Alginate Microcapsules Research Articles

A portable droplet generation system for ultra-wide dynamic range digital PCR based on a vibrating sharp-tip capillary

Monodisperse droplet has been widely used as a versatile tool in different disciplines including biosensing. Existing methods still struggle to balance the droplet generation performance with system simplicity. Here we introduce a novel droplet generation scheme based on the acoustic streaming generated from a vibrating sharp-tip capillary. The unique fluid pattern enables efficient droplet generation without any external pressure sources. This method achieved real-time modulation of droplet size over an ultra-wide range (6.77–661 μm), high throughput (up to 5000 droplets/s), and good monodispersity (<4%) with a power consumption below 60 mW. This method has enabled a multi-volume digital PCR with a dynamic range of ~6 orders of magnitude and multiplexing capability. It has also enabled a simple protocol to produce cell-laden alginate microcapsules in variable sizes with excellent biocompatibility. Overall, the present method combines high performance with small footprint and portability, which will be especially valuable for droplet applications requiring variable droplet size and performed in resource-limited settings.

Exosome loaded immunomodulatory biomaterials alleviate local immune response in immunocompetent diabetic mice post islet xenotransplantation

Foreign body response (FBR) to biomaterials compromises the function of implants and leads to medical complications. Here, we report a hybrid alginate microcapsule (AlgXO) that attenuated the immune response after implantation, through releasing exosomes derived from human Umbilical Cord Mesenchymal Stem Cells (XOs). Upon release, XOs suppress the local immune microenvironment, where xenotransplantation of rat islets encapsulated in AlgXO led to >170 days euglycemia in immunocompetent mouse model of Type 1 Diabetes. In vitro analyses revealed that XOs suppressed the proliferation of CD3/CD28 activated splenocytes and CD3+ T cells. Comparing suppressive potency of XOs in purified CD3+ T cells versus splenocytes, we found XOs more profoundly suppressed T cells in the splenocytes co-culture, where a heterogenous cell population is present. XOs also suppressed CD3/CD28 activated human peripheral blood mononuclear cells (PBMCs) and reduced their cytokine secretion including IL-2, IL-6, IL-12p70, IL-22, and TNFα. We further demonstrate that XOs mechanism of action is likely mediated via myeloid cells and XOs suppress both murine and human macrophages partly by interfering with NFκB pathway. We propose that through controlled release of XOs, AlgXO provide a promising new platform that could alleviate the local immune response to implantable biomaterials.

Zein–sodium alginate based microcapsules for essence controlled releasing coating as leather finishes

Currently the development and application of leather are strongly limited by the peculiar smells of the leather itself and the chemical residues in the leather. However, traditional finishing materials containing essences have a short release period, but also weaken the mechanical properties of the coating. Herein, we first report a route of crafting essence controlled releasing coatings as leather finishes comprising zein–sodium alginate microcapsules loaded with Artemisia argyi essence ([email protected]) and casein modified by caprolactam (Ca-Cpl), of which [email protected] was prepared by anti-solvent precipitation technique before physically blended with Ca-Cpl to prepare composite coating. The results showed that the average particle size of [email protected] was about 5.7 μm, and the accumulative release rate of essence in [email protected] was 48.3% after continuous release for 120 h. Besides, the [email protected]+Ca-Cpl film is transparent and has good flexibility, with pores and microspheres uniformly distributed inside. Moreover, the inhibition zones of the leather samples finished by [email protected]+Ca-Cpl against Escherichia coli (E. coli) (1st d) and Staphylococcus aureus (S. aureus) (2nd d) were 2.6 cm and 4.2 cm respectively, which hardly changed after continuing culture for 2 days. Moreover, expected sanitary, mechanical and antibacterial properties of the leather finished could be given by [email protected] based composites. This study provides a feasible way to prepare composite coating materials with functionality based on natural protein, polysaccharide and plant essence.

Biosynthesis of Lactobionic Acid in Whey-Containing Medium by Microencapsulated and Free Bacteria of Pseudomonas taetrolens

The aim of this research was to develop a method of its production from whey using bacteria of the species Pseudomonas taetrolens. Analyses of the lactobionic acid production method from whey showed that the following factors have a significant effect on its efficiency: the frequency of whey batch feeding, pH and the type of bacteria application, i.e. microencapsulated vs. free. Lactose and lactobionic acid were assayed using high performance liquid chromatography (HPLC) and liquid chromatography-electrospray ionization-tandem mass spectrometry (LC–ESI–MS). The highest concentration of lactobionic acid of 22.03 mg/cm3 was obtained when whey was batch fed at 72-h intervals, pH was maintained at 6.25 and bacteria were enclosed in alginate microcapsules.

Influence of the new formulation based on silver alginate microcapsules loaded with tannic acid on the microcirculation of the experimental periodontitis in rats

The microvascular changes caused by disorders of host immune response to oral microorganisms resulting in long-lasting inflammation of gums play a critical role in the periodontal lesion in the pathogenesis of chronic periodontitis. Current strategies of non-surgical periodontal therapy are aimed at the attainment of anti-inflammatory effects. We hypothesized that the usage of the microencapsulated form of anti-inflammatory substances with vasoactive effects could enhance the efficiency of the therapy by the prolonged release of active components. The prepared suspension of silver-alginate microcapsules loaded with tannic acid in the hydrogel was applied in vivo to the experimental model of periodontitis in rats induced by a ligature. The effect of this formulation was assessed by monitoring changes in local microcirculation performed by the Laser Doppler Flowmetry (1 and 24 h after application of hydrogel on intact gums and 21-days after the start of periodontitis' modeling). Application of the hydrogel containing multicomponent microcapsules to the affected area of gums allows correction of inflammatory microcirculatory disorders in model periodontitis. Immobilization of tannic acid into microcapsules allows increasing the correction of the following parameters: perfusion disorders, neurogenic tone of arterioles, myogenic tone of precapillary sphincters, as well as a venous outflow in the microvasculature of the gums. The hydrogel containing multicomponent microcapsules reduces the vascular inflammatory response in the model of periodontitis. Loading of silver-alginate microcapsules with tannic acid enhances the efficiency of microvascular disorders' correction in the model of periodontitis that suggests the prospects for application of this drug delivery system for non-surgical treatment of periodontitis.

Effects of various polysaccharides (alginate, carrageenan, gums, chitosan) and their combination with prebiotic saccharides (resistant starch, lactosucrose, lactulose) on the encapsulation of probiotic bacteria Lactobacillus casei 01 strain

The probiotics are extremely sensitive to various environmental factors, which imposes limitation on their health and functional effectiveness. Thus, development of delivery system for protection of viable cells while passing through different stages of the human digestion system is key factor in application of probiotic products. In our study, the effects of several polysaccharides such as alginate, κ-carrageenan, locust bean gum, gellan gum, xanthan gum and their combination with various prebiotic components (resistant starch, lactulose, lactosucrose) on encapsulation of probiotic Lactobacillus casei 01 strain were studied. Both regular and unregular beads with size distributions from 2 mm up to 5 mm were obtained. The encapsulation efficiencies varied from 64.4% up to 79%. Based on the texture's profiles, the capsules can be grouped into 5 clusters with squared Euclidean distance 3.5. Meanwhile, the starch-alginate and the lactosucrose LS55L – alginate beads were found to be the most stable and to have massive textural properties, whereas the gellan gum – xanthan gum and the chitosan coated alginate beads emerged as the softest. Encapsulation significantly improved the degree of gastric tolerance of probiotic cells even in the presence of pepsin. The INFOGEST in vitro digestion protocol was adapted to investigate the protection effects of different capsules. The highest survival (with loss rate of lower than 1 log CFU/g) was observed in the case of the cells encapsulated in starch-alginate beads. Moreover, the alginate microcapsules combined with lactosucrose LS55L also provided very promising shield for probiotics from the low pH of gastric conditions. Our findings suggest that incorporation of prebiotics into alginate-base encapsulation would be good idea in development of micro delivery systems that helps the survival of probiotics and their delivery to the target sites of action in human body.

Preparation and Properties of a Novel Sodium Alginate Microcapsule

In this study, sodium alginate was used as the main embedding material, and sodium polyacrylate had been immobilized on sodium alginate with calcium ions as crosslinking agent for preparing a new type of lactic acid bacteria entrapment material. The aim of this study was to investigate the viability of Lactococcus lactis NCU1315 under simulated gastrointestinal conditions and the physical properties of the microcapsules and their protective effects on Lactobacillusto develop a feasible and stable method for preparing microbial particles. The hardness of Alg-1 and Alg-2 microcapsules varied with time in simulated gastric juice and showed significant difference at the second and third hour (P < 0.05, P < 0.01). The particle size of Alg-1 and Alg-2 microcapsules varied with time in simulated gastric juice and showed significant difference at the second and third hour (P < 0.05, P < 0.01). Alg-1 had no significant effect on the growth of NCU1315, but Alg-2 had inhibitory effect on the growth of Lactococcus lactis NCU1315. The survival rate of Lactococcus lactis in Alg-1 and Alg-2 microencapsulated groups was significantly higher than that in Free cell group at 24h, 48h and 72h (P < 0.05, P < 0.01). However, the survival rate of Lactococcus lactis in Alg-1 and Alg-2 microencapsulated groups decreased with time (P<0.05, P<0.01).

Influence of Different Prebiotics on Viability of Lactobacillus casei, Lactobacillus plantarum and Lactobacillus rhamnosus Encapsulated in Alginate Microcapsules.

As the production and maintenance of a sufficient number of microencapsulated probiotics is still a test for the food industry, the present study addressed the testing of three prebiotics: chicory inulin, soluble potato starch, oligofructose and a control carbon source, namely glucose, as a component part of the encapsulation matrix. Using the extrusion encapsulation technique, it was possible to obtain microcapsules whose matrix composition and dimensions correspond to the requirements of the food industry. The microcapsules obtained showed significantly different physicochemical properties, with different survival rates during processing, storage and in simulated gastrointestinal conditions. The encapsulation efficiency was very high in relation to the dimensions of the microcapsules and the technique used (between 87.00–88.19%). The microcapsules obtained offered a very good viability (between 8.30 ± 0.00–9.00 ± 0, 02 log10 cfu/g) during the 30 days of storage at 2–8 degrees and also in the simulated gastrointestinal conditions (between 7.98–8.22 log10 cfu/g). After 30 days, the lowest viability was registered in the microcapsules with glucose 6.78 ± 0.15 log10 cfu/g. It was found that after 4 h of action of gastrointestinal juices on the microcapsules stored for 30 days, cell viability falls within the limits recommended by the Food and Agriculture Organization of the United Nations (FAO) (106–107 CFU/mL or g of food. This study demonstrated that using prebiotic encapsulation matrix increases cell viability and protection and that the extrusion encapsulation method can be used in the production of probiotic microcapsules for the food industry.

Alginate microcapsules as delivery and protective systems of Bacillus licheniformis in a simulated shrimp's digestive tract

This work aims to encapsulate Bacillus licheniformis, a marine probiotic, in alginate microparticles (AMPs), and the evaluation of its controlled and targeted release within a simulated shrimp digestive tract (DT). The encapsulation process was carried out using the ionic gelation technique. Both free and bacteria-loaded AMPs were physicochemically characterized by size, morphology, surface electrical charge, the survival, and the number of encapsulated bacteria after the encapsulation process, and the bacterial survival after 40-days of storage (at 4 °C and 25 °C). The in vitro release and survival studies of the bacteria were carried out using a protocol developed in our laboratory by implementing buffers of dissected organs from shrimp's DT. Results indicated that microparticles with an average size of 172–185 μm and negatively charged (−16.77 and − 17.66 mV, respectively) were obtained after using the ionic gelation method. The bacterial survival and encapsulation efficiency showed high cell viability and yield above 99%. Stability studies showed that the best storage temperature was 4 °C, in which it remained almost 100% of the bacteria viable for 15 days; however, cell viability declined to 55% survival after 30 days of storage at this temperature. Regardless of the cell viability reduction after 30 days, there are enough viable bacteria cells to be considered as a probiotic product. Release and survival studies showed that alginate particles had a protective effect on bacteria by keeping ca. 51.29% of viable probiotic within the shrimp intestine; in contrast, free bacteria only reached the shrimp intestine ca. 27.16% viable. Our results suggest that microparticles can be produced by a low-cost method that could ultimately benefit shrimp farming in a near future.

In Vitro Cytotoxic Protective Effect of Alginate-Encapsulated Capsaicin Might Improve Skin Side Effects Associated with the Topical Application of Capsaicin.

Chronic neuropathic pain, particularly peripheral pain, is a cause of great concern for diabetic patients. Current treatments include numerous agents such as capsaicinoids, a known deterrent of neuropathic pain despite the inconvenience associated with local side effects. In this context, the current work aims to elucidate the potential mechanisms involved in cytotoxicity by capsaicin and proposes an efficient formulation of capsaicin in alginate microcapsules, which significantly reduces side effects from capsaicin topical administration. For this, human dermal fibroblast cells were treated with alginate-microencapsulated capsaicin extracts and screened for potential cytotoxic effects produced by the treatment. Cell viability and morphology were examined, as well as oxidative stress status and anti-inflammatory potential. Our results show that the alginate encapsulated formulation of capsaicin exerted lower cytotoxic effects on human dermal fibroblasts as measured by cell viability and reactive oxygen species (ROS) production. Furthermore, the expression profiles of inflammatory cytokines were significantly altered by the treatment as compared with the control culture.

Encapsulation of Synthesized Plant Growth Regulator Based on Copper(II) Complex in Chitosan/Alginate Microcapsules.

A new copper complex, trans-diaqua-trans-bis [1-hydroxy-1,2-di (methoxycarbonyl) ethenato] copper (abbreviation Cu(II) complex), was synthesized and its plant growth regulation properties were investigated. The results show a sharp dependence of growth regulation activity of the Cu(II) complex on the type of culture and its concentration. New plant growth regulator accelerated the development of the corn root system (the increase in both length and weight) but showed a smaller effect on the development of the wheat and barley root systems. Stimulation of corn growth decreased with increasing Cu(II) complex concentration from 0.0001% to 0.01% (inhibition at high concentrations—0.01%). The development of corn stems was also accelerated but to a lesser extent. Chitosan-coated calcium alginate microcapsules suitable for delivery of Cu(II) complex to plants were prepared and characterized. Analysis of the FTIR spectrum showed that complex molecular interactions between functional groups of microcapsule constituents include mainly electrostatic interactions and hydrogen bonds. Microcapsules surface exhibits a soft granular surface structure with substructures consisting of abundant smaller particles with reduced surface roughness. Release profile analysis showed Fickian diffusion is the rate-controlling mechanism of Cu(II) complex releasing. The obtained results give new insights into the complexity of the interaction between the Cu(II) complex and microcapsule formulation constituents, which can be of great help in accelerating product development for the application in agriculture

How alginate properties influence in situ internal gelation in crosslinked alginate microcapsules (CLAMs) formed by spray drying.

Alginates gel rapidly under ambient conditions and have widely documented potential to form protective matrices for sensitive bioactive cargo. Most commonly, alginate gelation occurs via calcium mediated electrostatic crosslinks between the linear polyuronic acid polymers. A recent breakthrough to form crosslinked alginate microcapsules (CLAMs) by in situ gelation during spray drying ("CLAMs process") has demonstrated applications in protection and controlled delivery of bioactives in food, cosmetics, and agriculture. The extent of crosslinking of alginates in CLAMs impacts the effectiveness of its barrier properties. For example, higher crosslinking extents can improve oxidative stability and limit diffusion of the encapsulated cargo. Crosslinking in CLAMs can be controlled by varying the calcium to alginate ratio; however, the choice of alginates used in the process also influences the ultimate extent of crosslinking. To understand how to select alginates to target crosslinking in CLAMs, we examined the roles of alginate molecular properties. A surprise finding was the formation of alginic acid gelling in the CLAMs that is a consequence of simultaneous and rapid pH reduction and moisture removal that occurs during spray drying. Thus, spray dried CLAMs gelation is due to calcium crosslinking and alginic acid formation, and unlike external gelation methods, is insensitive to the molecular composition of the alginates. The 'extent of gelation' of spray dried CLAMs is influenced by the molecular weights of the alginates at saturating calcium concentrations. Alginate viscosity correlates with molecular weight; thus, viscosity is a convenient criterion for selecting commercial alginates to target gelation extent in CLAMs.

Suppression of Fibrotic Reactions of Chitosan-Alginate Microcapsules Containing Porcine Islets by Dexamethasone Surface Coating.

BackgroundThe microencapsulation is an ideal solution to overcome immune rejection without immunosuppressive treatment. Poor biocompatibility and small molecular antigens secreted from encapsulated islets induce fibrosis infiltration. Therefore, the aims of this study were to improve the biocompatibility of microcapsules by dexamethasone coating and to verify its effect after xenogeneic transplantation in a streptozotocin-induced diabetes mice.MethodsDexamethasone 21-phosphate (Dexa) was dissolved in 1% chitosan and was cross-linked with the alginate microcapsule surface. Insulin secretion and viability assays were performed 14 days after microencapsulation. Dexa-containing chitosan-coated alginate (Dexa-chitosan) or alginate microencapsulated porcine islets were transplanted into diabetic mice. The fibrosis infiltration score was calculated from the harvested microcapsules. The harvested microcapsules were stained with trichrome and for insulin and macrophages.ResultsNo significant differences in glucose-stimulated insulin secretion and islet viability were noted among naked, alginate, and Dexa-chitosan microencapsulated islets. After transplantation of microencapsulated porcine islets, nonfasting blood glucose were normalized in both the Dexa-chitosan and alginate groups until 231 days. The average glucose after transplantation were lower in the Dexa-chitosan group than the alginate group. Pericapsular fibrosis and inflammatory cell infiltration of microcapsules were significantly reduced in Dexa-chitosan compared with alginate microcapsules. Dithizone and insulin were positive in Dexa-chitosan capsules. Although fibrosis and macrophage infiltration was noted on the surface, some alginate microcapsules were stained with insulin.ConclusionDexa coating on microcapsules significantly suppressed the fibrotic reaction on the capsule surface after transplantation of xenogenic islets containing microcapsules without any harmful effects on the function and survival of the islets.

Microencapsulation with the usage of sodium alginate: A promising method for preserving stonewort (Characeae, Charophyta) oospores to support laboratory and field experiments

This work proposes the use of a biomaterial sodium alginate for microencapsulating stonewort oospores. The microencapsulation method has been adopted and optimized to improve research work carried out on the oospores. A detailed protocol for the production of microcapsules with stonewort oospores has been presented, with particular attention paid to the critical stages and factors interfering with the efficient production process. The advantages and disadvantages of this method have also been indicated. Microcapsules with oospores can be successfully used in various laboratory (observation of the germination phases) and field experiments (reintroduction of rare species of stonewort). Alginate microcapsule may consist of water taken directly from the habitat of the stonewort, a medium, as well as specific additives (antibiotics or fungicides). The hardness of the encasement is regulated by the concentration of the sodium alginate. The optimum alginate concentration for oospores is between 2 and 3%. Encasements produced with less than 2% sodium alginate concentration do not form circular microcapsules during gelation. On the other hand, concentration >3% may limit the oospores' ability to germinate (higher density of the microcapsule). In such a dense environment, the germinating primary cells may encounter difficulties in outgrowing the microcapsule. It has been shown that alginate encasement creates an effective protective layer for the oospores inside it. The oospore is protected from mechanical damage as well as from direct exposure to the external environment; especially from pathogens and other microorganisms that can inhibit its germination and limit the growth of the protonemal and primary rhizoidal cell. The main application of oospore microencapsulation using sodium alginate is facilitating further mechanical manipulations of oospores, which by nature are very small structures (max. length 1 mm), while a microcapsule with an oospore embedded inside it can have a diameter from 3 to 5 mm (as required).

Alginate-chitosan microcapsules improve vaccine potential of gamma-irradiated Listeria monocytogenes against listeriosis in murine model

Listeria monocytogenes is a cause of infectious food-borne disease in humans, characterized by neurological manifestations, abortion, and neonatal septicemia. It is intracellular bacterium, which limits the development of protective inactivated vacines. Adjuvants capable of stimulating cellular immune response are important tools for developing novel vaccines against intracellular bacteria. The aim of this study was to evaluate the vaccine potential of L. monocytogenes inactivated by gamma irradiation (KLM-γ) encapsulated in alginate microcapsules associated or not with chitosan against listeriosis in the murine model. At the fourth day after challenge there was a reduction in bacterial recovery in mice vaccinated with KLM-γ encapsulated with alginate or alginate-chitosan, with lower bacterial loads in the spleen (10 fold) and liver (100 fold) when compared to non-vaccinated mice. In vitro stimulation of splenocytes from mice vaccinated with alginate-chitosan-encapsulated KLM-γ resulted in lymphocyte proliferation, increase of proportion of memory CD4+ and CD8+ T cell and production of IL-10 and IFN-γ. Interestingly, the group vaccinated with alginate-chitosan-encapsulated KLM-γ had increased survival to lethal infection with lower L. monocytogenes-induced hepatic inflammation and necrosis. Therefore, KLM-γ encapsulation with alginate-chitosan proved to have potential for development of novel and safe inactivated vaccine formulations against listeriosis.

Multipotent mesenchymal stromal cells derived from porcine exocrine pancreas improve insulin secretion from juvenile porcine islet cell clusters.

Neonatal and juvenile porcine islet cell clusters (ICC) present an unlimited source for islet xenotransplantation to treat type 1 diabetes patients. We isolated ICC from pancreata of 14days old juvenile piglets and characterized their maturation by immunofluorescence and insulin secretion assays. Multipotent mesenchymal stromal cells derived from exocrine tissue of same pancreata (pMSC) were characterized for their differentiation potential and ability to sustain ICC insulin secretion in vitro and in vivo. Isolation of ICC resulted in 142±50×103 IEQ per pancreas. Immunofluorescence staining revealed increasing presence of insulin-positive beta cells between day 9 and 21 in culture and insulin content per 500IEC of ICC increased progressively over time from 1178.4±450µg/L to 4479.7±1954.2µg/L from day 7 to 14, P<.001. Highest glucose-induced insulin secretion by ICC was obtained at day 7 of culture and reached a fold increase of 2.9±0.4 compared to basal. Expansion of adherent cells from the pig exocrine tissue resulted in a homogenous CD90+ , CD34- , and CD45- fibroblast-like cell population and differentiation into adipocytes and chondrocytes demonstrated their multipotency. Insulin release from ICC was increased in the presence of pMSC and dependent on cell-cell contact (glucose-induced fold increase: ICC alone: 1.6±0.2; ICC+pMSC+contact: 3.2±0.5, P=.0057; ICC+pMSC no-contact: 1.9±0.3; theophylline stimulation: alone: 5.4±0.7; pMSC+contact: 8.4±0.9, P=.013; pMSC no-contact: 5.2±0.7). After transplantation of encapsulated ICC using Ca2+ -alginate (alg) microcapsules into streptozotocin-induced diabetic and immunocompetent mice, transient normalization of glycemia was obtained up to day 7 post-transplant, whereas ICC co-encapsulated with pMSC did not improve glycemia and showed increased pericapsular fibrosis. We conclude that pMSC derived from juvenile porcine exocrine pancreas improves insulin secretion of ICC by direct cell-cell contact. For transplantation purposes, the use of pMSC to support beta-cell function will depend on the development of new anti-fibrotic polymers and/or on genetically modified pigs with lower immunogenicity.

A Novel Alginate-Based Delivery System for the Prevention and Treatment of Pressure-Overload Induced Heart Failure.

Background: α-CGRP (alpha-calcitonin gene related peptide) is a cardioprotective neuropeptide. Our recent study demonstrated that the administration of native α-CGRP, using osmotic mini-pumps, protected against transverse aortic constriction (TAC) pressure-induced heart failure in mice. However, the short half-life of peptides and the non-applicability of osmotic pumps in humans limits the use of α-CGRP as a therapeutic agent for heart failure (HF). Here, we sought to comprehensively study a novel α-CGRP delivery system using alginate microcapsules to determine its bioavailability in vivo and to test for cardioprotective effects in HF mice. Methods: Native α-CGRP filled alginate microcapsules (200 µm diameter) were prepared using an electrospray method. The prepared alginate-α-CGRP microcapsules were incubated with rat cardiac H9c2 cells, mouse cardiac HL-1 cells, and human umbilical vein endothelial cells (HUVECs), and the cytotoxicity of the alginate-α-CGRP microcapsules was measured by a trypan-blue cell viability assay and a calcium dye fluorescent based assay. The efficacy of the alginate-α-CGRP microcapsules was tested in a TAC-pressure overload mouse model of heart failure. Male C57BL6 mice were divided into four groups: sham, sham-alginate-α-CGRP, TAC-only, and TAC-alginate-α-CGRP, and the TAC procedure was performed in the TAC-only and TAC-alginate-α-CGRP groups of mice to induce pressure-overload heart failure. After 2 or 15 days post-TAC, alginate-α-CGRP microcapsules (containing an α-CGRP dose of 6 mg/kg/mouse) were administered subcutaneously on alternate days, for 28 days, and echocardiography was performed weekly. After 28 days of peptide delivery, the mice were sacrificed and their hearts were collected for histological and biochemical analyses. Results: Our in vitro cell culture assays showed that alginate-α-CGRP microcapsules did not affect the viability of the cell lines tested. The alginate-α-CGRP microcapsules released their peptides for an extended period of time. Our echocardiography, biochemical, and histology data from HF mice demonstrated that the administration of alginate-α-CGRP microcapsules significantly improved all cardiac parameters examined in TAC-mice. When compared to sham mice, TAC significantly decreased cardiac functions (as determined by fraction shortening and ejection fraction) and markedly increased heart and lung weight, left ventricle (LV) cardiac cell size, cardiac apoptosis, and oxidative stress. In contrast, the administration of alginate-α-CGRP microcapsules significantly attenuated the increased heart and lung weight, LV cardiac cell size, apoptosis, and oxidative stress in TAC mice. Conclusion: Our results demonstrate that the encapsulation of α-CGRP in an alginate polymer is an effective strategy to improve peptide bioavailability in plasma and increase the duration of the therapeutic effect of the peptide throughout the treatment period. Furthermore, alginate mediates α-CGRP delivery, either prior to the onset or after the initiation of the symptom progression of pressure-overload, improves cardiac function, and protects hearts against pressure-induced HF.

Novel formulation of glucocorticoid based on silver alginate microcapsules for intraarticular drug delivery

The development of drug delivery systems for glucocorticoid drugs is a new strategy for optimization of glucocorticoid therapy, allowing the reduction of systemic side effects and the prolongation of a therapeutic one. For intraarticular glucocorticoids injection, widely used for therapy of osteoarthritis, the prolongation of drug release might also reduce the needle injection damage of a joint, due to reducing the number of injections operations. The current study introduces the novel system for water-insoluble glucocorticoid betamethasone delivery, based on silver alginate microcapsules, providing improved bioavailability, enhanced loading efficiency, and sustained release. The proposed system opens up the prospects for osteoarthritis therapy, enabling to overcome limitations of the intraarticular delivery of glucocorticoids.

Force Spectroscopy Imaging and Constriction Assays Reveal the Effects of Graphene Oxide on the Mechanical Properties of Alginate Microcapsules.

Microencapsulation of cells in hydrogel-based porous matrices is an approach that has demonstrated great success in regenerative cell therapy. These microcapsules work by concealing the exogenous cells and materials in a robust biomaterial that prevents their recognition by the immune system. A vast number of formulations and additives are continuously being tested to optimize cell viability and mechanical properties of the hydrogel. Determining the effects of new microcapsule additives is a lengthy process that usually requires extensive in vitro and in vivo testing. In this paper, we developed a workflow using nanoindentation (i.e., indentation with a nanoprobe in an atomic force microscope) and a custom-built microfluidic constriction device to characterize the effect of graphene oxide (GO) on three microcapsule formulations. With our workflow, we determined that GO modifies the microcapsule stiffness and surface properties in a formulation-dependent manner. Our results also suggest, for the first time, that GO alters the conformation of the microcapsule hydrogel and its interaction with subsequent coatings. Overall, our workflow can infer the effects of new additives on microcapsule surfaces. Thus, our workflow can contribute to diminishing the time required for the validation of new microcapsule formulations and accelerate their clinical translation.

Evaluation of the safety profile of the vaccine candidate Brucella melitensis 16MΔvjbR strain in goats

Small ruminant brucellosis is caused by the Gram negative cocci-bacillus Brucella (B.) melitensis, the most virulent Brucella species for humans. In goats and sheep, middle to late-term gestation abortion, stillbirths and the delivery of weak infected offspring are the characteristic clinical signs of the disease. Vaccination with the currently available Rev. 1 vaccine is the best option to prevent and control the disease, although it is far from ideal. In this study, we investigate the safety of the B. melitensis 16MΔvjbR strain during a 15-month period beginning at vaccination of young goats, impregnation, delivery and lactation. Forty, 4 to 6 months old, healthy female crossbreed goats were randomly divided into four groups (n = 10) and immunized subcutaneously with a single vaccine dose containing 1x109 CFU of B. melitensis 16MΔvjbR delivered in alginate microcapsules or non-encapsulated. Controls received empty capsules or the commercially available Rev.1 vaccine. Seven months post-vaccination, when animals were sexually mature, all goats were naturally bred using brucellosis-free males, and allowed to carry pregnancies to term. Blood samples to assess the humoral immune response were collected throughout the study. At two months post-delivery, all dams and their offspring were euthanized and a necropsy was performed to collect samples for bacteriology and histology. Interestingly, none of the animals that received the vaccine candidate regardless of the formulation exhibited any clinical signs associated with vaccination nor shed the vaccine strain through saliva, vagina or the milk. Gross and histopathologic changes in all nannies and offspring were unremarkable with no evidence of tissue colonization or vertical transmission to fetuses. Altogether, these data demonstrate that vaccination with the mutant strain 16MΔvjbR is safe for use in the non-pregnant primary host.