scholarly journals Hyaluronic Acid Based Hydrogels for Regenerative Medicine Applications

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
Assunta Borzacchiello ◽  
Luisa Russo ◽  
Birgitte M. Malle ◽  
Khadija Schwach-Abdellaoui ◽  
Luigi Ambrosio
Keyword(s):  
Hyaluronic Acid ◽  
Viscoelastic Properties ◽  
Structural Parameters ◽  
Weight Ratio ◽  
Rheological Behaviour ◽  
Biological Properties ◽  
Cross Linking ◽  
In Vitro Tests ◽  
The Cross

Hyaluronic acid (HA) hydrogels, obtained by cross-linking HA molecules with divinyl sulfone (DVS) based on a simple, reproducible, and safe process that does not employ any organic solvents, were developed. Owing to an innovative preparation method the resulting homogeneous hydrogels do not contain any detectable residual cross-linking agent and are easier to inject through a fine needle. HA hydrogels were characterized in terms of degradation and biological properties, viscoelasticity, injectability, and network structural parameters. They exhibit a rheological behaviour typical of strong gels and show improved viscoelastic properties by increasing HA concentration and decreasing HA/DVS weight ratio. Furthermore, it was demonstrated that processes such as sterilization and extrusion through clinical needles do not imply significant alteration of viscoelastic properties. Both SANS and rheological tests indicated that the cross-links appear to compact the network, resulting in a reduction of the mesh size by increasing the cross-linker amount. In vitro degradation tests of the HA hydrogels demonstrated that these new hydrogels show a good stability against enzymatic degradation, which increases by increasing HA concentration and decreasing HA/DVS weight ratio. Finally, the hydrogels show a good biocompatibility confirmed by in vitro tests.

scholarly journals The Effect of Oxidized Dopamine on the Structure and Molecular Chaperone Function of the Small Heat-Shock Proteins, αB-Crystallin and Hsp27

2021 ◽  
Vol 22 (7) ◽  
pp. 3700
Author(s):  
Junna Hayashi ◽  
Jennifer Ton ◽  
Sparsh Negi ◽  
Daniel E. K. M. Stephens ◽  
Dean L. Pountney ◽  
...  
Keyword(s):  
Heat Shock ◽  
Protein Aggregation ◽  
Molecular Chaperone ◽  
Cross Linking ◽  
Αb Crystallin ◽  
The Cross ◽  
Shock Proteins ◽  
And Function

Oxidation of the neurotransmitter, dopamine (DA), is a pathological hallmark of Parkinson’s disease (PD). Oxidized DA forms adducts with proteins which can alter their functionality. αB-crystallin and Hsp27 are intracellular, small heat-shock molecular chaperone proteins (sHsps) which form the first line of defense to prevent protein aggregation under conditions of cellular stress. In vitro, the effects of oxidized DA on the structure and function of αB-crystallin and Hsp27 were investigated. Oxidized DA promoted the cross-linking of αB-crystallin and Hsp27 to form well-defined dimer, trimer, tetramer, etc., species, as monitored by SDS-PAGE. Lysine residues were involved in the cross-links. The secondary structure of the sHsps was not altered significantly upon cross-linking with oxidized DA but their oligomeric size was increased. When modified with a molar equivalent of DA, sHsp chaperone functionality was largely retained in preventing both amorphous and amyloid fibrillar aggregation, including fibril formation of mutant (A53T) α-synuclein, a protein whose aggregation is associated with autosomal PD. In the main, higher levels of sHsp modification with DA led to a reduction in chaperone effectiveness. In vivo, DA is sequestered into acidic vesicles to prevent its oxidation and, intracellularly, oxidation is minimized by mM levels of the antioxidant, glutathione. In vitro, acidic pH and glutathione prevented the formation of oxidized DA-induced cross-linking of the sHsps. Oxidized DA-modified αB-crystallin and Hsp27 were not cytotoxic. In a cellular context, retention of significant chaperone functionality by mildly oxidized DA-modified sHsps would contribute to proteostasis by preventing protein aggregation (particularly of α-synuclein) that is associated with PD.

scholarly journals PTMAc-PEG-PTMAc hydrogel modified by RGDC and hyaluronic acid promotes neural stem cells' survival and differentiation in vitro

RSC Advances ◽  
2017 ◽  
Vol 7 (65) ◽  
pp. 41098-41104 ◽  
Author(s):  
Ruirui Yang ◽  
Caixia Xu ◽  
Tao Wang ◽  
Yuanqi Wang ◽  
Jingnan Wang ◽  
...  
Keyword(s):  
Stem Cells ◽  
Central Nervous System ◽  
Nervous System ◽  
Hyaluronic Acid ◽  
Neural Stem Cells ◽  
Biological Properties ◽  
Central Nervous System Injury ◽  
Bioactive Molecules

The enhancement of the biological properties of hydrogels by surface modifying with bioactive molecules is of great significance, especially for the treatment of central nervous system injury by combining engrafted cells.

scholarly journals Evaluation of an Improved Chitosan Scaffold Cross-Linked With Polyvinyl Alcohol and Amine Coupling Through 1-Ethyl-3-(3-Dimethyl Aminopropyl)-Carbodiimide (EDC) and 2 N-Hydroxysuccinimide (NHS) for Corneal Applications

2018 ◽  
Vol 6 (9) ◽  
pp. 1561-1570 ◽  
Author(s):  
Mohamed Ali Seyed ◽  
Kavitha Vijayaraghavan
Keyword(s):  
Cross Linking ◽  
In Vitro Tests ◽  
Human Amniotic Membrane ◽  
Limbal Stem Cells ◽  
Chitosan Scaffold ◽  
Polymeric Chains ◽  
Ft Ir ◽  
Colloidal State ◽  
Corneal Blindness

BACKGROUND: Corneal blindness resulting from various medical conditions affects millions worldwide. The rapid developing tissue engineering field offers design of a scaffold with mechanical properties and transparency similar to that of the natural cornea. AIM: The present study aimed at to prepare and investigate the properties of PVA/chitosan blended scaffold by further cross-linking with 1-Ethyl-3-(3-dimethyl aminopropyl)-carbodiimide (EDC) and 2 N-Hydroxysuccinimide (NHS) as potential in vitro carrier for human limbal stem cells delivery. MATERIAL AND METHODS: Acetic acid dissolved chitosan was added to PVA solution, uniformly mixed with a homogenizer until the mixture was in a colloidal state, followed by H2SO4 and formaldehyde added and the sample was allowed to cool, subsequently it was poured into a tube and heated in an oven at 60°C for 50 minutes. Finally, samples were soaked in a cross-linking bath with EDC, NHS and NaOH in H2O/EtOH for 24 h consecutively stirred to cross-link the polymeric chains, reduce degradation. After soaking in the bath, the samples were carefully washed with 2% glycine aqueous solution several times to remove the remaining amount of cross-linkers, followed by washed with water to remove residual agents. Later the cross-linked scaffold subjected for various characterization and biological experiments. RESULTS: After viscosity measurement, the scaffold was observed by Fourier transform infrared (FT-IR). The water absorbency of PVA/Chitosan was increased 361% by swelling. Compression testing demonstrated that by increasing the amount of chitosan, the strength of the scaffold could be increased to 16×10−1 MPa. Our degradation results revealed by mass loss using equation shows that scaffold degraded gradually imply slow degradation. In vitro tests showed good cell proliferation and growth in the scaffold. Our assay results confirmed that the membrane could increase the cells adhesion and growth on the substrate. CONCLUSION: Hence, we strongly believe the use of this improved PVA/chitosan scaffold has potential to cut down the disadvantages of the human amniotic membrane (HAM) for corneal epithelium in ocular surface surgery and greater mechanical strength in future after successful experimentation with clinical trials.

scholarly journals Polyphenols: From Theory to Practice

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2595
Author(s):  
Alberto Bertelli ◽  
Marco Biagi ◽  
Maddalena Corsini ◽  
Giulia Baini ◽  
Giorgio Cappellucci ◽  
...  
Keyword(s):  
Matrix Effect ◽  
Virgin Olive Oil ◽  
Extra Virgin Olive Oil ◽  
Biological Properties ◽  
Health Claims ◽  
In Vitro Tests ◽  
The Matrix ◽  
Gender Characteristics

Background: The importance of polyphenols in human health is well known; these compounds are common in foods, such as fruits, vegetables, spices, extra virgin olive oil and wine. On the other hand, the different factors that modulate the biological activity of these compounds are less well known. Conceptualization of the work: In this review we took into account about 200 relevant and recent papers on the following topics: “polyphenols bioavailability”, “polyphenols matrix effect”, “food matrix effect”, “polyphenols-cytochromes interaction”, after having reviewed and updated information on chemical classification and main biological properties of polyphenols, such as the antioxidant, anti-radical and anti-inflammatory activity, together with the tricky link between in vitro tests and clinical trials. Key findings: the issue of polyphenols bioavailability and matrix effect should be better taken into account when health claims are referred to polyphenols, thus considering the matrix effect, enzymatic interactions, reactions with other foods or genetic or gender characteristics that could interfere. We also discovered that in vitro studies often underrate the role of phytocomplexes and thus we provided practical hints to describe a clearer way to approach an investigation on polyphenols for a more resounding transfer to their use in medicine.

scholarly journals 3D Encapsulation Made Easy: A Coaxial-Flow Circuit for the Fabrication of Hydrogel Microfibers Patches

2019 ◽  
Vol 6 (2) ◽  
pp. 30 ◽  
Author(s):  
Chiara Campiglio ◽  
Francesca Ceriani ◽  
Lorenza Draghi
Keyword(s):  
Hyaluronic Acid ◽  
Regenerative Medicine ◽  
Closed Loop ◽  
Fiber Diameter ◽  
Cross Linking ◽  
Scaffold Fabrication ◽  
Cell Culturing ◽  
Viable Cells ◽  
Flow Circuit

To fully exploit the potential of hydrogel micro-fibers in the design of regenerative medicinal materials, we designed a simple, easy to replicate system for cell embedding in degradable fibrous scaffolds, and validated its effectiveness using alginate-based materials. For scaffold fabrication, cells are suspended in a hydrogel-precursor and injected in a closed-loop circuit, where a pump circulates the ionic cross-linking solution. The flow of the cross-linking solution stretches and solidifies a continuous micro-scaled, cell-loaded hydrogel fiber that whips, bends, and spontaneously assembles in a self-standing, spaghetti-like patch. After investigation and tuning of process- and solution-related parameters, homogeneous microfibers with controlled diameters and consistent scaffolds were obtained from different alginate concentrations and blends with biologically favorable macromolecules (i.e., gelatin or hyaluronic acid). Despite its simplicity, this coaxial-flow encapsulation system allows for the rapid and effortless fabrication of thick, well-defined scaffolds, with viable cells being homogeneously distributed within the fibers. The reduced fiber diameter and the inherent macro-porous structure that is created from the random winding of fibers can sustain mass transport, and support encapsulated cell survival. As different materials and formulations can be processed to easily create homogeneously cell-populated structures, this system appears as a valuable platform, not only for regenerative medicine, but also, more in general, for 3D cell culturing in vitro.

scholarly journals Fabrication and in vitro evaluation of stable collagen/hyaluronic acid biomimetic multilayer on titanium coatings

2013 ◽  
Vol 10 (84) ◽  
pp. 20130070 ◽  
Author(s):  
Haiyong Ao ◽  
Youtao Xie ◽  
Honglue Tan ◽  
Shengbing Yang ◽  
Kai Li ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Photoelectron Spectroscopy ◽  
Self Assembly ◽  
Human Mesenchymal Stem Cells ◽  
Biological Properties ◽  
Covalent Immobilization ◽  
Layer By Layer ◽  
Titanium Coating ◽  
Assembly Technique

Layer-by-layer (LBL) self-assembly technique has been proved to be a highly effective method to immobilize the main components of the extracellular matrix such as collagen and hyaluronic acid on titanium-based implants and form a polyelectrolyte multilayer (PEM) film by electrostatic interaction. However, the formed PEM film is unstable in the physiological environment and affects the long-time effectiveness of PEM film. In this study, a modified LBL technology has been developed to fabricate a stable collagen/hyaluronic acid (Col/HA) PEM film on titanium coating (TC) by introducing covalent immobilization. Scanning electron microscopy, diffuse reflectance Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to characterize the PEM film. Results of Sirius red staining demonstrated that the chemical stability of PEM film was greatly improved by covalent cross-linking. Cell culture assays further illustrated that the functions of human mesenchymal stem cells, such as attachment, spreading, proliferation and differentiation, were obviously enhanced by the covalently immobilized Col/HA PEM on TCs compared with the absorbed Col/HA PEM. The improved stability and biological properties of the Col/HA PEM covalently immobilized TC may be beneficial to the early osseointegration of the implants.

scholarly journals Cross-linking Electrospun Polydioxanone-Soluble Elastin Blends: Material Characterization

2008 ◽  
Vol 3 (1) ◽  
pp. 155892500800300 ◽  
Author(s):  
Michael J. McClure ◽  
Scott A. Sell ◽  
Catherine P. Barnes ◽  
Whitney C. Bowen ◽  
Gary L. Bowlin
Keyword(s):  
Femoral Artery ◽  
Material Properties ◽  
In Vivo Studies ◽  
Uniaxial Tensile ◽  
Cross Linking ◽  
Materials Testing ◽  
Uniaxial Tensile Testing ◽  
The Cross

The purpose of this study was to establish whether material properties of elastin co-electrospun with polydioxanone (PDO) would change over time in both the uncross-linked state and the cross-linked state. First, uncross-linked scaffolds were placed in phosphate buffered saline (PBS) for three separate time periods: 15 minutes, 1 hour, and 24 hours, and subsequently tested using uniaxial materials testing. Several cross-linking reagents were then investigated to verify their ability to crosslink elastin: 1–ethyl-3–(dimethylaminopropyl)-carbodiimide (EDC), ethylene glycol diglycidyl ether (EGDE), and genipin. Uniaxial tensile testing was performed on scaffolds cross-linked with EDC and genipin, yielding results that warranted further investigation for PDO-elastin blends. Material properties of the cross-linked scaffolds were then found within range of both pig femoral artery and human femoral artery. These results demonstrate PDO-elastin blends could potentially be favorable as vascular grafts, thus warranting future in vitro and in vivo studies.

Preparation and physical characterization of strongly swellable oligo(oxyethylene) lignin hydrogels

Holzforschung ◽  
2011 ◽  
Vol 65 (3) ◽  
Author(s):  
Lars Passauer ◽  
Klaus Fischer ◽  
Falk Liebner
Keyword(s):  
Dynamic Viscosity ◽  
Loss Modulus ◽  
Gelation Time ◽  
Rheological Behaviour ◽  
Diglycidyl Ether ◽  
Cross Linking ◽  
Available Water Content ◽  
The Cross ◽  
Poly Ethylene ◽  
Tan Δ

Abstract Highly swellable, mechanically stable hydrogels were obtained by cross-linking different technical lignins with poly(ethylene) glycol diglycidyl ether (PEGDGE). The gelation time and the properties of the products can be controlled by the extent of pre-oxidation and the cross-linking conditions, namely the dynamic viscosity η*, storage and loss modulus (G′; G″), and loss factor tan δ. The highest free swelling capacities (FSC) of up to 50 g water per g xerogel were obtained from pre-oxidized pine kraft lignin Indulin® AT and spruce organosolv lignin. Dynamic rheological measurements confirmed the typical rheological behaviour of gel structures, i.e. a linear decrease of dynamic viscosity about three orders of magnitude within a frequency range of 0.08 and 20 s-1. The results furthermore revealed a good mechanical sturdiness of the cross-linked lignin hydrogels. Sandy soils supplemented with small quantities of the hydrogels were found to feature a significantly increased plant-available water content. Based on the observed effects, oligo(oxyethylene) lignins are promising materials with respect to a prolonged water retention in soils.

scholarly journals A SEX-LINKED DEFECT IN THE CROSS-LINKING OF COLLAGEN AND ELASTIN ASSOCIATED WITH THE MOTTLED LOCUS IN MICE

1974 ◽  
Vol 139 (1) ◽  
pp. 180-192 ◽  
Author(s):  
David W. Rowe ◽  
Ermona B. McGoodwin ◽  
George R. Martin ◽  
Michael D. Sussman ◽  
Douglas Grahn ◽  
...  
Keyword(s):  
Coat Color ◽  
Cross Linking ◽  
Genetic Abnormality ◽  
Cross Link ◽  
Skin Collagen ◽  
The Cross ◽  
Tissue Abnormalities ◽  
Link Formation ◽  
Experimental Lathyrism

A genetic abnormality in collagen and elastin cross-linking resembling experimental lathyrism has been identified in mice. The defect is an X-linked trait, attributed to the mottled locus which also influences coat color. The affected mice have aneurysms of the aorta and its branches, weak skin, and bone deformities in a spectrum of severity varying with the alleles at the mottled locus. A defect in the cross-linking of collagen was demonstrated in the skin of the affected animals by a marked increase in collagen extractability and a reduced proportion of cross-linked components in the extracted collagen. A decrease in lysine-derived aldehyde levels was found in both skin collagen and aortic elastin similar to that found in lathyritic tissue. Furthermore the in vitro formation of lysine-derived aldehyde was reduced. Thus the cause of the connective tissue abnormalities in these mice appears to be a defect in cross-link formation due to an impairment in aldehyde formation.

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