Alginate-Catechol Cross-Linking Interferes with Insulin Secretion Capacity in Isolated Murine Islet Cells

Over the past three decades, human pancreatic islet isolation and transplantation techniques have developed as a routine clinical procedure for selected patients with type 1 diabetes mellitus. However, due to the donor shortage and required chronic systemic immunosuppression, the widespread application of islet transplantation is limited. To overcome these limitations, providing a physical barrier to transplanted islet cells with encapsulating biomaterial has emerged as a promising approach to enhance engraftment and promote islet survival post-transplantation. Alginate has been considered to be a reliable biomaterial, as it enhances islet survival and does not hamper hormone secretion. Alginate-catechol (Al-CA) hydrogel was reported to provide high mechanical strength and chemical stability without deformation over a wide range of pH values. In this study, we, demonstrated, for the first time in the literature, that encapsulation of murine pancreatic islet cells with Al-CA hydrogel does not induce cytotoxicity ex vivo for an extended period; however, it does markedly abate glucose-stimulated insulin secretion. Catechol should not be considered as a constituent for alginate gelation for encapsulating islet cells in the application of islet transplantation.

Alginate encapsulation preserves the quality and fertilizing ability of Mediterranean Italian water buffalo (Bubalus bubalis) and Holstein Friesian (Bos taurus) spermatozoa after cryopreservation

The use of artificial insemination (AI) in buffalo (Bubalus bubalis) is limited by poor ovarian activity during the hot season, seasonal qualitative patterns in semen, low resistance of sperm cells in the female tract, difficulties in estrus detection, and variable estrus duration. Although AI procedures are commonly used in bovine, use of AI has been limited in buffalo. In the zootechnical field, different studies have been conducted to develop techniques for improvement of fertilizing ability of buffalo spermatozoa after AI. In this study, for the first time, the use of alginate encapsulation and cryopreservation of buffalo spermatozoa is described, and the same procedure was performed with Holstein Friesian (Bos taurus) semen. Results obtained from in vitro analyses indicate that the encapsulation process does not have detrimental effects (compared to controls) on quality parameters (membrane integrity, progressive motility, path average velocity) in either species. Similarly, there were no detrimental effects after cryopreservation in either species. The fertilizing potential of encapsulated and cryopreserved semen was evaluated after AI in 25 buffalo and 113 bovine females. Pregnancy rates were not affected in either species. The results of this study show proof of concept for the use of frozen semen controlled-release devices in buffalo.

Biochemical composition, alginic acid yield and antioxidant activity of brown seaweeds from Mandapam region, Gulf of Mannar.

In this present study, four brown seaweeds viz Sargassum wightii Greville, Padina tetrastromatica Hauck, Chnoospora minima, Hormophysa triquetra (C. Ag.) Kutz, collected from Mandapam region of Gulf of Mannar were analyzed for its bioactive potentials. High protein content was observed in Hormophysa triquetra (15.34±0.01%) and carbohydrate (59.30±0.66%); lipid (0.55±0.002%) were recorded in Padina tetrastromatica. Total phenolic content (20±3.46 mg GAE /g) was found to be high in Sargassum wightii, whereas antioxidant activity (34.66±5.77 mg AAE /g) in Padina tetrastromatica. Flavonoid content (66.3±1.43 mg QE /g), DPPH radical scavenging activity (85.08±1.17%) and alginic acid yield (26.70%) was found to be high in Hormophysa triquetra. The viscosity of sodium alginate was found to be high in 5 hours of extraction period in all the seaweeds.

The antioxidant and anticoagulant activities of polysaccharides isolated from the brown algae Dictyopteris polypodioides growing on the Lebanese coast.

In this study, we attempt to isolate the polysaccharides from the brown seaweed Dictyopteris polypodioides (Dp) growing on the Lebanese coast. The percentages of the main polysaccharide alginic acid were 4.6% in May and 6.25% in July. The extracted yields of Fucoidan, Laminaran and Mannuronan (FLM) and Mannuronan (M) alone were respectively 0.75% and 0.38% in May and 1.15% and 0.67% in July. We performed the infrared spectroscopy in order to reveal the functional groups of alginate and mannuronan. Moreover, a non-destructive technique ¹ H NMR was used to determine the structure of alginate and the distribution of guluronic (G) and mannuronic acid (M) in the chain, allowing us therefore to calculate the ratio M/G. The latter was 0.96 showing a strong ability of alginate to capture heavy metals. The analysis of trace elements showed great amounts of K, Si, Na and Mg in both seasons. Moreover, Dictyopteris appears to be rich in fatty acids (10 items) with palmitic and oleic acids as main fatty acids. Furthermore, the anticoagulant activity of polysaccharides was investigated by activated partial thromboplastin time (APTT) clotting assay and the antioxidant activity was studied by electrolysis method. It has been shown that the FLM and M fractions of Dictyopteris polypodioides have a significant antioxidant and anticoagulant activities. Further investigations are imperative in order to develop new molecules based on these polysaccharides to be used as drugs or for healthcare in general.

Functional improvement of porcine neonatal pancreatic cell clusters via conformal encapsulation using an air-driven encapsulator

Transplantation of islet cells into diabetic patients is a promising therapy, provided that the islet cells are able to evade host immune rejection. With improved islet viability, this strategy may effectively reverse diabetes. We applied 2% calcium alginate to generate small and large capsules to encapsulate porcine neonatal pancreatic cell clusters (NPCCs) using an air-driven encapsulator. After encapsulation, the viability was assessed at 1, 4, 7, 14 and 28 days and secretion of functional insulin in response to glucose stimulation were tested at days 14 and 28. Selective permeability of the small alginate capsules was confirmed using various sizes of isothiocyanate-labeled dextran (FITC-dextran). Encapsulation of NPCCs was performed without islet protrusion in the small and large capsules. The viability of NPCCs in all experimental groups was greater than 90% at day 1 and then gradually decreased after day 7. The NPCCs encapsulated in large capsules showed significantly lower viability (79.50 +/- 2.88%) than that of naive NPCCs and NPCCs in small capsule (86.83 +/- 2.32%, 87.67 +/- 2.07%, respectively) at day 7. The viability of naive NPCCs decreased rapidly at day 14 (75.67 +/- 1.75%), whereas the NPCCs encapsulated in small capsules maintained (82.0 +/- 2.19%). After 14 and 28 days NPCCs' function in small capsules (2.67 +/- 0.09 and 2.13 +/- 0.09) was conserved better compared to that of naive NPCCs (2.04 +/- 0.25 and 1.53 +/- 0.32, respectively) and NPCCs in large capsules (2.04 +/- 0.34 and 1.13 +/- 0.10, respectively), as assessed by a stimulation index. The small capsules also demonstrated selective permeability. With this encapsulation technique, small capsules improved the viability and insulin secretion of NPCCs without islet protrusion.

Optimization of Alginic Acid in Laminaria japonica Aresch by Orthogonal Test / 中国中医药信息杂志

Objective To optimize the extraction technology of alginic acid in Laminaria japonica Aresch. Methods The influence of the amount of solvent, the extraction time and temperature (3 factors) on the alginic acid content and yield was investigated by orthogonal test L9(34), and carried on to inspect the methodology. Result The optimum extraction condition was A1B1C2, that was adding 30 times solvent (1%Na2CO3), whisk extracting for one hour at 60 ℃. Conclusion The temperature is the most important factor. The content of alginic acid decrease obviously at above 60 ℃. The optimum extraction technology is reasonable.

The Effect of Silk Fibroin-Alginic Acid Sponge Treatment as an Artificial Skin on Wound

PURPOSE: This study was designed to compare the wound healing effect of silk fibroin, alginate and fibroin/ alginate blend sponge with clinically used Nu gauze in a rat skin defect model. METHODS: Two full thickness excisions were made on the back of Sprague-Dawley rat. The excised wound was covered with either of the silk fibroin(SF), alginate (SA), or fibroin/alginate blend sponge(SF/SA). On the postoperative days of 3, 7, 10 and 14, the wound area was calculated by image analysis software. At the same time, a skin wound tissue was biopsied. RESULTS: Healing time 50% (HT(50)) of SF/SA sponge treated group was dramatically reduced as compared with that of control treatment. We also found that the HT50 of SF/SA sponge was significantly decreased as compared with either those of SF or SA treatment. Furthermore, SF/SA treatment significantly increased the size of epithelialization and collagen deposition as well as the number of PCNA positive cells on epidermal basement membrane as comapred with those of control treatment. CONCLUSION: Our results suggest that the wound healing effect of SF/SA blend sponge is the best among other treatments including SF and SA during the whole wound healing period.

The Development of Biodegradable Intrascleral Implant for Slow Releasing of Triamcinolone Acetonide

PURPOSE: In order to treat inflammatory and proliferative disorders of the posterior segment of the eye, the authors evaluated the use of a biodegradable intrascleral implant for slow release of triamcinolone acetonide (TA). METHODS: The intrascleral implant (1 mm thick and 3 mm in diameter) was made of alginic acid and PLA (poly (D, L-lactide)) containing 4 mg of TA. In vitro release of TA was evaluated by HPLC. To evaluate in vivo release of TA, the implant was placed into a scleral pocket in 18 rabbit eyes and the concentrations of TA in the aqueous humor, vitreous, and retina-choroid-sclera were measured by HPLC at 1, 2, 4, 8, and 12 weeks after implantation. The toxicity and biocompatibility of the implant were evaluated by slit lamp examination, IOP, electroretinogram, and light microscopy. RESULTS: In vitro study demonstrated that the implant released TA in controlled manner for at least 8 months. The TA detected in the vitreous after 8 to 12 weeks and was not detected in retina-choroid-sclera at 8 weeks after implantation. The TA was not detected in aqueous humor. No significant toxicity to the retina was observed. CONCLUSIONS: These results suggest that the intrascleral implant of TA could be a promising system for the delivery of steroids to the posterior segment of eye in cases of inflammatory or proliferative disorders of posterior segment.

Study of Sealant Gels for Vascular Anastomosis with Adhesive, Cyanoacrylate Glue and Intravascular Soluble Hollow Stents / 医疗卫生装备

Objective To research and make one kind of sealant gel to prevent glue from leaking effectively,and protect vascular anastomosis site,raise the vascular anastomosis patency.Methods The experiment was carried out based on theory and methods in chemistry;According to the membrane performance,the membrane water solubility,and other characters,the author took experiment on the alginic acid sodium,chitsan,the gelatin and other biological materials.Results Through the experiment by membrane performance,the alginic acid sodium met the requirement,which became the membrane with the CaCl2 reaction at once.Its membrane was not dissolved in the water.And the characters of its 1%-3% solution were good on fluidity and surface contact angle determines.The biological compatibility of the compound of it with 20% CaCl2 solution was good.Conclusion The characters of the composition,which is double component sealant made from 1-3% alginic acid sodium and 20%CaCl2 solution,is best in the biological experiment.Before new medical glue appeared in clinical,this gel is hopeful to be applied in clinic and provide theory basis for clinical anastomosis.

The Effect of Alginic Acid Sodium Salt on Delayed Adjustable Strabismus Surgery

The purpose of this study was to evaluate the effect of the alginic acid sodium salt on the delayed adjustable strabismus surgery by preventing the post operative tissue adhesion. 30 eyes of 15 rabbits had received an adjustable suture surgery. The alginic acid sodium salt of 4% was used during operation in 16 eyes among them by injecting it around the muscle, between the sclera and the conjunctiva. In the 3rd, 5th, 7th, 10th, and 14th day postoperatively, we measured the pulling forces and the moving distances of the muscles during the adjustment. Then the eyes were enucleated and the histopathologic changes of the eyes were determined using the light microscope. The pulling forces and the moving distances of the muscles during the adjustment were significantly different between the alginic acid sodium salt free group and the alginic acid sodium salt used group. In the alginic acid sodium salt used group, the pulling forces were decreased and the moving distances were increased than those of the alginic acid sodium salt free group. The light microscopic examination showed more fibrosis in the alginic acid sodium salt free group than in the alginic acid sodium salt used group. These results suggest that the alginic acid sodium salt is an effective substance for the delayed adjustable suture surgery.

Formula Optimization of Aspirin Chitosan-Sodium Alginate Microcapsules and Drug Releasing Mechanism Study / 中国药房

OBJECTIVE:To prepare aspirin chitosan-sodium alginate microcapsules(ACSPM)and to investigate its optimal formula and releasing mechanism.METHODS:The formula of ACSPM was optimized by the orthogonal design with entrapment ratio as index,and then ACSPM was prepared,with its release rate determined as well.The releasing mechanism of aspirin from the microcapsules was established by equation fitting of releasing kinetic model.RESULTS:The prepared microcapsules were uniform in size and contents.The optimized formula was as follows:the concentration of sodium polymannuronate and chitosan were 3.0% and 1.0%,respectively,and the proportion of polymannuronate to aspirin was 1∶ 4.The in vitro drug release was in line with both Higuchi equation and Peppas equation.CONCLUSION:This preparation technology was simple and the drug releasing mechanism of the preparation was chiefly characterized by drug diffusion including bulk erosion non-Fickian process.