Antimicrobial peptides (AMPs) have attracted great interest as they constitute one of the most promising alternatives against drug-resistant infections. Their amphipathic nature not only provides ...them antimicrobial and immunomodulatory properties but also the ability to self-assemble into supramolecular nanostructures. Here, we propose their use as self-assembling domains to drive hierarchical organization of intrinsically disordered protein polymers (IDPPs). Using a modular approach, hybrid protein-engineered polymers were recombinantly produced, thus combining designer AMPs and a thermoresponsive IDPP, an elastin-like recombinamer (ELR). We exploited the ability of these AMPs and ELRs to self-assemble to develop supramolecular nanomaterials by way of a dual-assembly process. First, the AMPs trigger the formation of nanofibers; then, the thermoresponsiveness of the ELRs enables assembly into fibrillar aggregates. The interplay between the assembly of AMPs and ELRs provides an innovative molecular tool in the development of self-assembling nanosystems with potential use for biotechnological and biomedical applications.
In article number 2005191, José Carlos Rodríguez‐Cabello and co‐workers report micrometric colporate biomorphs self‐assembled from an intrinsically disordered silk‐elastin‐like protein, in which the ...concurrent effect of hydrophobic, electrostatic and H‐bonding interactions are capable of generating and kinetically trapping complex and transient structures in time during desolvation processes. This platform provides a novel approach to understand the order‐disorder crosstalk and participating interactions in the self‐organization process of native proteins in living organisms and how they develop morphology.
One of the main challenges in regenerative medicine is the spatiotemporal control of angiogenesis, which is key for the successful repair of many tissues, and determines the proper integration of the ...implant through the generation of a functional vascular network. To this end, we have designed a three-dimensional (3D) model consisting of a coaxial binary elastin-like recombinamer (ELR) tubular construct. It displays fast and slow proteolytic hydrogels on its inner and outer part, respectively, both sensitive to the urokinase plasminogen activator protease. The ELRs used to build the scaffold included crosslinkable domains to stabilize the structure and a conjugated VEGF-derived peptide (QK) to induce angiogenesis. The mechanical and morphological evaluation of the ELR hydrogels proved their suitability for soft tissue regeneration. In addition, in vitro studies evidenced the effect of the QK peptide on endothelial cell spreading and anastomosis. Moreover, immunohistochemical analyses after subcutaneous implantation of the ELR hydrogels in mice showed the induction of a low macrophage response that resolved over time. The implantation of the 3D model constructs evidenced the ability of the fast proteolytic sequence and the QK peptide to guide cell infiltration and capillary formation in the pre-designed arrangement of the constructs. These results set the basis for the application of this type of scaffolds in regenerative medicine, where spatiotemporally controlled vascularization will help in the promotion of an optimal tissue repair.
Herein, we show the spatiotemporal control of angiogenesis in vivo by the combination of proteolytic sequences, with fast and slow degradation kinetics, and VEGF-mimetic peptide (QK) in a coaxial binary elastin-like recombinamer (ELR) tubular scaffold. These two bioactivities have been previously described for angiogenesis purposes, but have never been combined. This work demonstrates that the bioactivities act synergistically in promoting cell infiltration and subsequent vascularization, thus leading to a controlled evolution in space and time of the vascular microstructure within the hydrogel-like tubular scaffold. This effect has not been showed before and holds great potential for future vascular applications, which might be of great interest for a substantial part of Acta Biomaterialia readership.
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The chronic problems of the Spanish labor market have dramatically reappeared during the current Great Recession. Besides being astonishingly high, the Spanish unemployment rate is extremely volatile ...compared to other countries. This paper analyzes the main changes of the new labor market reform approved in Spain in 2012 in relation to the labor market situation. The reform aims to achieve higher internal flexibility to get an adjustment to business cycle fluctuations. However, it fails in other relevant areas, like suppressing dualism, improving the effectiveness of active labor market policies, enhancing productivity and maintaining the level of social protection of workers.
Complex recombinant biomaterials that merge the self‐assembling properties of different (poly)peptides provide a powerful tool for the achievement of specific structures, such as hydrogel networks, ...by tuning the thermodynamics and kinetics of the system through a tailored molecular design. In this work, elastin‐like (EL) and silk‐like (SL) polypeptides are combined to obtain a silk‐elastin‐like recombinamer (SELR) with dual self‐assembly. First, EL domains force the molecule to undergo a phase transition above a precise temperature, which is driven by entropy and occurs very fast. Then, SL motifs interact through the slow formation of β‐sheets, stabilized by H‐bonds, creating an energy barrier that opposes phase separation. Both events lead to the development of a dynamic microstructure that evolves over time (until a pore size of 49.9 ± 12.7 µm) and to a delayed hydrogel formation (obtained after 2.6 h). Eventually, the network is arrested due to an increase in β‐sheet secondary structures (up to 71.8 ± 0.8%) within SL motifs. This gives a high bond strength that prevents the complete segregation of the SELR from water, which results in a fixed metastable microarchitecture. These porous hydrogels are preliminarily tested as biomimetic niches for the isolation of cells in 3D cultures.
The combination of elastin and silk‐like polypeptides leads to a complex self‐assembly involving an entropy‐driven phase segregation of elastin from water and an increase in intermolecular interactions due to hydrogen bonding between silk domains. The different kinetics of both processes results in a peculiar hydrogel microarchitecture that evolves over time, whose pores act as biomimetic niches for three‐dimensional cell culture.
Temperature modulated differential scanning calorimetry (TMDSC) has been used to study the phase separation process of three elastin-like model polymers; chemically synthesized poly(GVGVP) and ...genetically engineered (GVGVP)
251 and (GVGIP)
320. By these means, the characteristic endothermic peak found for these polymers in conventional calorimetry is revealed as being composed of two components, one endothermic due to loss of hydrophobic hydration and an oppositely signed exothermic component due to the physical association of chains (Vander Waals cohesive interactions) with the magnitude of the exothermic component being less than one-third that of the endothermic component. The magnitude of both components seems to depend mainly on the mean hydrophobicity of the monomer and not on the polymer molecular weight or dispersity.
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Herein we present a system to obtain fibers from clickable elastin-like recombinamers (ELRs) that crosslink in situ during the electrospinning process itself, with no need for any ...further treatment to stabilize them. These ELR-click fibers are completely stable under in vitro conditions. A wrinkled fiber morphology is obtained. In addition to a random fiber orientation, oriented fibers with a high degree of alignment and coherence can also be obtained by using a rotational electrode. The production of multicomponent fibers means that different functionalities, such as cell-adhesion domains (RGD peptides), can be incorporated into them. In a subsequent study, two main cell lines present in the dermis and epidermis, namely keratinocytes and fibroblasts, were cultured on top of the ELR-click fibers. Adhesion, proliferation, fluorescence, immunostaining and histology studies showed the cytocompatibility of these scaffolds, thus suggesting their possible use for wound dressings in skin tissue engineering applications.
For the first time stable electrospun bioactive fibers are obtained by the in situ mixing of two “clickable” ELR components previously described by Gonzalez et al (Acta Biomaterialia 2014). This work describes an efficient system to prepare fibrous scaffolds based on peptidic polymers by electrospinning without the need of crosslinking agents that could be harmful for cells or living tissues. These bioactive fibers support cell growth due to the inclusion of RGD motifs (Staubli et al. Biomaterials 2017). Finally, the in vitro biocompatibility of the two main cell types found in the outer layers of skin, fibroblasts and keratinocytes, indicates that this system is of great interest to prepare elastic artificial skin substitutes for wound healing applications.
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•A novel Elastin Like Recombinamer has been designed for being used as a bioink.•ELR bioink demonstrated good printability and enabled the bioprinting of resolutive ...scaffolds.•Fibroblast, HUVEC and hMSCs were bioprinted by using the ELR bioink.•Cells were viable within the bioprinted ELR bioink and were proliferative, showing their natural morphology.•Confocal images of the bioprinted scaffolds demonstrated the viability of the fibroblast at the inner parts.
The versatility of 3D bioprinting techniques has demonstrated great potential for the development of artificial engineered tissues that more closely resemble native tissues. Despite this, challenges remain as regards the search for new bioinks that embrace all the complex parameters that this technique demands. In an attempt to develop such an advanced material, a novel smart material based on elastin-like recombinamers (ELRs) has been developed by molecularly programming its sequence to exhibit a sequential three-stage gelation process, thus providing printing attributes.
The thermoresponsive behavior of the ELR is exploited for the deposition of well-controlled fibres on a platform heated to 37 °C, and its recombinant nature ensures batch-to-batch reproducibility and its applicability to a desired target tissue by the introduction of selected bioactive amino-acid sequences into its molecular chain.
The biocompatible nature of the ELR enables the printing of loaded cells while providing a protective environment as part of the printing process. Thus, HFF-1 cells were found to be able to proliferate within the printed structures upon culture, displaying their natural morphology.
The results of this work highlight the applicability and novelty of the bioprinting of biomimetic ELR-based structures for advanced applications.
IntroductionThe QuantiFERON-TB Gold Plus (QFT-Plus) assay, which features two antigen-stimulated tubes (TB1 and TB2) instead of a single tube used in previous-generation interferon-gamma release ...assays (IGRAs), was launched in 2016. Despite this, data regarding the assay’s performance in the paediatric setting remain scarce. This study aimed to determine the performance of QFT-Plus in a large cohort of children and adolescents at risk of tuberculosis (TB) in a low-burden setting.MethodsCross-sectional, multicentre study at healthcare institutions participating in the Spanish Paediatric TB Research Network, including patients <18 years who had a QFT-Plus performed between September 2016 and June 2020.ResultsOf 1726 patients (52.8% male, median age: 8.4 years), 260 (15.1%) underwent testing during contact tracing, 288 (16.7%) on clinical/radiological suspicion of tuberculosis disease (TBD), 649 (37.6%) during new-entrant migrant screening and 529 (30.6%) prior to initiation of immunosuppressive treatment. Overall, the sensitivity of QFT-Plus for TBD (n=189) and for latent tuberculosis infection (LTBI, n=195) was 83.6% and 68.2%, respectively. The agreement between QFT-Plus TB1 and TB2 antigen tubes was excellent (98.9%, κ=0.961). Only five (2.5%) patients with TBD had discordance between TB1 and TB2 results (TB1+/TB2−, n=2; TB1−/TB2+, n=3). Indeterminate assay results (n=54, 3.1%) were associated with young age, lymphopenia and elevated C reactive protein concentrations.ConclusionsOur non-comparative study indicates that QFT-Plus does not have greater sensitivity than previous-generation IGRAs in children in both TBD and LTBI. In TBD, the addition of the second antigen tube, TB2, does not enhance the assay’s performance substantially.
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