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

Background@#The 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. @*Methods@#Dexamethasone 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. @*Results@#No 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. @*Conclusion@#Dexa 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.

Osteogenic Differentiation of Bone Marrow Stem Cell in Poly(Lactic-co-Glycolic Acid) Scaffold Loaded Various Ratio of Hydroxyapatite

BACKGROUND AND OBJECTIVES: Hydroxyapatite has biocompatibility and bioactivity and similar to bone of in human body. The purpose of this study is to evaluate osteogenic differentiation of bone marrow stem cell (BMSC) in PLGA Scaffold added various ratio of hydroxyapatite (HAp). METHODS AND RESULTS: PLGA and PLGA/HAp scaffold were prepared using solvent casting/salt-leaching method. BMSC was seeded on the PLGA and PLGA/HAp scaffold and the samples were cultured in 37degrees C incubator with 5% CO2 for 28 days. Alkaline phosphatase (ALP) was carried out to evaluate alkaline phosphatase activity at 1, 3, 7, 10 and 14 days. Alizarin Red S stating was performed to identify calcium in scaffold at 1, 7, 14, 21 and 28 days. Compressive strength was measured to evaluate mechanical property of scaffold. To confirm cell viability, MTT was carried out at 1, 3, 7, 14 and 28 days. RT-PCR was performed to verify specific marker expression of osteoblast and stem cell at 7, 14, 21 and 28 days. CONCLUSIONS: Osteogenic differentiation of BMSC was confirmed through ALP, RT-PCR, and alizarin red S staining in this study. These results suggest that HAp helps osteogenic differentiation of BMSC.

Sandwiched osmotic pump tablet for controlled release of water-insoluble drug / 药学学报

<p><b>AIM</b>To study sandwiched osmotic pump tablet for delivering water-insoluble drug for 24 hours.</p><p><b>METHODS</b>Sandwiched osmotic pump tablet was prepared using nifedipine as the model drug. The effects of various formulation variables and orifice size on drug release were studied. The mechanical properties of cellulose acetate membrane were also investigated.</p><p><b>RESULTS</b>Polyethylene oxide of drug layer and potassium chloride of push layer showed marked positive effects on drug release. In the range of 0.50 mm to 1.40 mm, orifice size hardly affects drug release. Cellulose acetate membrane is strong enough to assure the integrity of osmotic pump tablet and could sustain an internal pressure ranging from 0.34 MPa to 2.85 MPa.</p><p><b>CONCLUSION</b>Sandwiched osmotic pump tablet can deliver water-insoluble drug constantly for 24 hours. Release media and agitation rate scarcely affect drug release. Compared with the commercialized push-pull osmotic pump tablet, sandwiched osmotic pump tablet is easy in preparation with exempting identification of drug layer before drilling.</p>

Unitary-core osmotic pump tablet for controlled release of water-insoluble drug / 药学学报

<p><b>AIM</b>To study unitary-core osmotic pump tablet for delivering water-insoluble drug for 24 hours.</p><p><b>METHODS</b>Unitary-core osmotic pump tablet was prepared using nifedipine as the model drug. The effects of various core formulation variables on drug release were studied.</p><p><b>RESULTS</b>Polyethylene oxide and potassium chloride have comparable positive effects on drug release, whereas, nifedipine has markedly negative effect on drug release.</p><p><b>CONCLUSION</b>Unitary-core osmotic pump tablet is very easy in preparation and it can deliver water-insoluble drug in substantially constant rate for 24 hours.</p>

Development of Gentamicin Loaded PLGA Microspheres for the Treatment of Musculoskeletal Infection: In Vivo Evaluation / 대한정형외과연구학회지

PURPOSE: We evaluate in vitro and in vivo efficacy of newly developed gentamicin loaded PLGA microspheres for the treatment of musculoskeletal infection. MATERIALS AND METHODS: Controlled gentamicin sulfate releasing microspheres manufactured from biodegradable PLGA were prepared with an Oil/Oil solvent evaporation method for the treatment of musculoskeletal infection. The in vitro release amount of GS was analyzed by high performance liquid chromatography (HPLC) and the released GS activity was determined by microbiological assay using staphylococcus (S) aureus, respectively. The results of inhibition zone test agree well with the HPLC results obtained from the in vitro release test. RESULTS: The microspheres of different size were obtained with varying the experimental conditions, and the shape of microspheres was smooth and spherical. The PLGA microspheres release gentamicin for 67 days in in vitro test. There was significant inhibition around microphere PLGA from 1 day to 7th week in inhibition zone test The inhibition was reduced after 8th week. and there was no inhibition at 9th week PLGA microspheres. CONCLUSION: It can be suggested that GS/PLGA MSs implantable system that provided a prolonged delivery of GS was found to be effective against S. aureus infection for desired period.