Publications

There is a growing interest in developing natural hydrogel-based scaffolds to culture cells in a three-dimensional (3D) millieu that better mimics the in vivo cells' microenvironment. A promising approach is to use hydrogels from animal tissues, such as decellularized extracellular matrices; however, they usually exhibit suboptimal mechanical properties compared to native tissue and their composition with hundreds of different protein complicates to elucidate which stimulus triggers cell's responses. As simpler scaffolds, type I collagen hydrogels are used to study cell behavior in mechanobiology even though they are also softer than native tissues. In this work, type I collagen is mixed with bacterial nanocellulose fibers (BCf) to develop reinforced scaffolds with mechanical properties suitable for 3D cell culture. BCf were produced from blended pellicles biosynthesized from Komagataeibacter xylinus. Then, BCf were mixed with concentrated collagen from rat-tail tendons to form composite hydrogels. Confocal laser scanning microscopy and scanning electron microscopy images confirmed the homogeneous macro- and microdistribution of both natural polymers. Porosity analysis confirmed that BCf do not disrupt the scaffold structure. Tensile strength and rheology measurements demonstrated the reinforcement action of BCf (43% increased stiffness) compared to the collagen hydrogel while maintaining the same viscoelastic response. Additionally, this reinforcement of collagen hydrogels with BCf offers the possibility to mix cells before gelation and then proceed to the culture of the 3D cell scaffolds. We obtained scaffolds with human bone marrow-derived mesenchymal stromal cells or human fibroblasts within the composite hydrogels, allowing a homogeneous 3D viable culture for at least 7 days. A smaller surface shrinkage in the reinforced hydrogels compared to type I collagen hydrogels confirmed the strengthening of the composite hydrogels. These collagen hydrogels reinforced with BCf might emerge as a promising platform for 3D in vitro organ modeling, tissue-engineering applications, and suitable to conduct fundamental mechanobiology studies.

JTD Keywords: 3d cell culture, bacterial cellulose, collagen, composite hydrogels, 3d cell culture, Bacterial cellulose, Cellulose/collagen composite, Collagen, Composite hydrogels, Contraction, Cross-linking, Cytocompatibility, Fibroblasts, Matrix, Mechanical-properties, Reinforcement, Stiffness, Tissue engineering

Mimicking bone extracellular matrix (ECM) is paramount to develop novel biomaterials for bone tissue engineering. In this regard, the combination of integrin-binding ligands together with osteogenic peptides represents a powerful approach to recapitulate the healing microenvironment of bone. In the present work, we designed polyethylene glycol (PEG)-based hydrogels functionalized with cell instructive multifunctional biomimetic peptides (either with cyclic RGD-DWIVA or cyclic RGD-cyclic DWIVA) and cross-linked with matrix metalloproteinases (MMPs)-degradable sequences to enable dynamic enzymatic biodegradation and cell spreading and differentiation. The analysis of the intrinsic properties of the hydrogel revealed relevant mechanical properties, porosity, swelling and degradability to engineer hydrogels for bone tissue engineering. Moreover, the engineered hydrogels were able to promote human mesenchymal stem cells (MSCs) spreading and significantly improve their osteogenic differentiation. Thus, these novel hydrogels could be a promising candidate for applications in bone tissue engineering, such as acellular systems to be implanted and regenerate bone or in stem cells therapy.Copyright © 2023 Oliver-Cervelló, Martin-Gómez, Gonzalez-Garcia, Salmeron-Sanchez, Ginebra and Mas-Moruno.

JTD Keywords: biomaterials, cross-linking, dwiva, functionalization, hydrogel, integrin, kinetics, marrow stromal cells, matrices, multifunctionality, myogenic differentiation, osteogenic differentiation, regeneration, stem-cells, Biomimetic peptides, Dwiva, Functionalization, Hydrogel, Multifunctionality, Osteogenic differentiation, Poly(ethylene glycol) hydrogels

The term 'mechanosensation' describes the capacity of cells to translate mechanical stimuli into the coordinated regulation of intracellular signals, cellular function, gene expression and epigenetic programming. This capacity is related not only to the sensitivity of the cells to tissue motion, but also to the decryption of tissue geometric arrangement and mechanical properties. The cardiac stroma, composed of fibroblasts, has been historically considered a mechanically passive component of the heart. However, the latest research suggests that the mechanical functions of these cells are an active and necessary component of the developmental biology programme of the heart that is involved in myocardial growth and homeostasis, and a crucial determinant of cardiac repair and disease. In this Review, we discuss the general concept of cell mechanosensation and force generation as potent regulators in heart development and pathology, and describe the integration of mechanical and biohumoral pathways predisposing the heart to fibrosis and failure. Next, we address the use of 3D culture systems to integrate tissue mechanics to mimic cardiac remodelling. Finally, we highlight the potential of mechanotherapeutic strategies, including pharmacological treatment and device-mediated left ventricular unloading, to reverse remodelling in the failing heart.© 2022. Springer Nature Limited.

JTD Keywords: cardiomyocyte proliferation, cross-linking, extracellular-matrix, focal adhesions, gene-expression, mechanical regulation, myocardial-infarction, substrate stiffness affects, t-cells, Ventricular assist device

Type 1 Diabetes results from autoimmune response elicited against β-cell antigens. Nowadays, insulin injections remain the leading therapeutic option. However, injection treatment fails to emulate the highly dynamic insulin release that β-cells provide. 3D cell-laden microspheres have been proposed during the last years as a major platform for bioengineering insulin-secreting constructs for tissue graft implantation and a model for in vitro drug screening platforms. Current microsphere fabrication technologies have several drawbacks: the need for an oil phase containing surfactants, diameter inconsistency of the microspheres, and high time-consuming processes. These technologies have widely used alginate for its rapid gelation, high processability, and low cost. However, its low biocompatible properties do not provide effective cell attachment. This study proposes a high-throughput methodology using a 3D bioprinter that employs an ECM-like microenvironment for effective cell-laden microsphere production to overcome these limitations. Crosslinking the resulting microspheres with tannic acid prevents collagenase degradation and enhances spherical structural consistency while allowing the diffusion of nutrients and oxygen. The approach allows customization of microsphere diameter with extremely low variability. In conclusion, a novel bio-printing procedure is developed to fabricate large amounts of reproducible microspheres capable of secreting insulin in response to extracellular glucose stimuli.© 2022 The Authors. Advanced Materials Technologies published by Wiley‐VCH GmbH.

JTD Keywords: 3d bioprinter, beta-cell, biomaterial, collagen, encapsulation, mechanics, microspheres, survival, 3d bioprinter, ?-cell, Advanced material technologies, Biocompatibility, Cell encapsulations, Cells, Collagen, Cross-linking, Cytology, Drug delivery, Encapsulation, Fabrication, Flavonoids, Gelation, In-vitro, Insulin injections, Insulin release, Microspheres, Tannic acid, Tannins, Throughput, Tissue grafts, Type 1 diabetes, Β‐cell

Micro- and nanotexturization of surfaces can give to the parts different advanced functionalities, such as superhydrophobicity, self-cleaning, or antibacterial capabilities. These advanced properties in combination with the biocompatibility of Liquid Silicone Rubber are an interesting approach for obtaining high-performance medical devices. The industrial production of surface textures in polymeric materials is through the replication technique, and the best option to attain a high production rate is injection molding. Moreover, its low viscosity during processing can provide an accurate replication capacity by the easy filling by capillarity of the microtextures. An innovative replicating technique for Liquid Silicone Rubber is presented by studying the replication of different shaped textures within a diameter range of between 2 and 50 mu m. The copying process consists in the overmolding of a textured polymeric inlay obtained by nanoimprint lithography. At the end of the process, a textured part is obtained, while the imprinted film remains in the mold. The injection molding parameters are optimized to increase the replication accuracy, and their effect on texture replicability is analyzed and discussed. Finally, it is shown that the textured surfaces improve their wettability behavior, which is a necessary and important characteristic in the development of biomedical devices.

JTD Keywords: Cross-linking density, Injection molding, Microtextures, Nanoimprint lithography, Polymeric inlays, Silicone rubber, Stamp, Wettability

The mechanical properties of the extracellular matrix (ECM)–a complex, 3D, fibrillar scaffold of cells in physiological environments–modulate cell behavior and can drive tissue morphogenesis, regeneration, and disease progression. For simplicity, it is often convenient to assume these properties to be time-invariant. In living systems, however, cells dynamically remodel the ECM and create time-dependent local microenvironments. Here, we show how cell-generated contractile forces produce substantial irreversible changes to the density and architecture of physiologically relevant ECMs–collagen I and fibrin–in a matter of minutes. We measure the 3D deformation profiles of the ECM surrounding cancer and endothelial cells during stages when force generation is active or inactive. We further correlate these ECM measurements to both discrete fiber simulations that incorporate fiber crosslink unbinding kinetics and continuum-scale simulations that account for viscoplastic and damage features. Our findings further confirm that plasticity, as a mechanical law to capture remodeling in these networks, is fundamentally tied to material damage via force-driven unbinding of fiber crosslinks. These results characterize in a multiscale manner the dynamic nature of the mechanical environment of physiologically mimicking cell-in-gel systems.

JTD Keywords: Collagens, Fibrin, Extracellular matrix, Cross-linking, Cell physiology, Deformation, Fluorescence imaging, Cell biology

Bone tissue engineering demands alternatives overcoming the limitations of traditional approaches in the context of a constantly aging global population. In the present study, elastin-like recombinamers hydrogels were produced by means of carbodiimide-catalyzed crosslinking with citric acid, a molecule suggested to be essential for bone nanostructure. By systematically studying the effect of the relative abundance of reactive species on gelation and hydrogel properties such as functional groups content, degradation and structure, we were able to understand and to control the crosslinking reaction to achieve hydrogels mimicking the fibrillary nature of the extracellular matrix. By studying the effect of polymer concentration on scaffold mechanical properties, we were able to produce hydrogels with a stiffness value of 36.13 ± 10.72 kPa, previously suggested to be osteoinductive. Microstructured and mechanically-tailored hydrogels supported the growth of human mesenchymal stem cells and led to higher osteopontin expression in comparison to their non-tailored counterparts. Additionally, tailored hydrogels were able to rapidly self-mineralize in biomimetic conditions, evidencing that citric acid was successfully used both as a crosslinker and a bioactive molecule providing polymers with calcium phosphate nucleation capacity.

JTD Keywords: Biomimetic material, Biomineralisation, Bone tissue engineering, Cross-linking, Hydrogel, Mesenchymal stem cell

It has been extensively reported that diabetes mellitus (DM) patients have a higher risk of developing Alzheimer's disease (AD). but a mechanistic connection between both pathologies has not been provided so far Carbohydrate-derived advanced glycation endproducts (AGEs) have been implicated in the chronic complications of DM and have been reported to play an important role in the pathogenesis of AD. The earliest histopathological manifestation of AD is the apparition of extracellular aggregates of the amyloid beta peptide (A beta). To investigate possible correlations between AGEs and A beta aggregates with both pathologies. we have performed an immuhistochemical study in human post-mortem samples of AD, AD with diabetes (ADD). diabetic and nondemented controls ADD brains showed increased number of A beta dense plaques and receptor for AGEs (RACE)-positive and Tau-positive cells, higher AGEs levels and major microglial activation, compared to AD brain. Our results indicate that ADD patients present a significant increase of cell damage through a RAGE-dependent mechanism, suggesting that AGEs may promote the generation of an oxidative stress vicious cycle, which can explain the severe progression of patients with both pathologies.

JTD Keywords: Abeta, Alzheimer's disease, Rage, Ages, Diabetes, Immunohistochemistry, Advanced glycation endproducts, Beta-amyloid peptide, End-products, Oxidative stress, Advanced glycosylation, Synaptic dysfunction, Cross-linking