Addition Of Chondroitin Sulfate Research Articles

Can Hyaluronic Acid Combined with Chondroitin Sulfate in Viscosupplementation of Knee Osteoarthritis Improve Pain Symptoms and Mobility?

The objective of the present study was to assess the effect of intra-articular Hyaluronic acid (HA) and Chondroitin sulfate (CS) supplementation (Hialurom® Hondro (HH)) on pain symptoms and joint mobility. In total, 60 mg/mL sodium hyaluronate and 90 mg/mL CS were administered to 21 patients (17 females and 4 males) respecting the in-force requirements, excluding patients with some specific comorbidities. In addition to the clinical study (where the pain intensity (severity) and joint mobility were assessed), rheological characterization was conducted evaluating the following parameters: elastic modulus (G'), loss modulus (G″) oscillatory frequency (fc) at 0.5 Hz and 2.5 Hz, crossover frequency (fc), relaxation time (λ) where it was noticed that the addition of chondroitin sulfate (CS) to sodium hyaluronate (SH) significantly enhances and improves the viscoelastic properties, particularly at higher shear frequencies. A significant decrease in pain intensity felt by the subjects was found, from 7.48 (according to Wong-Baker scale)-pain close to 8 (the patient is unable to perform most activities), to more reduced values of 5.86-at 6 weeks after injection, 4.81-at 3 months after injection, and 5.24-at 6 months after injection, improvements in symptoms was fast and durable. Data related to the evolution of joint mobility show that at 6 weeks after injection, the mobility of joints increased by 17.8% and at 6 months by 35.61%. No serious adverse events were reported with undesired effects so that they would impose additional measures. Better resistance to enzymatic degradation and free radicals could be expected from the synergic combination of sodium hyaluronate and chondroitin sodium sulfate, this having a special importance for the patients, granting them the ability to perform more ample movements and reducing dependency on attendants, thus increasing quality of life.

Preparation of chondroitin sulfate and polyvinyl alcohol hydrogels as drug carriers

The chondroitin sulfate/polyvinyl alcohol based pH-sensitive hydrogels (CHS/PVA hydrogels) were synthesized by a free radical polymerization technique for controlled delivery of diclofenac sodium up to 72 h. Polymers chondroitin sulfate and polyvinyl alcohol were crosslinked with monomer acrylic acid by a cross-linker ethylene glycol dimethylacrylate in the presence of initiator ammonium persulfate. The process of polymerization was continued for 24 h at 65 °C. Fourier transform infrared spectroscopy (FTIR) indicated successful polymerization and crosslinking among the hydrogel contents. Differential scanning calorimetric (DSC) and thermogravimetric analysis (TGA) studies demonstrated that fabricated hydrogel has higher thermal stability. The pH sensitivity of designed CHS/PVA hydrogel was investigated by performing dynamic swelling and in vitro drug release tests in pH 1.2, 4.6, and 7.4 medium. Maximum swelling was observed at pH 7.4 when compared to pH 1.2 and 4.6. The sequence of drug release from the developed hydrogel was; pH 7.4 > 4.6 > 1.2. It has been shown that porosity, swelling, and release rate of diclofenac increased with the addition of chondroitin sulfate and acrylic acid, while decreased with increasing PVA composition. Cytotoxicity studies showed that the prepared hydrogel has no toxic effect on T84. Therefore, it can be demonstrated from the results that the CHS/PVA cross-linked hydrogel can be considered as a potential delivery carrier for the controlled release of diclofenac sodium.

Chondroitin Sulfate Improves Mechanical Properties of Gelatin Hydrogel for Cartilage Regeneration in Rats.

Cartilage injury is a common disease in daily life. Especially in aging populations, the incidence of osteoarthritis is increasing. However, due to the poor regeneration ability of cartilage, most cartilage injuries cannot be effectively repaired. Even cartilage tissue engineering still faces many problems such as complex composition and poor integration of scaffolds and host tissues. In this study, chondroitin sulfate, one of the main components of extracellular matrix (ECM), is chosen as the main natural component of the material, which can protect cartilage in a variety of ways. Moreover, the results show that the addition of chondroitin sulfate improves the mechanical properties of gelatin methacrylate (GelMA) hydrogel, making it able to effectively bear mechanical loads in vivo. Further, chondroitin sulfate is modified to obtain the oxidized chondroitin sulfate (OCS) containing aldehyde groups via sodium periodate. This special group improves the interface integration and adhesion ability of the hydrogel to host cartilage tissue through schiff base reactions. In summary, GelMA/OCS hydrogel is a promising candidate for cartilage regeneration with good biocompatibility, mechanical properties, tissue integration ability, and excellent cartilage repair ability.

Construction of developmentally inspired periosteum-like tissue for bone regeneration

The periosteum, a highly vascularized thin tissue, has excellent osteogenic and bone regenerative abilities. The generation of periosteum-mimicking tissue has become a novel strategy for bone defect repair and regeneration, especially in critical-sized bone defects caused by trauma and bone tumor resection. Here, we utilized a bone morphogenetic protein-2 (BMP-2)-loaded scaffold to create periosteum-like tissue (PT) in vivo, mimicking the mesenchymal condensation during native long bone development. We found that BMP-2-induced endochondral ossification plays an indispensable role in the construction of PTs. Moreover, we confirmed that BMP-2-induced PTs exhibit a similar architecture to the periosteum and harbor abundant functional periosteum-like tissue-derived cells (PTDCs), blood vessels, and osteochondral progenitor cells. Interestingly, we found that the addition of chondroitin sulfate (CS), an essential component of the extracellular matrix (ECM), could further increase the abundance and enhance the function of recruited PTDCs from the PTs and finally increase the regenerative capacity of the PTs in autologous transplantation assays, even in old mice. This novel biomimetic strategy for generating PT through in vivo endochondral ossification deserves further clinical translation.

Human trabecular meshwork cell behavior is influenced by collagen scaffold pore architecture and glycosaminoglycan composition.

Glaucoma is a degenerative eye disease in which damage to the optic nerve leads to a characteristic loss of vision. The primary risk factor for glaucoma is an increased intraocular pressure that is caused by an imbalance of aqueous humor generation and subsequent drainage through the trabecular meshwork (TM) drainage system. The small size, donor tissue limitations, and high complexity of the TM make it difficult to research the relationship between the TM cells and their immediate environment. Thus, a biomaterial-based approach may be more appropriate for research manipulations and in vitro drug development platforms. In this work, human TM (hTM) cells were cultured on various collagen scaffolds containing different glycosaminoglycans (GAGs) and different pore architectures to better understand how hTM cells respond to changes in their extracellular environment. Cellular response was measured by quantifying cellular proliferation and expression of an important extracellular matrix protein, fibronectin. The pore architecture of the scaffolds was altered using freeze-casting technique to make both large and small pores that were aligned or with a non-aligned random structure. The composition of the scaffolds was altered with the addition of chondroitin sulfate and/or hyaluronic acid. It was found that the hTM cells grown on large pore scaffolds proliferate more than those grown on small pores. There was an increase in the fibronectin expression with the incorporation of GAGs, and its morphology was changed by the underlying pore architecture. This work will help provide an insight into the behavior of hTM cells when introducing changes in their microenvironment.

Chondroitin sulfate increases cell transfection efficiency by DNA-PEI complexes

One of the most popular nonviral delivery systems for gene therapy constructs are carriers based on polyethylenimine (PEI) DNA complexes. A number of disadvantages associated with the lack of targeted delivery and increased cytotoxicity are overcome by adding auxiliary molecules to the complexes. An example of this is chondroitin sulfate (CS). The purpose of this work was to assess the effect of CS on the transfection properties of DNA–PEI complexes under different conditions of their preparation and transfection protocols. All complexes were prepared in solutions with high and low ionic strength. Transfection of C26 cells was performed according to two protocols differing in the presence of serum in the medium. The portion of transfected cells, transgene expression level, and cell viability were the main parameters of assessing the transfection efficiency. In binary DNA–PEI complexes prepared in different salt conditions, using different transfection protocols, the difference in the portion of transfected cells reached ten times. Addition of CS improved this transfection efficiency indicator up to 6.5 times, while the maximum difference in this indicator for the corresponding ternary complexes was reduced to 2.5 times. Changes in the proportion of CS in the composition of the complexes had an insignificant effect on their transfection properties. In the case of complexes prepared in high ionic strength solutions, the order of CS addition was also important. The best results of transfection efficiency were achieved with ternary complexes prepared in low ionic strength solutions, using a serum-free protocol, while these indicators were comparable with the data for Lipofectamine 2000. The addition of chondroitin sulfate improves the transfection properties of DNA–PEI complexes and makes them less dependent on the methods of preparation and transfection.

Hyaluronan-Chondroitin Sulfate Anomalous Crosslinking Due to Temperature Changes.

Glycosaminoglycans are a wide class of biopolymers showing great lubricating properties due to their structure and high affinity to water. Two of them, hyaluronic acid and chondroitin sulfate, play an important role in articular cartilage lubrication. In this work, we present results of the all-atom molecular dynamics simulations of both molecules placed in water-based solution. To mimic changes of the physiological conditions, especially temperature, of the synovial fluid in joints under successive load (e.g., walking, jogging, jumping), simulations have been performed at different physiological temperatures in the range of 300 to 320 Kelvin (normal intra-articular temperature is 305 K). The stability of the biopolymeric network at equilibrium (isothermal and isobaric) conditions has been studied. To understand the process of physical crosslinking, the dynamics of intra- and intermolecular hydrogen bonds forming and breaking have been studied. The results show that following addition of chondroitin sulfate, hyaluronan creates more intermolecular hydrogen bonds than when in homogeneous solution. The presence of chondroitin in a hyaluronan network is beneficial as it may increase its stability. Presented data show hyaluronic acid and chondroitin sulfate as viscosity modifiers related to their crosslinking properties in different physicochemical conditions.

Injectable silk fibroin hydrogels functionalized with microspheres as adult stem cells-carrier systems

Hydrogels are good candidate materials for cell delivery scaffolds because they can mimic the physical, chemical, electrical and biological properties of most of the native tissues. In this study, composite biosynthetic hydrogels were produced by combining the bio-functionality of silk fibroin (SF) with the structural versatility of polyethylene-glycol-diacrylated (PEGDa). The formation of a photopolymerizable PEGDa-SF hydrogel (PSFHy) was optimized for 3D-cell culture. Functionalization of the 3D-PSFHy with protein microspheres (MS) was required to increase the porosity and cell-adhesive properties of the material. Cardiac mesenchymal stem cells, which were cultured within the MS-embedding PSFHy, exhibited good viability and expression of proteins that are characteristic of the initial phases of the cardiac muscle differentiation process. Further, the addition of chondroitin sulfate into the scaffolds improved the cell viability. A cell-preconditioning of the scaffold was also performed, suggesting a potential application of these sponge-like scaffolds for analysing the effects of several extracellular microenvironments, produced by different kinds of cells, on the stem cells fate. The results presented herein highlight on the possibility to use the PSFHys functionalized with MS as stem cell-carrier systems with sponge-like properties, potential ultrasound-imaging contrast agents and controlled biochemical factor delivery.

Effect of the addition of glycosaminoglycans on bone and cartilaginous development of broiler chickens

Locomotion issues in broiler production may decrease performance (carcass yield and traits) and lead to high financial losses. This study evaluates the addition of glucosaminoglycans in broiler diets to minimize the lack of proper bone development and joint weakening. The experiment was conducted using 2,160 broilers randomly distributed in a factorial pattern (3 × 3) using 3 levels of glucosamine sulfate (0, 0.12, and 0.24%) and 3 levels of chondroitin sulfate addition (0, 0.08, and 0.16%). Eight repetitions were used for each treatment, distributed in 72 pens with 30 broilers each. There was a quadratic effect on feed conversion for broilers from 1 to 42 d old (P = 0.0123) for the addition of chondroitin, and better feed conversion was obtained by adding 0.08% of chondroitin. The relative tibia weight, the width of the proximal epiphysis and diaphysis presented a linear increased effect in broilers at 42 d old. An interaction was found between the amount of chondroitin × glucosamine and the number of chondrocytes in the proximal cartilage of the tibia (P = 0.0072). There was a quadratic effect of glucosamine levels (P = 0.0107) in the birds that had received the 0.16% addition of chondroitin, and the presence of 0.18% glucosamine increased the number chondrocytes in the cartilage of broilers. These results provide the first evidence that broilers may benefit from increased dietary chondroitin sulfate. These results indicate that the addition of glucosamine and chondroitin sulfates in broiler feed rations might alleviate leg conditions and decrease financial losses in the broiler industry.

Surface physical chemistry properties in coated bacterial cellulose membranes with calcium phosphate

Bacterial cellulose has become established as a new biomaterial, and it can be used for medical applications. In addition, it has called attention due to the increasing interest in tissue engineering materials for wound care. In this work, the bacterial cellulose fermentation process was modified by the addition of chondroitin sulfate to the culture medium before the inoculation of the bacteria. The biomimetic process with heterogeneous calcium phosphate precipitation of biological interest was studied for the guided regeneration purposes on bacterial cellulose. FTIR results showed the incorporation of the chondroitin sulfate in the bacterial cellulose, SEM images confirmed the deposition of the calcium phosphate on the bacterial cellulose surface, XPS analysis showed a selective chemical group influences which change calcium phosphate deposition, besides, the calcium phosphate phase with different Ca/P ratios on bacterial cellulose surface influences wettability. XTT results concluded that these materials did not affect significantly in the cell viability, being non-cytotoxic. Thus, it was produced one biomaterial with the surface charge changes for calcium phosphate deposition, besides different wettability which builds new membranes for Guided Tissue Regeneration.

Biopolymer-based hydrogels for cartilage tissue engineering

Hydrogels hold a macromolecular structure comparable to that of native tissues and thus are very attractive materials for tissue engineering. The authors prepared three-dimensional bioartificial matrices based on methacrylated gelatin and chondroitin sulfate that can be tuned to closely mimic the natural environment of specific cell types – for example, chondrocytes. The authors investigated the hydrogel’s gel yield, swellability, mechanical strength, cytocompatibility, degradation and effect on chondrocyte redifferentiation. Furthermore, porcine chondrocytes were photoencapsulated into hydrogels and cultivated for 21 d. It was found that the methacrylation of chondroitin sulfate is crucial for the generation of stable hydrogels with methacrylated gelatin. Compared to pure gelatin, hybrid hydrogels possessed significantly higher swellability, while the mechanical strength remained constant. The hydrogel properties could be controlled by the mass fraction and the cross-linking density. The hydrogels as well as the cross-linking conditions were proven to render cytocompatible. Furthermore, it was found that the addition of chondroitin sulfate promoted a spherical morphology and thus chondrocyte phenotype retention. Thus, it is suggested that chondroitin sulfate is a potential redifferentiating agent of articular chondrocytes. In summary, hydrogels based on both chondroitin sulfate and gelatin hold tunable physical and biological properties and are preferable matrices for cartilage tissue engineering.

494. Glycosaminoglycans in Gene Delivery: An Effective Strategy for Enhancement of Transfection Efficiency of Amphipathic Peptides for Localized and Systemic Applications?

Glycosaminoglycans (GAGs) are negatively charged, linear, sulphated polysaccharides. Cell surface glycosaminoglycans have often been described as portals of cellular entry of cationic peptides and polymers used for gene delivery. On the other hand, exogenous glycosaminoglycans have generally been considered as impediments towards DNA delivery mediated through cationic vectors since they are likely to destabilize these electrostatically assembled complexes. However, recent reports have shown that exogenous glycosaminoglycans can also aid DNA delivery by reducing cytotoxicity and enhancing cellular uptake in some cationic polymers. Our laboratory has shown that addition of small amounts of exogenous GAGs to different cationic arginine-rich peptide-DNA nanocomplexes leads to an increase in their gene delivery efficiency. We observed formation of a ‘GAG coat’ on the nanocomplex surface which improved extracellular stability and subsequent cellular entry along with improved endosomal release and enhanced accumulation near the nucleus. However very little work has been done to understand the role of exogenous glycosaminoglycans on gene delivery by amphipathic peptides. We have developed a set of amphipathic peptides which exhibit high transfection efficiency in multiple cell lines. We explored the effect of addition of chondroitin sulphate to the peptide-DNA nanocomplexes. We observed an increase in nanocomplex size, decrease in surface charge and stability towards nuclease degradation at wt/wt ratios of 0.25 of chondroitin sulfate/peptide indicating its shielding effect. Enhanced transfection efficiency was also observed in multiple cell lines. Interestingly, maximum increase was observed in human keratinocyte cell line. Preliminary transfection results indicate that presence of CD44 could act as primary binding site for coated nanocomplexes leading to increased internalization. In addition, transfection in presence of inhibitors like Bafilomycin A1 indicates that the endosomal escape property of chondroitin sulphate might also play a part. This is being further verified through colocalization studies in presence of endosomal and lysosomal markers. Moreover, on topical application to human skin tissue, we observed increase in DNA delivery with the coated nanocomplexes. Since the skin tissue is also rich in glycosaminoglycans, we are exploring how the skin architecture might be helpful in aiding DNA delivery by GAG-coated nanocomplexes. Interestingly, while the transfection efficiency of the native nanocomplexes was compromised in presence of serum, addition of chondroitin sulfate was able to restore the transfection efficiency. Although the cellular uptake of the coated nanocomplexes was almost equal to that of the uncoated ones in presence of serum, the endosomal escape of the nanocomplexes was higher in coated nanocomplexes which could contribute towards the overall enhancement in transfection. All these results reveal the potential use of glycosaminoglycans to improve the transfection efficiency of amphipathic peptides for localized applications in skin as well as in vivo applications.

Preparation and Characterization of Poly(vinyl alcohol)-chondroitin Sulphate Hydrogel as Scaffolds for Articular Cartilage Regeneration

The aim of the study was to develop PVA-CS hydrogel scaffolds using glutaraldehyde as a cross-linking agent by chemical cross-linking method in order to obtain biomimetic scaffolds for articular cartilage regeneration. The introduction of PVA enhances the mechanical and bioadhesive properties to the native tissue while chondroitin sulphate enhances the glycosaminoglycan content of extracellular matrix. The role of hydrogel as cartilage regeneration scaffold was evaluated by swelling study, porosity, rheological behaviour,in vitrodegradation, and quantification of released chondroitin sulphate.In vivoresults showed that cross-linked hydrogels repaired defects with no sign of inflammation as it was well anchored to tissue in the formation of new articular surface. It may be concluded that the addition of chondroitin sulphate to the PVA polymer develops a novel composite with significant applications in cartilage tissue engineering.

Microvascular permeability to water is independent of shear stress, but dependent on flow direction

Endothelial cells in a cultured monolayer change from a "cobblestone" configuration when grown under static conditions to a more elongated shape, aligned with the direction of flow, after exposure to sustained uniform shear stress. Sustained blood flow acts to protect regions of large arteries from injury. We tested the hypothesis that the stable permeability state of individually perfused microvessels is also characteristic of flow conditioning. In individually perfused rat mesenteric venular microvessels, microvascular permeability, measured as hydraulic conductivity (Lp), was stable [mean 1.0 × 10(-7) cm/(s × cmH2O)] and independent of shear stress (3-14 dyn/cm(2)) for up to 3 h. Vessels perfused opposite to the direction of normal blood flow exhibited a delayed Lp increase [ΔLp was 7.6 × 10(-7) cm/(s × cmH2O)], but the increase was independent of wall shear stress. Addition of chondroitin sulfate and hyaluronic acid to perfusates increased the shear stress range, but did not modify the asymmetry in response to flow direction. Increased Lp in reverse-perfused vessels was associated with numerous discontinuities of VE-cadherin and occludin, while both proteins were continuous around the periphery of forward-perfused vessels. The results are not consistent with a general mechanism for graded shear-dependent permeability increase, but they are consistent with the idea that a stable Lp under normal flow contributes to prevention of edema formation and also enables physiological regulation of shear-dependent small solute permeabilities (e.g., glucose). The responses during reverse flow are consistent with reports that disturbed flows result in a less stable endothelial barrier in venular microvessels.

Characterisation of freeze-dried type II collagen and chondroitin sulfate scaffolds

Collagen type-II is the dominant type of collagen in articular cartilage and chondroitin sulfate is one of the main components of cartilage extracellular matrix. Afibrillar and fibrillar type-II atelocollagen scaffolds with and without chondroitin sulfate were prepared using casting and freeze-drying methods. The scaffolds were characterised to highlight the effects of fibrillogenesis and chondroitin sulfate addition on viscosity, pore structure, porosity and mechanical properties. Microstructure analysis showed that fibrillogenesis increased the circularity of pores significantly in collagen-only scaffolds, whereas with it, no significant change was observed in chondroitin sulfate-containing scaffolds. Addition of chondroitin sulfate to afibrillar scaffolds increased the circularity of the pores and the proportion of pores between 50 and 300μm suitable for chondrocytes growth. Fourier transform infrared spectroscopy explained the bonding between chondroitin sulfate and afibrillar collagen- confirmed with rheology results- which increased the compressive modulus 10-fold to 0.28kPa. No bonding was observed in other scaffolds and consequently no significant changes in compressive modulus were detected.

Role of chondroitin sulfate C in the action of anthrax toxin

Anthrax toxin is produced by Bacillus anthracis, the causative agent of anthrax, and is responsible for the majority of disease symptoms. The toxin consists of 3 proteins, protective antigen (PA), lethal factor (LF), and edema factor (EF), which combine to form lethal and edema toxin. Glycosaminoglycans, which are present on the surface of cells, were investigated with regard to their role in toxicity resulting from anthrax toxin exposure. Lethal toxin-induced cytotoxicity of the RAW 264.7 cells was significantly inhibited by the addition of chondroitin sulfate C as determined by the MTT assay. By contrast, several other glycosaminoglycans, including heparin, heparan sulfate, and dermatan sulfate did not show significant levels of inhibition. Studies utilizing fluorescence-labeled PA demonstrated decreased PA binding to RAW 264.7 cells with the addition of chondroitin sulfate C. Formation of PA oligomers at the surface of cells after binding was also inhibited by chondroitin sulfate C. Interestingly, enzymatic degradation of endogenous chondroitin sulfate C from the cell surface with chondroitinase ABC was accompanied by increased sensitivity to the toxin. These findings were further confirmed by pretreating cells with sodium chlorate to reduce the degree of cell surface glycosaminoglycans sulfation. In addition, chondroitin sulfate C effectively inhibits edema toxin-induced cAMP accumulation in cells. Our results indicate that chondroitin sulfate C may play an important role in the toxicity of anthrax toxin.

Differential Use of Chondroitin Sulfate to Regulate Hyaluronan Binding by Receptor CD44 in Inflammatory and Interleukin 4-activated Macrophages

CD44 is a cell surface receptor for the extracellular matrix glycosaminoglycan hyaluronan and is involved in processes ranging from leukocyte recruitment to wound healing. In the immune system, the binding of hyaluronan to CD44 is tightly regulated, and exposure of human peripheral blood monocytes to inflammatory stimuli increases CD44 expression and induces hyaluronan binding. Here we sought to understand how mouse macrophages regulate hyaluronan binding upon inflammatory and anti-inflammatory stimuli. Mouse bone marrow-derived macrophages stimulated with tumor necrosis factor α or lipopolysaccharide and interferon-γ (LPS/IFNγ) induced hyaluronan binding by up-regulating CD44 and down-regulating chondroitin sulfation on CD44. Hyaluronan binding was induced to a lesser extent in interleukin-4 (IL-4)-activated macrophages despite increased CD44 expression, and this was attributable to increased chondroitin sulfation on CD44, as treatment with β-d-xyloside to prevent chondroitin sulfate addition significantly enhanced hyaluronan binding. These changes in the chondroitin sulfation of CD44 were associated with changes in mRNA expression of two chondroitin sulfotransferases, CHST3 and CHST7, which were decreased in LPS/IFNγ-stimulated macrophages and increased in IL-4-stimulated macrophages. Thus, inflammatory and anti-inflammatory stimuli differentially regulate the chondroitin sulfation of CD44, which is a dynamic physiological regulator of hyaluronan binding by CD44 in mouse macrophages.

Synthesis Conditions of Nano-Hydroxyapatite Using Chondroitin Sulfate by Co-Precipitation Method

The introduction of biomineralization was coupled with the co-precipitation synthesis process of nano-hydroxyapatite with the addition of chondroitin sulfate as a template agent. The effect of a variety of processing conditions on the properties of final hydroxyapatite (HA) product was investigated by orthogonal design. The ratio of calcium to phosphorus was detected by chemical analysis, the phase composition was evaluated by X-ray diffraction (XRD), and the powder morphology was characterized by transmission electron microscope (TEM). The process scheme, moreover, was optimized by the analysis of four aspects which may have different extent of influence on product properties. It can be concluded from the results that product properties can be affected remarkably by the content of chondroitin sulfate and the pH value of reactant, less remarkably by the reaction temperature and slightly by the reaction time.

Hyaluronan Induces Cell Death in Activated T Cells through CD44

In the immune system, leukocyte activation induces CD44 to bind hyaluronan, a component of the extracellular matrix. Here we used gain and loss of hyaluronan-binding mutants of CD44 to examine the consequence of hyaluronan binding in T cells. Jurkat T cells transfected with CD44 mutated at S180, which prevented the addition of chondroitin sulfate, displayed constitutively high levels of hyaluronan binding. These cells were more susceptible to activation-induced cell death, whereas cells expressing a CD44 mutant unable to bind hyaluronan (R41A) were resistant to cell death. In TCR or PMA activated Jurkat T cells, hyaluronan induced rapid cell death. This depended on the level of hyaluronan binding by the cell, and the amount and size of hyaluronan. High molecular mass hyaluronan had the greatest effect and cell death occurred independently of Fas and caspase activation. In splenic T cells, high hyaluronan binding occurred in a subpopulation of cells undergoing activation-induced cell death. In addition, hyaluronan induced cell death in approximately 10% of reactivated splenic T cells when Fas-dependent apoptosis was prevented by Ab blocking or in Fas negative MRL/lpr T cells. This demonstrates that hyaluronan can induce cell death in activated, high hyaluronan binding T cells via a Fas-independent mechanism.

Thermoresponsive hydrogels based on poly(N-isopropylacrylamide)/chondroitin sulfate

Abstract A fast, thermoresponsive hydrogel composed of poly( N -isopropylacrylamide) (PNIPAm) and chondroitin sulfate (ChS) was synthesized using precipitation polymerization. ChS was introduced to increase the water absorption of the PNIPAm hydrogel, and the precipitation polymerization method was used to induce a porous network morphology to enhance the thermal response of the hydrogel. PNIPAm/ChS hydrogels (15:7.5 wt.%) underwent a very fast deswelling, within a period of approximately 2 min, due to the presence of a large free water content (∼90–94%), which was associated with the interconnected filamentous morphology within the hydrogel. The swelling ratio was greatly enhanced by the addition of ChS. The hydrogels exhibited stable thermoactuation behavior, following a volume change of 75% while cycling the temperature between 20 and 45 °C.