Pericardial bioscaffold coated with ECM gels and urothelial cells for the repair of a rabbit urinary bladder defect.

Repair of damaged or faulty complex modular organs such as the urinary bladder is a current clinical challenge. The design of constructs for reconstructive urological surgery can draw advantage from the bioactivity of natural extracellular matrix (ECM) bioscaffolds, as well as the activity provided by cells seeded into constructs. Considering these benefits, this work compares the performance of pericardial ECM bioscaffolds and constructs seeded with gel-supported urothelial cells in the repair of urinary bladder defects in rabbits.

Permselectivity of Silk Fibroin Hydrogels for Advanced Drug Delivery Neurotherapies.

A promising trend in tissue engineering is using biomaterials to improve the control of drug concentration in targeted tissue. These vehicular systems are of specific interest when the required treatment time window is higher than the stability of therapeutic molecules in the body. Herein, the capacity of silk fibroin hydrogels to release different molecules and drugs in a sustained manner was evaluated.

Identification of Individual Target Molecules Using Antibody-Decorated DeepTip Atomic-Force Microscopy Probes.

A versatile and robust procedure is developed that allows the identification of individual target molecules using antibodies bound to a DeepTip functionalized atomic-force microscopy probe. The model system used for the validation of this process consists of a biotinylated anti-lactate dehydrogenase antibody immobilized on a streptavidin-decorated AFM probe. Lactate dehydrogenase (LDH) is employed as target molecule and covalently immobilized on functionalized MicroDeck substrates.

Statistical Study of Low-Intensity Single-Molecule Recognition Events Using DeepTip Probes: Application to the Pru p 3-Phytosphingosine System.

The interaction between the plant lipid transfer protein Pru p 3 and phytosphingosine was assessed using an atomic force microscope. Phytosphingosine was covalently immobilized on DeepTip probes and Pru p 3 on MicroDeck functionalized substrates. Single-molecular interaction events between both molecules were retrieved and classified and the distribution for each one of the identified types was calculated.

Modulation of Cell Response through the Covalent Binding of Fibronectin to Titanium Substrates.

Titanium (Ti-6Al-4V) substrates were functionalized through the covalent binding of fibronectin, and the effect of the existence of this extracellular matrix protein on the surface of the material was assessed by employing mesenchymal stem cell (MSC) cultures. The functionalization process comprised the usage of the activation vapor silanization (AVS) technique to deposit a thin film with a high surface density of amine groups on the material, followed by the covalent binding of fibronectin to the amine groups using the N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide (EDC/NHS) crosslinking chemistry. The biological effect of the fibronectin on murine MSCs was assessed in vitro.

Application of single cell force spectroscopy (SCFS) to the assessment of cell adhesion to peptide-decorated surfaces.

The adhesion forces of cells to peptide-coated functionalized materials were assessed through the Single Cell Force Spectroscopy (SCFS) technique in order to develop a methodology that allows the fast selection of peptide motifs that favor the interaction between cells and the biomaterial. Borosilicate glasses were functionalized using the activated vapor silanization process (AVS) and subsequently decorated with an RGD- containing peptide using the EDC/NHS crosslinking chemistry. It is shown that the RGD-coated glass induces larger attachment forces on mesenchymal stem cell cultures (MSCs), compared to the bare glass substrates.

Resistance to Degradation of Silk Fibroin Hydrogels Exposed to Neuroinflammatory Environments.

Central nervous system (CNS) diseases represent an extreme burden with significant social and economic costs. A common link in most brain pathologies is the appearance of inflammatory components that can jeopardize the stability of the implanted biomaterials and the effectiveness of therapies. Different silk fibroin scaffolds have been used in applications related to CNS disorders.

Variation in the Elastic Modulus and Increased Energy Dissipation Induced by Cyclic Straining of Major Ampullate Gland Silk.

The trends exhibited by the parameters that describe the mechanical behaviour of major ampullate gland silk fibers spun by spiders is explored by performing a series of loading-unloading tests at increasing values of strain, and by the subsequent analysis of the true stress-true strain curves obtained from these cycles. The elastic modulus, yields stress, energy absorbed, and energy dissipated in each cycle are computed in order to evaluate the evolution of these mechanical parameters with this cyclic straining. The elastic modulus is observed to increase steadily under these loading conditions, while only a moderate variation is found in the yield stress.

Axonal Guidance Using Biofunctionalized Straining Flow Spinning Regenerated Silk Fibroin Fibers as Scaffold.

After an injury, the limited regenerative capacity of the central nervous system makes the reconnection and functional recovery of the affected nervous tissue almost impossible. To address this problem, biomaterials appear as a promising option for the design of scaffolds that promote and guide this regenerative process. Based on previous seminal works on the ability of regenerated silk fibroin fibers spun through the straining flow spinning (SFS) technique, this study is intended to show that the usage of functionalized SFS fibers allows an enhancement of the guidance ability of the material when compared with the control (nonfunctionalized) fibers.

The Spider Silk Standardization Initiative (S3I): A powerful tool to harness biological variability and to systematize the characterization of major ampullate silk fibers spun by spiders from suburban Sydney, Australia.

The true stress-true strain curves of 11 Australian spider species from the Entelegynae lineage were tensile tested and classified based on the values of the alignment parameter, α*, in the framework of the Spider Silk Standardization Initiative (S3I). The application of the S3I methodology allowed the determination of the alignment parameter in all cases, and were found to range between α* = 0.03 and α* = 0.

High-Yield Characterization of Single Molecule Interactions with DeepTip Atomic Force Microscopy Probes.

Single molecule interactions between biotin and streptavidin were characterized with functionalized DeepTip probes and used as a model system to develop a comprehensive methodology for the high-yield identification and analysis of single molecular events. The procedure comprises the covalent binding of the target molecule to a surface and of the sensing molecule to the DeepTip probe, so that the interaction between both chemical species can be characterized by obtaining force-displacement curves in an atomic force microscope. It is shown that molecular resolution is consistently attained with a percentage of successful events higher than 90% of the total number of recorded curves, and a very low level of unspecific interactions.

Massive production of fibroin nano-fibrous biomaterial by turbulent co-flow.

Among the different polymers (proteins, polysaccharides, etc.) that make up natural fibers, fibroin is a protein produced by silk spinning animals, which have developed an optimized system for the conversion of a highly concentrated solution of this protein into high-performance solid fibers. This protein undergoes a self-assembly process in the silk glands that result from chemical gradients and by the application of mechanical stresses during the last step of the process.

Differences in the Elastomeric Behavior of Polyglycine-Rich Regions of Spidroin 1 and 2 Proteins.

Two different polyglycine-rich fragments were selected as representatives of major ampullate gland spidroins (MaSp) 1 and 2 types, and their behavior in a water-saturated environment was simulated within the framework of molecular dynamics (MD). The selected fragments are found in the sequences of the proteins MaSp1a and MaSp2.2a of with respective lengths of 36 amino acids (MaSp1a) and 50 amino acids (MaSp2.

Relating spidroin motif prevalence and periodicity to the mechanical properties of major ampullate spider silks.

Spider dragline fibers exhibit incredible mechanical properties, outperforming many synthetic polymers in toughness assays, and possess desirable properties for medical and other human applications. These qualities make dragline fibers popular subjects for biomimetics research. The enormous diversity of spiders presents both an opportunity for the development of new bioinspired materials and a challenge for the identification of fundamental design principles, as the mechanical properties of dragline fibers show both intraspecific and interspecific variations.

Aging is accompanied by T-cell stiffening and reduced interstitial migration through dysfunctional nuclear organization.

Age-associated changes in T-cell function play a central role in immunosenescence. The role of aging in the decreased T-cell repertoire, primarily because of thymic involution, has been extensively studied. However, increasing evidence indicates that aging also modulates the mechanical properties of cells and the internal ordering of diverse cell components.

Strategies for the Biofunctionalization of Straining Flow Spinning Regenerated Fibers.

High-performance regenerated silkworm () silk fibers can be produced efficiently through the straining flow spinning (SFS) technique. In addition to an enhanced biocompatibility that results from the removal of contaminants during the processing of the material, regenerated silk fibers may be functionalized conveniently by using a range of different strategies. In this work, the possibility of implementing various functionalization techniques is explored, including the production of fluorescent fibers that may be tracked when implanted, the combination of the fibers with enzymes to yield fibers with catalytic properties, and the functionalization of the fibers with cell-adhesion motifs to modulate the adherence of different cell lineages to the material.

Postischemic Neuroprotection of Aminoethoxydiphenyl Borate Associates Shortening of Peri-Infarct Depolarizations.

Brain stroke is a highly prevalent pathology and a main cause of disability among older adults. If not promptly treated with recanalization therapies, primary and secondary mechanisms of injury contribute to an increase in the lesion, enhancing neurological deficits. Targeting excitotoxicity and oxidative stress are very promising approaches, but only a few compounds have reached the clinic with relatively good positive outcomes.

Unexpected high toughness of silk gut.

Silk gut fibers were produced from the silkworm silk glands by the usual procedure of immersion in a mildly acidic solution and subsequent stretching. The morphology of the silk guts was assessed by scanning electron microscopy, and their microstructure was assessed by infrared spectroscopy and X-ray diffraction. It was found that both naturally spun and silk guts share a common semicrystalline microstructure.

Decellularization of porcine esophageal tissue at three diameters and the bioscaffold modification with EETs-ECM gel.

Damaged complex modular organs repair is a current clinical challenge in which one of the primary goals is to keep their biological response. An interesting case of study it is the porcine esophagus since it is a tubular muscular tissue selected as raw material for tissue engineering. The design of esophageal constructs can draw on properties of the processed homologous extracellular matrix (ECM).

Improved cell adhesion to activated vapor silanization-biofunctionalized Ti-6Al-4V surfaces with ECM-derived oligopeptides.

Titanium implants are widely used in traumatology and various orthopedic fields. Titanium and other metallic-based implants have limited structural and functional integration into the body, which translates into progressive prosthesis instability and the need for new surgical interventions that have enormous social and economic impacts. To enhance the biocompatibility of titanium implants, numerous biofunctionalization strategies have been developed.

Human Stem Cell Transplantation for Retinal Degenerative Diseases: Where Are We Now?

: Irreversible visual impairment is mainly caused by retinal degenerative diseases such as age-related macular degeneration and retinitis pigmentosa. Stem cell research has experienced rapid progress in recent years, and researchers and clinical ophthalmologists are trying to implement this promising technology to treat retinal degeneration. The objective of this systematic review is to analyze currently available data from clinical trials applying stem cells to treat human retinal diseases.

Expression of spidroin proteins in the silk glands of golden orb-weaver spiders.

The expression of spidroins in the major ampullate, minor ampullate, flagelliform, and tubuliform silk glands of Trichonephila clavipes spiders was analyzed using proteomics analysis techniques. Spidroin peptides were identified and assigned to different gene products based on sequence concurrence when compared with the whole genome of the spider. It was found that only a relatively low proportion of the spidroin genes are expressed as proteins in any of the studied glands.

Silk Fibroin: An Ancient Material for Repairing the Injured Nervous System.

Silk refers to a family of natural fibers spun by several species of invertebrates such as spiders and silkworms. In particular, silkworm silk, the silk spun by larvae, has been primarily used in the textile industry and in clinical settings as a main component of sutures for tissue repairing and wound ligation. The biocompatibility, remarkable mechanical performance, controllable degradation, and the possibility of producing silk-based materials in several formats, have laid the basic principles that have triggered and extended the use of this material in regenerative medicine.

Basic Principles in the Design of Spider Silk Fibers.

The prominence of spider silk as a hallmark in biomimetics relies not only on its unrivalled mechanical properties, but also on how these properties are the result of a set of original design principles. In this sense, the study of spider silk summarizes most of the main topics relevant to the field and, consequently, offers a nice example on how these topics could be considered in other biomimetic systems. This review is intended to present a selection of some of the essential design principles that underlie the singular microstructure of major ampullate gland silk, as well as to show how the interplay between them leads to the outstanding tensile behavior of spider silk.

Biotechnology and Biomaterial-Based Therapeutic Strategies for Age-Related Macular Degeneration. Part II: Cell and Tissue Engineering Therapies.

Age-related Macular Degeneration (AMD) is an up-to-date untreatable chronic neurodegenerative eye disease of multifactorial origin, and the main causes of blindness in over 65 y.o. people.