Key Engineering Materials Vols. 342-343

Abstract: This study evaluated periodontal repair and biomaterial reaction following implantation of a newly fabricated calcium phosphate chitosan block bone and chitosan membrane on the regeneration of 1- wall intrabony defects in the beagle dogs. The surgical control group received a flap operation only, while experimental group was treated with calcium phosphate chitosan block bone and/or chitosan membrane. All dogs were uneventful healing without any complication. The subjects were sacrificed 8 weeks after the experimental surgery, and a comparative histological and histometric examination was done. Chitosan membrane group significantly enhanced bone regeneration compared to control, CaP-chitosan block bone and combination group. Chitosan membrane remnants were observed in chitosan and combination group, while CaP-chitosan bone materials were resorbed completely. These results suggest that Chitosan membrnae significantly enhanced bone and cementum formation in advanced periodontal defects.

Abstract: Thermosensitive scaffold was suggested for the partial replacement of nucleus in degenerated intervertebral disc with a minimally invasive surgical procedure. Biocompatible and thermosensitive scaffolds were prepared by coupling reaction of Pluronic with chitosan and it was inserted in degenerative spinal motion segments. To confirm the regeneration of degenerative discs and subsequent structural stability, cell proliferation and morphological changes were evaluated using relaxation time, quantity of DNA and histological examination. As a result, inserted group showed higher relaxation time, reduced the decrement of DNA contents, and accumulated GAG amount. The results confirmed the potential of thermosensitive scaffolds and minimally invasive surgical procedure for the regeneration of degenerative discs.

Abstract: Glucans have been reported to stimulate immunity and to promote wound healing. Adult human dermal fibroblast (aHDF) cultured in serum free (serum-starvation). Proliferation of aHDF was measured at various concentrations of β-glucan by MTT assay, and migration was observed for 36h on microscope. The result of fibroblast bioassay, β-glucan had positive influence. In this study, the direct effects of β-glucan on proliferation and migration of human dermal fibroblasts were examined in vitro. That means β-D-glucan has the effect to enhance proliferation and aHDF migration speed, and has the potential as a wound healing agent.

Abstract: Mechano-active scaffolds were fabricated from very elastic poly(L-lactide-co-ε-carprolactone). The scaffolds with 80 % porosity and 300~500 μm pore size were prepared by a gel-pressing method. As a control group for elastic properties of polymer scaffolds, rigid poly L-lactide scaffolds were fabricated. The scaffolds were seeded with chondrocytes and cultured to evaluate the effect of elastic properties of polymer scaffolds for the differentiation and the ECM secretion of chondrocytes. Also, the chondrocytes-seeded constructs were implanted in nude mice subcutaneously to investigate their biocompatibility and cartilage formation. From the biochemical analyses, chondrogenic differentiation was sustained and enhanced significantly and chondral extracellular matrix was increased through mechanical stimulation of dynamic environment in the dynamic body systems. Histological analysis showed that implants of PLCL constructs formed mature and well-developed cartilaginous tissue, as evidenced by chondrocytes within lacunae. Consequently, the elastic PLCL scaffolds could be used to engineer cartilage in mechanically dynamic environments

Abstract: Mechano-active scaffolds were fabricated from very elastic poly(lactide-co-carprolactone) by a gel-pressing method. The scaffolds were seeded with bone marrow stromal cells and the continuous compressive deformation was applied to cell-polymer constructs in the chondrogenic media. Then, they were implanted in nude mice subcutaneously to evaluate for the effect of dynamic compression for regeneration of cartilage. From the biochemical analyses, chondrogenic differentiation was sustained and enhanced significantly and chondral extracellular matrix was increased through mechanical stimulation. Histological analyses showed that implants stimulated mechanically formed mature and well-developed cartilaginous tissue, as evidenced by bone marrow derived chondrocytes within lacunae. Consequently, the periodic application of dynamic compression can encourage bone marrow stromal cells to differentiation to chondrogenic lineage and to maintain their phenotypes.

Abstract: The goal of this study was to investigate release tendency of brain-derived neurotrophic factor (BDNF) from poly(L-lactide-co-glycolide) (PLGA) and small intestine submucosa (SIS) scaffold prepared by ice-leaching method. A porous scaffold consisting of PLGA and SIS as carrier of BDNF has been prepared in the presence of ice particle. SEM image of the PLGA/SIS scaffold showed an interconnected pore structure. The release behavior of BDNF loaded PLGA/SIS scaffold was examined for 4 weeks period at phosphate buffered saline (PBS, pH 7.4) at 37 oC. The sustained release of BDNF over 4 weeks was observed from the PLGA/SIS scaffold. These results indicate that the sustained release of BDNF from PLGA/SIS scaffold can be very useful for application in the tissue engineering.

Abstract: Microcapsules of alginate cross-linked with divalent cations are the most common system for cell immobilization. In this work, the polyion complex (PIC) microcapsules were made using sodium alginate/barium chloride as the wall materials and gelatin/poly (vinyl alcohol) (PVA) as the extracellular matrices. The result of the permeability experiment of microcapsules using proteins with different molecular weight showed that the capsule has a molecular weight cut-off (MWCO) of 150 kDa. The hepatocytes encapsulated in microcapsules with gelatin and PVA in the core rapidly aggregated as incubation time increased. The aggregated hepatocytes showed high ammonia removal and albumin synthesis, showing a high potential for use in a bio artificial liver system.

Abstract: Hydrotropic block copolymers, consisting of a hydrophilic poly(ethylene glycol) (PEG) block and a hydrotropic polymer, poly(2-(4-(vinyl benzyloxy)-N,N-diethylnicotinamide)) [P(VBODENA)], block, were synthesized by atom transfer radical polymerization (ATRP) for aqueous solubilization of paclitaxel, a representative poorly water-soluble drug. These polymers showed an excellent solubilizing effect for paclitaxel in aqueous media in comparison with the corresponding hydrotropic agent and a control micelle (PEG-PLA) and such effect was significantly dependent on the polymer concentration and composition. Paclitaxel could be solubilized into polymer micelles in aqueous media without use of an organic solvent. Due to their promising properties such as micellar characteristics and hydrotropic solubilization, the hydrotropic polymer micelle system can be useful for formulation of paclitaxel and other poorly soluble drugs.

Abstract: Vectors are vital aspect of gene delivery system which decides the success of gene therapy. Efficient transfection with minimum or no toxicity, are two principal aims of any gene delivery system. In this our study, we rationally developed biodegradable water soluble poly(ßamino ester) (PAE) based on spermine (SPR) and poly (ethylene glycol) (PEG), by Michael-type addition reaction and further studied for its potential as a gene carrier. Confirmation of synthesized PAE was done by proton NMR spectroscopy. In gel retardation assay, the PAEs have shown good DNA binding ability over wide range of polyplexes. The addition of PEG over SPR resulted in a novel PAE with higher degree of safety and transfection efficiency as compared with polyethylenimine 25K (PEI) when studied in 293T human kidney carcinoma cells.

Abstract: The objective of this study is to develop a new type of cationic nanoparticles for the intracellular drug delivery to breast cancer. Poly(ester amine) (PEA) based on polyethylenimine and polycaprolactone was synthesized to make cationic PEA nanoparticles for all-trans retinoic acid (RA). In the 1H-NMR study, the proton signals of RA appeared in the spectrum of RA-loaded PEA nanoparticles in CDCL3, whereas they disappeared in D2O, suggesting that hydrophobic inner-core with hydrophilic outer-shell formed in water. RA release was faster at lower drug content and RA was released over a period of 20 days. RA-loaded PEA nanoparticles showed enhanced cytotoxicity compared with RA itself, whereas nanoparticles of PEA themselves did not show it. These results indicated that the cationic PEA provided an efficient intracellular delivery of RA.