Response of bloom-forming cyanobacterium Microcystis aeruginosa to 17β-estradiol at different nitrogen levels

Co-existence of cyanobacterial harmful algal blooms (CyanoHABs) and steroid estrogens (SEs) has been an increasing concern in eutrophic waters. The cellular responses and biodegradation of 17β-estradiol (E2) in cyanobacterium Microcystis aeruginosa were investigated at different nitrogen levels. During the 10-d experiment, the growth of M. aeruginosa was stimulated by 10-100 μg L^-1 of E2 at the lowest nitrogen level of 0.5 mg L^-1, whereas the presence of E2 inhibited the cyanobacterial growth at 5 mg L^-1 of nitrogen. With nitrogen concentration increased to 50 mg L^-1, the impact of E2 on levels of growth rate and chlorophyll a (Chla) alleviated. Exposure to E2 also promoted the superoxide dismutase activity of M. aeruginosa, coupled with cellular oxidative damage as indicated by the increasing malondialdehyde content. A sufficient nitrogen supply mitigated the oxidative stress of E2 through enhancing the synthesis of detoxification-related enzymes. Simultaneously, the secretion of tryptophan-like substances in loosely- and tightly-bound extracellular polymeric substances was triggered for adapting to an E2 addition in the short term. Moreover, significant biodegradation of E2 was observed, and the process followed a first-order kinetic reaction. The obtained half-lives decreased with nitrogen levels and ranged from 2.47 to 2.81 and 3.39-5.04 d, respectively, at 10 and 100 μg L^-1 of E2. These results provide a better understanding of the potential effects of SEs on CyanoHABs formation, as well as the important role of CyanoHABs on SEs removal in aquatic ecosystems, which should be fully considered in the control of combined pollution.

Cellular response to collagen-elastin composite materials

Collagen is used extensively in tissue engineering due to its biocompatibility, near-universal tissue distribution, low cost and purity. However, native tissues are composites that include diverse extracellular matrix components, which influence strongly their mechanical and biological properties. Here, we provide important new findings on the differential regulation, by collagen and elastin, of the bio-response to the composite material. Soluble and insoluble elastin had differing effects on the stiffness and failure strength of the composite films. We established that Rugli cells bind elastin via EDTA-sensitive receptors, whilst HT1080 cells do not. These cells allowed us to probe the contribution of collagen alone (HT1080) and collagen plus elastin (Rugli) to the cellular response. In the presence of elastin, Rugli cell attachment, spreading and proliferation increased, presumably through elastin-binding receptors. By comparison, the attachment and spreading of HT1080 cells was modified by elastin inclusion, but without affecting their proliferation, indicating indirect modulation by elastin of the response of cells to collagen. These new insights highlight that access to elastin dominates the cellular response when elastin-binding receptors are present. In the absence of these receptors, modification of the collagen component and/or physical properties dictate the cellular response. Therefore, we can attribute the contribution of each constituent on the ultimate bioactivity of heterogeneous collagen-composite materials, permitting informed, systematic biomaterials design. STATEMENT OF SIGNIFICANCE: In recent years there has been a desire to replicate the complex extracellular matrix composition of tissues more closely, necessitating the need for composite protein-based materials. In this case both the physical and biochemical properties are altered with the addition of each component, with potential consequences on the cell. To date, the different contributions of each component have not been deconvolved, and instead the cell response to the scaffold as a whole has been observed. Instead, here, we have used specific cell lines, that are sensitive to specific components of an elastin-collagen composite, to resolve the bio-activity of each protein. This has shown that elastin-induced alteration of the collagen component can modulate early stage cell behaviour. By comparison the elastin component directly alters the cell response over the short and long term, but only where appropriate receptors are present on the cell. Due to the widespread use of collagen and elastin, we feel that this data permits, for the first time, the ability to systematically design collagen-composite materials to promote desired cell behaviour with associated advantages for biomaterials fabrication.

Cellular responses to thermoresponsive stiffness memory elastomer nanohybrid scaffolds by 3D-TIPS

Increasing evidence suggests the contribution of the dynamic mechanical properties of the extracellular matrix (ECM) to regulate tissue remodeling and regeneration. Following our recent study on a family of thermoresponsive 'stiffness memory' elastomeric nanohybrid scaffolds manufactured via an indirect 3D printing guided thermally-induced phase separation process (3D-TIPS), this work reports in vitro and in vivo cellular responses towards these scaffolds with different initial stiffness and hierarchically interconnected porous structure. The viability of mouse embryonic dermal fibroblasts in vitro and the tissue responses during the stiffness softening of the scaffolds subcutaneously implanted in rats for three months were evaluated by immunohistochemistry and histology. Scaffolds with a higher initial stiffness and a hierarchical porous structure outperformed softer ones, providing initial mechanical support to cells and surrounding tissues before promoting cell and tissue growth during stiffness softening. Vascularization was guided throughout the digitally printed interconnected networks. All scaffolds exhibited polarization of the macrophage response from a macrophage phenotype type I (M1) towards a macrophage phenotype type II (M2) and down-regulation of the T-cell proliferative response with increasing implantation time; however, scaffolds with a more pronounced thermo-responsive stiffness memory mechanism exerted higher inflammo-informed effects. These results pave the way for personalized and biologically responsive soft tissue implants and implantable device with better mechanical matches, angiogenesis and tissue integration. Statement of Significance This work reports cellular responses to a family of 3D-TIPS thermoresponsive nanohybrid elastomer scaffolds with different stiffness softening both in vitro and in vivo rat models. The results, for the first time, have revealed the effects of initial stiffness and dynamic stiffness softening of the scaffolds on tissue integration, vascularization and inflammo-responses, without coupling chemical crosslinking processes. The 3D printed, hierarchically interconnected porous structures guide the growth of myofibroblasts, collagen fibers and blood vessels in real 3D scales. In vivo study on those unique smart elastomer scaffolds will help pave the way for personalized and biologically responsive soft tissue implants and implantable devices with better mechanical matches, angiogenesis and tissue integration.

Influence of nanoporous titanium niobium alloy surfaces produced via hydrogen peroxide oxidative etching on the osteogenic differentiation of human mesenchymal stromal cells

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.

Novel imiquimod nanovesicles for topical vaccination

Development of needle and pain free noninvasive immunization procedures is a top priority for public health agencies. In this work the topical adjuvant activity of the immunomodulator imiquimod (IMQ) carried by ultradeformable archaeosomes (UDA₂) (nanovesicles containing sn-2,3 ether linked phytanyl saturated archaeolipids) was surveyed and compared with that of ultradeformable liposomes lacking archaeolipids (UDL₂) and free IMQ, using the model antigen ovalbumin and a seasonal influenza vaccine in Balb/c mice. UDA₂ (250 ± 94 nm, -26 ± 4 mV Z potential) induced higher IMQ accumulation in human skin and higher production of TNF-α and IL-6 by macrophages and keratinocytes than free IMQ and UDL₂. Mixed with ovalbumin, UDA₂ was more efficient at generating cellular response, as measured by an increase in serum IgG2a and INF-γ production by splenocytes, compared with free IMQ and UDL₂. Moreover, mixed with a seasonal influenza vaccine UDA₂ produced same IgG titers and IgG2a/IgG1 isotypes ratio (≈1) than the subcutaneously administered influenza vaccine. Topical UDA₂ however, induced highest stimulation index and INF-γ levels by splenocytes. UDA₂ might be a promising adjuvant for topical immunization, since it produced cell-biased systemic response with ≈ 13-fold lower IMQ dose than the delivered as the commercial IMQ cream, Aldara.

Acute and oral exposure to imidacloprid does not affect the number of circulating hemocytes in the stingless bee Melipona quadrifasciata post immune challenge

In the present work, the effects of the neonicotinoid imidacloprid formulation on the total hemocyte counts (THC) and differential hemocyte counts (DHC) were investigated in foraging workers of the stingless bee Melipona quadrifasciata under (or not) the challenge with the bacteria Escherichia coli. The THC was not altered with the insecticide exposure and/or bacterial infection. However, the DHC of the bees changed with the imidacloprid exposure and/or bacterial infection. The number of prohemocytes (stem cells) increased in bees exposed to imidacloprid, but it did not change after the bacterial infection. The number of plasmatocytes (phagocytic cells) increased in imidacloprid-exposed and uninfected bees and decreased in infected bees regardless of the exposure to imidacloprid. On the other hand, there was a reduction of granulocytes, the most active immune cells, after imidacloprid exposure and an increase of granulocytes after the infection. Previous studies have shown that the neonicotinoids exposure can impair the immune system of bees. Our findings showed that the relative number of granulocytes declined with imidacloprid exposure, but the overall capacity of hemocyte responses in terms of total numbers after bacterial infection persisted even after the insecticide exposure.

Early cellular responses of germ-free and specific-pathogen-free mice to Francisella tularensis infection

Bacteria that are highly virulent, expressing high infectivity, and able to survive nebulization, pose great risk to the human population. One of these is Francisella tularensis, the etiological agent of tularemia. F. tularensis is a subject of intense scientific interest due to the fact that vaccines for its immunoprophylaxis in humans are not yet routinely available. One of the substantial obstacles in developing such vaccines is our insufficient knowledge of processes that initiate and regulate the expression of effective protective immunity against intracellular bacteria. Here, we present data documenting the different pattern of cellular behavior occurring in an environment unaffected by microbiota using the model of germ-free mice mono-associated with F. tularensis subsp. holarctica strain LVS in comparison with a classic specific-pathogen-free murine model during early stages of infection.

Development of micro mechanical device having two-dimensional array of micro chambers for cell stretching

This paper presents a novel cell stretching micro device having two-dimensional array of micro chambers. It enables an in situ time-lapse observation of stretched cell by using an optical microscope with high measurement efficiency. The presented device consists of a cell culture dish and the array of micro chambers made of silicone elastomer and extension structures made of photocurable resin, and is fabricated with MEMS technology. The fabrication process of the thin micro chamber array combines photoresist mold and lift-off process based on conventional photolithography. The fabricated device has 134micro chambers in 5μm or less thickness. It was demonstrated that the fabricated micro device could be used to make in-situ time-lapse observation of cell responses to stretching under optical microscopy. In addition, the influence of the chamber thickness to the quality of the microscope image observed was evaluated. It is confirmed that the proposed device having two-dimensional array of the thin micro chambers makes it possible to observe cell response for stretch stimuli with high quality and efficiency.

A microfluidic in-line ELISA for measuring secreted protein under perfusion

Recent progress in the development of microfluidic microphysiological systems such as 'organs-on-chips' and microfabricated cell culture is geared to simulate organ-level physiology. These tissue models leverage microengineering technologies that provide capabilities of presenting cultured cells with input signals in a more physiologically relevant context such as perfused flow. Proteins that are secreted from cells have important information about the health of the cells. Techniques to quantify cellular proteins include mass spectrometry to ELISA (enzyme-linked immunosorbent assay). Although our capability to perturb the cells in the microphysiological systems with varying inputs is well established, we lack the tools to monitor in-line the cellular responses. User intervention for sample collection and off-site is cumbersome, causes delays in obtaining results, and is especially expensive because of collection, storage, and offline processing of the samples, and in many case, technically impractical to carry out because of limitated sample volumes. To address these shortcomings, we report the development of an ELISA that is carried out in-line under perfusion within a microfluidic device. Using this assay, we measured the albumin secreted from perfused hepatocytes without and under stimulation by IL-6. Since the method is based on a sandwich ELISA, we envision broad application of this technology to not just organs-on-chips but also to characterizing the temporal release and measurement of soluble factors and response to drugs.

Mechanisms of auxin signaling

The plant hormone auxin triggers complex growth and developmental processes. Its underlying molecular mechanism of action facilitates rapid switching between transcriptional repression and gene activation through the auxin-dependent degradation of transcriptional repressors. The nuclear auxin signaling pathway consists of a small number of core components. However, in most plants each component is represented by a large gene family. The modular construction of the pathway can thus produce diverse transcriptional outputs depending on the cellular and environmental context. Here, and in the accompanying poster, we outline the current model for TIR1/AFB-dependent auxin signaling with an emphasis on recent studies.

Identification of mycobacterial bacterioferritin B for immune screening of tuberculosis and latent tuberculosis infection

OBJECTIVES

It remains necessary and urgent to search for novel mycobacterial antigens to increase the sensitivity and specificity for tuberculosis (TB) diagnosis and latent TB infection (LTBI) screening. Antigens capable of inducing strong immune responses during Mycobacterium tuberculosis (M.tb) infection would be good candidates.

METHODS

Cellular responses specific to M.tb derived bacterioferritin B (BfrB) were assessed by IFN-γ ELISPOT in three human cohorts, including healthy controls (HCs), LTBI population and pulmonary TB (PTB) patients. Its significance in TB diagnosis and LTBI identification was further analyzed.

RESULTS

BfrB-specific IFN-γ responses in PTB and LTBI groups were significantly higher than that in HCs. However, BfrB-specific IFN-γ release was not as strong as that to ESAT-6 or CFP-10 in PTB patients whereas comparable in LTBI cohort with possible complementary properties to ESAT-6 or CFP-10. More interestingly, there were a considerable number of HCs with high BfrB-specific cellular responses. When HCs with high BfrB-specific cellular responses were subgrouped into ESAT-6/CFP-10^hi (SFUs = 3, 4, 5) and ESAT-6/CFP-10^lo (SFUs < 3) groups, those who belonged to ESAT-6/CFP-10^hi group exhibited higher PPD responsiveness than ESAT-6/CFP-10^lo group.

CONCLUSIONS

PTB and LTBI groups exhibit higher BfrB-specific IFN-γ responses than HCs. Although BfrB is not as immunodominant as ESAT-6/CFP-10 during acute M.tb infection, comparable BfrB-specific cellular immune responses are observed in LTBI population with the potential to increase the sensitivity for LTBI screening. Moreover, strong BfrB-specific IFN-γ release in the healthy cohort is probably cautionary in identifying leaky LTBI from HCs. BfrB might thus be considered as an additional biomarker antigen for LTBI identification.

Molecular mechanisms of the yeast adaptive response and tolerance to stresses encountered during ethanol fermentation

During ethanol fermentation, yeast cells encounter various stresses including sugar substrates-induced high osmolarity, increased ethanol concentration, oxygen metabolism-derived reactive oxygen species (ROS), and elevated temperature. To cope with these fermentation-associated stresses, appropriate adaptive responses are required to prevent stress-induced cellular dysfunctions and to acquire stress tolerances. This review will focus on the cellular effects of these stresses, molecular basis of the adaptive response to each stress, and the cellular mechanisms contributing to stress tolerance. Since a single stress can cause diverse effects, including specific and non-specific effects, both specific and general stress responses are needed for achieving comprehensive protection. For instance, the high-osmolarity glycerol (HOG) pathway and the Yap1/Skn7-mediated pathways are specifically involved in responses to osmotic and oxidative stresses, respectively. On the other hand, due to the common effect of these stresses on disturbing protein structures, the upregulation of heat shock proteins (HSPs) and trehalose is induced upon exposures to all of these stresses. A better understanding of molecular mechanisms underlying yeast tolerance to these fermentation-associated stresses is essential for improvement of yeast stress tolerance by genetic engineering approaches.

T cell cytokine responses in peripheral blood mononuclear cells from patients with multidrug-resistant tuberculosis following stimulation with proteins purified from Mycobacterium tuberculosis MDR clinical isolates

OBJECTIVE

Tuberculosis (TB) is a devastating disease that remains a major health threat worldwide. The appearance of Mycobacterium tuberculosis strains resistance to current antibiotics is a growing problem, both in the third world and in developed countries. Completion of genomic sequencing of M. tuberculosis provides a strong foundation for subsequent identification of proteins to aid the understanding of protein function and the discovery of new drug targets or a TB vaccine. This study employed a proteomics approach to identify proteins from antibiotic resistant M. tuberculosis isolates and compare them to drug-sensitive isolates to determine the role of T cells in multidrug-resistant (MDR)-TB patients against M. tuberculosis-purified proteins (Rv0147) as compared with healthy subjects.

METHODS

Proteins were extracted by Triton X-114 detergent-phase separation and precipitated by adding saturated ammonium sulfate to the supernatant. Following isoelectric focusing, proteins were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis. Mass spectrometry was performed, and protein sequences were determined. Peripheral bloom mononuclear cells (PBMCs) were cultured, and autologous T cells were isolated from PBMCs by negative selection. Cells were subsequently cultured at 37°C in 5% CO₂, followed by stimulation with 10μg/mL of the protein candidate (Rv0147) for 72h. Culture supernatants were assayed for interleukin (IL)-10 and interferon (IFN)-γ by enzyme-linked immunosorbent assay.

RESULTS

The identified proteins included Rv3057c, Rv0009, Rv3161c, Rv3614c, Rv0685, Rv2986c, Rv0443, Rv2114, Rv3311, Rv0831, Rv3804, and Rv3614c, and our results showed that the majority of upregulated or overexpressed proteins belonged to pathways associated with cellular metabolism, cell wall integrity, respiration, or cell membrane construction. Additionally, Rv1876 from MDR-TB isolates was predicted to be involved in the expression of bacterioferritin exclusively in MDR-TB-related resistance to first-line TB drugs. Furthermore, Rv2031c (HspX) was induced under oxygen-deficient conditions, and hypothetical protein (Rv2744c) and two membrane- and cell-wall-fraction proteins (Rv0379 and Rv1886c) were also identified. Analysis revealed increased percentages of INF-γ and decreased IL-10 levels in MDR-TB patients as compared with those observed in normal subjects.

CONCLUSION

Four identified membrane or membrane-associated proteins, including bacterioferritin, GroEs, HspX, and Ef-Tu, may be potential targets for the development of novel prophylactic diagnostics and therapeutic strategies against TB. Our results suggested that T cells stimulated by the protein candidate Rv0147 may be shifted to T helper 1 status in MDR-TB patients.

Osteoblast and stem cell response to nanoscale topographies: a review

To understand how cells respond to the nanoscale extracellular environment in vivo, cells from various sources have been cultured on nanoscale patterns fabricated using bottom-up and top-down techniques. Human fetal osteoblasts (hFOBs) and stem cells are some of them and they are known to be overtly responsive to nanoscale topographies - allowing us to investigate the hows and whys of the response in vitro. Information gathered from these in vitro studies could be used to control the cells, i.e. make the stem cells differentiate or retain their characteristics without the use of medium supplements. In this review, hFOB and stem cell responses to nanotopographies are summarized and discussed to shed some light on the influence of patterns on the reactions. Although both types of cells are responsive to nanoscale topographies, the responses are found to be unique to topographical dimension, shape, orientation and the types of cells used. This implies that cellular responses are influenced by multitude of factors and that if done right, cheaper self-assembled nanotopographies can be tailored to control the cells. A new self-assembly, powder-based technique is also included to provide an insight into the future of nanofabrication.

Cellular responses of the tiger shrimp Penaeus monodon haemocytes after lipopolysaccharide injection

This study was aimed at investigating the in vivo effects of lipopolysaccharide (LPS) injection on Penaeus monodon haemocytes at a cellular level. Cellular responses of LPS-injected shrimp were analysed using flow cytometry. Results showed that LPS injection caused total haemocyte count (THC) and count of large cells (semigranular and granular cells) decline. In LPS-injected shrimp, percentage of large cells decreased at the initial stage, and returned to the original level later. After LPS infection, non-specific esterase activity, reactive oxygen species (ROS) production and nitric oxide (NO) production in haemocytes were significantly induced, while apoptotic cell ratio of haemocytes increased. PO activity in plasma increased in shrimp received LPS at 2 μg g(-1) after 3-12 h and at 8 μg g(-1) after 3-6 h, and then returned to the initial levels. These results demonstrated that LPS induced immune responses on haemocytes, including production of ROS and NO, and release of esterase and PO. On the other hand, THC reduction might be due to the ROS/NO-induced apoptosis. Haemocyte apoptosis which would eliminate damaged or weak cells and contribute to haemocyte renewal, may be a defending strategie against pathogens.

MicroRNA-1 properties in cancer regulatory networks and tumor biology

Short non-coding microRNAs have been identified to orchestrate crucial mechanisms in cancer progression and treatment resistance. MicroRNAs are involved in posttranscriptional modulation of gene expression and therefore represent promising targets for anticancer therapy. As mircoRNA-1 (miR-1) exerted to be predominantly downregulated in the majority of examined tumors, miR-1 is classified to be a tumor suppressor with high potential to diminish tumor development and therapy resistance. Here we review the complex functionality of miR-1 in tumor biology.

Effects of hierarchical micro/nano-topographies on the morphology, proliferation and differentiation of osteoblast-like cells

Coating the surfaces of titanium-based implants with appropriate hierarchical micro/nano-topographies resembling the structure of natural bone significantly enhances their biological performance. However, the relationship between nanostructures surfaces and their effects on modulating cellular response is not clearly understood. Moreover, it is not clear whether the surface chemistry or topography is the main factor on modulating cellular behavior, because the commonly used surface modification techniques for titanium-based implants simultaneously modify surface topography and chemistry. The aim of this study is to investigate osteoblast-like cell adhesion, proliferation and differentiation on hierarchical micro/nano-topographies with similar surface chemistry but different nano-scale features. Micro-arc oxidation and post hydrothermal treatment were employed to fabricate micro/nano-topographies on titanium. According to the morphological features, they were classified as microcrater (micro-topography), nanoplate (hierarchical topography with nanoplates) and nanoleaf (hierarchical topography with nanoleaves). The response of osteoblast like cells (SaOS-2) was studied on each surface after sputtering with a thin layer of gold (Au) to minimize the influence of surface chemistry. The morphological evaluation after histochemical staining revealed that the adherent cells were polygonal-shaped on microcrater surface, roundish on nanoplate surface and elongated on nanoleaf surface. Additionally, compared to microcrater surface, nanoplate surface slowed down cell proliferation and exhibited no enhancement on cell differentiation. However, nanoleaf surface supported cell proliferation and promoted cell differentiation. The results indicate that tuning morphological features of nanostructures on micro-topography can serve as a promising strategy to specifically modulate cellular response, such as cell morphology, proliferation, differentiation and mineralization.

Characteristics and osteogenic effect of zirconia porous scaffold coated with β-TCP/HA

PURPOSE

The purpose of this study was to evaluate the properties of a porous zirconia scaffold coated with bioactive materials and compare the in vitro cellular behavior of MC3T3-E1 preosteoblastic cells to titanium and zirconia disks and porous zirconia scaffolds.

MATERIALS AND METHODS

Titanium and zirconia disks were prepared. A porous zirconia scaffold was fabricated with an open cell polyurethane disk foam template. The porous zirconia scaffolds were coated with β-TCP, HA and a compound of β-TCP and HA (BCP). The characteristics of the specimens were evaluated using scanning electron microscopy (SEM), energy dispersive x-ray spectrometer (EDX), and x-ray diffractometry (XRD). The dissolution tests were analyzed by an inductively coupled plasma spectrometer (ICP). The osteogenic effect of MC3T3-E1 cells was assessed via cell counting and reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

The EDX profiles showed the substrate of zirconia, which was surrounded by the Ca-P layer. In the dissolution test, dissolved Ca(2+) ions were observed in the following decreasing order; β-TCP > BCP > HA (P<.05). In the cellular experiments, the cell proliferation on titanium disks appeared significantly lower in comparison to the other groups after 5 days (P<.05). The zirconia scaffolds had greater values than the zirconia disks (P<.05). The mRNA level of osteocalcin was highest on the non-coated zirconia scaffolds after 7 days.

CONCLUSION

Zirconia had greater osteoblast cell activity than titanium. The interconnecting pores of the zirconia scaffolds showed enhanced proliferation and cell differentiation. The activity of osteoblast was more affected by microstructure than by coating materials.

Genetically engineered silk-collagen-like copolymer for biomedical applications: production, characterization and evaluation of cellular response

Genetically engineered protein polymers (GEPP) are a class of multifunctional materials with precisely controlled molecular structure and property profile. Representing a promising alternative for currently used materials in biomedical applications, GEPP offer multiple benefits over natural and chemically synthesized polymers. However, producing them in sufficient quantities for preclinical research remains challenging. Here, we present results from an in vitro cellular response study of a recombinant protein polymer that is soluble at low pH but self-organizes into supramolecular fibers and physical hydrogels at neutral pH. It has a triblock structure denoted as C2S(H)48C2, which consists of hydrophilic collagen-inspired and histidine-rich silk-inspired blocks. The protein was successfully produced by the yeast Pichia pastoris in laboratory-scale bioreactors, and it was purified by selective precipitation. This efficient and inexpensive production method provided material of sufficient quantities, purity and sterility for cell culture study. Rheology and erosion studies showed that it forms hydrogels exhibiting long-term stability, self-healing behavior and tunable mechanical properties. Primary rat bone marrow cells cultured in direct contact with these hydrogels remained fully viable; however, proliferation and mineralization were relatively low compared to collagen hydrogel controls, probably because of the absence of cell-adhesive motifs. As biofunctional factors can be readily incorporated to improve material performance, our approach provides a promising route towards biomedical applications.

Surface plasmon resonance fiber sensor for real-time and label-free monitoring of cellular behavior

This paper reports on the application of an optical fiber biosensor for real-time analysis of cellular behavior. Our findings illustrate that a fiber sensor fabricated from a traditional telecommunication fiber can be integrated into conventional cell culture equipment and used for real-time and label-free monitoring of cellular responses to chemical stimuli. The sensing mechanism used for the measurement of cellular responses is based on the excitation of surface plasmon resonance (SPR) on the surface of the optical fiber. In this proof of concept study, the sensor was utilized to investigate the influence of a number of different stimuli on cells-we tested the effects of trypsin, serum and sodium azide. These stimuli induced detachment of cells from the sensor surface, uptake of serum and inhibition of cellular metabolism, accordingly. The effects of different stimuli were confirmed with alamar blue assay, phase contrast and fluorescence microscopy. The results indicated that the fiber biosensor can be successfully utilized for real-time and label-free monitoring of cellular response in the first 30 min following the introduction of a stimulus. Furthermore, we demonstrated that the optical fiber biosensors can be easily regenerated for repeated use, proving this platform as a versatile and cost-effective sensing tool.

Developmental changes in cellular and humoral responses of the burying beetle Nicrophorus vespilloides (Coleoptera, Silphidae)

Necrophagous beetles of the genus Nicrophorus have developed various defence mechanisms that reduce the negative effects of adverse environmental conditions. However, many physiological and ecological aspects, including the functioning of the immune system in burying beetles, are still unknown. In this study, we show developmental changes in cellular and humoral responses of larvae, pupae, and adults of Nicrophorus vespilloides. We assessed changes in total haemocyte count, phenoloxidase activity, and phagocytic ability of haemocytes. We found that during larval development there is a progressive increase in humoral and cellular activities, and these responses are correlated with alterations of total haemocyte counts in the haemolymph. In the pupal stage, a sharp drop in the number of phagocytic haemocytes and an increase in phenoloxidase activity were observed. In adults, cellular and humoral responses remained at a lower level. It is probable that high lytic activity of anal and oral secretions produced by parents supports a lower response of the immune system in the initial phase of larval development. In the studied stages, we also observed differences in polymerisation of F-actin cytoskeleton of haemocytes, number of haemocytes forming filopodia, and filopodia length. These results suggest that the differences in immune responses during various stages of development of N. vespilloides are associated with a dynamically changing environment and different risks of infection. For the first time a detailed analysis of stage-specific alterations in immune system activity during development of the burying beetle is presented.

Oriented collagen nanocoatings for tissue engineering

Collagens are among the most widely present and important proteins composing the human total body, providing strength and structural stability to various tissues, from skin to bone. In this paper, we report an innovative approach to bioactivate planar surfaces with oriented collagen molecules to promote cells proliferation and alignment. The Langmuir-Blodgett technique was used to form a stable collagen film at the air-water interface and the Langmuir-Schaefer deposition was adopted to transfer it to the support surface. The deposition process was monitored by estimating the mass of the protein layers after each deposition step. Collagen films were then structurally characterized by atomic force, scanning electron and fluorescent microscopies. Finally, collagen films were functionally tested in vitro. To this aim, 3T3 cells were seeded onto the silicon supports either modified or not (control) by collagen film deposition. Cells adhesion and proliferation on collagen films were found to be greater than those on control both after 1 (p<0.05) and 7 days culture. Moreover, the functionalization of the substrate surface triggered a parallel orientation of cells when cultured on it. In conclusion, these data demonstrated that the Langmuir-Schaefer technique can be successfully used for the deposition of oriented collagen films for tissue engineering applications.

Cellular Response to Ionizing Radiation: A MicroRNA Story

MicroRNAs (miRNAs) represent a class of small non-coding RNA molecules that regulate gene expression at the post-transcriptional level. They play a crucial role in diverse cellular pathways. Ionizing radiation (IR) is one of the most important treatment protocols for patients that suffer from cancer and affects directly or indirectly cellular integration. Recently it has been discovered that microRNA-mediated gene regulation interferes with radio-related pathways in ionizing radiation. Here, we review the recent discoveries about miRNAs in cellular response to IR. Thoroughly understanding the mechanism of miRNAs in radiation response, it will be possible to design new strategies for improving radiotherapy efficiency and ultimately cancer treatment.