Therapeutic synthetic and natural materials for immunoengineering.

Immunoengineering is a rapidly evolving field that has been driving innovations in manipulating immune system for new treatment tools and methods. The need for materials for immunoengineering applications has gained significant attention in recent years due to the growing demand for effective therapies that can target and regulate the immune system. Biologics and biomaterials are emerging as promising tools for controlling immune responses, and a wide variety of materials, including proteins, polymers, nanoparticles, and hydrogels, are being developed for this purpose. In this review article, we explore the different types of materials used in immunoengineering applications, their properties and design principles, and highlight the latest therapeutic materials advancements. Recent works in adjuvants, vaccines, immune tolerance, immunotherapy, and tissue models for immunoengineering studies are discussed.

Therapeutic Peptides, Proteins and their Nanostructures for Drug Delivery and Precision Medicine.

Peptide and protein nanostructures with tunable structural features, multifunctionality, biocompatibility and biomolecular recognition capacity enable development of efficient targeted drug delivery tools for precision medicine applications. In this review article, we present various techniques employed for the synthesis and self-assembly of peptides and proteins into nanostructures. We discuss design strategies utilized to enhance their stability, drug-loading capacity, and controlled release properties, in addition to the mechanisms by which peptide nanostructures interact with target cells, including receptor-mediated endocytosis and cell-penetrating capabilities. We also explore the potential of peptide and protein nanostructures for precision medicine, focusing on applications in personalized therapies and disease-specific targeting for diagnostics and therapeutics in diseases such as cancer.

Peptide Hydrogels and Nanostructures Controlling Biological Machinery.

Peptides are versatile building blocks for the fabrication of various nanostructures that result in the formation of hydrogels and nanoparticles. Precise chemical functionalization promotes discrete structure formation, causing controlled bioactivity and physical properties for functional materials development. The conjugation of small molecules on amino acid side chains determines their intermolecular interactions in addition to their intrinsic peptide characteristics. Molecular information affects the peptide structure, formation, and activity. In this Perspective, peptide building blocks, nanostructure formation mechanisms, and the properties of these peptide materials are discussed with the results of recent publications. Bioinstructive and stimuli-responsive peptide materials have immense impacts on the nanomedicine field including drug delivery, cellular engineering, regenerative medicine, and biomedicine.

The effects of tarantula cubensis extract on renal ischemia reperfusion injury in rats.

BACKGROUND: Renal ischemia-reperfusion (IR) related acute kidney injury (AKI) is an important health problem and has not yet been fully treated. Tarantula cubensis extract (TCE) is a homeopathic drug that has antiinflammatory and antioxidant effects. This study aimed to investigate the effects of TCE on renal ischemia-reperfusion injury in rats. METHODS: This study was carried out on 48 Spraque-Dawley male rats, which were divided into six groups. The first, second, and third groups were control, sham, and IR groups, respectively. Group four received IR and 0.2 mL of 96% ethanol. Group five and six received ischemia and reperfusion and TCE 0.01 and 0.1 mg per rat (which correspond to approximately 0.04 mg/kg, and 0.4 mg/kg), respectively. Tumor necrosis factor alpha (TNF-α), interleukin-1beta (IL-1ß), total antioxidant status (TAS), and total oxidant status (TOS) levels in renal tissue were measured by enzyme-linked immunosorbent assay (ELISA). Oxidative stress index (OSI) was obtained by proportioning TAS and TOS. Superoxide dismutase (SOD), myeloperoxidase (MPO) activities, and malondialdehyde (MDA) levels were determined by manual spectrophotometric methods. The histopathological changes were evaluated via hematoxylineosin and immunohistochemical staining. RESULTS: In IR group, renal tissue TNF-α and IL-1ß levels were significantly higher than control group (p < 0.0001 for both), and low(p < 0.0001 for both) and high dose (p < 0.0001 for both) TCE administration decreased these markers. Low and high doses of TCE decreased OSI values compared with IR group (p = 0.04 and p = 0.001 respectively). Although TCE decreased MDA levels, it was not statistically significant. MPO levels significantly decreased. In addition, TCE has been found to prevent hemorrhage, cast formation, and dilatation caused by IR in renal tissues stained with hematoxylin-eosin. And also, the most intense nuclear factor kappa B (NFκB) and caspase-3 immunopositivity found in IR group was decreased in both of the TCE groups. DISCUSSION: Although TCE showed a protective effect by inhibiting inflammation against IR damage in renal tissues, there was no clear effect on oxidative stress. Larger and more detailed studies are needed to clarify the issue.

Probe microscopy methods and applications in imaging of biological materials.

Atomic force microscopy is an emerging tool for investigating the biomolecular aspects of cellular interactions; however, cell and tissue analyses must frequently be performed in aqueous environment, over rough surfaces, and on complex adhesive samples that complicate the imaging process and readily facilitate the blunting or fouling of the AFM probe. In addition, the shape and surface chemistry of the probe determine the quality and types of data that can be acquired from biological materials, with certain information becoming available only within a specific range of tip lengths or diameters, or through the assistance of specific chemical or biological functionalization procedures. Consequently, a broad range of probe modification techniques has been developed to extend the capabilities and overcome the limitations of biological AFM measurements, including the fabrication of AFM tips with specialized morphologies, surface coating with biologically affine molecules, and the attachment of proteins, nucleic acids and cells to AFM probes. In this review, we underline the importance of probe choice and modification for the AFM analysis of biomaterials, discuss the recent literature on the use of non-standard AFM tips in life sciences research, and consider the future utility of tip functionalization methods for the investigation of fundamental cell and tissue interactions.

N-Cadherin Mimetic Peptide Nanofiber System Induces Chondrogenic Differentiation of Mesenchymal Stem Cells.

Cadherins are vital for cell-to-cell interactions during tissue growth, migration, and differentiation processes. Both biophysical and biochemical inputs are generated upon cell-to-cell adhesions, which determine the fate of the mesenchymal stem cells (MSCs). The effect of cadherin interactions on the MSC differentiation still remains elusive. Here we combined the N-Cadherin mimetic peptide (HAV-PA) with the self-assembling E-PA and the resultant N-cadherin mimetic peptide nanofibers promoted chondrogenic differentiation of MSCs in conjunction with chondrogenic factors as a synthetic extracellular matrix system. Self-assembly of the precursor peptide amphiphile molecules HAV-PA and E-PA enable the organization of HAV peptide residues in close proximity to the cell interaction site, forming a supramolecular N-cadherin-like system. These bioactive peptide nanofibers not only promoted viability and enhanced adhesion of MSCs but also augmented the expression of cartilage specific matrix components compared to the nonbioactive control nanofibers. Overall, the N-cadherin mimetic peptide nanofiber system facilitated MSC commitment into the chondrogenic lineage presenting an alternative bioactive platform for stem-cell-based cartilage regeneration.

Impedance-based viscoelastic flow cytometry.

Elastic nature of the viscoelastic fluids induces lateral migration of particles into a single streamline and can be used by microfluidic based flow cytometry devices. In this study, we investigated focusing efficiency of polyethylene oxide based viscoelastic solutions at varying ionic concentration to demonstrate their use in impedimetric particle characterization systems. Rheological properties of the viscoelastic fluid and particle focusing performance are not affected by ionic concentration. We investigated the viscoelastic focusing dynamics using polystyrene (PS) beads and human red blood cells (RBCs) suspended in the viscoelastic fluid. Elasto-inertial focusing of PS beads was achieved with the combination of inertial and viscoelastic effects. RBCs were aligned along the channel centerline in parachute shape which yielded consistent impedimetric signals. We compared our impedance-based microfluidic flow cytometry results for RBCs and PS beads by analyzing particle transit time and peak amplitude at varying viscoelastic focusing conditions obtained at different flow rates. We showed that single orientation, single train focusing of nonspherical RBCs can be achieved with polyethylene oxide based viscoelastic solution that has been shown to be a good candidate as a carrier fluid for impedance cytometry.

The antiapoptotic and antioxidant effects of eugenol against cisplatin-induced testicular damage in the experimental model.

Testicular dysfunction or damage is among the critical side effects of chemotherapeutic drugs like cisplatin. This study was mapped out to assess the possible therapeutic effect of eugenol on cisplatin-induced testicular damage. In this experimental study, a single dose of cisplatin (15 mg/kg) was given intraperitoneally. After 72 hr of cisplatin injection, rats were sacrificed and testis tissues were removed. Tissues were examined by biochemical, histopathological and immunohistochemical methods. While tissue lipid peroxidation product and apoptotic marker levels increased, antioxidant enzyme activities of testis tissue were decreased in the cisplatin group. Additionally, histopathological damage was also determined in testis tissue. Contrary to all these results, the severity of damage in the tissue was reduced histopathologically owing to eugenol treatment. The lipid peroxidation decreased and antioxidant enzyme activities increased in the eugenol treatment group. It has been determined that eugenol has a therapeutic effect on oxidative stress and apoptosis against cisplatin-induced testicular damage.

Anti-oxidant and anti-inflamatuar effectiveness of caftaric acid on gastric ulcer induced by indomethacin in rats.

In this study, we evaluated the anti-oxidant and anti-inflammatory effect of caftaric acid against ulcer produced by indomethacin in gastric mucosa. Female Sprague Dawley albino rats were divided into five groups: control (saline group, n = 8), negative control (indomethacin group, n = 8), positive control (omeprazole group, n = 8), low dose therapy (caftaric acid, n = 8), and high dose therapy (caftaric acid, n = 8). At the end of the experiment, all rats were sacrificed and gastric mucosa samples were removed for macroscopic and biochemical analysis. In our study, we detected that oxidant parameter values and cytokine levels increased in the negative control group, but total antioxidant status reduced, whereas, cytokine and oxidant parameter levels were significantly reduced due to low and high doses of caftaric acid administration. But another important point to note is that high dose caftaric acid therapy performed gastroprotective effect as omeprazole. In the macroscopic evaluation, there were reductions in ulcer sizes with a low and high dose of caftaric acid administration in contrast to the negative control group. As a result of our study, caftaric acid showed anti-oxidant and anti-inflammatory effects in indomethacin-induced gastric ulcer in rats.

Force and time-dependent self-assembly, disruption and recovery of supramolecular peptide amphiphile nanofibers.

Biological feedback mechanisms exert precise control over the initiation and termination of molecular self-assembly in response to environmental stimuli, while minimizing the formation and propagation of defects through self-repair processes. Peptide amphiphile (PA) molecules can self-assemble at physiological conditions to form supramolecular nanostructures that structurally and functionally resemble the nanofibrous proteins of the extracellular matrix, and their ability to reconfigure themselves in response to external stimuli is crucial for the design of intelligent biomaterials systems. Here, we investigated real-time self-assembly, deformation, and recovery of PA nanofibers in aqueous solution by using a force-stabilizing double-pass scanning atomic force microscopy imaging method to disrupt the self-assembled peptide nanofibers in a force-dependent manner. We demonstrate that nanofiber damage occurs at tip-sample interaction forces exceeding 1 nN, and the damaged fibers subsequently recover when the tip pressure is reduced. Nanofiber ends occasionally fail to reconnect following breakage and continue to grow as two individual nanofibers. Energy minimization calculations of nanofibers with increasing cross-sectional ellipticity (corresponding to varying levels of tip-induced fiber deformation) support our observations, with high-ellipticity nanofibers exhibiting lower stability compared to their non-deformed counterparts. Consequently, tip-mediated mechanical forces can provide an effective means of altering nanofiber integrity and visualizing the self-recovery of PA assemblies.

Recent advances in bioactive 1D and 2D carbon nanomaterials for biomedical applications.

One-dimensional (1D) carbon nanotubes (CNTs) and the two-dimensional (2D) graphene represent the most widely studied allotropes of carbon. Due to their unique structural, electrical, mechanical and optical properties, 1D and 2D carbon nanostructures are considered to be leading candidates for numerous applications in biomedical fields, including tissue engineering, drug delivery, bioimaging and biosensors. The biocompatibility and toxicity issues associated with these nanostructures have been a critical impediment for their use in biomedical applications. In this review, we present an overview of the various materials types, properties, functionalization strategies and characterization methods of 1D and 2D carbon nanomaterials and their derivatives in terms of their biomedical applications. In addition, we discuss various factors and mechanisms affecting their toxicity and biocompatibility.

Gemcitabine Integrated Nano-Prodrug Carrier System.

Peptide nanomaterials have received a great deal of interest in drug-delivery applications due to their biodegradability, biocompatibility, suitability for large-scale synthesis, high drug-loading capacities, targeting ability, and ordered structural organization. The covalent conjugation of drugs to peptide backbones results in prolonged circulation time and improved stability of drugs. Therapeutic efficacy of gemcitabine, which is used for breast cancer treatment, is severely compromised due to its rapid plasma degradation. Its hydrophilic nature poses a challenge for both its efficient encapsulation into nanocarrier systems and its sustained release property. Here, we designed a new peptide prodrug molecule for the anticancer drug gemcitabine, which was covalently conjugated to the C-terminal of 9-fluorenylmethoxy carbonyl (Fmoc)-protected glycine. The prodrug was further integrated into peptide nanocarrier system through noncovalent interactions. A pair of oppositely charged amyloid-inspired peptides (Fmoc-AIPs) were exploited as components of the drug-carrier system and self-assembled into one-dimensional nanofibers at physiological conditions. The gemcitabine integrated nanoprodrug carrier system exhibited slow release and reduced the cellular viability of 4T1 breast cancer cell line in a time- and concentration-dependent manner.

Spatial Organization of Functional Groups on Bioactive Supramolecular Glycopeptide Nanofibers for Differentiation of Mesenchymal Stem Cells (MSCs) to Brown Adipogenesis.

Spatial organization of bioactive moieties in biological materials has significant impact on the function and efficiency of these systems. Here, we demonstrate the effect of spatial organization of functional groups including carboxylate, amine, and glucose functionalities by using self-assembled peptide amphiphile (PA) nanofibers as a bioactive scaffold. We show that presentation of bioactive groups on glycopeptide nanofibers affects mesenchymal stem cells (MSCs) in a distinct manner by means of adhesion, proliferation, and differentiation. Strikingly, when the glutamic acid is present in the glycopeptide backbone, the PA nanofibers specifically induced differentiation of MSCs into brown adipocytes in the absence of any differentiation medium as shown by lipid droplet accumulation and adipogenic gene marker expression analyses. This effect was not evident in the other glycopeptide nanofibers, which displayed the same functional groups but with different spatial organization. Brown adipocytes are attractive targets for obesity treatment and are found in trace amounts in adults, which also makes this specific glycopeptide nanofiber system an attractive tool to study molecular pathways of brown adipocyte formation.

Multivalent Presentation of Cationic Peptides on Supramolecular Nanofibers for Antimicrobial Activity.

Noncovalent and electrostatic interactions facilitate the formation of complex networks through molecular self-assembly in biomolecules such as proteins and glycosaminoglycans. Self-assembling peptide amphiphiles (PA) are a group of molecules that can form nanofibrous structures and may contain bioactive epitopes to interact specifically with target molecules. Here, we report the presentation of cationic peptide sequences on supramolecular nanofibers formed by self-assembling peptide amphiphiles for cooperative enhanced antibacterial activity. Antibacterial properties of self-assembled peptide nanofibers were significantly higher than soluble peptide molecules with identical amino acid sequences, suggesting that the tandem presentation of bioactive epitopes is important for designing new materials for bactericidal activity. In addition, bacteria were observed to accumulate more rapidly on peptide nanofibers compared to soluble peptides, which may further enhance antibacterial activity by increasing the number of peptide molecules interacting with the bacterial membrane. The cationic peptide amphiphile nanofibers were observed to attach to bacterial membranes and disrupt their integrity. These results demonstrate that short cationic peptides show a significant improvement in antibacterial activity when presented in the nanofiber form.

Hierarchical Self-Assembly of Histidine-Functionalized Peptide Amphiphiles into Supramolecular Chiral Nanostructures.

Controlling the hierarchical organization of self-assembling peptide amphiphiles into supramolecular nanostructures opens up the possibility of developing biocompatible functional supramolecular materials for various applications. In this study, we show that the hierarchical self-assembly of histidine- (His-) functionalized PAs containing d- or l-amino acids can be controlled by both solution pH and molecular chirality of the building blocks. An increase in solution pH resulted in the structural transition of the His-functionalized chiral PA assemblies from nanosheets to completely closed nanotubes through an enhanced hydrogen-bonding capacity and π-π stacking of imidazole ring. The effects of the stereochemistry and amino acid sequence of the PA backbone on the supramolecular organization were also analyzed by CD, TEM, SAXS, and molecular dynamics simulations. In addition, an investigation of chiral mixtures revealed the differences between the hydrogen-bonding capacities and noncovalent interactions of PAs with d- and l-amino acids.

Supramolecular Peptide Nanofiber Morphology Affects Mechanotransduction of Stem Cells.

Chirality and morphology are essential factors for protein function and interactions with other biomacromolecules. Extracellular matrix (ECM) proteins are also similar to other proteins in this sense; however, the complexity of the natural ECM makes it difficult to study these factors at the cellular level. The synthetic peptide nanomaterials harbor great promise in mimicking specific ECM molecules as model systems. In this work, we demonstrate that mechanosensory responses of stem cells are directly regulated by the chirality and morphology of ECM-mimetic peptide nanofibers with strictly controlled characteristics. Structural signals presented on l-amino acid containing cylindrical nanofibers (l-VV) favored the formation of integrin ß1-based focal adhesion complexes, which increased the osteogenic potential of stem cells through the activation of nuclear YAP. On the other hand, twisted ribbon-like nanofibers (l-FF and d-FF) guided the cells into round shapes and decreased the formation of focal adhesion complexes, which resulted in the confinement of YAP proteins in the cytosol and a corresponding decrease in osteogenic potential. Interestingly, the d-form of twisted-ribbon like nanofibers (d-FF) increased the chondrogenic potential of stem cells more than their l-form (l-FF). Our results provide new insights into the importance and relevance of morphology and chirality of nanomaterials in their interactions with cells and reveal that precise control over the chemical and physical properties of nanostructures can affect stem cell fate even without the incorporation of specific epitopes.

Peptide-Based Materials for Cartilage Tissue Regeneration.

Cartilaginous tissue requires structural and metabolic support after traumatic or chronic injuries because of its limited capacity for regeneration. However, current techniques for cartilage regeneration are either invasive or ineffective for long-term repair. Developing alternative approaches to regenerate cartilage tissue is needed. Therefore, versatile scaffolds formed by biomaterials are promising tools for cartilage regeneration. Bioactive scaffolds further enhance the utility in a broad range of applications including the treatment of major cartilage defects. This chapter provides an overview of cartilage tissue, tissue defects, and the methods used for regeneration, with emphasis on peptide scaffold materials that can be used to supplement or replace current medical treatment options.

Supramolecular Nanostructure Formation of Coassembled Amyloid Inspired Peptides.

Characterization of amyloid-like aggregates through converging approaches can yield deeper understanding of their complex self-assembly mechanisms and the nature of their strong mechanical stability, which may in turn contribute to the design of novel supramolecular peptide nanostructures as functional materials. In this study, we investigated the coassembly kinetics of oppositely charged short amyloid-inspired peptides (AIPs) into supramolecular nanostructures by using confocal fluorescence imaging of thioflavin T binding, turbidity assay and in situ small-angle X-ray scattering (SAXS) analysis. We showed that coassembly kinetics of the AIP nanostructures were consistent with nucleation-dependent amyloid-like aggregation, and aggregation behavior of the AIPs was affected by the initial monomer concentration and sonication. Moreover, SAXS analysis was performed to gain structural information on the size, shape, electron density, and internal organization of the coassembled AIP nanostructures. The scattering data of the coassembled AIP nanostructures were best fitted into to a combination of polydisperse core-shell cylinder (PCSC) and decoupling flexible cylinder (FCPR) models, and the structural parameters were estimated based on the fitting results of the scattering data. The stability of the coassembled AIP nanostructures in both fiber organization and bulk viscoelastic properties was also revealed via temperature-dependent SAXS analysis and oscillatory rheology measurements, respectively.

Glycosaminoglycan-Mimetic Signals Direct the Osteo/Chondrogenic Differentiation of Mesenchymal Stem Cells in a Three-Dimensional Peptide Nanofiber Extracellular Matrix Mimetic Environment.

Recent efforts in bioactive scaffold development focus strongly on the elucidation of complex cellular responses through the use of synthetic systems. Designing synthetic extracellular matrix (ECM) materials must be based on understanding of cellular behaviors upon interaction with natural and artificial scaffolds. Hence, due to their ability to mimic both the biochemical and mechanical properties of the native tissue environment, supramolecular assemblies of bioactive peptide nanostructures are especially promising for development of bioactive ECM-mimetic scaffolds. In this study, we used glycosaminoglycan (GAG) mimetic peptide nanofiber gel as a three-dimensional (3D) platform to investigate how cell lineage commitment is altered by external factors. We observed that amount of fetal bovine serum (FBS) presented in the cell media had synergistic effects on the ability of GAG-mimetic nanofiber gel to mediate the differentiation of mesenchymal stem cells into osteogenic and chondrogenic lineages. In particular, lower FBS concentration in the culture medium was observed to enhance osteogenic differentiation while higher amount FBS promotes chondrogenic differentiation in tandem with the effects of the GAG-mimetic 3D peptide nanofiber network, even in the absence of externally administered growth factors. We therefore demonstrate that mesenchymal stem cell differentiation can be specifically controlled by the combined influence of growth medium components and a 3D peptide nanofiber environment.

Supramolecular GAG-like Self-Assembled Glycopeptide Nanofibers Induce Chondrogenesis and Cartilage Regeneration.

Glycosaminoglycans (GAGs) and glycoproteins are vital components of the extracellular matrix, directing cell proliferation, differentiation, and migration and tissue homeostasis. Here, we demonstrate supramolecular GAG-like glycopeptide nanofibers mimicking bioactive functions of natural hyaluronic acid molecules. Self-assembly of the glycopeptide amphiphile molecules enable organization of glucose residues in close proximity on a nanoscale structure forming a supramolecular GAG-like system. Our in vitro culture results indicated that the glycopeptide nanofibers are recognized through CD44 receptors, and promote chondrogenic differentiation of mesenchymal stem cells. We analyzed the bioactivity of GAG-like glycopeptide nanofibers in chondrogenic differentiation and injury models because hyaluronic acid is a major component of articular cartilage. Capacity of glycopeptide nanofibers on in vivo cartilage regeneration was demonstrated in microfracture treated osteochondral defect healing. The glycopeptide nanofibers act as a cell-instructive synthetic counterpart of hyaluronic acid, and they can be used in stem cell-based cartilage regeneration therapies.