycaprolactone (PCL) were spun with equal parameters. HCEC-12 was cultured on the scaffolds for 3 to 7 days. Scaffolds were evaluated by light microscopy, porometry, light transmission, scanning electron microscopy (SEM), live/dead staining and cell viability assay.Electro-spun fibers from PMMA (2.99 ± 0.24 µm) showed significantly higher diameters than PCL (2.29 ± 0.11 µm; p = 0.003) and PLGA (1.84 ± 0.21 µm; p 0.001), while fibers from PCL also showed larger diameters than those from PLGA (p = 0.002). PMMA scaffolds (26.77 ± 17.48 µm) had significantly larger interstitial spaces than those from PCL (13.30 ± 5.47 µm; p = 0.04) and PLGA (10.42 ± 6.15 µm; p = 0.002), while PCL and PLGA did not differ significantly (p = 0.26). SEM analysis revealed that only PLGA fibers preserved a normal HCEC-12 morphology. PLGA and PCL did not differ in cell number, death, or viability after 7 days of HCEC-12 cultivation. PMMA showed significantly higher cytotoxicity (p 0.001; PLGA: 1626.2 ± 183.8 RLU; PMMA: 841.9 ± 92.7 RLU; PCL: 1580.2 ± 171.02 RLU).The biodegradable PLGA and PCL electro-spun scaffolds resulted in equal biocompatibility, while PMMA showed cytotoxicity. Only PLGA preserved hCEC morphology and consequently seems to be a promising candidate for TEEG construction.

Amniotic membrane (AM) is an essential tool in ocular surface reconstruction. In this study, we analyzed the differential effects of glycerol and straight storage at − 80 °C for up to 6 months on the structural, biological, and mechanical properties of amniotic membrane (AM). Human placentae of 11 different subjects were analyzed. AMs were stored at − 80 °C, either with a 1:1 mixture of Dulbecco’s modified Eagle medium and glycerol (glycerol) or without any medium or additives (straight). Histological image analysis, tensile strength, cell viability, and basic fibroblast growth factor (bFGF) secretion were evaluated at 0.5, 1, 3, and 6 months. Histologically, neither glycerol nor straight storage significantly altered the epithelial or stromal structure of the AM. However, the cell number of the stroma was significantly reduced during the freezing process, independently of the storage method (p = 0.05–0.001). Tensile strength and Young’s modulus were not influenced by the storage method, but longer storage periods significantly increased the tensile strength of the AMs (p = 0.028). Cell viability was higher in glycerol rather than straight AM samples for up to 3 months of storage (p = 0.047–0.03). Secretion of bFGF at 3 months of storage was significantly higher in glycerol versus straight frozen AM samples (p = 0.04). Glycerol led to higher cell viability and higher bFGF secretion for up to 3 months of AM storage. However, no significant differences between the two methods were observed at 6 months of storage at − 80 °C.

Producción Científica, Coronary artery disease is the leading cause of death around the world. Endovascular stenting is the preferred treatment option to restore blood flow in the coronary arteries due to the lower perioperative morbidity when compared with more invasive treatment options. However, stent failure is still a major clinical problem, and further technological solutions are required to improve the performance of current stents. Here, we developed coronary stents covered with elastin-like recombinamers (ELRs) by exploiting a layer-by-layer technique combined with catalyst-free click chemistry. The resulting ELR-covered stents were intact after an in vitro simulated implantation procedure by balloon dilatation, which evidenced the elastic performance of the membrane. Additionally, the stents were mechanically stable under high flow conditions, which is in agreement with the covalent and stable nature of the click chemistry crosslinking strategy exploited during the ELR-membrane manufacturing and the successful embedding of the stent. Minimal platelet adhesion was detected after blood exposure in a Chandler loop as shown by scanning electron microscopy. The seeding of human endothelial progenitor cells (EPCs) on the ELR-membranes resulted in a confluent endothelial layer. These results prove the potential of this strategy to develop an advanced generation of coronary stents, with a stable and bioactive elastin-like membrane to exclude the atherosclerotic plaque from the blood stream or to seal coronary perforations and aneurysms, while providing a luminal surface with minimal platelet adhesion and favouring endothelialization., German federal and state governments (project StUpPD_330-18), Ministerio de Economía, Industria y Competitividad (projects PCIN-2015-010 / MAT2016-78903-R), Junta de Castilla y León (project VA317P18)

The control of cell behaviour through material geometry is appealing as it avoids the requirement for complex chemical surface modifications. Significant advances in new technologies have been made to the development of polymeric biomaterials with controlled geometry and physico-chemical properties. Solution blow spinning technique has the advantage of ease of use allowing the production of nano or microfibres and the direct fibre deposition on any surface in situ. Yet, in spite of these advantages, very little is known about the influence of such fibres on biological functions such as immune response and cell migration. In this work, we engineered polymeric fibres composed of either pure poly(lactic acid) (PLA) or blends of PLA and polyethylene glycol (PEG) by solution blow spinning and determined their impact on dendritic cells, highly specialised cells essential for immunity and tolerance. We also determined the influence of fibres on cell adhesion and motility. Cells readily interacted with fibres resulting in an intimate contact characterised by accumulation of actin filaments and focal adhesion components at sites of cell-fibre interactions. Moreover, cells were guided along the fibres and actin and focal adhesion components showed a highly dynamic behaviour at cell-fibre interface. Remarkably, fibres did not elicit any substantial increase of activation markers and inflammatory cytokines in dendritic cells, which remained in their immature (inactive) state. Taken together, these findings will be useful for developing new biomaterials for applications in tissue engineering and regenerative medicine.

Purpose We compared the SLc Original (SLc) and One-Use Plus (OUP) microkeratomes for ultrathin Descemet's stripping automated endothelial keratoplasty (DSAEK) lamella preparation and storage, vis-a-vis accuracy, endothelial cell loss (ECL) and lamellar surface roughness (LSR). Methods Twenty-five human corneas were dissected with single-use heads of different sizes aiming for a posterior lamella (PL) thickness of 85 μm, after which they were incubated for 6 days in a 5% dextran medium. Before preparation (0 hr) and 1, 24, and 144 hr after dissection, ECL and corneal thickness (CCT) were measured by ultrasound pachymetry (USP) and optical coherence tomography (OCT). Lamellar surface roughness (LSR) was assessed by scanning electron microscopy (SEM) and evaluated by two masked observers. Results Prior to cutting, CCTs did not differ between OCT and USP measurements, with a high correlation between the two modalities (r2 = 0.8; p

Charged poly(N-isopropylacrylamide-co-methacrylic acid) [P(NiPAM-co-MAA)] microgels can stabilize thermo- and pH-sensitive emulsions. By placing charged units at different locations in the microgels and comparing the emulsion properties, we demonstrate that their behaviors as emulsion stabilizers are very different from molecular surfactants and rigid Pickering stabilizers. The results show that the stabilization of the emulsions is independent of electrostatic repulsion although the presence and location of charges are relevant. Apparently, the charges facilitate emulsion stabilization via the extent of swelling and deformability of the microgels. The stabilization of these emulsions is linked to the swelling and structure of the microgels at the oil-water interface, which depends not only on the presence of charged moieties and on solvent polarity but also on the microgel (core-shell) morphology. Therefore, the internal soft and porous structure of microgels is important, and these features make microgel-stabilized emulsions characteristically different from classical, rigid-particle-stabilized Pickering emulsions, the stability of which depends on the surface properties of the particles.

Studying (neuro)muscular disorders is a major topic in biomedicine with a demand for suitable model systems. Continuous cell culture (in vitro) systems have several technical advantages over in vivo systems and became widely used tools for discovering physiological/pathophysiological mechanisms in muscle. In particular, myoblast cell lines are suitable model systems to study complex biochemical adaptations occurring in skeletal muscle and cellular responses to altered genetic/environmental conditions. Whereas most in vitro studies use extensively characterized murine C2C12 cells, a comprehensive description of an equivalent human cell line, not genetically manipulated for immortalization, is lacking. Therefore, we characterized human immortal myoblastic RCMH cells using scanning (SEM) and transmission electron microscopy (TEM) and proteomics. Among more than 6200 identified proteins we confirm the known expression of proteins important for muscle function. Comparing the RCMH proteome with two well-defined nonskeletal muscle cells lines (HeLa, U2OS) revealed a considerable enrichment of proteins important for muscle function. SEM/TEM confirmed the presence of agglomerates of cytoskeletal components/intermediate filaments and a prominent rough ER. In conclusion, our results indicate RMCH as a suitable in vitro model for investigating muscle function-related processes such as mechanical stress burden and mechanotransduction, EC coupling, cytoskeleton, muscle cell metabolism and development, and (ER-associated) myopathic disorders.

Journal of hematology & oncology 9(1), 4 (2016). doi:10.1186/s13045-016-0234-9, Published by Biomed Central, London

The influence of architecture on polymer interactions is investigated and differences between branched and linear copolymers are found. A comprehensive picture is drawn with the help of a fluorescence approach (using pyrene and 4HP as probe molecules) together with IR or NMR spectroscopy and X-ray/light scattering measurements. Five key aspects are addressed: (1) synergistic intramolecular complexation within miktoarm stars. The proximity of thermoresponsive poly(propylene oxide) (PPO) and poly(dimethylaminoethyl methacrylate) (PDMAEMA) within a miktoarm star leads to complexation between these weakly interacting partners. Consequently, the original properties of the constituents are lost, showing hydrophobic domains even at low temperatures, at which all homopolymers are water soluble. (2) Unimolecular micelles for miktoarm stars. The star does not exhibit intermolecular self-assembly in a large temperature range, showing unimers up to 55 °C. This behavior was traced back to a reduced interfacial tension between the PPO–PDMAEMA complex and water (PDMAEMA acts as a “microsurfactant”). (3) Unimolecular to multimolecular micelle transition for stars. The otherwise stable unimolecular micelles self-assemble above 55 °C. This aggregation is not driven by PPO segregation, but by collapse of residual PDMAEMA. This leads to micrometer-sized multilamellar vesicles stabilized by poly(ethylene oxide) (PEO). (4) Prevention of pronounced complexation within diblock copolymers. In contrast to the star copolymers, PPO and PDMAEMA adapt rather their homopolymer behavior within the diblock copolymers. Then they show their immanent LCST properties, as PDMAEMA turns insoluble at elevated temperatures, whereas PPO becomes hydrophobic below room temperature. (5) Two-step micellization for diblock copolymers. Upon heating of linear copolymers, the dehydration of PPO is followed by self-assembly into spherical micelles. An intermediate prevalence of unimolecular micelles is revealed in a small temperature window between PPO collapse and self-assembly of PEO-b-PPO. Also for PPO-b-PDMAEMA, PPO segregation prevails after initial weak complexation, leading to micelles with a PPO core. Considerable amounts of water are entrapped within the collapsed PDMAEMA domains above 55 °C (skin effect), preventing PPO–PDMAEMA complexation within precipitating PPO-b-PDMAEMA. Further, collapsed PDMAEMA is rather polar as sensed by pyrene and 4HP. In summary, advanced macromolecular architectures can lead to an unprecedented intramolecular self-assembly behavior, where internal complexation prevents intermolecular aggregation.

It has long been appreciated that material chemistry and topology profoundly affect cell adhesion and migration. Here, aqueous poly(N-isopropyl acrylamide) nanogels are designed, synthesized and printed in form of colloidal arrays on glass substrates using wrinkled polydimethylsiloxane templates. Using low-temperature plasma treatment, nanogels are chemically grafted onto glass supports thus leading to highly stable nanogel layers in cell culture media. Liquid cell atomic force microscopy investigations show that surface-grafted nanogels retain their swelling behavior in aqueous media and that extracellular matrix protein coating do not alter their stability and topography. It is demonstrated that surface-grafted nanogels could serve as novel substrates for the analysis of cell adhesion and migration. Nanogels influence size, speed, and dynamics of focal adhesions and cell motility forcing cells to move along highly directional trajectories. Moreover, modulation of nanogel state or spacing serves as an effective tool for regulation of cell motility. It is suggested that nanogel arrays deposited on solid surfaces could be used to provide a precise and tunable system to understand and control cell migration. Additionally, such nanogel arrays will contribute to the development of implantable systems aimed at supporting and enhancing cell migration during, for instance, wound healing and tissue regeneration.