Papers by Author: Se Heang Oh

Abstract: Electrospinning is a fabrication process that can produce highly porous nano-scale fiber-based matrices using an electrostatically driven jet of polymer solution. This method represents an attractive approach for polymeric biomaterial processing which provides the membrane structure that may retain mechanical strengths, flexibility, and high surface area. In this study, we prepared a guided bone regeneration (GBR) membrane with selective permeability, hydrophilicity, good mechanical strength and adhesiveness with bone using polycaprolactone (PCL) and Tween 80 by the electrospinning method. The prepared PCL and PCL/Tween 80 electrospun sheets were characterized via morphology observation, mechanical property, water absorbability, and model nutrient permeability. It was observed that the PCL/Tween 80 (3 wt%) electrospun sheet have an effective permeation of nutrients as well as the good mechanical strength to maintain a secluded space for the bone regeneration. From the results, the hydrophilized PCL/Tween 80 (3 wt%) electrospun sheet seem to be a good candidate as a GBR membrane.

Abstract: Chitosan cylindrical scaffolds with gradually increasing pore size along the longitudinal direction were fabricated by a novel centrifugation method to investigate pore size effect on cell interactions. The scaffold was fabricated by the centrifugation of a cylindrical mold containing fibril-like chitosans. The pore size ranges of the scaffold could be controlled by adjusting the centrifugal speed: the scaffold with gradually increasing pore size (from ~80 #m to ~400 #m) and porosity (from ~82 % to ~93 %) along the cylindrical axis was obtained by applying the centrifugal speed, 3,000 rpm. The scaffold sections were examined for their in vitro cell interactions using different kinds of cells (fibroblasts, chondrocytes, and osteoblasts) in terms of scaffold pore sizes. It was observed that different kinds of cells were shown to have different pore size ranges in the scaffold for effective cell growth. The chitosan scaffold section with ~400 #m pore size showed better cell growth for chondrocytes and osteoblasts, while the scaffold section with ~190 #m pore size was better for fibroblast growth. The pore size gradient scaffolds fabricated by the centrifugation method can be a good tool for the systematic studies of the interactions between cells or tissues and scaffolds with different pore size.

Abstract: Porous polydioxanone (PDO)/polyvinyl alcohol (PVA) scaffolds were fabricated by blending PDO with a small amount of PVA to improve the hydrophilicity and cell/tissue compatibility of the scaffolds for tissue engineering applications. PDO/PVA scaffolds with different PVA compositions up to 10 wt% were fabricated by a melt-molding particulate-leaching method (non-solvent method). The prepared scaffolds exhibited highly porous, uniform open-cellular pore structures. The PDO/PVA scaffolds with PVA compositions more than 5 % were easily wetted in cell culture medium. The hydrophilized PDO/PVA (5 wt%) scaffold showed better cell adhesion and growth than the control hydrophobic PDO scaffold. The PDO/PVA (5 wt%) scaffold also showed faster tissue infiltration into the scaffold than the PDO scaffold. It seems that 5 wt% addition of PVA to PDO to fabricate PDO/PVA scaffolds is enough for improving the hydrophilicity and cell/tissue compatibility of the scaffolds.

Abstract: In this study, muscle-derived stem cell (MDSC)/Pluronics/polycaprolactone (PCL) microparticle hybrid mixture was prepared as a potential injectable urethral bulking agent for the treatment of urinary incontinence. The MDSCs were isolated from the gastrocnemius muscles of SD rats by a modified preplate method and characterized through FACS analysis using various primary antibodies (CD34, Sca-1, CD45 and desmin). The hybrid mixture was prepared by the mixing of PCL microparticles (diameter, 100~200 μm) and MDSCs-containing thermo-sensitive Pluronic (F127/F68 mixture) solution (4.5/5.5, w/v). The hybrid mixture was easily injected through 18G needle into the body and stably remained in the applied site without initial volume decrease, owing to a well-packed structure of PCL particles exhibited in the hybrid mixture. It was observed that the MDSCs were stably grown in the hybrid mixture without severe inflammation and immune reaction. From the results, we recognized that the hybrid mixture can be a good candidate as an injectable bulking agent for the treatment of urinary incontinence, due to their good injectability, volume retention and biocompatibility.

Abstract: Meniscus is the most commonly injured structure in the knee joint. Resection of the meniscus as well as the torn menisci is known to induce the degeneration of the articular cartilage. Replacement of the resected meniscus by allograft is limited by its availability and potential disease transmission. Artificial prostheses are being tried in an attempt to regenerate the meniscal tissue and we developed the biodegradable porous polycaprolactone(PCL) scaffold, which acts as a temporary scaffold to enable the regeneration of a new tissue in time. We report the results of rabbit implantation model. Biodegradable PCL scaffold coated with type I collagen with pores sized 100~150 +m and with compression modulus 400 kpa were fabricated by melt-molding particulate- leaching method. The molds were made using the native meniscus of the rabbit. Medial meniscus of right knee was partially removed through arthrotomy, leaving anterior 1/5 of the meniscus, after sectioning medial collateral ligament. The implant was attached to the peripheral capsule and remnant anterior meniscus with sutures. The medial meniscus of the left knee was removed and served as a control without replacement. The regenerated meniscus was harvested at 4 & 12wks after implantation. In addition to the routine histology of the tissue regenerated and remnant scaffold, junction between the normal meniscus and the regenerated tissue, and cartilage surface degeneration was observed. After 4 and 12 weeks the scaffolds, although considerable amount of the materials remained, were largely filled and covered with fibrous tissue which was assumed to be derived from synovial tissue of peripheral capsule. The tissue grossly resembling the native meniscus was maintained and spindle shaped cells with extracellular matrices were observed histologically. Neither cells with chondrocytic phenotype nor distinct cartilage matrices were observed until 12 weeks. The bonding between the regenerated tissue and the peripheral synovial capsule was firm and solid in all cases. The tissue bridges between the native meniscus and the regenerated tissue were found in 9/10 operated knees. Articular surface degeneration was not different between experimental and control groups except one case. More or less, the extrusion of the meniscus was found in almost all knees. This study revealed that meniscal replacement with PCL polymer prosthesis was feasible and led to adequate tissue formation. Long term studies on adaptive remodeling will be required.

Abstract: This study was designed to evaluate the effect of polyethylene glycol (PEG) and nonsteroidal anti-inflammatory drug (ibuprofen) on the prevention of postoperative tissue adhesion. For this, we synthesized poly(L-lactic acid)-PEG diblock copolymers and used them to prepare ibuprofen-loaded films as tissue adhesion barrier films. We also prepared lower critical solution temperature (LCST)-controllable Pluronic F127/F68 mixtures including mildly crosslinked alginate and ibuprofen as tissue adhesion barrier gels. The prepared films and gels with/without ibuprofen were evaluated by the observations of peritoneal tissue adhesion via animal study using a rat model.