Chondrus crispus treated with ultrasound as a polysaccharides source with improved antitumoral potential.

Ultrasound-assisted extraction was used to recover gelling biopolymers and antioxidant compounds from Chondrus crispus with improved biological potential. The optimal processing conditions were evaluated using a Box-Behnken design, and the impact on the biological and thermo-rheological properties of the carrageenan fraction and on the bioactive features of the soluble extracts were studied. The optimum extraction parameters were defined by extraction time of ~34.7 min; solid liquid ratio of ~2.1 g/100 g and ultrasound amplitude of ~79.0% with a maximum power of 1130 W. The dependent variables exhibited maximum carrageenan yields (44.3%) and viscoelastic modulus (925.9 Pa) with the lowest gelling temperatures (38.7 °C) as well as maximum content of the extract in protein (22.4 mg/g), gallic acid (13.4 mg/g) and Trolox equivalents antioxidant capacity (182.4 mg TEAC/g). Tested hybrid carrageenans exhibited promising biological activities (% of growth inhibition around 91% for four human cancer cellular lines: A549; A2780; HeLa 229; HT-29).

Sodium hyaluronate-g-2-((N-(6-aminohexyl)-4-methoxyphenyl)sulfonamido)-N-hydroxyacetamide with enhanced affinity towards MMP12 catalytic domain to be used as visco-supplement with increased degradation resistance.

The present paper describes the functionalization of sodium hyaluronate (NaHA) with a small molecule (2-((N-(6-aminohexyl)-4-methoxyphenyl)sulfonamido)-N-hydroxyacetamide) (MMPI) having proven inhibitory activity against membrane metalloproteins involved in inflammatory processes (i.e. MMP12). The obtained derivative (HA-MMPI) demonstrated an increased resistance to the in-vitro degradation by hyaluronidase, viscoelastic properties close to those of healthy human synovial fluid, cytocompatibility towards human chondrocytes and nanomolar affinity towards MMP 12. Thus, HA-MMPI can be considered a good candidate as viscosupplement in the treatment of knee osteoarticular disease.

Latent-transforming growth factor beta-binding protein-2 (LTBP-2) is required for longevity but not for development of zonular fibers.

Latent-transforming growth factor beta-binding protein 2 (LTBP-2) is a major component of arterial and lung tissue and of the ciliary zonule, the system of extracellular fibers that centers and suspends the lens in the eye. LTBP-2 has been implicated previously in the development of extracellular microfibrils, although its exact role remains unclear. Here, we analyzed the three-dimensional structure of the ciliary zonule in wild type mice and used a knockout model to test the contribution of LTBP-2 to zonule structure and mechanical properties. In wild types, zonular fibers had diameters of 0.5-1.0 micrometers, with an outer layer of fibrillin-1-rich microfibrils and a core of fibrillin-2-rich microfibrils. LTBP-2 was present in both layers. The absence of LTBP-2 did not affect the number of fibers, their diameters, nor their coaxial organization. However, by two months of age, LTBP-2-depleted fibers began to rupture, and by six months, a fully penetrant ectopia lentis phenotype was present, as confirmed by in vivo imaging. To determine whether the seemingly normal fibers of young mice were compromised mechanically, we compared zonule stress/strain relationships of wild type and LTBP-2-deficient mice and developed a quasi-linear viscoelastic engineering model to analyze the resulting data. In the absence of LTBP-2, the ultimate tensile strength of the zonule was reduced by about 50%, and the viscoelastic behavior of the fibers was altered significantly. We developed a harmonic oscillator model to calculate the forces generated during saccadic eye movement. Model simulations suggested that mutant fibers are prone to failure during rapid rotation of the eyeball. Together, these data indicate that LTBP-2 is necessary for the strength and longevity of zonular fibers, but not necessarily for their formation.

Monopotassium phosphate-reinforced in situ forming injectable hyaluronic acid hydrogels for subcutaneous injection.

Monopotassium phosphate and pH modulation-reinforced hydrogel based on hyaluronic acid (HA) grafted with dopamine (dopa) was fabricated as one of subcutaneous injection formulations of donepezil (DPZ). Both incorporation of KH2PO4 and pH adjustment finally attributed to tuning viscoelastic and biodegradable properties of hydrogel system. Appropriate gelation time for in situ gel formation, single syringe injectability, self-healing capability, and viscoelastic features were accomplished with the optimization of KH2PO4 concentration in hydrogel systems. DPZ base (as a poorly water soluble drug) was encapsulated in poly(lactic-co-glycolic acid) (PLGA) microsphere (MS) and it was further embedded in the hydrogel structure for sustained drug release. Biodegradability of designed KH2PO4-incorporated HA-dopa/DPZ MS hydrogel system was assessed by optical imaging and the remained gel weight of crosslinked HA-dopa hydrogel group was 3.4-fold higher than that of unmodified HA-dopa mixture group on day 14 (p < 0.05). Subcutaneous injection of KH2PO4-incorporated HA-dopa/DPZ MS hydrogel did not induce any severe systemic toxicities. All these data suggest that designed HA-dopa/DPZ MS hydrogel structure crosslinked by KH2PO4 incorporation and pH adjustment can be one of promising subcutaneous injection formulations for sustained drug delivery.

Calcium Signaling Regulates Valvular Interstitial Cell Alignment and Myofibroblast Activation in Fast-Relaxing Boronate Hydrogels.

The role viscoelasticity in fibrotic disease progression is an emerging area of interest. Here, a fast-relaxing hydrogel system is exploited to investigate potential crosstalk between calcium signaling and mechanotransduction. Poly(ethylene glycol) (PEG) hydrogels containing boronate and triazole crosslinkers are synthesized, with varying ratios of boronate to triazole crosslinks to systematically vary the extent of stress relaxation. Valvular interstitial cells (VICs) encapsulated in hydrogels with the highest levels of stress relaxation (90%) exhibit a spread morphology by day 1 and are highly aligned (80 ± 2%) by day 5. Key myofibroblast markers, including α-smooth muscle actin (αSMA) and collagen 1a1 (COL1A1), are significantly elevated. VIC myofibroblast activation decreases by 42 ± 18% through inhibition of mechanotransduction, independently of VIC morphology and alignment. Calcium signaling through a transient receptor potential vanilloid 4 (TRPV4) is found to regulate VIC spreading, alignment, and activation in a time dependent manner. Inhibition of calcium signaling at early time points results in disturbed cell alignment, decreased mechanotransduction, and diminished activation, while inhibition at later time points only causes partially reduced myofibroblast activation. These results suggest a potential crosstalk mechanism, where calcium signaling acts upstream of mechanosensing and can regulate VIC myofibroblast activation independently of mechanotransduction.

3D printing of self-healing ferrogel prepared from glycol chitosan, oxidized hyaluronate, and iron oxide nanoparticles.

Hydrogel systems that show self-healing ability after mechanical damage are receiving increasing attention. However, self-healing hydrogels suitable for biomedical applications are limited owing to complex preparation methods. Furthermore, few studies have demonstrated the self-healing property of ferrogels. In this study, we demonstrated that glycol chitosan (GC) and oxidized hyaluronate (OHA) can be used to form a self-healing ferrogel in the presence of superparamagnetic iron oxide nanoparticles (SPIONs) without additional chemical cross-linkers. The overall characteristics of GC/OHA/SPION ferrogel varied based on the GC/OHA ratio, SPION content, and total polymer concentration. Interestingly, GC/OHA/SPION ferrogel was used to fabricate 3D-printed constructs of various shapes via an extrusion printing method. These constructs were responsive to the magnetic field, suggesting their potential application in 4D printing. This approach to developing self-healing ferrogels with biocompatible polysaccharides may prove useful in designing and fabricating drug delivery systems and tissue engineering scaffolds, via 3D printing.

Pressure-Sensitive Tissue Adhesion and Biodegradation of Viscoelastic Polymer Blends.

Viscoelastic blends of biodegradable polyesters with low and high molecular weight distributions have remarkably strong adhesion (significantly greater than 1 N/cm2) to soft, wet tissue. Those that transition from viscous flow to elastic, solidlike behavior at approximately 1 Hz demonstrate pressure-sensitivity yet also have sufficient elasticity for durable bonding to soft, wet tissue. The pressure-sensitive tissue adhesive (PSTA) blends produce increasingly stronger pull-apart adhesion in response to compressive pressure application, from 10 to 300 s. By incorporating a stiffer high molecular weight component, the PSTA exhibits dramatically improved burst pressure (greater than 100 kPa) when used as a tissue sealant. The PSTA's biodegradation mechanism can be switched from erosion (occurring primarily over the first 10 days) to bulk chemical degradation (and minimal erosion) depending on the chemistry of the high molecular weight component. Interestingly, fibrosis toward the PSTA is reduced when fast-occurring erosion is the dominant biodegradation mechanism.

Physicochemical, bioactive and rheological properties of an exopolysaccharide produced by a probiotic Pediococcus pentosaceus M41.

This study aimed to investigate the physicochemical properties, health-promoting benefits and rheological properties of an EPS produced by a novel probiotic Pediococcus pentosaceus M41 isolated from a marine source. P. pentosaceus M41 was able to produce an EPS with average molecular weight of 682.07 kDa. EPS-M41 consisted of arabinose, mannose, glucose and galactose with a molar ratio of 1.2:1.8:15.1:1.0. EPS-M41 structure could be proposed as →3)α-D-Glc(1→2)ß-D-Man(1→2)α-D-Glc(1→6)α-D-Glc(1→4)α-D-Glc(1→4)α-D-Gal(1→ with arabinose linked at the terminals. At concentration of 10 mg.ml-1, the antioxidant capacity was 76.5% and 48.9% for DPPH and ABTS, respectively. EPS-M41 inhibited 86.8% and 90.8% of the α-amylase and α-glucosidase activities, respectively, at 100 µg.ml-1. A 77.5% and 46.4% of antitumor inhibition occurred by EPS-M41 against Caco-2 and MCF-7 cells, respectively. The apparent viscosity (ƞ) of all EPS-M41 solutions decreased with shear rate increases. Salt type and pH value had an impact on the rheological properties of EPS-M41.

Obtaining and Characterization of the PLA/Chitosan Foams with Antimicrobial Properties Achieved by the Emulsification Combined with the Dissolution of Chitosan by CO2 Saturation.

A new method of obtaining functional foam material has been proposed. The materials were created by mixing the poly lactic acid (PLA) solution in chloroform, chitosan (CS) dissolved in water saturated with CO2 and polyethylene glycol (PEG), and freeze-dried for removal of the solvents. The composite foams were characterized for their structural (SEM, FT-IR, density, porosity), thermal (DSC), functional (hardness, elasticity, swelling capacity, solubility), and biological (antimicrobial and cytotoxic) properties. Chitosan in the composites was a component for obtaining their foamed form with 7.4 to 22.7 times lower density compared to the neat PLA and high porosity also confirmed by the SEM. The foams had a hardness in the range of 70-440 kPa. The FT-IR analysis confirmed no new chemical bonds between the sponge ingredients. Other results showed low sorption capacity (2.5-7.2 g/g) and solubility of materials (less than 0.2%). The obtained foams had the lower Tg value and improved ability of crystallization compared to neat PLA. The addition of chitosan provides the bacteriostatic and bactericidal properties against Escherichia coli and Staphylococcus aureus. Biocompatibility studies have shown that the materials obtained are not cytotoxic to the L929 cell line.

Photoinduced chitosan-PEG hydrogels with long-term antibacterial properties.

Photochemical processes offer the possibility of preparing functional hydrogels under green conditions that are compatible with both synthetic and natural polymers. In this study, chitosan-based poly(ethylene) glycol (PEG) were successfully synthesized under light irradiation in aqueous medium. Kinetic studies under irradiation showed that less than 2 min were necessary to obtain fully cross-linked networks. Thermomechanical analyses and swelling experiments indicated that introduction of chitosan overall weakens the hydrogel network but can create domains of higher thermal stability than the PEG-alone structure. The resulting chitosan-PEG hydrogels demonstrated a tremendous inhibition (100%) of bacterial growth (Escherichia coli and Staphylococcus aureus). After 6 months' ageing, one of the hydrogels preserved a high antifouling activity against Escherichia coli. This interesting result, which could be correlated with the network features, demonstrates the strong potential of these photochemical methods to obtain robust bio-functional materials.

Corneal Wound Healing Effects of Mesenchymal Stem Cell Secretome Delivered Within a Viscoelastic Gel Carrier.

Severe corneal injuries often result in permanent vision loss and remain a clinical challenge. Human bone marrow-derived mesenchymal stem cells (MSCs) and their secreted factors (secretome) have been studied for their antiscarring, anti-inflammatory, and antiangiogeneic properties. We aimed to deliver lyophilized MSC secretome (MSC-S) within a viscoelastic gel composed of hyaluronic acid (HA) and chondroitin sulfate (CS) as a way to enhance corneal re-epithelialization and reduce complications after mechanical and chemical injuries of the cornea. We hypothesized that delivering MSC-S within HA/CS would have improved wound healing effects compared the with either MSC-S or HA/CS alone. The results showed that a once-daily application of MSC-S in HA/CS enhances epithelial cell proliferation and wound healing after injury to the cornea. It also reduced scar formation, neovascularization, and hemorrhage after alkaline corneal burns. We found that combining MSC-S and HA/CS increased the expression of CD44 receptors colocalized with HA, suggesting that the observed therapeutic effects between the MSC-S and HA/CS are in part mediated by CD44 receptor upregulation and activation by HA. The results from this study demonstrate a reproducible and efficient approach for delivering the MSC-S to the ocular surface for treatment of severe corneal injuries. Stem Cells Translational Medicine 2019;8:478-489.

Cell-matrix tension contributes to hypoxia in astrocyte-seeded viscoelastic hydrogels composed of collagen and hyaluronan.

Astrocyte activation is crucial for wound contraction and glial scar formation following central nervous system injury, but the mechanism by which activation leads to astrocyte contractility and matrix reorganization in the central nervous system (CNS) is unknown. Current means to measure cell traction forces within three-dimensional scaffolds are limited to analyzing individual or small groups of cells, within extracellular matrices, whereas gap junctions and other cell-cell adhesions connect astrocytes to form a functional syncytium within the glial scar. Here, we measure the viscoelastic properties of cell-seeded hydrogels to yield insight into the collective contractility of astrocytes as they exert tension on the surrounding matrix and change its bulk mechanical properties. Our results indicate that incorporation of the CNS matrix component hyaluronan into a collagen hydrogel increases expression of the intermediate filament protein GFAP and results in a higher shear storage modulus of the cell/matrix composite, establishing the correlation between astrocyte activation and increased cell contractility. The effects of thrombin and blebbistatin, known mediators of actomyosin-mediated contraction, verify that cell-matrix tension dictates the hydrogel mechanical properties. Viability assays indicate that increased cell traction exacerbates cell death at the center of the scaffold, and message level analysis reveals that cells in the hyaluronan-containing matrix have a ~ 3-fold increase in HIF-1α gene expression. Overall, these findings suggest that astrocyte activation not only increases cell traction, but may also contribute to hypoxia near sites of central nervous system injury.

Physicochemical properties, immunostimulatory activity of the Lachnum polysaccharide and polysaccharide-dipeptide conjugates.

The physicochemical properties and the immunoregulatory actions in vitro of an exopolysaccharide from Lachnum (LEP) and its conjugation with a dipeptide (LEP-RH) were investigated aiming to improve their functional characteristics. The structure characteristic of the LEP and LEP-RH were determined via FT-IR and NMR. The physicochemical properties were evaluated by scanning electron microscopy (SEM), rheometer, and differential scanning calorimeter (DSC). SEM results showed that LEP-RH had a rough surface and relatively loose distribution that different from LEP. Rheological studies of LEP and LEP-RH at the same concentration indicated that LEP and LEP-RH have similar shear-thinning behaviors and gel-like structures, while LEP-RH has a better thermal stability than LEP. Bioassay results showed that treatment with the higher dosage (200 µg/mL) of LEP and LEP-RH stimulated the proliferation, cytokine secretion (IL-2, IL-6 and TNF-α) of RAW264.7 macrophages.

New technology and practice of dust pollution control with foam jet in underground mines.

Foam is used as an efficient means of dust suppression in underground coal mines. The poor performance of conventional adding device of foaming agent restricts its wide application. The objective of this study is to propose and investigate a new parallel jet adding device (PJAD). Experimental results show that PJAD requires a greater water flow to produce negative pressure than the single stage jet adding device (SJAD) and is harder to generate cavitation. PJAD consumes a less pressure loss than SJAD and realizes any adding proportion below 1%, which is especially suitable for precision addition of foaming agent. A foaming system used for dust suppression is put forward with PJAD adding foaming agent. Field application indicates that foam achieves a far better dust suppression effect than the roadheader water spraying, and the foam cost is significantly reduced due to the low adding proportion of foaming agent. The marked dust suppression effect makes us believe that the proposed PJAD will greatly promote the large-scale application of foam technology used for dust suppression in underground coal mines.

Sulfobetaines Meet Carboxybetaines: Modulation of Thermo- and Ion-Responsivity, Water Structure, Mechanical Properties, and Cell Adhesion.

A procedure for the preparation of copolymers bearing sulfobetaine and carboxybetaine methacrylic-based monomers by free-radical polymerization is described and discussed. A combination of monomers affects the upper critical solution temperature (UCST) in water and in the presence of a simple NaCl electrolyte while retaining the zwitterionic character. In addition, hydrogel samples were prepared and showed tunable water structure and mechanical properties. The total nonfreezable water content decreases with the amount of carboxybetaine segment in the hydrogel feed and the compression moduli were in a range of 0.7-1.6 MPa. Responses to external conditions such as temperature and ion strength were investigated and a potential application such as modulated thermal detection is proposed. The presence of the carboxylate group in the carboxybetaine segment enables a small fluorescence probe and peptide bearing RDG motif to be attached to polymer and hydrogel samples, respectively. The hydrogel samples functionalized with the RGD motif exhibit controlled cell adhesion. Such synthetic strategy based on combination of different zwitterionic segments offers a simple pathway for the development of zwitterionic materials with programmable properties.

Nucleoside-Based Self-Assembling Drugs for Localized Drug Delivery.

We have synthesized a range of gelators based on the nucleoside analogues gemcitabine and lamivudine, characterizing representative gels from the series using rheology and transmission electron microscopy. Growth inhibition studies of gemcitabine derivatives confirmed the feasibility of these compounds as novel treatments, indicating the potential of nucleoside-based gelators for localized drug delivery.

Exploring Orthogonal Hydrogen Bonding towards Designing Organic-Salt-Based Supramolecular Gelators: Synthesis, Structures, and Anticancer Properties.

A series of primary ammonium monocarboxylate (PAM) salts derived from ß-alanine derivatives of pyrene and naphthalene acetic acid, along with the parent acids, were explored to probe the plausible role of orthogonal hydrogen bonding resulting from amide⋅⋅⋅amide and PAM synthons on gelation. Single-crystal X-ray diffraction (SXRD) studies were performed on two parent acids and five PAM salts in the series. The data revealed that orthogonal hydrogen bonding played an important role in gelation. Structure-property correlation based on SXRD and powder X-ray diffraction data also supported the working hypothesis upon which these gelators were designed. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and cell migration assay on a highly aggressive human breast cancer cell line, MDA-MB-231, revealed that one of the PAM salts in the series, namely, PAA.B2, displayed anticancer properties, and internalization of the gelator salt in the same cell line was confirmed by cell imaging.

The Efficacy of a Viscoelastic Foam Overlay on Prevention of Pressure Injury in Acutely Ill Patients: A Prospective Randomized Controlled Trial.

PURPOSE: The purpose of this study was to compare a viscoelastic foam overlay (VEFO) to a standard hospital mattress for pressure injury (PI) prevention. We also compared interface pressures (IPs) of the VEFO to our facility's standard hospital mattress. DESIGN: Prospective, randomized controlled trial. SUBJECTS AND SETTING: Data analysis was based on 110 participants (55 in each group) who were 19 years or older, had a Braden Scale for Pressure Sore Risk score of 16 or less, and were cared for on a neurology, oncology, or pulmonology inpatient care unit. The research setting was the Samsung Medical Center in Seoul, South Korea. METHODS: Participants were divided into 2 groups: the experimental group were based on a VEFO on top of the standard hospital mattress used in our facility. Participants in the control group were placed on a standard hospital mattress with/without air overlay. All patients were given standard nursing care for prevention of PI. Skin assessments were completed daily over a period of 2 weeks. In addition, we compared IPs of the standard hospital mattress and the VEFO in participants randomly allocated to the intervention group. Interface pressure was measured over the sacral/coccygeal area with subjects in the supine position. Pressures were measured immediately before and immediately following placement of the VEFO and just before data collection began. Data were collected between October 2013 and November 2014. Pressure injury incidence was compared between groups using the χ test, and IPs were compared using the paired t test. INSTRUMENTS: Pressure injury development was determined using the staging system described in guidelines from the National Pressure Ulcer Advisory Panel, European Pressure Ulcer Advisory Panel, and Pan Pacific Pressure Injury Alliance in 2014. Interface pressure was measured using a device manufactured for this purpose. RESULTS: The incidence of PI development was significantly lower in subjects assigned to the experimental group as compared to those in the control group (3.6%-27.3% over the 2-week data collection period; P = .001). The maximum IP was significantly lower on the VEFO with standard hospital mattress than on the standard hospital mattress (paired t = 8.87, P < .001). CONCLUSIONS: Patients managed with a VEFO had a significantly lower incidence of PI than those managed with a standard hospital mattress. Additional research is needed to further characterize the efficacy of the VEFO, its effect on PI healing, and its effect of PI prevention in high-risk populations such as critically ill patients.

The first of the viscoceuticals? A shear thickening gum induces gastric satiety in rats.

We examined the effect of gavage of 4 ml of a viscous shear-thickening polysaccharide solution (15% w/w) extracted from the fronds of the mamaku tree fern (Cythea medullaris) in reducing appetite and delaying gastric emptying in twenty six Sprague Dawley rats. After two weeks habituation to a pelleted chow, the rats were gavaged on alternate days with either the mamaku extract or with the same volume of deionised water for a total of five times over a period of two weeks. The body mass and food intake of each rat were determined daily and the weights of their stomach contents determined on euthanasia two hours after the final gavage. The rats gavaged with the mamaku gum consumed significantly lower quantities of chow on the day of gavage. The weights of the stomach contents of rats two hours after gavage with mamaku extract were significantly greater than those following gavage with water. The failure of the rats dosed with mamaku to lose body weight likely resulted from the overall adverse effect of gavage on food intake, the limited numbers of doses of the gum and the rebound hyperphagia on days when the rats were not gavaged. Together the results indicate that gavage with mamaku gum delayed gastric emptying with respect to that of rats dosed with water and supressed appetite for 12-24 hours after dosage.

Hyaluronan in Medical Practice.

Hyaluronan is the major extracellular matrix glycosaminoglycan polymer present in vertebrate tissues, with a molar mass that can reach several megaDaltons. It is particularly prominent in the matrix of tissues undergoing rapid turnover, in fetal tissues, and wherever regeneration and repair are occurring. Hyaluronan has highly varied biological functions often dependent on molar mass, however they are highly dependent on source of hyaluronan, its purity and nature of contaminants. Hyaluronan of highmolar- mass is known for its anti-angiogenic, anti-inflammatory and immunosuppressive properties, unlike hyaluronan of low-molar-mass that has the opposite effects. Hyaluronan also has a broad range of clinical applications, such as intra-articular injection, in ophthalmology, otolaryngology, wound healing, and commercially in the cosmetic industry, as well as in drug delivery systems. Currently, polymers of hyaluronan are modified in order to improve their properties, including bioavailability and resistance to degradation. Because of greatly increased interest currently in hyaluronan, the multiple functions of the polymer are presented here, including medicine and industry, as well as recent progress in the formulation of hyaluronan-based materials.