Microbial exopolysaccharides: Unveiling the pharmacological aspects for therapeutic advancements.

Microbial exopolysaccharides (EPSs) have emerged as a fascinating area of research in the field of pharmacology due to their diverse and potent biological activities. This review paper aims to provide a comprehensive overview of the pharmacological properties exhibited by EPSs, shedding light on their potential applications in various therapeutic areas. The review begins by introducing EPSs, exploring their various sources, significance in microbial growth and survival, and their applications across different industries. Subsequently, a thorough examination of the pharmaceutical properties of microbial EPSs unveils their antioxidant, immunomodulatory, antimicrobial, antidepressant, antidiabetic, antiviral, antihyperlipidemic, hepatoprotective, anti-inflammatory, and anticancer activities. Mechanistic insights into how different EPSs exert these therapeutic effects have also been discussed in this review. The review also provides comprehensive information about the monosaccharide composition, backbone, branches, glycosidic bonds, and molecular weight of pharmacologically active EPSs from various microbial sources. Furthermore, the factors that can affect the pharmacological activities of EPSs and approaches to improve the EPSs' pharmacological activity have also been discussed. In conclusion, this review illuminates the immense pharmaceutical promise of microbial EPS as versatile bioactive compounds with wide-ranging therapeutic applications. By elucidating their structural features, biological activities, and potential applications, this review aims to catalyze further research and development efforts in leveraging the pharmaceutical potential of microbial EPS for the advancement of human health and well-being, while also contributing to sustainable and environmentally friendly practices in the pharmaceutical industry.

Characterization and optimization of exopolysaccharide extracted from a newly isolated halotolerant cyanobacterium, Acaryochloris Al-Azhar MNE ON864448.1 with antiviral activity.

Several antiviral agents lost their efficacy due to their severe side effects and virus mutations. This study aimed to identify and optimize the conditions for exopolysaccharide (EPS) production from a newly isolated cyanobacterium, Acaryochloris Al-Azhar MNE ON864448.1, besides exploring its antiviral activity. The cyanobacterial EPS was purified through DEAE-52 cellulose column with a final yield of 83.75%. Different analysis instruments were applied for EPS identification, including Fourier-transform infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA), and gas chromatographic-mass spectrometry (GC-MS). Plackett-Burman's design demonstrated that working volume (X1), EDTA (X2), inoculum size (X3), CaCl2 (X4), and NaCl (X5) are the most important variables influencing EPS production. Central composite design (CCD) exhibited maximum EPS yield (9.27 mg/mL) at a working volume of 300 mL in a 1 L volumetric flask, EDTA 0.002 g/L, inoculum size 7%, CaCl2 0.046 g/L, and NaCl 20 g/L were applied. EPS showed potent antiviral activities at different stages of herpes simplex virus type-1 and 2 (HSV-1, HSV-2), adenovirus (ADV) and coxsackievirus (A16) infections. The highest half-maximal inhibitory concentration (IC50) (6.477 µg/mL) was recorded during HSV-1 internalization mechanism, while the lowest IC50 (0.005669 µg/mL) was recorded during coxsackievirus neutralization mechanism.

Photo-triggered caffeic acid delivery via psyllium polysaccharide- gellan gum-based injectable bionanogel for epidermoid carcinoma treatment.

Here, the simultaneous effect of chemo- and photothermal therapy against epidermoid carcinoma (EC) was investigated. A novel hydrogel, termed bionanogel (BNG), was designed using psyllium mucilage polysaccharide and bacterial gellan gum, incorporated with nanocomplex carrying caffeic acid (CA) and IR-820, and further characterized. The dual effect of BNG and 808 nm laser (BNG + L) on EC was investigated. Staining and scratch assays were performed to analyze their therapeutic effect on EC. In vivo evaluations of BNG + L in xenograft models were performed. Rapid transition, limited swelling, degradability and high tensile strength indicated BNG stability and sustained drug release. Irradiation with 808 nm laser light at 1.25 W /cm2 for 4 min resulted in a temperature increase of 53 °C and facilitated cell ablation. The in vitro studies showed that BNG + L suppressed cancer progression via a late apoptotic effect. The in vivo study showed that the slow release of CA from BNG + L significantly attenuated EC with low mitotic index and downregulation of proteins involved in cancer proliferation such as EGFR, AKT, PI3K, ERK, mTOR and HIF-1α. Thus, BNG could be a novel medium for targeted and controlled drug delivery for the treatment of epidermoid cancer when triggered by NIR light.

Structural, rheological properties and antioxidant activities analysis of the exopolysaccharide produced by Rhizobium leguminosarum bv. viciae VF39.

Microbial exopolysaccharide is an eco-friendly and non-toxic biopolymeric materials widely used in various industrial fields such as pharmaceutical, food and cosmetics based on its structural, rheological and physiochemical properties. A microbial exopolysaccharide (VF39-EPS) was directly isolated from Rhizobium leguminosarum bv. viciae VF39. Structural analysis using FTIR and 2D NMR spectroscopy confirmed the complete chemical structures of VF39-EPS as 3-hydroxybutanoylglycan with octasaccharide repeating units containing two pyruvyl, two acetyl, and one 3-hydroxybutanoyl group. VF39-EPS exhibited thermal stability up to 275 °C and showed characteristic rheological behaviors of structural fluid with weak gel-like properties above 4 % the aqueous solution, suggesting VF39-EPS as a potential effective thickener or hydrogel scaffolder. Flow behavior tests validated broad stability at a wide range of both pHs from 2 to 12 and temperatures from 25 to 75 °C, and even in the presence of various salts. Furthermore, VF39-EPS showed excellent antioxidant effects of 78.5 and 62.4 % (n = 3, p < 0.001) in DPPH scavenging activity and hydroxyl radical scavenging activity, respectively. Therefore, those structural, rheological and antioxidant properties suggest that VF39-EPS could be one of the excellent biomaterial candidates for cosmetic, food and pharmaceutical industries based on its characteristic rheological behaviors in various condition and excellent antioxidant activity.

Multiple Bio-Actives Loaded Gellan Gum Microfibers from Microfluidics for Wound Healing.

Wound healing, known as a fundamental healthcare issue worldwide, has been attracting great attention from researchers. Here, novel bioactive gellan gum microfibers loaded with antibacterial peptides (ABPs) and vascular endothelial growth factor (VEGF) are proposed for wound healing by using microfluidic spinning. Benefitting from the high controllability of microfluidics, bioactive microfibers with uniform morphologies are obtained. The loaded ABPs are demonstrated to effectively act on bacteria at the wound site, reducing the risk of bacterial infection. Besides, sustained release of VEGF from microfibers helps to accelerate angiogenesis and further promote wound healing. The practical value of woven bioactive microfibers is demonstrated via animal experiments, where the wound healing process is greatly facilitated because of the excellent circulation of air and nutritious substances. Featured with the above properties, it is believed that the novel bioactive gellan gum microfibers would have a remarkable effect in the field of biomedical application, especially in promoting wound healing.

Extraction and characterization of exopolysaccharides from Lactiplantibacillus plantarum strain PRK7 and PRK 11, and evaluation of their antioxidant, emulsion, and antibiofilm activities.

Exopolysaccharides (EPS) are produced by probiotic bacteria Lactiplantibacillus plantarum PRK7 and L. plantarum PRK11. The structure of EPS-7 and EPS-11 was characterized by Fourier-transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), gas chromatography-mass spectroscopy (GCMS), and thermogravimetric analysis (TGA). Further, in in vitro studies antioxidant, emulsion, and antibiofilm activity were investigated. The FTIR spectrum confirmed the presence of polysaccharides in EPS-7 and EPS-11, with absorbance at 1654.93 and 1655.33 cm-1, respectively. H1 NMR further confirmed the presence of glucose, galactose, xylose, and mannose. Sugar derivatives in EPS-7 and EPS-11 were further confirmed with GCMS. The SEM analysis revealed that EPS-7 had a weblike structure and EPS-11 had a smooth porous layer. The result of the TGA revealed that EPS-7 and EPS-11 had greater thermal stability at 319.1 and 300.1 °C, respectively. Furthermore, EPS-7 and EPS-11 showed a good percentage of free radical scavenging in DPPH (89.77 % and 93.1 %), ABTS (57.65 % and 58.63 %), hydroxyl radical scavenging (44.46 % and 40.308 %), and reducing power assay. The emulsion activity was confirmed with edible oils such as coconut oil, sesame oil, almond oil, castor oil, and neem oil. The highest emulsion activity for EPS-7 and EPS-11 was found with coconut and castor oil. In addition, the antibiofilm activity against pathogens revealed that EPS can prevent biofilm formation. Thus, it was found that EPS-7 and EPS-11 possess good structural characteristics and their biological activity makes them ideal for applications in the food and pharmaceutical industry.

Recent advances in the biological activities of microbial exopolysaccharides.

Microbial exopolysaccharides (EPSs) are valuable extracellular macromolecules secreted as capsules or slime layers. Various microorganisms, including bacteria, yeasts, fungi, and algae have been studied for their ability to produce EPSs. Microbial EPSs exist as homopolysaccharides or heteropolysaccharides with various properties such as different monosaccharide compositions, structural conformation, molecular weight, and functional groups. They are cost-effective alternatives to plant and animal-derived polysaccharides because the microbial cells produced them in large quantities by biotechnological processes using low-cost substrates such as industrial wastes in a short time. Microbial EPSs are safe, biodegradable, and compatible polymers. They have extensive bioactivities, including antibacterial, antifungal, antiviral, antioxidant, antitumor, antidiabetic, antiulcer, anticoagulant, antiaging, immunomodulatory, wound healing, and cholesterol-lowering activities. Microbial EPSs owing to biological activities, special biochemical structures, and attractive physicochemical properties find plenty of potential applications in various industries. The enhancement of the production of EPSs and improving their properties can be provided by genetic engineering methods. The current review aims to provide a comprehensive examination of the therapeutic activities of microbial EPSs in infectious diseases and metabolic disorders, with a focus on the mechanisms involved. Also, the effect of the physicochemical characteristics of EPSs on these bioactivities was discussed to reveal the structure-activity relationship.

Structure, antioxidant properties, and protective effects on DNA damage of exopolysaccharides from Clostridium butyricum.

Exopolysaccharides (EPSs) of probiotics are naturally nontoxic antioxidants with some interesting biological activities. This research aims to explore the structural and antioxidant properties of the EPS from Clostridium butyricum, a probiotics widely existed in human and animal intestines. EPS of C. butyricum RO-07 was purified through a combination of anion-exchange column chromatography and gel chromatography and determined to be composed of glucosamine, arabinose, galactosamine, galactose, glucose, and xylose in a molar ratio of 1:1:1:2:1:1 with a molecular weight 1.23 × 104  Da. It exhibited a stronger antioxidant activity than ascorbic acid, with scavenging activities up to 75.2% and 95.0% against hydroxyl radical (•OH) and superoxide radical (O2 - •), respectively. It also performed protective effects on DNA against radiation destruction by ultraviolet and reactive oxygen species generated oxidation stress. With these superior advantages in oxidants and radiation resistance, the EPS from C. butyricum RO-07 therefore has great potential to be applied in food and cosmetic industry.

Physicochemical, rheological, and bioactive properties of exopolysaccharide produced by a potential probiotic Enterococcus faecalis 84B.

Exopolysaccharides (EPS) have attracted a great interest due to their potential health-promoting properties and industrial applications. This study aimed to investigate the physicochemical, rheological, and biological properties of an EPS produced by a potential probiotic strain Enterococcus faecalis 84B. The results show that the extracted EPS, designated EPS-84B, had an average molecular weight of 604.8 kDa, particles size diameter of 322.0 nm, and mainly composed of arabinose and glucose with a molar ratio of 1:2. Furthermore, EPS-84B exhibited a shear-thinning behavior and had a high melting point. The rheological properties of EPS-84B were strongly influenced by the type of salt than by the pH value. EPS-84B displayed ideal viscoelastic properties, with both viscous and storage moduli increasing with frequency. The antioxidant activity of EPS-84B at a concentration of 5 mg/mL was 81.1 % against DPPH and 35.2 % against ABTS. At 5 mg/mL, the antitumor activity of EPS-84B against Caco-2 and MCF-7 cell lines was 74.6 and 38.6 %, respectively. In addition, the antidiabetic activity of EPS-84B towards α-amylase and α-glucosidase was 89.6 and 90.0 %, respectively at 100 µg/mL. The inhibition of foodborne pathogens by EPS-84B was up to 32.6 %. Overall, EPS-84B has promising properties that could be utilized in food and pharmaceutical industries.

Beneficial Effect of Polysaccharide Gel Made of Xanthan Gum and Locust Bean Gum on Bovine Oocytes.

The present study examined the effect of polysaccharides gels made of xanthan gum and locust bean gum (gel culture system) on oocyte maturation and explored the molecules causing the beneficial effect of the gel culture system. Oocytes and cumulus cells complexes were collected from slaughterhouse-derived ovaries and cultured on a plastic plate or gel. The gel culture system improved the rate of development to the blastocyst stage. The oocytes that matured on the gel contained high lipid contents and F-actin formation, and the resultant 8-cell stage embryos had low DNA methylation levels compared to their plate counterparts. RNA sequencing of the oocytes and embryos revealed the differentially expressed genes between the gel and plate culture systems, and upstream regulator analysis revealed estradiol and TGFB1 as top activated upstream molecules. The medium of the gel culture system contained higher concentrations of estradiol and TGFB1 than that of the plate cultures system. Supplementation of the maturation medium with either estradiol or TGFB1 resulted in high lipid content in oocytes. In addition, TGFB1 improved the developmental ability of the oocytes and increased F-actin content while reducing DNA methylation levels in the 8-cell stage embryos. In conclusion, the gel culture system is useful for embryo production, potentially through the upregulation of TGFB1.

Structural elucidation of the exopolysaccharide from Streptococcus thermophilus XJ53 and the effect of its molecular weight on immune activity.

EPS53, a homogeneous exopolysaccharide (EPS) was isolated from Streptococcus thermophiles XJ53 fermented in skimmed milk via anion exchange column chromatography. The relative molecular weight of EPS53 was above 6.7 × 105 g/mol; its repeating structural unit of EPS53 consisted of ß-T-Galp, ß-1,3-Galf, α-1,3-Glcp and ß-1,3,6-Glcp residues in a molar ratio of 1:1:1:1, with ß-T-Galp attached to the O-6 position of ß-1,3,6-Glcp，identical to the EPS produced from S. thermophilus SFi39. EPS53-D, purified under similar conditions as EPS53 except for the deproteinization of trichloroacetic acid (TCA), had a lower molecular weight but the same repeating structural unit. The effects of EPS53 and EPS53-D on proliferation, phagocytosis and nitric oxide (NO) release of macrophage RAW264.7 were compared. EPS53 exhibited stronger immune activity than EPS53-D, suggesting that the molecular weight might have an important effect on the activity of EPS molecules. Treatment with TCA might affect the activities of native EPSs produced by fermentation.

Structural and Functional Characterization of Exopolysaccharide Produced by a Novel Isolate Bacillus sp. EPS003.

An exopolysaccharide (EPS)-producing soil bacterium was isolated and characterized using 16S rRNA as Bacillus sp. EPS003. EPS was precipitated using ethanol and % composition of total carbohydrate, and protein was determined. Monosaccharide composition was identified using thin layer chromatography (TLC), and it was found to be a levan. Fourier transform infrared (FTIR) spectrum revealed the peaks for carboxyl, hydroxyl, and amide functional groups. 1H nuclear magnetic resonance (NMR) spectrum further confirmed the presence of fructose monomer. Field emission scanning electron microscopic images (FE-SEM) revealed porous and amorphous characteristics of EPS which was further confirmed with broad peaks in X-ray diffraction (XRD) spectrum. Elemental composition was determined using energy-dispersive X-ray analysis (EDAX). Thermogravimetric analysis (TGA) of EPS resulted in a residual mass of 33.81% at 548 °C indicating high thermal stability. In addition, solubility index and water-holding capacity of EPS were found to be 56% and 264%, respectively, making EPS suitable for various applications. Further, antioxidant potential of EPS was studied using hydroxyl and DPPH radical scavenging assays. In vitro cytotoxicity assessment using L929 cells and SK-MEL-3 cell lines clearly indicated that the EPS produced by the novel isolate Bacillus sp. EPS003 could serve as a potential anticancer agent.

Characterization of Probiotic Pichia sp. DU2-Derived Exopolysaccharide with Oil-in-Water Emulsifying and Anti-biofilm Activities.

Probiotic-derived exopolysaccharides are considered as promising sources of carbohydrate with extensive applications in many industries. In the current study, yeast strains were isolated from chicken ingluvies and gizzard samples. According to molecular identification, EPS-producing yeast (Pichia sp. DU2) showed the most similarity to Pichia cactophila (99.67%). Pichia sp. DU2 showed probiotic properties. EPS of Pichia sp. DU2 showed emulsifying activity. The formed emulsions showed 53% (colza oil) and 100% (p-xylene) stability after 24 h. These emulsions were oil-in-water and have stability in the presence of NaCl, KCl, and also acidic and basic conditions. Also, the EPS showed anti-biofilm (29.7-47.6% and 19.06-55.26% against B. cereus and Y. enterocolitica, respectively) and flocculating activities (31.4%). FT-IR showed the presence of various functional groups in EPS structure. Also, its heteropolysaccharide nature was revealed in 1H-NMR and HPLC analysis. This emulsifying EPS showed significant thermal stability and negative zeta potential, which make it a promising carbohydrate for various industries. Finally, according to the predicted model, the maximal EPS production was achieved at reaction time 36 h, pH 6, yeast extract concentration 1.0%, and sucrose concentration 5%. Pichia sp. DU2 with probiotic properties and producing EPS with emulsifying, anti-biofilm, and flocculating activities can be considered as promising yeast strain in various industries like food and pharmaceutical industries.

Fabrication Methods and Form Factors of Gellan Gum-Based Materials for Drug Delivery and Anti-Cancer Applications.

Despite the success of cancer therapeutics, off target cell toxicity prevails as one of the main challenges of cancer treatment. Exploration of drug delivery methods is a growing field of research, which involves a variety of materials and processing techniques. A natural polymer, gellan gum presents physicochemical properties that enable drug loading for sustained release in a broad range of environmental conditions and anatomical locations. Gellan gum is an anionic exopolysaccharide, produced via fermentation by Sphingomonas elodea, which gels in the presence of cations. Additionally, it is biocompatible and nontoxic. Multiple physical and chemical gelation processes have been reported for the use of gellan gum in drug delivery applications to produced varying form factors, including hydrogels, nanohydrogels, beads, films, or patches, with tunable mechanical and physicochemical properties. The resulting formulations have shown promising outcomes for drug delivery including improving drug bioavailability, drug solubility, and drug release over time, without compromising biocompatibility or the introduction of adverse effects. This review presents studies in which gellan gum has been processed to enable the delivery of antibiotics, antiallergens, anti-inflammatory, or antifungal molecules with a special focus on drugs for anticancer applications.

Acidic Exo-Polysaccharide Obtained from Bacillus sp. NRC5 Attenuates Testosterone-DMBA-Induced Prostate Cancer in Rats via Inhibition of 5 α-Reductase and Na+/K+ ATPase Activity Mechanisms.

Bacillus sp. NRC5 is a new strain that grows in Egyptian beaches. This strain produces acidic exo-polysaccharide that have excellent antioxidant, anti-inflammatory and anti-tumor properties. The current study aimed to introduce a new natural product feasible for prostate cancer therapies. The anti-prostate cancer of acidic exo-polysaccharide produced from marine Bacillus sp. NRC5 (EBPS) was determined using 7,12-dimethylbenz-(a)-anthracene; DMBA-induced prostate cancer in male Sprague Dawley rats. Rats were subcutaneously injected with testosterone (3 mg/kg/day for 3 months) and a single dose of DMBA (65 mg/kg) for induction of prostate cancer. EBPS was administrated orally at dose 200 mg/kg/day for 3 months. To study protective effect of EBPS, animals received EBPS before cancer induction, meanwhile in therapeutic effect animals received EBPS after cancer induction. EBPS debug oxidative stress and inflammatory conditions associated with prostate cancer. EBPS either protective or therapeutic material considerably reduced cancer growth rate-limiting enzyme-i.e., 5-α-reductase (46.89 ± 1.72 and 44.86 ± 2.56 µg Eq/mL) and Na+/K+ ATPase (0.44 ± 0.03 and 0.42 ± 0.02 µg Eq/mL), compared to cancer control (69.68 ± 3.46 µg Eq/mL). In addition, both cancer biomarkers-i.e., prostate-specific antigen and carcinoembryonic antigen were significantly lowered as evidence of the ability of EBPS to protect and treat prostate cancer in chemically induced rats. EBPS showed protective and therapeutic efficacy on testosterone-DMBA-induced prostate cancer rats with a good safety margin. This study may go to clinical trials after a repeated study on another type of small experimental animal, their offspring, and one big experimental animal.

Fast stress relaxing gellan gum that enhances the microenvironment and secreting function of bone mesenchymal stem cells.

This study shows tunable stress relaxing gellan gum (GG) hydrogel for enhanced cell growth and regenerative medicine. The molecular weight and physical crosslinking density of GG were tuned and characterized with physicochemical analysis and mechanical tests. The result showed that a decrease in the molecular weight of the GG correlated with a decline in the mechanical properties but faster stress relaxing character. We also discovered that human-derived bone marrow stem cells (hBMSC) showed active viability, proliferation, and remodeling in the fast stress relaxing GG hydrogel. In particular, hBMSC showed an enhanced release profile of growth factors and exosomes (Exo) in the fast stress relaxing GG hydrogel. The secretome obtained from hBMSC embedded in hydrogel exhibited similar cytotoxicity and wound healing properties to that of secretome extracted from hBMSC cultured in a tissue culture plate (TCP) a standard culture condition. Thus, this work demonstrates the potential of fast stress relaxing GG hydrogels for medical application.

Exopolysaccharide produced by Lactiplantibacillus plantarum RO30 isolated from Romi cheese: characterization, antioxidant and burn healing activity.

Microbial exopolysaccharides (EPSs) extracted from lactic acid bacteria (LAB) are generally recognized as safe. They have earned popularity in recent years because of their exceptional biological features. Therefore, the present study main focus was to study EPS-production from probiotic LAB and to investigate their antioxidant and burn wound healing efficacy. Seventeen LAB were isolated from different food samples. All of them showed EPS-producing abilities ranging from 1.75 ± 0.05 to 4.32 ± 0.12 g/l. RO30 isolate (from Romi cheese) was chosen, due to its ability to produce the highest EPS yield (4.23 ± 0.12 g/l). The 16S rDNA sequencing showed it belonged to the Lactiplantibacillus plantarum group and was further identified as L. plantarum RO30 with accession number OL757866. It displayed well in vitro probiotic properties. REPS was extracted and characterized. The existence of COO-, OH and amide groups corresponding to typical EPSs was confirmed via FTIR. It was constituted of glucuronic acid, mannose, glucose, and arabinose in a molar ratio of 2.2:0.1:0.5:0.1, respectively. The average molecular weight was 4.96 × 104 g/mol. In vitro antioxidant assays showed that the REPS possesses a DPPH radical scavenging ability of 43.60% at 5 mg/ml, reducing power of 1.108 at 10 mg/ml, and iron chelation activity of 72.49% and 89.78% at 5 mg/ml and 10 mg/ml, respectively. The healing efficacy of REPS on burn wound models in albino Wistar rats showed that REPS at 0.5% (w/w) concentration stimulated the process of healing in burn areas. The results suggested that REPS might be useful as a burn wound healing agent.

Fabrication and Evaluation of Gellan Gum/Hyaluronic Acid Hydrogel for Retinal Tissue Engineering Biomaterial and the Influence of Substrate Stress Relaxation on Retinal Pigment Epithelial Cells.

Cell therapies for age-related macular degeneration (AMD) treatment have been developed by integrating hydrogel-based biomaterials. Until now, cell activity has been observed only in terms of the modulus of the hydrogel. In addition, cell behavior has only been observed in the 2D environment of the hydrogel and the 3D matrix. As time-dependent stress relaxation is considered a significant mechanical cue for the control of cellular activities, it is important to optimize hydrogels for retinal tissue engineering (TE) by applying this viewpoint. Herein, a gellan Gum (GG)/Hyaluronic acid (HA) hydrogel was fabricated using a facile physical crosslinking method. The physicochemical and mechanical properties were controlled by forming a different composition of GG and HA. The characterization was performed by conducting a mass swelling study, a sol fraction study, a weight loss test, a viscosity test, an injection force study, a compression test, and a stress relaxation analysis. The biological activity of the cells encapsulated in 3D constructs was evaluated by conducting a morphological study, a proliferation test, a live/dead analysis, histology, immunofluorescence staining, and a gene expression study to determine the most appropriate material for retinal TE biomaterial. Hydrogels with moderate amounts of HA showed improved physicochemical and mechanical properties suitable for injection into the retina. Moreover, the time-dependent stress relaxation property of the GG/HA hydrogel was enhanced when the appropriate amount of HA was loaded. In addition, the cellular compatibility of the GG/HA hydrogel in in vitro experiments was significantly improved in the fast-relaxing hydrogel. Overall, these results demonstrate the remarkable potential of GG/HA hydrogel as an injectable hydrogel for retinal TE and the importance of the stress relaxation property when designing retinal TE hydrogels. Therefore, we believe that GG/HA hydrogel is a prospective candidate for retinal TE biomaterial.

Low molecular-weight polyguluronate phosphate: An immunostimulant by activating splenocyte/macrophage invitro and improving immune response invivo.

The substituents and backbones are two main factors affecting immune activities of polysaccharides. In the present study, we firstly evaluated the immunostimulating effects of phosphorylated, sulfated, H-phosphonated and nitrated derivatives of low-molecular-weight polymannuronate (LPM) and polyguluronate (LPG) on splenocytes and peritoneal macrophages in vitro. The results showed that the phosphate group was the best substituent to enhance the immune activities, and LPG phosphate (LPGP) had much better activity than LPM phosphate (LPMP). Further studies showed that LPGP not only promoted the proliferation of mouse splenocytes in the presence of either LPS or Con A, but also acted as an excellent peritoneal macrophage activator to enhance the cell phagocytosis, energy metabolism, cytokines release and activities of intracellular enzymes. The studies in RAW264.7 cells revealed that LPGP activated the TBK1-IκBα-NF-κB and the TBK1-IRF3 pathway. Moreover, LPGP rescued the immune response in the Cyclophosphamide-treated mice in vivo. In conclusion, LPGP is a potential alginate-based biological response modifier (BRM).

3D bioprinting of gellan gum-based hydrogels tethered with laminin-derived peptides for improved cellular behavior.

The treatment of skeletal muscle defects is still a topic of noteworthy concern since surgical intervention is not capable of recovering muscle function. Herein, we propose myoblasts laden in laminin-inspired biofunctionalized gellan gum hydrogels as promising tissue-engineered skeletal muscle surrogates. Gellan gum-based hydrogels were developed by combining native gellan gum (GG) and GG tethered with laminin-derived peptides (CIKVAVS (V), KNRLTIELEVRTC (T) or RKRLQVQLSIRTC (Q)), using different polymer content (0.75%-1.875%). Hydrogels were characterized in terms of compressive modulus, molecules trafficking, and C2C12 adhesion. Hydrogels with higher polymeric content (1.125%-1.875%) showed higher stiffness whereas hydrogels with lower polymer content (0.75%-1.125%) showed higher fluorescein isothiocyanate-dextran molecules diffusion. Cell spreading was achieved regardless of the laminin-derived peptide but preferred in hydrogels with higher polymer content (1.125%-1.875%). Taken together, hydrogels with 1.125% of polymer content were selected for printability analysis. GG-based inks showed a non-newtonian, shear-thinning, and thixotropic behavior suitable for printing. Accordingly, all inks were printable, but inks tethered with T and Q peptides presented some signs of clogging. Cell viability was affected after printing but increased after 7 days of culture. After 7 days, cells were spreading but not showing significant signs of cell-cell communications. Therefore, cell density was increased, thus, myocytes loaded in V-tethered GG-based inks showed higher cell-cell communication, spreading morphology, and alignment 7, 14 days post-printing. Overall, myoblasts laden in laminin-inspired biofunctionalized GG-based hydrogels are a promising skeletal muscle surrogate with the potential to be used as in vitro model or explored for further in vivo applications.