جستجوی مقالات مرتبط با کلیدواژه « alginate » در نشریات گروه « پزشکی »

The study focused on the amylase enzyme, widely used in the industrial starch liquefaction process. We looked into the best way to immobilize the native strain Bacillus licheniformis, which is the only alpha-amylase-producing bacterium, by trapping it in calcium alginate gel. This is a promising way to increase enzyme output.

We examined the effects of alginate content, biomass age, initial cell loading (ICL), bead size, and solidification duration in calcium chloride solution on enzyme synthesis. We conducted batch fermentations using both immobilized and free cells.

Alpha-amylase production significantly increased with the alginate concentration ratio, achieving a maximum enzyme yield of 23.5 U/mL at a 30 g/l alginate concentration, utilizing an initial cell loading of 1.5 g in 150-200 beads per flask. These involved cells from a 12-hour culture with a bead size of 5.0 mm, were solidified for 24 hours in a 2.5% (w/v) calcium chloride solution. The yield of the immobilized cells was approximately 111.71% higher than that of the free cells, which produced 11.1 U/ml. The immobilized cells consistently generated alpha-amylase over five repeated cycles, attaining a peak value of 23.5 U/ml during the first cycle, which was 2.2-fold more than the control (free cells).

We used a basic mass balance analysis to understand the growth of both fractions and the dynamics of amylase production in free cells and cells immobilized in Ca-alginate beads. The production of alpha-amylase in immobilized cells results in enhanced volumetric activities during fermentation. Notable advantages of this technique encompass prolonged stability, reuse and recycling, and the potential for adaptable regeneration.

We aimed to compare the gene expression of parotid gland derived stem cell in a three (3D) alginate hydrogel culture with that of a two-dimensional one (2D).

Five rats were sacrificed and the parotid glands were removed and cultured in DMEM/F12 medium supplemented with 15% FBS. The cells were characterized by flow cytometry and immunocytochemistry for evaluating the expression of genes. The cells were encapsulated in alginate hydrogel, then the differentiation was compared with that of a 2D culture. qRT-PCR was performed in order to evaluate the expression of Amy1, Cldn3, Cidn4, Ki67, Cyclin D1, Dpt, Meox2, Aquaporin 5, Pparg, Bpifa2e and Tp63 genes.

The harvested cells immunoreacted with CD90, CD44, and CD29, however, the immunophenotyping of CD45 and CD34 were negative. The immunocytochemistry results showed that they were strongly immunostained with K-7 and E-cadherin, but less with K-14. In the 3D culture, the cells differentiated into organoid bodies with round shape, there was duct-like structure extended from one pole. The qRT-PCR in the 3D culture showed increase in the expression of Amy1, Ki67, aquaporin5, Pparg, Bpifa2e and Tp63 genes compared to 2D culture. In contrast Cldn3, Cldn4, cyclin D1, Dpt and Meox2 genes were strongly expressed in the 2D culture.

The results of flow cytometry and immunocytochemistry confirmed the properties of the isolated cells were parotid gland-derived mesenchymal stem cells. They differentiated into organoid body in the 3D culture using alginate as scaffold which expressed parotid gland differentiation genes.

An artificial ovary based on the alginate (ALG) hydrogel has been widely implemented to preserve prepubertal female fertility. However, this platform is not fully capable of successful an ovary microenvironment simulation for follicle development, holding great potential for its improvement. Therefore, this experimental study aimed to evaluate the effect of an amniotic membrane extract (AME) -loaded hydrogel on the mouse preantral follicles in vitro development. In order to have better follicle development, first, the impact of different concentrations of follicle-stimulating hormone (FSH) was evaluated on the mouse preantral follicles encapsulated in ALG. Later, the appropriate dose was adjusted for the follicles encapsulated in the ALG-AME hydrogel. Results demonstrated that 100 mIU/ml FSH showed a significant follicle survival rate compared with 10 mIU/ml FSH (P=0.005). According to MTT assay finding, the rate of weight loss, and rheology evaluations, ALG containing 1 mg/ml AME was identified as an optimal sample of follicle culture instead of other AME concentrations. Follicle diameter significantly increased in the ALG-AME 1 hydrogel compared with the ALG control group without AME (P=0.027). The storage modulus of ALG-AME 1 was 773 Pa and retained the follicle morphology for 13 days. No statistically substantial difference was seen in survival, antrum cavity formation, and competent oocyte in terms of the normal chromosomal arrangement and meiotic spindle rate in comparison with the control group. It can be concluded that ALG-AME 1 could not significantly impact the mouse preantral follicle.

A cardiac infarction is the leading cause of death worldwide. Although the common treatments, including medication and various grafts, are unable to return the patients to their normal life, a cardiac patch is a promising technique in the field of tissue engineering that can stimulate the natural regeneration process of the diseased tissue via a scaffold with appropriate mechanical properties, biocompatibility and electrical conductivity. In this study, the composite scaffolds based on alginate (ALG) were fabricated through freeze-drying and coated with different concentrations of graphene oxide (GO) to make ALG/xGO (x=0.01, 0.05 and 0.1 wt. %) scaffolds. The scaffolds were characterized in terms of morphology, physicochemical structure, tensile strength, electrical conductivity, and cell response and gene expression. The presence of GO provided interconnected pores in the composite scaffolds. Adding GO up to 0.1 wt.% significantly enhanced Young’s modulus up to 5.5 MPa and electrical conductivity up to 8.59 S.m-1 (p≤0.05). Additionally, GO improved the vitality of human umbilical vein endothelial cells (HUVECs) compared to the scaffold without GO.  Investigating cell attachment of L929 fibroblasts indicated that the optimal content of GO at 0.05 wt.% can provide better places for cellular nesting due to the appropriate size of pores for cell/material interactions. The increase in the amount of GO up to 0.1 wt.% lead to a significant increase in gene expression of VEGFR-2 compared to the other scaffolds and tissue culture plate. We found that the prepared ALG/0.1GO composite scaffold could be appropriate for further experiments on cardiac tissue engineering applications.

Osteoarthritis (OA) can arise from various factor including trauma, overuse, as well as degeneration resulting from age or disease. The specific treatment options will vary based on the severity of the condition, and the affected joints. Some common treatments for OA include lifestyle modifications, medications, physical therapy, surgery and tissue engineering (TE). For cartilage tissue engineering (CTE), three-dimension (3D) scaffolds are made of biocompatible natural polymers, which allow for the regeneration of new cartilage tissue. An ideal scaffold should possess biological and mechanical properties that closely resemble those of the cartilage tissue, and lead to improved functional of knee. These scaffolds are specifically engineered to serve as replacements for damaged and provide support to the knee joint. 3D-bioprinted scaffolds are made of biocompatible materials natural polymers, which allow for the regeneration of new cartilage. The utilization of 3D bioprinting method has emerged as a novel approach for fabricating scaffolds with optimal properties for CTE applications. This method enables the creation of scaffolds that closely mimic the native cartilage in terms of mechanical characteristics and biological functionality. Alginate, that has the capability to fabricate a cartilage replacement customized for each individual patient. This polymer exhibits hydrophilicity, biocompatibility, and biodegradability, along with shear -thinning properties. These unique properties enable alginate to be utilized as a bio-ink for 3D bioprinting method. Furthermore, chondrogenesis is the complex process through which cartilage is formed via a series of cellular and molecular signaling. Signaling pathway is as a fundamental mechanism in cart ilage formation, enhanced by the incorporation of biomolecules and growth factors that induce the differentiation of stem cells. Accordingly, ongoing review is focusing to promote of 3D bioprinting scaffolds through the utilization of advanced biomolecules-loading of alginate-based that has the capability to fabricate a cartilage replacement tailored specifically to each patient's unique needs and anatomical requirements. Level of evidence: III

As the repair capacity of the nervous system is low, stem cell therapy is a trend for replacement therapy. Dental pulp stem cells (DPSCs) have the potential to differentiate into many tissues, such as neurons. Harmine (7-methoxy-1methyl-9H-pyrido[3,4-b] indole) is an alkaloidal component of medicinal plants with a long history in traditional medicine. Alginate is a biocompatible hydrogel widely used as a biomaterial base in various scaffolds.

This study investigated whether harmine and encapsulation of cells in alginate hydrogel could improve DPSCs differentiation into neural cells.

DPSCs were cultured under standard stem cell culture conditions, then encapsulated in alginate hydrogel, and treated with differentiation medium with and without harmine. After 14 days, cell proliferation and differentiation were assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, real-time polymerase chain reaction (RT-PCR), and flow cytometry.

Harmine (5 and 10 M) significantly increased the proliferation and viability of DPSCs compared to the control group in both two-dimensional and three-dimensional culture systems (P < 0.05). The expression levels of three neural cell markers (nestin, microtubule-associated protein [MAP-2], and -tubulin III) in DPSCs-derived neural cells cultured in two-dimensional and three-dimensional culture systems were significantly increased in harmine-treated two-dimensionalandthree-dimensional culture systems compared to the control group (P < 0.05).

Either harmine or alginate hydrogel had an accelerating effect on DPSCs differentiation into neural cells. Harmine also increased the proliferation of the cells.

Nanotechnology offers several opportunities to improve conventional drugs to avoid issues that pharmaceutical industries are facing nowadays. Hydrophobic and hydrophilic drugs have been found to be more readily soluble in mixed polymer nanohydrogels, which improves their solubility in solution. An attempt has been made in the present study to enhance the efficacy of beta-lactam antibiotics by making nanoformulation using mixed polymer nanohydrogels derived from natural polymers sodium alginate and chitosan. As a consequence, this formulation permitted amoxicillin (MOX) to be entrapped in alginate hydrogels and, in addition, chitosan-induced cationic charges on the surface of nanoparticles. Physicochemical characterizations and swelling properties, encapsulation efficiency, MOX release profile at different pH, and MTT assay to establish the toxicity of synthesized nanocomposite were investigated.   There was a significant improvement in the effectiveness of the encapsulated drug amoxicillin against Gram-negative bacteria Escherichia coli compared to the aqueous solution of the drug. It has been calculated that the encapsulation efficiency was approximately 64% by spectrophotometry, and antibiotic sensitivity tests in the presence of Gram-negative bacteria have shown that the encapsulated drug within nanohydrogels has superior antibacterial efficacy against them. This formulation with cationic surface charge may be a superior alternative to inactivate beta-lactam antibiotic-resistant Gram-negative bacteria than the standard medications available.

In the present study, a novel bioink was suggested based on the OAlg, GL, and SF hydrogels.

The composition of the bioink was optimized by the rheological and printability measurements, and the extrusion-based 3D bioprinting process was performed by applying the optimum OAlg-based bioink.

The results demonstrated that the viscosity of bioink was continuously decreased by increasing the SF/GL ratio, and the bioink displayed a maximum achievable printability (92 ± 2%) at 2% (w/v) of SF and 4% (w/v) of GL. Moreover, the cellular behavior of the scaffolds investigated by MTT assay and live/dead staining confirmed the biocompatibility of the prepared bioink.

The bioprinted OAlg-GL-SF scaffold could have the potential for using in skin tissue engineering applications, which needs further exploration.

 Cell transplantation with hydrogel-based carriers is one of the advanced therapeutics for challenging diseases, such as spinal cord injury. Electrically conductive hydrogel has received much attention for its effect on nerve outgrowth and differentiation. Besides, a load of neuroprotective substances, such as lithium chloride can promote the differentiation properties of the hydrogel.

 In this study, alginate/collagen/reduced graphene oxide hydrogel loaded with lithium chloride (AL/CO/rGO Li+) was prepared as an injectable cell delivery system for neural tissue regeneration. After determining the lithium-ion release profile, an MTT assay was performed to check neural viability. In the next step, real-time PCR was performed to evaluate the expression of cell adhesion and neurogenic markers.

 Our results showed that the combination of collagen fibers and rGO with alginates increased cell viability and the gene expression of collagen-binding receptor subunits such as integrin α1, and β1. Further, rGO contributed to the controlled release of lithium-ion hydrogel in terms of its plenty of negatively charged functional groups. The continuous culture of NSCs on AL/CO/rGO Li+ hydrogel increased neurogenic genes’ expressions of nestin (5.9 fold), NF200 (36.8 fold), and synaptophysin (13.2 fold), as well as protein expression of NF200 and synaptophysin after about 14 days.

 The simultaneous ability of electrical conduction and lithium-ion release of AL/CO/rGO Li+ hydrogel could provide a favorable microenvironment for NSCs by improving their survival, maintaining cell morphology, and expressing the neural marker. It may be potentially used as a therapeutic approach for stem cell transplantation in a spinal cord injury.

The main objective of the current assay was to evaluate the antibacterial and regenerative effects of hydrogel nanocomposite containing pure natural zeolite (clinoptilolite) integrated with alginate (Alg) as wound healing/dressing biomaterials.

The zeolites were size excluded, characterized by SEM, DLS, XRD, FTIR, and XRF, and then integrated into Alg hydrogel followed by calcium chloride crosslinking. The Alg and alginate zeolite (Alg/Zeo) hydrogel was characterized by swelling and weight loss tests, also the antibacterial, hemocompatibility, and cell viability tests were performed. In animal studies, the burn wound was induced on the back of rats and treated with the following groups: control, Alg hydrogel, and Alg/Zeo hydrogel.

The results showed that the hydrodynamic diameter of zeolites was 367 ± 0.2 nm. Zeolites did not show any significant antibacterial effect, however, the hydrogel nanocomposite containing zeolite had proper swelling as well as hemocompatibility and no cytotoxicity was observed. Following the creation of a third-degree burn wound on the back of rats, the results indicated that the Alg hydrogel and Alg/Zeo nanocomposite accelerated the wound healing process compared with the control group. Re-epithelialization, granulation tissue thickness, collagenization, inflammatory cell recruitment, and angiogenesis level were not significantly different between Alg and Alg/Zeo nanocomposite.

These findings revealed that although the incorporation of zeolites did not induce a significant beneficial effect in comparison with Alg hydrogel, using zeolite capacity in hydrogel for loading the antibiotics or other effective compounds can be considered a promising wound dressing.

Statement of the Problem: 

The administration of both platelet rich plasma (PRP) and silicon dioxide (SiO2) to the bone defects accelerates bone repair and regeneration. Application of both of them may show synergistic regenerative effects. 

Our objective was to evaluate the possible synergistic osteogenic effects of PRP and SiO2 by injecting them using an ad hoc device.

In this experimental study, PRP/SiO2 scaffolds were fabricated by in situ casting method with the help of CaCl2 as the gelation factor and alginate as the stroma; and then, the biodegradability and spatial arrangement were assessed. The injectable scaffold was introduced into the 40 rabbit mandibular defects by an ad hoc two-channel injecting device. Five defects received PRP/SiO2/alginate as the treatment; the other sets of defects were treated by PRP/alginate, SiO2/alginate, and the last five defects served as the control groups by getting only alginate injections. The osteogenicity of the scaffolds was evaluated by radiological and histological procedures; they were then compared with each other. Analysis of variance and least significant difference tests were used to analyze the data.

The SiO2-treated group showed a significant higher bone area compared to PRP/ SiO2-treated groups on day 40 (p= 0.013). The number of osteocytes was higher in SiO2-treated than the control groups on both 20 and 40 days (p= 0.032 and 0.022, respectively). The number of osteoclast was also higher in SiO2-treated than PRP-treated group (p= 0.028). In addition, the cells of this group had just started to create Haversian systems in newly formed bone tissues.

Silica demonstrated a superior osteogenic activity over PRP in both short and long term periods. Evidently, they showed no synergistic regenerative effects. Our ad hoc device was efficiently capable of inserting the scaffolds into the injured sites with no difficulties or complications.

Insulin insufficiency due to the reduced pancreatic beta cell number is the hallmark of diabetes, resulting inan intense focus on the development of beta-cell replacement options. One approach to overcome the problem is tosearch for alternative sources to induce insulin-producing cells (IPCs), the advent of mesenchymal stem cells (MSCs)holds great promise for producing ample IPCs. Encapsulate the MSCs with alginate improved anti-inflammatory effectsof MSC treatment. This study aimed to evaluate the differentiation of wharton jelly-derived MScs into insulin producingcells using alginate encapsulation. In this experimental study, we established an efficient IPCs differentiation strategy of humanMSCs derived from the umbilical cord’s Wharton jelly with lentiviral transduction of Pancreas/duodenum homeoboxprotein 1 (PDX1) in a 21-day period using alginate encapsulation by poly-L-lysine (PLL) and poly-L-ornithine (PLO)outer layer. During differentiation, the expression level of PDX1 and secretion of insulin proteins were increased. Results showed that during time, the cell viability remained high at 87% at day 7. After 21 days, the differentiated beta-like cells in microcapsules were morphologically similar to primary beta cells. Evaluation of the expression of PDX1 and INS by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) on days 7, 14 and 21 of differentiation exhibited the highest expression on day 14. At the protein level, the expression of these two pancreatic markers was observed after PDX1 transduction. Results showed that the intracellular and extracellular insulin levels in the cells receiving PDX1 is higher than the control group. The current data showed that encapsulation with alginate by PLL and PLO outer layer permitted to increase the microcapsules’ beta cell differentiation. Encapsulate the transduced-MSCs with alginate can be applied in an in vivo model in order to do the further analysis.

In this study, alginate, magnetite, and hydroxyapatite were used to fabricate alginate-hydroxyapatite (Alg-Hap), alginate-Fe3O4 (Alg-Fe3O4), and alginate-magnetic hydroxyapatite (Alg-mHap) using ferric chloride (III) crosslinker to remove cefixime from an aqueous solution. FTIR, SEM, VSM, BET, and XRD tests were used to determine the functional groups, morphology, magnetization behavior, surface area, and crystallinity of catalysts, respectively. The optimal pH for the Fenton reaction was determined to be 3.3 for Alg-Hap and Alg-Fe3O4 catalysts and 4 for Alg-mHap catalysts. Increases in the concentration of hydrogen peroxide (1 to 3 mM) and the amount of catalyst (50 to 90 gr/L) increased the percentage of degradation to approximately 8% and 6%, respectively. The degradation efficiency of cefixime by using Alg-mHap as the best catalyst in the Fenton process was achieved 91%, at optimum condition (pH of 4, catalyst amount of 90 gr/L, initial cefixime concentration of 5 mg/L, H2O2 concentration of 3 mM within 90 min). Moreover, the second-order kinetic equation fits the experimental data for cefixime degradation for all three catalysts. Furthermore, not only did the catalysts display a negligible iron leaching (0.92 mg/L for Alg-mHap) but also after three consecutive cycles, the catalysts indicated long-term stability. Comparison between synthesized catalysts and other methods proved its effectiveness.

Today, stem cells are the best candidates for cell therapy and tissue engineering. Adipose-derived Stem Cells (ADSCs) are an essential source of cells in replacement therapies of many diseases.

This study compared the proliferation of ADSCs in alginate and fibrin scaffolds.

Adipose-derived stem cells were isolated from adipose tissue and cultured in alginate or fibrin scaffolds with a medium containing PRP 10% or FBS 10%. Then, the cell viability percentage was assessed by MTT assay and trypan blue staining. Also, the percentages of living, apoptotic, and necrotic cells were assessed by flow cytometry assay on the fourth and eighth days.

The cell viability rate was significantly higher in the fibrin scaffold group with PRP than in other groups on the fourth and eighth days (P < 0.05). Moreover, the rate of necrotic cells was significantly lower in the fibrin scaffold group than in the other groups (P < 0.05). Besides, the percentage of living cells was significantly higher in the fibrin scaffold group with PRP than in the other groups on the fourth and eighth days (P < 0.05). Also, the percentage of early apoptotic cells was significantly lower in fibrin with PRP than in other groups on the fourth day. There was no significant difference in the rate of late apoptotic cells between the groups (P > 0.05).

These findings indicate the positive effect of PRP on the survival and proliferation of ADSCs compared with FBS. Therefore, PRP can be considered a suitable supplement to replace animal sera like FBS.