Assessment of apoptosis and oxidative stress in cryopreserved ovary after grafting in fibrin-alginate scaffold with endothelial cells and melatonin in wistar rats.

OBJECTIVE: Infertility is a significant public health concern affecting 10-15% of couples. Young women undergoing gonadotoxic treatment are at higher risk of ovarian dysfunction and infertility. To mitigate this risk, ovarian tissue freezing and transplantation have been developed as a novel strategy. However, challenges such as follicular loss and dysfunction during the freezing process, and ovarian damage during transplantation, persist. This study aimed to investigate the potential of using appropriate antifreeze, antioxidant, wound healing, and biological hydrogels to reduce these injuries. Specifically, the effect of fibrin scaffold with endothelial cells and melatonin on apoptotic gene expression and antioxidants in cryopreserved ovaries after transplantation was examined. METHODS: A total of 36 adult female wistar rats) 6-8-week-old and weighing from 200 to 220 g) were divided equally into six groups (n = 6): 1) control group (C), 2) transplanted ovarian tissue after vitrification and thawing process (Group 1), 3) transplanted vitrified/thawed ovarian tissue while encapsulated in Fib/Alg hydrogel (Group 2), 4) transplanted vitrified/thawed ovarian tissue while encapsulated in Fib/Alg hydrogel in addition with melatonin (Group 3), 5) transplanted vitrified/thawed ovarian tissue while encapsulated in Fib/Alg hydrogel in addition with endothelial cells (Group 4) and 6) transplanted vitrified/thawed ovarian tissue while encapsulated in Fib/Alg hydrogel in addition with melatonin endothelial cells (Group 5). The ovaries were auto-transplanted in the rats' lumbar region. After 14 days, the ovaries were removed. Antioxidant levels (SOD, GPx, MDA, and TAC) were evaluated using ELISA, and apoptotic gene expressions (Bax/Bcl2 and caspase 3) were analyzed by real-time RT-PCR to determine apoptosis. RESULTS: In the transplanted frozen ovary group, Bax/Bcl2 and caspase 3 gene expression increased significantly (P<0.05), while antioxidant levels (SOD, GPx, MDA, and TAC) decreased. The encapsulated frozen ovary group showed decreased gene expression and increased antioxidant levels. The ovary group encapsulated with fibrin scaffold, endothelial cells, and melatonin had the most significant decrease in gene expression and increase in antioxidant levels (P<0.05). CONCLUSION: Coordinated action of Fibrin-based scaffold with endothelial cells and melatonin could decrease apoptosis gene expression and increase antioxidant levels in cryopreserved ovaries after transplantation, providing valuable insights into preserving fertility in young women undergoing gonadotoxic treatment.

Carbon dots-facilitated on-demand dissolution of Ca-alginate hydrogel via site-specific mineralization for wound healing.

On-demand dissolution of hydrogels has shown much potential in easy and pain-free removal of wound dressings. This work firstly describes a type of carbon dots (CDs) for dissolving Ca-alginate hydrogel via site-specific mineralization method. The CDs were characterized by two features, which included presence of primary/secondary amine groups and generation of calcium crystals with Ca2+. Especially, the amount of primary/secondary amine groups on CDs played key role in determining whether hydrogel could be dissolved. When there were sufficient primary/secondary amine groups, the mineralization occurred on CDs rather than alginates due to the hydrogen bond between primary/secondary amine and carboxyl of alginates. Thereby, this promoted the gel-sol transition through Ca2+ capture from the hydrogels. Moreover, antibacterial test revealed Ca2+ capture from cell walls, while in vivo test revealed hypoxia relief due to porous structures of the renewed hydrogels. Overall, CDs with sufficient primary/secondary amine groups could dissolve Ca-alginate hydrogel through site-specific mineralization method, accompanying by additional functions of antibacterial and hypoxia relief.

Honeycomb-like biomimetic scaffold by functionalized antibacterial hydrogel and biodegradable porous Mg alloy for osteochondral regeneration.

Introduction: Osteochondral repair poses a significant challenge due to its unique pathological mechanisms and complex repair processes, particularly in bacterial tissue conditions resulting from open injuries, infections, and surgical contamination. This study introduces a biomimetic honeycomb-like scaffold (Zn-AlgMA@Mg) designed for osteochondral repair. The scaffold consists of a dicalcium phosphate dihydrate (DCPD)-coated porous magnesium scaffold (DCPD Mg) embedded within a dual crosslinked sodium alginate hydrogel (Zn-AlgMA). This combination aims to synergistically exert antibacterial and osteochondral integrated repair properties. Methods: The Zn-AlgMA@Mg scaffold was fabricated by coating porous magnesium scaffolds with DCPD and embedding them within a dual crosslinked sodium alginate hydrogel. The structural and mechanical properties of the DCPD Mg scaffold were characterized using scanning electron microscopy (SEM) and mechanical testing. The microstructural features and hydrophilicity of Zn-AlgMA were assessed. In vitro studies were conducted to evaluate the controlled release of magnesium and zinc ions, as well as the scaffold's osteogenic, chondrogenic, and antibacterial properties. Proteomic analysis was performed to elucidate the mechanism of osteochondral integrated repair. In vivo efficacy was evaluated using a rabbit full-thickness osteochondral defect model, with micro-CT evaluation, quantitative analysis, and histological staining (hematoxylin-eosin, Safranin-O, and Masson's trichrome). Results: The DCPD Mg scaffold exhibited a uniform porous structure and superior mechanical properties. The Zn-AlgMA hydrogel displayed consistent microstructural features and enhanced hydrophilicity. The Zn-AlgMA@Mg scaffold provided controlled release of magnesium and zinc ions, promoting cell proliferation and vitality. In vitro studies demonstrated significant osteogenic and chondrogenic properties, as well as antibacterial efficacy. Proteomic analysis revealed the underlying mechanism of osteochondral integrated repair facilitated by the scaffold. Micro-CT evaluation and histological analysis confirmed successful osteochondral integration in the rabbit model. Discussion: The biomimetic honeycomb-like scaffold (Zn-AlgMA@Mg) demonstrated promising results for osteochondral repair, effectively addressing the challenges posed by bacterial tissue conditions. The scaffold's ability to release magnesium and zinc ions in a controlled manner contributed to its significant osteogenic, chondrogenic, and antibacterial properties. Proteomic analysis provided insights into the scaffold's mechanism of action, supporting its potential for integrated osteochondral regeneration. The successful in vivo results highlight the scaffold's efficacy, making it a promising biomaterial for future applications in osteochondral repair.

Sodium alginate hydrogel encapsulating microglia cell lysate subjected to serum starvation for mitigating glioma cells.

Glioma is the most common malignant tumor in the brain, accounting for over 80% of all primary intracranial tumors. The current clinical treatment has shown certain limitations. Although M1 type microglia can secrete various pro-inflammatory cytokines and are expected to be used for glioma treatment, direct use of microglia may lead to overactivation and trigger immune storms. Therefore, we first found that serum starvation can stimulate the transformation of microglia into M1 type. Subsequently, we found through comparative experiments that the inhibitory effect of microglial cell lysis medium on glioma cells was stronger than that of microglial cell culture medium. Finally, we successfully prepared sodium alginate hydrogel loaded with microglia lysis solution to achieve sustained inhibitory effect on the growth of glioma and avoid its proliferation.

Hydrogen Production in Microbial Electrolysis Cells Using an Alginate Hydrogel Bioanode Encapsulated with a Filter Bag.

The bacterial anode of microbial electrolysis cells (MECs) is the limiting factor in a high hydrogen evolution reaction (HER). This study focused on improving biofilm attachment to a carbon-cloth anode using an alginate hydrogel. In addition, the modified bioanode was encapsulated by a filter bag that served as a physical barrier, to overcome its low mechanical strength and alginate degradation by certain bacterial species in wastewater. The MEC based on an encapsulated alginate bioanode (alginate bioanode encapsulated by a filter bag) was compared with three controls: an MEC based on a bare bioanode (non-immobilized bioanode), an alginate bioanode, and an encapsulated bioanode (bioanode encapsulated by a filter bag). At the beginning of the operation, the Rct value for the encapsulated alginate bioanode was 240.2 Ω, which decreased over time and dropped to 9.8 Ω after three weeks of operation when the Geobacter medium was used as the carbon source. When the MECs were fed with wastewater, the encapsulated alginate bioanode led to the highest current density of 9.21 ± 0.16 A·m-2 (at 0.4 V), which was 20%, 95%, and 180% higher, compared to the alginate bioanode, bare bioanode, and encapsulated bioanode, respectively. In addition, the encapsulated alginate bioanode led to the highest reduction currents of (4.14 A·m-2) and HER of 0.39 m3·m-3·d-1. The relative bacterial distribution of Geobacter was 79%. The COD removal by all the bioanodes was between 62% and 88%. The findings of this study demonstrate that the MEC based on the encapsulated alginate bioanode exhibited notably higher bio-electroactivity compared to both bare, alginate bioanode, and an encapsulated bioanode. We hypothesize that this improvement in electron transfer rate is attributed to the preservation and the biofilm on the anode material using alginate hydrogel which was inserted into a filter bag.

Matrix stiffening facilitates stemness of liver cancer stem cells by YAP activation and BMF inhibition.

Matrix stiffening is one of the major risk factors for hepatocellular carcinoma (HCC) and drives tumor progression. The extracellular matrix (ECM) stiffness of HCC displays mechanical heterogeneity, with stiffness increasing from the core to the invasive frontier. The distribution of liver cancer stem cells (CSCs) is related to this mechanical property. However, it is not sufficiently understood how heterogeneous matrix stiffness regulates the stemness of CSCs. In this study, we developed an adjustable gelatin/alginate hydrogel to investigate the effect of various matrix stiffnesses on CSC stemness under three-dimensional culture conditions. Gelatin/alginate hydrogel with the stiffness of soft (5 kPa), medium (16 kPa), and stiff (81 kPa) were prepared by altering the concentration of calcium ions. It was found that a stiffer matrix promoted stemness-associated gene expression, reduced drug sensitivity, enhanced sphere-forming and clonogenic ability, and tumorigenic potential. Mechanistically, matrix stiffening facilitates CSC stemness by increasing Yes-associated protein (YAP) activity and inhibiting Bcl-2 modifying factor (BMF) expression. Knockdown of YAP or overexpression of BMF significantly attenuated matrix stiffening-induced stemness, suggesting the involvement of YAP and BMF in this process. Together, our results unravel the regulatory mechanism of heterogeneous matrix stiffness on CSC stemness and also provide a novel therapeutic strategy for eradicating CSCs and improving the efficiency of HCC treatment.

Ionic Polymerization-Based Synthesis of Bioinspired Adhesive Hydrogel Microparticles with Tunable Morphologies from Microfluidics.

Shape-anisotropic hydrogel microparticles have attracted considerable attention for drug-delivery applications. Particularly, nonspherical hydrogel microcarriers with enhanced adhesive and circulatory abilities have demonstrated value in gastrointestinal drug administration. Herein, inspired by the structures of natural suckers, we demonstrate an ionic polymerization-based production of calcium (Ca)-alginate microparticles with tunable shapes from Janus emulsion for the first time. Monodispersed Janus droplets composed of sodium alginate and nongelable segments were generated using a coflow droplet generator. The interfacial curvatures, sizes, and production frequencies of Janus droplets can be flexibly controlled by varying the flow conditions and surfactant concentrations in the multiphase system. Janus droplets were ionically solidified on a chip, and hydrogel beads of different shapes were obtained. The in vitro and in vivo adhesion abilities of the hydrogel beads to the mouse colon were investigated. The anisotropic beads showed prominent adhesive properties compared with the spherical particles owing to their sticky hydrogel components and unique shapes. Finally, a novel computational fluid dynamics and discrete element method (CFD-DEM) coupling simulation was used to evaluate particle migration and contact forces theoretically. This review presents a simple strategy to synthesize Ca-alginate particles with tunable structures that could be ideal materials for constructing gastrointestinal drug delivery systems.

Synergistic effect of Cydonia oblonga and its extracted silver nanoparticles for improving antioxidant and antibacterial activity of 3D printed alginate-based hydrogel as wound dressing.

The current research studies the synergistic effect of Cydonia oblonga and its extracted nano bio­silver as a natural and eco-friendly agent for the improvement of three-dimensional (3D)-printed alginate wound dressings. Therefore, Cydonia oblonga extract was first prepared and silver nanoparticles were extracted from it through a green and simple method. The Cydonia oblonga and its extracted bio-based nanoparticles were then added to 3D printing alginate-based ink. Subsequently, a 3D structural extrusion printer was employed to create the porous hydrogel-based wound dressings. The morphological investigation demonstrated that using the extraction method the bio-based silver nanoparticles were successfully prepared, having an average size of 17.95 ± 4.50 nm. The Cydonia oblonga extract showed comparable antioxidant activity to the commercial antioxidant and an excellent total phenol content. In addition, the results showed the combination of Cydonia oblonga extracts/silver nanoparticles significantly improved the antibacterial performance of alginate-based bioinks. In vivo, and in vitro studies confirmed their biocompatibility and significant efficacy in the treatment of burn wounds.

Functionalization of Alginate Hydrogels with a Multifunctional Peptide Supports Mesenchymal Stem Cell Adhesion and Reduces Bacterial Colonization.

Hydrogels with cell adhesive moieties stand out as promising materials to enhance tissue healing and regeneration. Nonetheless, bacterial infections of the implants represent an unmet major concern. In the present work, we developed an alginate hydrogel modified with a multifunctional peptide containing the RGD cell adhesive motif in combination with an antibacterial peptide derived from the 1-11 region of lactoferrin (LF). The RGD-LF branched peptide was successfully anchored to the alginate backbone by carbodiimide chemistry, as demonstrated by 1H NMR and fluorescence measurements. The functionalized hydrogel presented desirable physicochemical properties (porosity, swelling and rheological behavior) to develop biomaterials for tissue engineering. The viability of mesenchymal stem cells (MSCs) on the peptide-functionalized hydrogels was excellent, with values higher than 85 % at day 1, and higher than 95 % after 14 days in culture. Moreover, the biological characterization demonstrated the ability of the hydrogels to significantly enhance ALP activity of MSCs as well as to decrease bacterial colonization of both Gram-positive and Gram-negative models. Such results prove the potential of the functionalized hydrogels as novel biomaterials for tissue engineering, simultaneously displaying cell adhesive activity and the capacity to prevent bacterial contamination, a dual bioactivity commonly not found for these types of hydrogels.

Tortuosity Engineering of Water Channels to Customized Water Supply for Enhancing Hydrogel Solar Evaporation.

Hydrogel as a solar evaporator shows great potential in freshwater production. However, hydrogels often lead to an imbalance between solar energy input and water supply management due to their excessively high saturated water content. Thus, achieving a stable water-energy-balance in hydrogel evaporators remains challenging. Here, by tortuosity engineering designed water transport channels, a seamless high-tortuosity/low-tortuosity/high-tortuosity structured hydrogel (SHLH structure hydrogel) evaporator is developed, which enables the hydrogel with customized water transport rate, leading to the controlled water supply at the evaporator interface. An excellent equilibrium between the photothermal conversion and water supply is established, and the maximum utilization of solar energy is realized, thereby achieving an excellent evaporation rate of 3.64 kg m-2 h-1 under one solar illumination. This tortuosity engineering controlled SHLH structured evaporator provides a novel strategy to attain water-energy-balance and expands new approaches for constructing hydrogel-based evaporators with tailored water transportation capacity.

The impact of copper nanoparticles surfactant on the structural and biological properties of chitosan/sodium alginate wound dressings.

Multifunctional wound dressings based on hydrogels are an efficacious and practicable strategy in therapeutic processes and accelerated chronic wound healing. Here, copper (Cu) nanoparticles were added to chitosan/sodium alginate (CS/SA) hydrogels to improve the antibacterial properties of the prepared wound dressings. Due to the super-hydrophobicity of Cu nanoparticles, polyethylene glycol (PEG) was used as a surfactant, and then added to the CS/SA-based hydrogels. The CS/SA/Cu hydrogels were synthesized with 0, 2, 3.5, and 5 wt% Cu nanoparticles. The structural and morphological properties in presence of PEG were evaluated using Fourier-transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), and field emission scanning electron microscopy (FESEM). The biodegradation and swelling properties of the hydrogels were investigated in phosphate buffer saline (PBS) at 37 °C for up to 30 days. Cell viability and adhesion, as well as antibacterial behavior, were investigated via MTT assay, FESEM, and disk diffusion method, respectively. The obtained results showed that PEG provided new intra- and intermolecular bonds that affected significantly the hydrogels' degradation and swelling ratio, which increased up to ~1200 %. Cell viability reached ~110 % and all samples showed remarkable antibacterial behavior when CS/SA/Cu containing 2 wt% was introduced. This study provided new insights regarding the use of PEG as a surfactant for Cu nanoparticles in CS/SA hydrogel wound dressing, ultimately affecting the chemical bonding and various properties of the prepared hydrogels.

Metabolomic Profiling and Characterization of a Novel 3D Culture System for Studying Chondrocyte Mechanotransduction.

Articular chondrocytes synthesize and maintain the avascular and aneural articular cartilage. In vivo these cells are surrounded by a 3D pericellular matrix (PCM) containing predominantly collagen VI. The PCM protects chondrocytes and facilitates mechanotransduction, and PCM stiffness is critical in transmitting biomechanical signals to chondrocytes. Various culture systems with different hydrogels have been used to encapsulate chondrocytes for 3D culture, but many lack either the PCM or the in vivo stiffness of the cartilage matrix. Here, we demonstrate that primary chondrocytes cultured in alginate will form a pericellular matrix and display a phenotype similar to in vivo conditions. We found that primary human and bovine chondrocytes, when cultured in alginate beads with addition of sodium L-ascorbate for 7 days, had a pronounced PCM, retained their phenotype, and synthesized both collagens VI and II. This novel culture system enables alginate-encapsulated chondrocytes to develop a robust PCM thereby creating a model system to study mechanotransduction. We also observed distinct compression-induced changes in metabolomic profiles between the monolayer-agarose and alginate-released agarose-embedded chondrocytes indicating physiological changes in cell metabolism. Our data suggest that 3D preculture of chondrocytes in alginate before encapsulation in physiologically-stiff agarose leads to a pronounced development of pericellular matrix that is sustained in the presence of ascorbate. This novel model can be useful in studying the mechanism by which chondrocytes respond to cyclical compression and other types of loading simulating in vivo physiological conditions.

Green NiO nanoparticle-integrated PVA-alginate hydrogel: potent nanocatalyst for efficient reduction of anthropogenic water pollutants.

Hydrogel nanocatalyst composed of nickel oxide (NiO) nanoparticles embedded in PVA-alginate hydrogels were potentially explored toward the reduction of anthropogenic water pollutants. The NiO nanoparticles was accomplished via green method using waste pineapple peel extract. The formation of the nanoparticles was affirmed from different analytical techniques such as UV-Vis, FTIR, XRD, TGA, FESEM, and EDS. Spherical NiO nanoparticles were obtained having an average size of 11.5 nm. The nano NiO were then integrated into PVA-alginate hydrogel matrix forming a nanocomposite hydrogel (PVALg@ NiO). The integration of nano NiO rendered an improved thermal stability to the parent hydrogel. The PVALg@ NiO hydrogel was utilized as a catalyst in the reduction of 4-nitrophenol (4-NP), potassium hexacyanoferrate (III), rhodamine B (RhB), methyl orange (MO), and malachite green (MG) in the presence of a reducing agent, i.e., NaBH4. Under optimized conditions, the reduction reactions were completed by 4.0 min and 3.0 min for 4-NP and potassium hexacyanoferrate (III), respectively, and the rate constant was estimated to be 1.14 min-1 and 2.15 min-1. The rate of reduction was found to be faster for the dyes and the respective rate constants were be 0.17 s-1 for RhB, MG and 0.05 s-1 for MO. The PVALg@ NiO hydrogel nanocatalyst demonstrated a recyclability of four runs without any perceptible diminution in its catalytic mettle. The efficacy of the PVALg@ NiO hydrogel nanocatalyst was further examined for the reduction of dyes in real water samples collected from different sources and the results affirm its high catalytic potential. Thus, this study paves the path for the development of a sustainable hydrogel nanocatalyst for reduction of hazardous pollutants in wastewater treatment.

Bacteriophage-cocktail hydrogel dressing to prevent multiple bacterial infections and heal diabetic ulcers in mice.

Bacteriophage (phage) has been reported to reduce the bacterial infection in delayed-healing wounds and, as a result, aiding in the healing of said wounds. In this study we investigated whether the presence of phage itself could help repair delayed-healing wounds in diabetic mice. Three strains of phage that target Salmonella enterica, Escherichia coli, and Pseudomonas aeruginosa were used. To prevent the phage liquid from running off the wound, the mixture of phage (phage-cocktail) was encapsulated in a porous hydrogel dressing made with three-dimensional printing. The phage-cocktail dressing was tested for its phage preservation and release efficacy, bacterial reduction, cytotoxicity with 3T3 fibroblast, and performance in repairing a sterile full-thickness skin wound in diabetic mice. The phage-cocktail dressing released 1.7%-5.7% of the phages embedded in 24 h, and reduced between 37%-79% of the surface bacteria compared with the blank dressing (p <.05). The phage-cocktail dressing exhibited no sign of cytotoxicity after 3 days (p <.05). In vivo studies showed that 14 days after incision, the full-thickness wound treated with a phage-cocktail dressing had a higher wound healing ratio compared with the blank dressing and control (p <.01). Histological analysis showed that the structure of the skin layers in the group treated with phage-cocktail dressing was restored in an orderly fashion. Compared with the blank dressing and control, the repaired tissue in the phage-cocktail dressing group had new capillary vessels and no sign of inflammation in its dermis, and its epidermis had a higher degree of re-epithelialization (p <.05). The slow-released phage has demonstrated positive effects in repairing diabetic skin wounds.

Zeolite-Loaded Hydrogels as Wound pH-Modulating Dressings for Diabetic Wound Healing.

Wound pH has emerged as a promising therapeutic target in diabetic foot ulcers (DFU). Here, we aimed to develop a microparticle-loaded hydrogel for pH modulation in wound fluid. In a screen of polymeric and inorganic microparticles, zeolites were identified as pH-modulating microparticles. Zeolites were encapsulated in a calcium cross-linked alginate hydrogel, a biocompatible matrix clinically used as a wound dressing. This hydrogel potently neutralized hydroxide ions in serum-containing simulated wound fluid. These findings encourage a further development of this pH-modulating device as a molecular therapeutic system for DFUs.

Disaggregation and fibrillation during sol-gel transition of alginate hydrogels.

The rheological and morphological characteristics of Ca-crosslinked alginate hydrogels with two different M/G ratios, α-L-guluronate (G)-rich and ß-D-mannuronate (M)-rich, each with one alginic acid concentration, were investigated. It was found that the stiffness and elasticity of alginate hydrogels are derived from the thickness and density of the fibril network structures. In aqueous alginate solution, ball-like aggregates of alginates are present. Time-resolved small-angle X-ray scattering and time-domain nuclear magnetic resonance measurements suggest that the disaggregation of alginate aggregates and loose fibrillation occur in the early stage of the sol-gel transition. After these induction stage, direct gelation is finally caused by the formation of the egg-box junction. G-rich alginate hydrogel has a higher stiffness and a thicker and denser fibril network structure than M-rich alginate hydrogel. The former also exhibits faster and more significant changes in physical properties during the sol-gel transition.

Establishing a 3D-cultured system based on alginate-hydrogel embedding benefits the in vitro maturation of porcine Oocytes.

The in vitro maturation (IVM) quality of oocytes is directly related to the subsequent developmental potential of embryos and a fundamental of in vitro embryo production. However, conventional IVM methods fail to maintain the gap-junction intercellular communication (GJIC) between cumulus-oocyte complexes (COCs), which leads to insufficient oocyte maturation. Herein, we investigated the effects of three different three-dimensional (3D) culture methods on oocyte development in vitro, optimized of the alginate-hydrogel embedding method, and assessed the effects of the alginate-hydrogel embedding method on subsequent embryonic developmental potential of oocytes after IVM and parthenogenetic activation (PA). The results showed that Matrigel embedding and alginate-hydrogel embedding benefited the embryonic developmental potential of oocytes after IVM and PA. With the further optimization of alginate-hydrogel embedding, including crosslinking and decrosslinking of parameters, we established a 3D culture system that can significantly increase oocyte maturation and the blastocyst rate of embryos after PA (27.2 ± 1.5 vs 36.7 ± 2.8, P < 0.05). This 3D culture system produced oocytes with markedly increased mitochondrial intensity and membrane potential, which reduced the abnormalities of spindle formation and cortical granule distribution. The alginate-hydrogel embedding system can also remarkably enhance the GJIC between COCs. In summary, based on alginate-hydrogel embedding, we established a 3D culture system that can improve the IVM quality of porcine oocytes, possibly by enhancing GJIC.

Soft yet mechanically robust injectable alginate hydrogels with processing versatility based on alginate/hydroxyapatite hybridization.

The salient gelling feature of alginate via forming the egg-box structure with calcium ions has received extensive interests for different applications. Owing to the interfacial incompatibility of rigid inorganic solids with soft polymers, the requirement of overall stereocomplexation with calcium released from uniformly distributed solids in alginate remains a challenge. In this study, a novel alginate-incorporated calcium source was proposed to tackle the intractable dispersion for the preparation of injectable alginate hydrogels. Calcium phosphate synthesis in alginate solution yielded CaP-alginate hybrids as a calcium source. The physicochemical characterization confirmed the CaP-alginate hybrid was a nano-scale alginate-hydroxyapatite complex. The colloidally stable CaP-alginate hybrids were uniformly dispersed in alginate solutions even under centrifugation. The calcium-induced gelling of the CaP-alginate hybrids-loaded alginate solutions formed soft yet tough hydrogels including transparent sheets and knittable threads, confirming the homogeneous gelation of the hydrogel. The gelation time, injectability and mechanical properties of the hydrogels could be adjusted by changing preparation parameters. The prepared hydrogels showed uniform porous structure, excellent swelling, wetting properties and cytocompatibility, showing a great potential for applications in different fields. The present strategy with organic/inorganic hybridization could be exemplarily followed in the future development of functional hydrogels especially associated with the interface integration.

Alginate Hydrogel Integrated with a Human Fibroblast-Derived Extracellular Matrix Supports Corneal Endothelial Cell Functionality and Suppresses Endothelial-Mesenchymal Transition.

Human corneal transplantation is still the only option to restore the function of corneal endothelial cells (CECs). Therefore, there is an urgent need for hCEC delivery systems to replace the human donor cornea. Here, we propose an alginate hydrogel (AH)-based delivery system, where a human fibroblast-derived, decellularized extracellular matrix (ECM) was physically integrated with AH. This AH securely combined with the ECM (ECM-AH) was approximately 50 µm thick, transparent, and permeable. The surface roughness and surface potential provided ECM-AH with a favorable microenvironment for CEC adhesion and growth in vitro. More importantly, ECM-AH could support the structural (ZO-1) and functional (Na+/K+-ATPase) markers of hCECs, as assessed via western blotting and quantitative polymerase chain reaction, which were comparable with those of a ferritic nitrocarburizing (FNC)-coated substrate (a positive control). The cell density per unit area was also significantly better with ECM-AH than the FNC substrate at day 7. A simulation test of cell engraftment in vitro showed that hCECs were successfully transferred into the decellularized porcine corneal tissue, where they were mostly alive. Furthermore, we found out that the endothelial-mesenchymal transition (EnMT)-inductive factors (Smad2 and vimentin) were largely declined with the hCECs grown on ECM-AH, whereas the EnMT inhibitory factor (Smad7) was significantly elevated. The difference was statistically significant compared to that of the FNC substrate. Moreover, we also observed that TGF-ß1-treated hCECs showed faster recovery of cell phenotype on the ECM. Taken together, our study demonstrates that ECM-AH is a very promising material for hCEC culture and delivery, which endows an excellent microenvironment for cell function and phenotype maintenance.

Enhancing Alginate Hydrogels as Possible Wound-Healing Patches: The Synergistic Impact of Reduced Graphene Oxide and Tannins on Mechanical and Adhesive Properties.

Hydrogels are three-dimensional crosslinked materials known for their ability to absorb water, exhibit high flexibility, their biodegradability and biocompatibility, and their ability to mimic properties of different tissues in the body. However, their application is limited by inherent deficiencies in their mechanical properties. To address this issue, reduced graphene oxide (rGO) and tannins (TA) were incorporated into alginate hydrogels (Alg) to evaluate the impact of the concentration of these nanomaterials on mechanical and adhesive, as well as cytotoxicity and wound-healing properties. Tensile mechanical tests demonstrated improvements in tensile strength, elastic modulus, and toughness upon the incorporation of rGO and TA. Additionally, the inclusion of these materials allowed for a greater energy dissipation during continuous charge-discharge cycles. However, the samples did not exhibit self-recovery under environmental conditions. Adhesion was evaluated on pig skin, revealing that higher concentrations of rGO led to enhanced adhesion, while the concentration of TA did not significantly affect this property. Moreover, adhesion remained consistent after 10 adhesion cycles, and the contact time before the separation between the material and the surface did not affect this property. The materials were not cytotoxic and promoted healing in human fibroblast-model cells. Thus, an Alg/rGO/TA hydrogel with enhanced mechanical, adhesive, and wound-healing properties was successfully developed.